The International Journal of Prosthodontics, Pre-Print

Background: A large number of dental restorations are constructed from heat-pressed lithium disilicate (LDS) glass-ceramic ingots. These ingots' mechanical properties have not been adversely affected by repressing or repeating their processing. Despite this, little is known about the stainability of these LDS ceramic ingots that have been repeatedly processed. Objective: To evaluate change in colour of ceramic crowns constructed from 3 different repressed ceramic ingots: lithium disilicate (LS), lithium silicate material reinforced with zirconia (ZLS) and repressed lithium silicate crowns with high-density micronization technology (LS- HDM) following immersion in tea, and cola solutions and followed by brushing. Materials & Methods: Three distinct heat-processed LDS ceramic ingots representing three groups (N= 24) E-max (EM), Lisi (Li), and Celtra (CA) were used to manufacture seventy-two identical ceramic crowns. Three subgroups (n = 8) representing the experimental (tea, and cola) and control (artificial saliva) groups were created from each group. Colour changes were measured at the beginning, following tea and cola staining, and after brushing, using the CIE L * a * b * system. The colour change (ΔE, ΔL, Δa, and Δb) were evaluated using one-way ANOVA, and post-hoc analysis was done to determine any significant differences between the groups. Results: The analysis revealed significant differences in color attributes (L, a, and b values) among crown materials, with variations observed following immersion in saliva and staining solutions. While all materials exhibited a decrease in L values post-immersion, only CA showed significant changes in a and b values, indicating shifts in red and yellow components. Additionally, the overall color change (ΔE) remained below acceptability thresholds post-brushing, suggesting minimal perceptible differences. These findings underscore the material-specific responses to staining agents. Conclusion: Immersion of ceramic crowns made from LS, LS-HDM, and ZLS in tea and cola solutions resulted in noticeable color changes. However, regular tooth brushing effectively restored the satisfactory color appearance of stained ceramic crowns fabricated from repeatedly processed LS-based ingots.

Objective: To evaluate, in situ, the color stability of a printed resin (PR), milled resin (MR), and bisacrylic resin (BR) after exposure to coffee and cigarette smoke. Materials and Methods: Twelve participants per group (Control, coffee consumers, and smokers) used intraoral devices containing the specimens resins. Seventy-two samples of each resin were prepared, and initial surface roughness and color readings recorded. Participants wore the device, containing two samples of each resin, for 15 days, brushing three times per day. Final color and surface roughness measurements were obtained. Water sorption and solubility analyses were conducted (n=20). Data were analyzed using ANOVA and Tukey tests (α=0.05). Results: BR had the highest alterations in surface roughness under control conditions and after cigarette smoke exposure (p<0.05). PR showed the highest surface roughness and MR the lowest alteration after coffee consumption (p<0.05). After coffee consumption, BR exhibited higher color change than PR (p<0.05); and following cigarette smoke exposure, BR showed the highest alteration (p<0.05), while MR had the lowest (p<0.05). Cigarette smoke caused the highest color change across all resins. BR exhibited highest water sorption and solubility (p<0.05). Conclusion: Printed and milled resins demonstrated better color stability and less alteration in surface roughness change compared to bis-acrylic resin. Clinical Significance: The results suggest that clinicians may achieve better esthetic outcomes by opting for digital methods, especially in patients exposed to common staining agents like coffee and cigarette smoke.

Objectives: Primary stability is considered critical for osseointegration of immediately-loaded implants. However, evidence does not conclude whether this is equally critical for early or delayed-loaded protocols. This systematic review aims to determine the significance of primary stability, as measured by insertion torque (IT) and/or implant stability quotient (ISQ), in achieving osseointegration of non-immediate loaded implants. Materials & Methods: Three electronic databases were searched. Studies were included if they measured IT and/or ISQ at time of placement and reported survival for up to 1 year. For studies where at least one implant failed, a random effects meta-analysis was carried out for the odds of survival. Results: 3431 publications were screened; 79 were accepted for analysis. These comprised of 28 RCTs, 12 CCTs, 10 cohort studies, and 29 case series. Twenty-one studies provided individual implant data for a total of 1413 implants. Seven studies were included for metaanalysis. 264 implants were placed with ISQ <60, and 249 with IT <35. Survival of implants placed with ISQ <60 and IT <35 were 97.7% and 95.2% respectively. Meta-analysis found no evidence that an ISQ≥60 was less likely to fail compared with ISQ<60 (OR 0.54, 95%CI 0.17-1.75, P=0.31), or that an IT≥35 resulted in higher odds of failure compared to IT<35 (OR 0.82, 95%CI 0.13-5.40, P=0.84). Conclusions: This study found no evidence to support an IT≥35 or ISQ≥60 for non-immediately loaded implants results in higher survival than those below these values.

We report a clinical case about occlusal rehabilitation under a digital workflow for partial edentulism using multifunctional Gothic arch tracing devices. The individualized Gothic arch tracing devices were designed based on the virtual patient model, enabling the recording of the centric relation, previewing the aesthetics of maxillary teeth, and aiding in assessment of the temporomandibular joint function. Serving as a pre-implant treatment, the removable partial dentures were delivered to the patient within two follow-up visits, establishing a stable occlusal relationship. Based on the previously recorded centric relation, the final implantsupported fixed prostheses were applied. The patient expressed satisfaction with the restoration in terms of aesthetics and functionality.

Purpose: To evaluate the wear resistance and surface roughness of subtractively manufactured resin matrix ceramics and additively manufactured hybrid composites, both subjected to different surface treatments and thermomechanical aging. Materials and Methods: Two additively manufactured materials and one subtractively manufactured polymer-infiltrated resin ceramic were used to fabricate square-shaped specimens.These specimens were divided into two subgroups based on surface treatment (n = 12). After surface roughness measurements and SEM analysis, the specimens were subjected to thermomechanical aging. Pre- and post-aging scans were analyzed to calculate wear depth. Surface roughness and SEM analyses were repeated, and 2-way ANOVA with Tukey’s HSD test was used for statistical analysis. Results: Glazed surfaces exhibited significantly higher wear depth than polished ones (p = .018). Vita Enamic showed significantly greater wear depth compared to both VarseoSmile Crown Plus (p = 0.002) and P-Crown V2 (p = 0.001). For polished surfaces, Vita Enamic had significantly greater wear depth than VarseoSmile Crown. Plus (p = 0.001) and P-Crown V2 (p < .05). Initially, surface roughness values for glazed surfaces were similar (p = .076), but aging increased roughness significantly, with glazed P Crown V2 being rougher than glazed VarseoSmile Crown Plus (p = .001). After aging, glazed surfaces had significantly higher surface roughness than polished ones across all materials. Conclusion: Material type and surface treatment affected surface roughness and wear depth during thermomechanical aging. Glazed surfaces showed higher wear depth and roughness, with the glaze layer removed after aging. Polished surfaces exhibited greater wear for subtractive materials.

Aim: The aim of this in vitro study was to evaluate and compare the fit and fracture load of 3D printed and milled composite onlays. Materials and methods: An onlay preparation of a lower right molar was duplicated 28 times by means of 3D printing (Model 2.0, Nextdent, 3D systems, Soesterburg, the Netherlands). Fourteen onlays were milled (Brilliant Crios, Coltène, Whaledent AG, Switzerland) and 14 onlays were 3D printed (Nextdent C&B MHF, 3D systems, Soesterburg, the Netherlands). The marginal and internal fit were evaluated using the silicone-replica technique. For each impression, two sections were made in the silicone material. Each slice was photographed using a digital microscope and 13 measurements were performed on both slices using ImageJ. Next the onlays were cemented on their corresponding models (relyX Universal/SBU+, 3M ESPE, Seefeld, Germany) and tested in a universal testing machine (AGS-X, Shimadzu, Tokyo, Japan) to determine the fracture load. Results: The printed onlays showed a significant better marginal and internal fit (p<0.05). The marginal and internal fit for the 3D printed onlays was respectively 78µm (SD 23µm) and 222µm (SD 30µm) and for the milled onlays 100µm (SD 38µm) and 249µm (SD 55µm). In contrast, the milled onlays showed significant better results in terms of fracture load (p<0.05). Conclusion:Within the limits of this in vitro study, the printing process demonstrated a better fit, but with lower mechanical properties. Both the fit of the 3D printed and milled composite onlays were within the clinical acceptable limits. 

Purpose: The effect of mouth rinses on staining and roughness of interim restorations produced by additive manufacturing is unclear. This study investigated how surface treatments and mouth rinses affect staining, surface roughness, and the role of polishing on staining. Methods: 320 disc-shaped specimens were produced from four resin materials (n=80) using conventional and additive methods. Each group was divided into two groups (n=40) according to surface applications: conventional (Group C) and sealant (Group S). After measuring surface roughness, groups were divided into four subgroups (n=10) and immersed in mouth rinses: LISTERINE (LIS), chlorhexidine gluconate 0.2% (CHX), chlorhexidine gluconate 0.1% (ELU), and artificial saliva (AS). Specimens were stored for one day (T1) and seven days (T2) in these solutions. Color measurements were performed before and after storage using a spectrophotometer, and color differences were calculated via the CIELab system. Post assessment, specimens were polished, and ∆E values were remeasured. Data were statistically analyzed with 1-Way ANOVA and Bonferroni tests (α=0.05). Results: The highest surface roughness values were observed in the PMMA, and the lowest were in printed groups among the conventional and sealanted groups (P < .05). LIS had the highest ∆E values against all mouth rinses. The surface sealant applied groups showed the lowest ∆E values and surface roughness in all time points. The process of polishing reduced ∆E values in all tested groups. Conclusions: Printed resins have sufficient optical and surface properties for interim restorations. Long-term use of mouth rinses may cause discolouration but using surface sealant and polishing may reduce this discolouration.

Purpose: This in vitro study is of significant importance as it examines the effects of reusing cobalt-chromium-tungsten-containing alloy powder on metal-ceramic bond strength and microstructure, providing valuable insights into the field of dental materials. Materials and Methods: Thirty bar and nine square-shaped cobalt-chromium frameworks were produced by the conventional lost wax (Group C, [nBar=10, nSquare=3]) and selective laser melting technique (virgin powder, Group V [nBar=10, nSquare=3]; 25-times reused powder, Group R [nBar=10, nSquare=3]). X-ray diffraction, scanning electron microscopy, and ONH analysis were used to evaluate the casting ingot, powders, and frameworks' phase compositions, grain size, and microstructure. Three-point bend tests were used to assess the metal-ceramic bond strengths. Metal-ceramic bond strength values were compared using a one-way analysis of variance. Results: The bond strengths did not show significant differences (P>.05) between Groups C (29.95 ±4.60), V (31.32 ±3.44), and R (29.90 ±5.50). The recycled alloy powder's grain size (14.1 ±6.33 µm) was more significant than that of the virgin alloy powder (12.24 ±6.03 µm). Twenty-five times reused alloy powder had a greater N concentration than virgin powder. Group V and R had similar X-ray diffraction patterns, but the Group R frameworks had porous microstructure. Conclusion: Reusing cobalt-chromium alloy powder 25 times did not affect the metal-ceramic bond strength. Recycling the cobalt-chromium alloy powder is advisable.

Purpose: This longitudinal clinical trial studied the clinical performance of chairside CAD/CAM fabricated lithium disilicate crowns (IPS e.max CAD; Ivoclar) over ten years of service. Materials and Methods: 100 CAD/CAM lithium disilicate crowns were fabricated using the CEREC 3 system (Dentsply Sirona). The crowns were adhesively bonded in consecutive groups with one of three cements. ML = self-etching bonding agent and resin cement (MultiLink-Automix; Ivoclar), EC = self-adhesive resin cement (Experimental Cement; Ivoclar), and SC =self-adhesive, light-cured resin cement (SpeedCem; Ivoclar). Results: Mild sensitivity was reported on 15% of the teeth at 1 week. All sensitivity resolved by 4 weeks. At 6 months, 2 (8.7%) of the crowns cemented with ML and 3 (7.7%) of the crowns cemented with EC were described as slightly sensitive by the patient. No patient required treatment for sensitivity and there was no reported sensitivity at any subsequent recalls. The percent alpha scores were above 95% for color match and margin adaptation at all recall intervals. Four crowns debonded, 3 cemented with EC (13, 20 and 36 months) and 1 with ML (36 months). A second MultiLink crown debonded at 110 months (9 years, 2 months). There were four reported cases of crown fracture between 6 years 3 months and 9 years 9 months. There were two biological failures; one due to endodontic treatment and one due to fracture and loss of the core. Conclusions: The lithium disilicate crowns performed very well over 10 years. This study was supported by a grant from Ivoclar.

Insufficient vertical space is often a great challenge for prosthodontic treatment of patients with teeth overeruption. This case report describes a simple technique using clear aligners to intrude over-erupted molars. A 27-year-old woman was diagnosed with left mandibular dentition defect, yet the left third molar was presented in lower arch. However, the prosthetic rehabilitation was limited by the opposing over-erupted molars. Clear aligners therapy (CAT) was used to regain the necessary interocclusal space. After initial molar distalization, subsequent 2.14 mm and 1.3mm intrusion for left maxillary first and second molar was designed to solve the door-wedge effect dilemma. Without mini-screws, considerable intrusion (1.9 mm and 0.9 mm for left maxillary first and second molar, respectively) was achieved within 6 months with minimal discomfort. Radiological and clinical examinations revealed a favorable occlusal relationship and improved alignment for both arches. Outcomes in the case revealed that intruding over-erupted molars via CAT may be an effective approach. Keywords: Pre-prosthetic treatment; Molar intrusion; Clear aligners therapy; Minimal discomfort; Case report

Purpose: The aim of this study was to evaluate the fracture resistance of primary tooth crowns fabricated at different thicknesses using two different 3D printing technologies: stereolithography (SLA) and digital light processing (DLP). Materials and Methods: A typodont primary second molar tooth was scanned. Using the scanned model, three dies and crowns with thicknesses of 0.5 mm, 1.0 mm and 1.5 mm were created digitally. A total of 60 dies were fabricated from Crom-Cobalt (Cr-Co) using a laser sintering device. Ten crowns per thickness were produced using two types of 3D printers: SLA and DLP. The fracture resistance of the crowns was tested after thermal aging (5/55 oC and 30 s dwell time). The data were analyzed with Independent sampleT-test. Results: There was no significant difference in fracture resistance between the manufacturing methods for crowns in all three thickness groups (p > 0.05). The highest average fracture value was observed in crowns with a thickness of 1.5 mm manufactured using SLA 3D printing. Conclusion: Within the limits of this study, the 3D printing manufacturing method did not affect the fracture resistance of 3D printed primary tooth crowns. It was concluded that these crowns have sufficient fracture resistance and can be used as an alternative treatment option for complete crown of primary teeth. 

Purpose: This study comprises the fifth and final part of a comprehensive investigation of the positions of the temporomandibular joint condyles. In this evaluation, we wanted to investigate the neuromuscular position of the mandible. Materials and Methods: The neuromuscular condylar positions were recorded by four independent operators in 81 fully dentate subjects with healthy oral function using a central bearing point system and rapid closing movements. The "most frequent adduction point" was determined, and the recordings were repeated twice for each subject. The subjects' maxillary casts were mounted in an articulator using an individual facebow transfer, subsequently the mandibular. casts were mounted with a central-bearing-point registration on the tip of the Gothic arch, i.e. in centric condylar position. A custom-made electronic measuring articulator was used to determine the spatial distance between the condyles in centric relation, maximal occlusion and the newly determined neuromuscular position. Results: The reproducibility of the neuromuscular registrations was on average 0.52±0.16 mm (range 0.04-2.53 mm) with the right and left side averaged. The spatial distances of the condyles between maximal intercuspal position and neuromuscular positions were 0.88±0.30 mm (range 0.12-5.98 mm), again averaged for the right and left sides, whereas the ones between the centric condylar position and the neuromuscular positions were 0.83±0.27 mm (range 0.10-7.89 mm). Conclusions: The neuromuscular mandibular position is neither identical to maximal intercuspal position nor to centric relation. It can therefore be concluded, that the registration of the neuromuscular adduction field should not be recommended for prosthodontic restorations in dentate or edentulous patients.

Purpose: This study aims to evaluate the accuracy of the impression method using an intraoral scanner and the conventional method based on the implant number and angulation with multiple implants. Materials and Methods: Six implants were placed in the maxillary edentulous typodont using 3D modeling software. Eight implants were placed in another maxillary edentulous typodont. The implant placement angulation for each model was different. 3D designing and printing were performed to produce reference models. These models were scanned to obtain reference scan data (RSD). In the conventional impression method, reference models were used, and a gypsum model was produced. Scan data was obtained by the lab scanner (Group CI). Models were scanned and the scan data was obtained (Group IS). The distance and angulation deviation were compared. Results: In models with six implants, except for the distance deviation in Model 6-20, the mean values of all distance and angulation deviations were lesser in Group CI than in Group IS (P < 0.05). In models with eight implants, except for the distance deviation in Model 8-20, the mean values of distance and angulation deviations were lesser in Group CI than in Group IS, and significant differences were observed between the two groups for Models 8-0, 8-10, and 8-20 (P < 0.05). Conclusion: In cases where multiple implants are placed in the completely edentulous arch in vitro, conventional impressions are more accurate than intraoral scans. In the cases of lack of implant parallelism, intraoral scans can be used as a replacement for conventional impressions.

Purpose: Clinical scientific evidence of the accuracy of intraoral scanning (IOS) impressions for multiple implant-supported prostheses in partially edentulous arches is limited. This in vivo study aimed to evaluate the accuracy of IOS impressions for multiple implants by comparing them with analog impressions. Materials and Methods: Patients with three adjacent implants in partially edentulous arches were recruited. For each arch, IOS impressions were obtained. Using the analog splinted impression technique, casts were obtained and scanned with an extraoral scanner. Using metrology software, the distances and angles between the implants were measured in all IOS and analog impression Standard Tessellation Language files. The absolute values of the distance and angular deviation were calculated and analyzed by comparing the two impression methods. Results: Thirty-four patients with partially edentulous arches were enrolled. The distance deviation between the IOS and analog impressions was 85.09 ± 58.73 µm, which was significantly lower than the clinically acceptable error (150 µm; P < .001). The angular deviation was 0.515 ± 0.426°. Distance deviations were significantly correlated with the interimplant distances (r = 0.384, P = .001) and angulations (r = 0.278, P =.022). Conclusions: For multiple implant-supported prostheses in partially edentulous arches, the distance deviation between the IOS and analog impression was within the clinicall acceptable range of misfit and increased with increasing interimplant distance and angulation. Keywords: accuracy, implants, impression, partially edentulous, scanning

Purpose. The aim of this in vitro study was to evaluate the effect of build angle on the flexural strength (FS), elastic modulus (E), and hardness (VH) of stereolithography (SLA) based 3D-printed custom tray resin. Material and Methods. 3D-printed specimens with dimensions of 65.0 mm × 10.0 mm × 3.3 mm ± 0.2 mm were manufactured with different build angles (90, 120, 135, 150, 180 degrees) using custom tray resin. For preparing the specimens in the control groups, the autopolymerizing (AP) resin and the ultraviolet polymerizing (UV) resin were used. FS and E were determined by a three-point bending test, and hardness was evaluated with the VH test. Fracture surfaces were evaluated with scanning electron microscopy (SEM). Statistical analysis of the data was made using a one way ANOVA followed by the Dunnett T3 test. Results. Considering all parameters, the UV group was statistically significantly lower than the other groups. The mean E value of the 90D group was statistically significantly different than those of the 150D group (P=.000) and the 180D group (P=.002). The mean E value of the 120D group was statistically significantly different than those of the 150D group (P=.003) and the 180D group (P=.013). The AP group showed a higher mean VH number (20.20 ±2.08), and the difference was statistically significant compared to the 3D-printed groups (P<.005). Conclusions. Considering its mechanical properties, it was appropriate to arrange the build angles to different degrees when manufacturing reliable custom trays using SLA. 3D printed custom tray production method was a more standard method compared to AP and UV.

Aims: This in vitro study aimed to assess the trueness and precision of various intraoral scanners (IOSs) in relation to endocrown restorations. Methods: One human mandibular molar was mounted within an acrylic resin block. The tooth was prepared for an endocrown restoration, involving a 2-millimeter cusp reduction, a 3.5-millimeter pulp chamber depth, and a butt joint margin. The sample was scanned by three different IOSs (3Shape TRIOS 4, Carestream 3800, and Medit i700), with 10 scans taken by each, and then converted into STL files. A high-precision scanner captured a reference scan, which was also converted into an STL file. Trueness was assessed by superimposing each sample scan onto the reference, while precision was determined by superimposing the STL files within each group. Statistical analysis was performed using one-way ANOVA with Tukey HSD post hoc test and the Mann Whitney U Test (α = 0.05). Results: The study found that TRIOS 4 exhibited the highest trueness. (22.44 ± 15.01 μm), followed by Medit i700 (24.59 ± 12.80 μm) and CS 3800 (29.05 ± 7.75 μm). In terms of precision, CS 3800 had the best results (21.55 ± 8.87 μm), followed by Medit i700 (43.80 ± 17.42 μm) and TRIOS 4 (47.28 ± 13.93 μm). Only the differences between the precision of the CS 3800 and the other two scanners were statistically significant. Conclusions: The study found that all three scanners had similar trueness, but CS 3800 had significantly better precision than the other two scanners. However, all of the scanners demonstrated acceptable levels of accuracy in the context of endocrown preparation.  Keywords: Intraoral scanner, digital impression, endocrown, accuracy, precision, trueness

Purpose: To address the challenges of obtaining accurate digital impressions for the fabrication of fixed restorations on multiple implants in full-arch edentulous cases. Materials and Methods: An approach to the use of extended design scan bodies (EDSBs) and advanced digital technologies in full-arch implant rehabilitation is presented. Clinical and laboratory treatment sequences are illustrated, focusing on intraoral scanning, restorative materials, and digital fabrication techniques. Results: EDSBs provide accurate digital impression results, maintaining precision over longer distances and proving effective for both fixed and removable implant restorations. Conclusions: Using EDSBs with L-shaped and T-shaped extensions creates a stable reference framework during scanning, overcoming the lack of reliable landmarks on edentulous mucosa and enhancing digital impression accuracy and clinical outcomes. Keywords: Complete-arch, edentulous, implant restorations, intraoral scanning, scan bodies, scan flag.

Purpose: This study aimed to evaluate the hydrolytic behavior of different computer-aided design/computer-aided manufacturing (CAD/CAM) resin matrix ceramics (RMCs) in different food-simulating liquids (FSLs). Materials and methods: Five different CAD/CAM blocks, one from polymer-infiltrated ceramic networks (PICNs; Vita Enamic (EN)) and four from resin-based composites (RBCs; Lava Ultimate (UL), Cerasmart (CER), Brilliant Crios (BR), and Block HC (HC)) were selected. Forty specimens were prepared for each material, and they randomly distributed to each FSLs. The specimens were kept in a desiccator initially, then placed in 5 ml of liquid at 37±1°C for 30 days and weighed at various time intervals. Percentage mass change (Mg%), sorption (SP), percentage of liquid absorbed (SP%), solubility (SL), percentage solubility (SL%), and percentage of liquid absorbed by the polymer matrix (SPpm) water absorption of the specimens were evaluated. Significance was evaluated at p<0.05 levels. Results: Hydrolytic behavior of the materials showed statistical differences in terms of SP, SL, SP%, and SL% values depending on the liquid environment (p=0.001). The highest SP values were obtained from the HC material in saliva, and the lowest values were obtained from the BR in ethanol. The highest SL values were obtained from the CER and EN in heptane, and the lowest values were obtained from the HC in ethanol. However, all results detected in the study remained below the ISO threshold values. Conclusions: All materials tested exhibited clinically acceptable hydrolytic behavior over the time tested. Not only the material content but also many factors can affect the hydrolytic behavior.

Purpose: The aim of this article was to present a method for predicting dental materials lifetime, using in vitro thermally accelerated ageing. The technique was tested to compare the behavior of 3 resin base materials for denture. Materials and Methods: Bar-shaped samples of the poly(methyl methacrylate) PMMA based-resin Probase Hot (Probase), CAD/CAM disc Ivobase CAD (IvoCAD) and high-impact resin IvoCAP were aged in artificial saliva for 15, 30, 45, 60, 90, 120 and 180 days at 55°C, 75°C and 90°C. Flexural strength and surface roughness of the 3 resins for each ageing duration and temperature were measured for 3 samples (n=189). Using the time-temperature equivalence principle and the Arrhenius model, a master curve was constructed, the activation energy of the simulated ageing process was calculated and the lifetime of each material was estimated, based on degradation of flexural strength value over time. Results: The mean initial flexural strength was 87.98 ± 7.37, 79.35 ± 10.01 and 97.31 ± 4.97 MPa for IvoCAD, IvoCAP and Probase, respectively. Activation energies of the ageing in artificial saliva were measured at 81.9, 82.6 and 66.2 kJ/mol, respectively, and average lifetimes at 37°C were estimated at 19.5, 14.4 and 9.2 years. Conclusion: In this first approach to estimating the in vitro lifetime in artificial saliva of resin-based materials for dentures, the three materials met the expected criteria, validating the estimation method. Therefore, thermally-accelerated ageing and the Arrhenius model could be an interesting tool to add to routine tests used to validate new polymer materials and manufacturing processes.  Keywords: CAD-CAM materials, resin-based dentures, ageing, mechanical properties, surface roughness

Purpose: The study aims to produce CAD-CAM reference samples for shade communication milled from the material of the restoration zirconia (ZrO2) and zirconia-reinforced lithium silicate (ZLS) and evaluate the color difference with the corresponding conventional Vita Classical (VC) shade tab. Furthermore, it aims to verify the color consistency of the materials. Materials and methods: Five-five samples were milled out of ZrO2 and ZLS in five different colors and their color parameters were compared with the corresponding VC tabs both visually and digitally. For digital evaluation, images were taken of the samples and VC tabs and analyzed in Adobe Photoshop to extract L*a*b values. Color difference (ΔE00) was calculated using the CIEDE 2000 formula. Multilevel mixed-effects linear regression model was used to derive estimates of the mean ∆E00. Results: Color difference was significantly higher than 1.8 ΔE00 in the case of all the ZrO2, ZLS A3, B2 and C2 samples. Color difference was also found during the visual comparison. Comparing the same color samples the ΔE exceeded 0.8 in some cases but stayed under 1.8 ΔE00 in every case and showed no color difference visually. Conclusion: Comparing CAD-CAM samples and VC shade tabs visible and measurable color differences (ΔE00>AT50:50%) were found in the case of all ZrO2 and three out of five evaluated shades of ZLS samples. The color consistency of the blocks was acceptable. Better shade communication thus more reliable shade reproduction is achieved when reference photos are sent with a color sample made from the restoration’s material. Keywords: color difference, shade, communication, CAD-CAM

Some of the critical clinical challenges encountered in the treatment of adult patients with deep overbite and worn dentition include correction of deep overbite, establishment of an appropriate occlusal vertical dimension (OVD), and maintenance of long-term occlusal stability. Although Angle’s Class II division 2-associated deep anterior overbite is common in orthodontic treatment, simple prosthodontic treatment with great improvement of deep anterior overbite and worn dentition is infrequently reported. A 51-year-old man with Class II Division 2 malocclusion presented with hypo-divergent facial pattern, reduced lower facial height, and protuberant lips. Intraoral examination revealed unevenly worn dentition and an Angle’s Class II division 2-associated deep and traumatic anterior overbite. Based on the challenges of the presentation, it was imperative to design an protocol to ensure a predictable and favorable prognosis. According to the current protocols, prosthetic treatment of occlusal rehabilitation was applied. Following the 3-month evaluation period using interim prostheses, full-mouth ceramic restorations were completed. Significant post-treatment functional and aesthetic improvements were achieved with resultant stable inter-incisal contacts either immediately after treatment or during the 2-year follow-up period. Full mouth rehabilitation offers brilliant prospects for improved function, enhanced aesthetics, and improved health of the entire stomatognathic system of Angle’s Class II division 2 patient associated with deep overbite and worn dentitions.  Keywords: full mouth rehabilitation, Class II Division 2 malocclusion, deep overbite, worn dentition, resin-bonded ceramic restorations

Purpose: This study aims to compare the surface roughness (SR), contact angle (CA), surface free energy (SFE), and bacterial adhesion of resin-based materials used in additive, subtractive, and conventional manufacturing techniques. Materials and Methods: This study involved four groups of 23 specimens: Indirect conventional resin composite (ICRC), subtractively manufactured resin composite (SMRC), additively manufactured resin composite (AMRC), and soda-lime-silica glass (SLSG). One specimen per group was analyzed by Energy Dispersive X-ray Spectroscopy (EDS) before polishing. Following the  polishing procedure, SR, CA, and SFE were measured. The sterilized specimens were divided into two subgroups for Streptococcus mutans and Streptococcus mitis adhesion. One randomly selected specimen from each group was also reserved for visualization of bacterial adhesion using Scanning Electron Microscopy (SEM), and bacterial adhesion was quantified in the remaining specimens (n=10). Data for SR, CA, SFE, and bacterial adhesion were analyzed using one-way ANOVA, Tukey post-hoc tests, and Pearson correlation (α = .05). Results: Among the resin groups, the ICRC group had the lowest SR values (P < .001). The higher CA was observed in the SMRC group than AMRC (P = .016). AMRC displayed significantly lower S. mitis adhesion compared to ICRC and SMRC (P < .001 and P = .003, respectively). A positive correlation was found between SR and S.mutans adhesion (R = .455, P < .003). Conclusion: Resin materials designed for different manufacturing techniques exhibited diverse surface characteristics. Nevertheless, the 3D printable permanent resin demonstrated comparable S. mutans adhesion to that of ICRC and SMRC. Keywords: Bacterial adhesion, substractive, additive, indirect composite, roughness, surface free energy, Streptococcus mutans

Purpose: The purpose of this study is to compare the stress distribution between all-on four and all-on six treatment concept with various prosthetics framework materials through finite element analysis. Materials and Methods: A three-dimensional finite element model of edentulous maxilla was simulated using computerized topographical data of a patient. Four implants were placed according to All-on four concept. In addition to the all-on four concept, two more axial implants were placed in anterior region to create the all-on six concept. Four framework materials were investigated: Cobalt-Chrome (CoCr), Zirconium (Zr), Titanium (Ti) and Polyetheretherketone (PEEK). 100 N load was applied at anterior region, 150 N oblique load was applied at premolars and 200 N oblique load was applied at molars region simultaneously. Principal stresses in bone, the Von Mises stresses in implant and frameworks were calculated and compared. Results: All-on six concept showed lower von Mises on implant, and framework, and principal stress values on the bone, than all-on four concept. PEEK exhibited highest stress values on bone and implants, while CoCr showed least stress values. Conclusion: Stress distribution was influenced by the framework materials. The use of framework material with appropriate physical properties on the correct indication might be particularly important in determining the success of the implant-supported prostheses. Keywords: Cobalt-Chrome, Zirconium, Titanium, PEEK, All-on four, Finite element analysis

Purpose: To inspect the impact of polyethylene fiber (Ribbond) on the long-span, 3D-printed, interim fixed dental prosthesis regarding fracture strength. Materials and Methods: A stainless steel platform was fabricated to replicate the partial edentulism for a maxillary four-unit fixed dental prosthesis. The prosthesis was fabricated by a Formlabs SLA 3D printer. The specimens were allocated into four groups of 20 each: experimental reinforced Group A (prosthesis with a slot reinforced with fiber); experimental Group B (prosthesis with a slot filled with 3D-printed material), negative control Group C (prosthesis with a slot); and control Group D (full-contour prosthesis). Fracture strength exams were performed with a universal tester. The fracture patterns were examined. A statistical analysis was conducted using one-way ANOVA and Tukey HSD test. Results: The control group exhibited a significantly higher mean flexural load (D: 306.32 ± 50.76 N) compared to the other groups (A: 194.37 ± 68.02 N; B: 178.25 ± 42.67 N; and C: 156.68 ± 29.73 N; [P < .001]). No differences were identified among Groups A, B, and C. The fracture pattern differed between the nonreinforced Groups B, C, and D and reinforced Group A, with catastrophic failure observed in the nonreinforced group and unseparated failure observed in the reinforced group. Conclusions: The study findings demonstrate that the incorporation of Ribbond in 3D-printed, interim fixed dental prostheses does not significantly enhance their fracture strength. However, it does lead to a noticeable change in the fracture behavior, shifting from a complete failure to an incomplete fracture pattern.

The aim of this short communication is to present a technique to rehabilitate severely discolored teeth with computer-aided designed and computer-aided manufactured (CAD-CAM) zirconia crowns. After confirming the absence of periapical lesions and sufficient crown structure, any caries or fractured restorations can be removed and replaced by an interim composite restoration. A shoulder subgingival preparation is performed and scanned with an intraoral scanner to design a CAD-CAM zirconia crown using a monolithic zirconia material. This crown is highly polished using a specific polishing kit, but not glazed. This technique is suggested to be useful in cases of dark discolored teeth due to staining endodontic materials such as resorcinol-formaldehyde resin. Keywords: computer-aided design, computer-aided manufacturing, tooth discoloration

This study aimed to investigate the efficiency of different cements for luting implant restorations. Standard restorations were bonded with different cements, including a zincoxide-based temporary cement (ZOE), a resin-modified glass ionomer cement (GIC) and a resin-based, eugenol-free cement (RBEFC). The restorations were stored under moist conditions and were subsequently subjected to thermal cycling and mechanical loading (TCML). Retention forces were determined with an axial tensile test and removabilty of the restorations was analyzed with a pneumatic crown remover. GIC provided significantly higher retention forces than RBEFC, which provided significantly higher values than ZOE. After storage, retention forces were significantly higher than after TCML. With regard to removability, no significant differences were identified between ZOE and RBEFC, but a significantly higher number of applications was required to remove restorations luted with RBEFC. All cements provided sufficient retention forces, yet removal of restoration might be more demanding if luted with RBEFC.

This retrospective study evaluated the clinical long-term survival of 1405 double-crown retained removable partial dentures (DRPDs) over 30 years of follow-up. Kaplan Meier survival rate for DRPDs was 96.6% after 5 years, 88.2% after 10 years, 61.7% after 20 years, and 38.3% after 30 years. Survival rates of abutment teeth were 94.3% after 5 years, 80.2% after 10 years, 51% after 20 years, and 27% after 30 years. Key failure risk factors of DRPDs were age, ≤ 3 abutment teeth, and complete denture in opposing jaw. Abutment teeth failure risk factors included age, anterior abutment teeth, punctual support, and non-vital teeth. Keywords: removable partial denture, double crowns, survival rate, severely reduced dentition, clinical study

Purpose. Evaluate the influence of different Co-Cr framework manufacturing techniques on the bond strength between metal and two types of veneering ceramic with and without a metal primer. Materials and Methods. 72 metal specimens were fabricated using the same Co-Cr alloy (Keramit NP; Nobil Metal) with three different techniques: ingots for casting (Keramit NP); disks for CAD/CAM milling (Synergy Drive Keramit NP); and powder for SLM (Keramit NP-S). Each of the 24-specimen groups, was divided into two subgroups, according to the application, or not, of Nobil Metal Bonding (NMB) (Nobil Metal). Two different veneering ceramic systems were used: Ceramco iC (Dentsply) and Noritake super porcelain EX-3 (Noritake). The bond strength of the metal-ceramic system was evaluated using the three-point bending test and the modality of failure with SEM analysis. Three-way Anova with interactions was used to evaluate the influence of the metal production process, the presence or absence of the bonding agent and the type of veneering ceramic on ceramic-metal adhesion. Results. All specimens exceeded the minimum bond strength of 25 MPa required by ISO Standard 9693 – 1:2012. The highest values of adhesion were registered for specimens manufactured with casted metal/Noritake veneering ceramic (40.59 ± 7.30 MPa). The lowest values were registered for specimens manufactured with CAD/CAM metal/NMB/Ceramco iC veneering ceramic (29.47 ± 3.38 MPa). Conclusions. The fabrication method and the type of veneering ceramic had a significant influence on the mean bond strength. The application of the NMB did not show an influence on bond strength.

Purpose. The aim of this prospective clinical study was to evaluate the 12 and 24-month clinical results of overlay and one-piece endodontic crown restorations applied with additively manufactured 3D printed permanent ceramic-filled resin (PCR) according to the Modified US Public Health Service (USPHS) criteria. Materials and Methods. A total of 33 indirect restorations (16 overlay, 17 endocrown) (4 premolar, 29 molar) produced using PCR (Formlabs) were applied to 30 patients by a single dentist. The restorations were evaluated according to the modified USPHS criteria at baseline (7 days), 12 and 24 months times by two independent evaluators. The study registration number is NCT05168852. In the comparisons of the dependent criteria scores, the Related Samples Cochran Q test was used, and in post-hoc paired comparisons, the Bonferroni test. The Fisher-Freeman-Halton test was applied in the comparisons of categorical variables according to the restoration type groups (α = 0.05). Results. No statistically significant difference was determined between the evaluation criteria scores at baseline, 12 months, and 24 months for the marginal adaptation (P=0.05), retention (P=1), interproximal contact (P=0.368), color match (P=1), surface texture (P=1), and patient satisfaction (P=1). The only score criteria that showed a statistically significant difference between baseline and 24 months (P=0.001) among all other criteria was marginal discoloration. This criteria’s score change was from 100% A score to 69.7% A score. Conclusion. In the 2-year follow-up of indirect single-tooth restorations produced with 3D-printed PCR, all restorations showed acceptable clinical performance. (≥99.5%A+B score at 2 years). Keywords: 3D printing, permanent crown resin, clinical study, indirect restoration, fixed restoration

Purpose. The objective of this clinical study was to evaluate comfort, satisfaction, chewing ability and complications with digital complete dentures (DCD) and conventional complete dentures (CCD). Materials and methods. For 16 edentulous patients, two sets of upper and lower dentures were fabricated by students in a university dental clinic. The impression for the DCD was done using indirect scanning of the cast. When the patients were pain free, each set of dentures was worn for four weeks. OHIP-14 and a DSI (Denture Satisfaction Index)were used to measure patient satisfaction and chewing ability respectively. Both questionnaires were administered before fabrication and after wearing each set. Adjustments made during the follow up period were included. At the end of the study, patients could express which set of dentures they preferred. The 25 dental students involved in fabricating the dentures, were questioned in terms of discomfort, preference and future use for both techniques. Results. OHIP-14 showed significantly higher scores for the DCD for the domain concerning psychological discomfort. DSI showed no significant difference for both sets of dentures. In terms of complications, a significant difference was found for occlusion. The DCD required more occlusal adjustments. A minority of the patients (37.5%) chose the DCD as their favourite set. The students preferred the wax try-in and workflow of the CCD. Conclusions. The CCD and DCD showed differences in patient satisfaction. Chewing ability was comparable for both sets of dentures. More occlusal complications were seen in the DCD. Both students and patients preferred the CCD.

Purpose: To evaluate the mechanical properties of the 3D printed provisional restoration material that was repaired using different materials. Material and Methods: The bar specimens have been manufactured using three-dimensional printing technology in accordance with the ISO 10477:2020 standards and divided into 5 groups randomly. For repair material application and replacement on the standardized silicone mold, the test specimens were ground at the center by 1x2x2 mm. No grinding was done on the control group specimens. Flowable composite, bis-acrylic composite resin, polymethyl methacrylate resin, and temporary 3D printing resin are utilized as repair materials (n=16). The specimens underwent a three-point-bending (3PB) test, with a cross-head speed of 1mm/min, in order to assess their flexural strength (FS) and flexural modulus (FM). The data received statistical analysis with one-way ANOVA and Tukey test. A Weibull analysis was performed, and the Weibull modulus of specimens was calculated. Results: Control group specimens were showed the highest FS (142±12.6 MPa) and FM (4497±1205 MPa) values. Among the test groups, the utilization of temporary 3D printing resin as a repair material exhibited the greatest FS (67±33.3 MPa) values and showed statistical significance when compared to all other groups. Conclusion: Repairing 3D-printed provisional resin material weakens its mechanical properties. However, utilizing the own resin made of 3D-printed provisional resin material can be an effective choice for implementing minor modifications and additions.

Purpose: The aim of this study is to examine the effect of gastric acid on the surface roughness of additive and subtractive manufacturing resin. Materials and Methods: In this study, two subtractive manufacturing CAD-CAM resin nanoceramic (CerasmartTM270 (CS), LavaTM Ultimate (LU)) and two additive manufacturing 3D printing permanent resin (VarseoSmile Crownplus (VSP), Crowntec (CT)) was used. CS and LU samples were turned into 10 mm diameter cylinders with a scraper and cut into 2 mm slices on the cutting device. CT and VSP samples were produced on a 3D printer (2mm thickness-10mm diameter) (n:15). All samples were exposed to a cycle of 60 seconds of gastric acid, 5 seconds of distilled water, and 30 minutes of artificial saliva, 6 times a day for 10 days. Surface roughness mean (Ra) and depth (Rz) was measured with a contact profilometer at baseline and after gastric acid cycling. Data were analyzed using SPSS (22.0), One way ANOVA, post-hoc Tukey's and Independent-t test (p <.05). Results: Ra-Rz values of CT and VSP were significantly higher than CS and LU at baseline and after the gastric acid cycle (p <.05). After the gastric acid cycle, the Ra-Rz values of all materials increased significantly compared to the baseline (p <.05) but the Ra values of all materials were at a clinically acceptable level (<0.2µm). Conclusion: Although additive manufacturing 3D printing permanent resins offered higher roughness values, they weren’t at a clinically unacceptable level. Therefore, they can be an alternative to subtractive manufacturing CAD-CAM resin nanoceramics. 

This study examined changes in facial geometry while playing wind instruments. Nine musicians participated (6 men, 3 women, mean age 52 years) in part 1 of the study, and 3 musicians participated (3 women, mean age 41 years) in part 2. In part 1, the high and low notes of each instrument were selected as test sounds. Facial geometry data were recorded using a 3D scanner. In part 2, facial geometry data were recorded using a 4D scanner while a melody was played. Data were superimposed and analyzed using 3D analysis software. Numerical values and color maps of deviations were obtained. The results of part 1 revealed that the median 3D deviation was 1.1 mm (range 0.42-1.45 mm), indicating that facial geometry while playing high and low notes was varied. The results of part 2 showed that the stable part was the frontal region and dorsal part of the nose. The approach used in this study has potential applications for evaluating facial geometry during musical instrument performances.  Keywords: dentistry for musicians, geometric evaluation, 3D scanning, high and low notes, facial scanner

Purpose. The purpose of this in vitro study was to evaluate the effect of a staining solution on color stability of resins for complete dentures produced with conventional and digital technologies. Materials and Methods. 60 resin specimens were prepared and divided in 6 groups of 10 specimens each: Probase Hot (PH, Ivoclar AG), IvoBase CAD (IBC, Ivoclar AG), Ivotion Dent (ID, Ivoclar AG), Ivotion Dent Multi (IDM, Ivoclar AG), Dima Print Denture Base (DPDB, Kulzer), and Dima Print Denture Teeth (DPDT, Kulzer). One surface of each specimen was polished following the manufacturer’s instructions. The CIELab color differences were evaluated before and after immersion for 28 days in a coffee solution and measured as DE using two dental spectrophotometers. One specimen for each group was selected for SEM analysis at baseline and at 28-day. Results. Data analysis was performed by Kruskal-Wallis test and post-hoc Dunn test for comparison. Regarding specimens analyzed with VITA Easyshade, IDM white zone (polished and unpolished) scored higher (∆E= 0.87 and ∆E = 1.15 respectively). All milled samples (IBC, ID, IDM pink zone), scored significantly higher as compared to PH and DPDT. Regarding Spectroshade, IDM pink zone performed better, regarding both polished and unpolished specimens (∆E=1.57 and ∆E=2.07 respectively). ID demonstrated a statistic higher color stability compared to PH and DPDT. Regarding the SEM analysis any differences in surface morphology was observed between baseline and 28-days immersion analyses. Conclusions. Color stability is significantly higher in resin specimens obtained with digital technologies as compared to conventional resin specimens after immersion in a staining solution. 

Purpose: This paper aims to identify specific personality traits that could potentially undermine the overall satisfaction of the patient with the prosthodontic treatment. Materials and Methods: A literature review was conducted to identify the personality traits (PT) relevant to patients requiring dental treatment. Later, a Delphi process was employed to classify the selected PT into risk levels to prosthodontic treatment satisfaction, ultimately leading to the development of a personality risk profile (PRP) proposal. The expert panel consisted of specialists with over ten years of practice. The Delphi process involved three rounds of evaluation and consensus building. Results: Twenty-six PT associated with dental treatment satisfaction were identified. Following the three rounds of the Delphi method, a consensus was achieved, resulting in the classification of these PT into three PRP, as follows: Low Risk (cooperative, understanding, compliant, trusting, concerned about their health, willing, thankful, and responsible), Moderate Risk (Insecure, Over-informed, Demanding, Appearance-obsessed, and Pessimistic), and High Risk (mistrustful, skeptical, unwilling, defiant attitude, unrealistic expectations, neglectful, treatment resistant, patient refers negatively about other dentists, violent, irresponsible, idealise the dentist, and controller). Conclusions: This study identified and categorized PT that have the potential to adversely impact prosthodontics treatment satisfaction. Through this PRP proposal, dental professionals can recognize these patients before initiating prosthodontic interventions. Keywords: Delphi Technique, Personality Traits, Dental Care, Prosthodontics, Patient Satisfaction, Psychological Classification

Purpose: The purpose of the current study was to investigate the shear bond strength of composite resin in five different ceramic repair systems for three different ceramic materials. Materials and Methods: 225 monolithic zirconia (Zr) and lithium disilicate (LDS) and cobalt chromium (CoCr) specimens with feldspathic porcelain (FP) veneer were fabricated (N=75 per material). The specimens underwent thermo-cycling and were randomly divided into five groups for the following intra-oral repair systems (n=15): 1) Clearfil Ceramic Primer Plus, Kuraray Noritake, Japan; 2) Ibond Intraoral Repair Kit, Kulzer, Germany; 3) VOCO Cimara, VOCO GmbH Germany; 4) Ivoclar Vivadent, Ceramic Repair System Kit, IvoclarVivadent, Liechtenstein; 5) Ultradent Porcelain Repair Kit, Ultradent Products Inc, USA. After surface conditioning, composite was applied using a cylindrical mold and a second round of thermocycling was performed. Each specimen was then subjected to shear load until failure. Microshear bond strength was compared using analysis of variance (one-way ANOVA, Tukey´s test, a <0.05). Results: Type of porcelain repair kit significantly affected the shear bond strength. For Zr, the repair systems from Kulzer and VOCO had significantly higher shear bond strength than the other systems (p<0.001) without significant difference between Kulzer and VOCO. For the LDS and CoCr with FP, hydrofluoric acid had the highest shear bond strength (p<0.001). Conclusion: For zirconia, a 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) system should be used. The results also suggest that a cleaning bur may be beneficial. For glass-based ceramics and feldspathic porcelain, etching with hydrofluoric acid remains the product of choice. Keywords: Ceramic repair, ceramics, composite resins, shear bond strength

This paper presents an efficient method for fabricating a full-arch implant prosthesis within one day, using a verification index through a three-dimensional (3D)-printed surgical guide. The technique involves the use of simple impression coping and laboratory analogs to ensure accurate prosthesis placement. Directly using 3D-printed surgical guides as a verification index simplifies and streamlines the procedure, offering a significant clinical advantage. This approach provides a clinically relevant advancement in prosthodontic practices by demonstrating a practical and instructive approach to enhance treatment outcomes.

Lab-side-fabricated abutments and hybrid zirconia crowns, which are bonded to titanium bases with resin-based composites, require disinfection before insertion. This study investigated the effect of cleaning procedures (ultrasonic, autoclaving) and aging methods (24h, 90d, thermocycling) on the shear bond strength between alumina particle air-abraded titanium and zirconia (3Y-, 4Y- and 5Y-TZP) specimens luted with phosphate monomer containing adhesive systems and resin-based composite. Autoclaving significantly improved SBS (F (27,231) = 17.265, p < .001) compared to no cleaning and three-stage disinfection. No differences were identified with regard to zirconia or aging methods. Bond strength initially benefits from autoclaving but continuously approaches the comparative values over longer periods.

Purpose: This study evaluates the antibiofilm action of 2.5 mg/mL peracetic acid (PA), 0.5 mg/mL cetylpyridinium chloride (CPC), and 160 mg/mL N-Acetylcysteine (NAC) against multispecies biofilm of Streptococcus mutans, Staphylococcus aureus, Candida albicans, and Candida glabrata, developed on surfaces of heat-polymerizing acrylic resin (AR) and cobaltchromium (Co-Cr) alloy. Materials and Methods: A multispecies biofilm was grown on the surface of AR and Co-Cr specimens (Ø 12×3mm). After biofilm maturation, the specimens were immersed in experimental solutions and evaluated through biofilm viability (CFU) (n=9), biofilm metabolic activity (XTT) (n=9), biofilm-covered areas (Live/Dead) (n=2), effects on the extracellular polymeric substance (EPS) (n=2) and biofilm morphology (n=1). Data were analyzed by ANOVA and the Tukey post-test or Kruskal-Wallis followed by the Dunn post-test (α=.05). Results: Overall, all evaluated solutions impacted biofilm viability. PA presented wider activity by reducing CFU of all microorganisms on both surfaces, XTT (P<.001) and Live/Dead (P<.001). NAC had a notorious effect in reducing the viability of bacteria without affecting the yeasts. NAC reduced XTT on AR (P=.006) and Co-Cr (P=.003) but did not reduce the aggregated biofilm layer. CPC had distinct effect according to the surface, being most effective in reducing CFU on AR than the Co-Cr surface. However, it did not influence XTT, and the amount of residual aggregated biofilm. Conclusions: PA provided the greatest antibiofilm action, while CPC and NAC showed intermediate action. Nonetheless, no solution was able to completely remove the biofilm adhered to the surfaces of heat-polymerizing AR and Co-Cr alloy. Keywords: Biofilms. Removable partial denture. Denture cleansers. Cobalt-chromium alloys. Acrylic resin

Purpose: To evaluate the preferences of dental practitioners for tooth-supported crowns dental ceramics by means of an online survey and to assess the influence of age, gender, years of experience, and dental specialty on those preferences. Materials and Methods: An anonymous questionnaire was delivered online through Google Surveys, targeting 796 dentists. It contained 17 dichotomous, closed questions with two sections. The first section dealt with general characteristics, including age, gender, years of experience, training in prosthodontics, and hours worked per week. The second section included questions regarding preferences of different materials for crowns, and the use of digital workflows. Analyses were carried out with Stata 14.0 software (StataCorp, TX, USA). A significance level of p=0.05 was adopted. Results: 248 surveys were answered. Practitioners in Chile preferred lithium disilicate for the anterior region (55.2%) but also for the posterior area (40.7%), regardless of their age, gender, years since graduation, hours worked per week or any training in prosthodontics. Chilean dentists over 50 years old considered zirconia almost 4 times more than those under 30 years old for anterior crowns (51.85%). 59.68% of dentists take digital impressions, and 37.10% have access to chairside CAD/CAM technology. In this group, 54.4% preferred feldspathic ceramic for anterior and 23.9% for posterior crowns. Conclusions: While there is a wide range of dental ceramic materials, these results provide a snapshot of the current trends in Chile where lithium disilicate is the most preferred ceramic material for tooth-supported crowns, and metal-ceramic is the least preferred material. Keywords: Ceramics, survey, zirconia, CAD/CAM, questionnaire

Purpose: To investigate the available evidence on the accuracy of conventional and digital workflows for complete arch implant supported frameworks. Materials and methods: This scoping review was conducted according to the 5-stage framework of Arksey and O’Malley. A systematic literature search was performed adhering to the PRISMA guidelines to identify studies with a direct comparison of conventional and digital methods for the fabrication of complete arch implant supported frameworks. 58 in-vitro studies with the focus on edentulous arches with at least four implants published between 2000 and 2024 were included. The reported outcomes were examined to determine the value of a statistical analysis for adding up the individual errors to a cumulative error of the workflow. Results: Evidence on the accuracy assessment of digital and conventional workflows for complete arch implant supported frameworks is available. However, also studies with the same assessment methods and outcome units appear to be too heterogeneous to perform a statistical analysis of error accumulation. While there is no consensus in the impression and cast fabrication stage, digital techniques show a superior accuracy for the fabrication of complete arch implant supported frameworks compared to conventional casting. Conclusion: In-vitro studies assessing the accuracy of entire workflows and classifying their outcomes regarding the clinical relevance are lacking. Keywords: computer-aided design, intraoral scanning, dental implants, dimensional measurement accuracy, CAD-CAM

Purpose: Sintering procedures influence the properties of zirconia. This study evaluated the effect of varying sintering rates on flexural strength (σ) of 3, 4, and 5 mol% yttria (Y) containing monochrome (Mo) and multilayer (Mu) zirconia. Materials and Methods: 270 specimens (width×length×thickness = 11.2×20×1.5 mm) were prepared from Mo and Mu of 3Y, 4Y, and 5Y zirconia and randomly sintered at regular (RS: 10 °C/min), fast (FS: 35 °C/min), and speed (SS: 70 °C/min) sintering (n = 15/group). Three-point bending test was determined for σ. ANOVA and Bonferroni test were analyzed for significant differences of σ (a=0.05). The microstructure and crystalline [monoclinic (m), tetragonal (t), and cubic (c)] phases were evaluated by SEM and XRD.Results: σ of zirconia was affected by zirconia type, shade pattern, and sintering rate. Significant higher σ for 3Y>4Y>5Y (p<0.05). Significant greater σ for Mu>Mo (p<0.05). Significant reduction of σ upon SS than RS and FS (p<0.05). However, no significant effect on σ upon varying sintering rates within each type of zirconia (p>0.05). SEM indicated greater grain size in 5Y than in 4Y and 3Y. XRD indicated higher t phase in 3Y, whereas higher c phase in 5Y. Mo indicated a higher c phase than Mu.Conclusions: σ was influenced by Y content (3Y>4Y>5Y), shade pattern (Mu>Mo), and sintering rate (RS@FS>SS). Nonetheless, no influence of varying sintering rates on σ for each type of zirconia, suggesting sintering zirconia with RS and FS for expecting higher σ and at SS for acceptable σ for chair-side cost-effective restoration. Keywords: flexural strength, monochrome zirconia, multilayer zirconia, sintering rate, sintering process.

Purpose: To evaluate the elution of residual monomers from resins used in additive and subtractive manufactured permanent restorations over a period of one month, using highperformance liquid chromatography (HPLC). Materials and Methods: Two additive manufacturing permanent crown resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and a subtractive manufacturing resin nanoceramic (Cerasmart, CS) were used to fabricate 30 disc-shaped samples (10 × 2 mm) (n=10). The elution of bisphenol A ethoxylate dimethacrylate (BisEMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) monomers was measured with HPLC at 1 day and 30 days after immersion. One-way analysis of variance (ANOVA) and post-hoc Tukey tests were used to evaluate differences in eluted monomer concentrations. Paired-sample t tests were used to test the differences in monomer concentration between storage times. Results: CS released BisEMA and UDMA residual monomers, while VS and CT released BisEMA and TEGDMA residual monomers. The residual monomer elution from CT was consistently lower than that from VS for both BisEMA (p <0.001) and TEGDMA (p <0.001). CS showed a decreasing release pattern in BisEMA (p =0.002) and UDMA (p <0.001) residuel monomers, whereas VS and CT showed an increasing release pattern in BisEMA (p <0.001) and TEGDMA (p <0.001) residuel monomers. Conclusions: The additive manufactured composite resins released higher amounts of residual monomers than the subtractive manufactured resin nanoceramic. Although the amounts of residual monomers released in the additive manufactured composite resins increased over time in contrast to subtractive manufactured resin nanoceramic, these values were below cytotoxic levels.

Purpose: The improvement of computer-aided design and computer-aided manufacturing (CAD/CAM) has changed the methods of fabricating laminate veneers. The objectives of this study were to evaluate the marginal and internal fit of ceramic veneers manufactured with different CAD/CAM techniques. Materials and methods: A metal die was made by copying a prepared plastic maxillary central right incisor and scanned for designing a laminate veneer. One hundred laminate veneers were made with four different CAD/CAM techniques (n=25), including milled lithium disilicate (MLD), heat-pressed lithium disilicate with 3-dimensional (3D) printed wax patterns (PLD), milled zirconia (MZ), and 3Dprinted zirconia (PZ). The virtual marginal and internal fit of fabricated veneers was evaluated with digital crown fitting software. The actual marginal and internal fit was measured with the silicone replica method under a digital microscope. The measured data were analyzed using the one-way analysis of variance and the Turkey test. Results: There were significant differences in marginal and internal fit (P < 0.001) among manufacturing techniques. Both the virtual and actual marginal and internal gaps were higher in the PLD and PZ groups compared to the MLD and MZ groups. Conclusion: All four CAD/CAM techniques of manufacturing veneers, that is, milled lithium disilicate, heat-pressed lithium disilicate with 3D-printed wax patterns, milled zirconia, and 3D-printed zirconia, have clinically acceptable marginal and internal fit. Milled zirconia and lithium disilicate veneers demonstrated superior marginal and internal fit compared to 3D-printed zirconia and heat-pressed lithium disilicate veneers with 3D-printed wax patterns. Keywords: Ceramic laminate veneers, silicone replica, marginal fit, zirconia, lithium disilicate

Purpose. To compare the influence of 0, 45 and 90 degrees build direction on fracture load and surface roughness of additively manufactured three-unit fixed provisional restoration, and to compare with provisionals fabricated using conventional materials. Material and methods. Mandibular typodont right second molar and premolar were prepared for missing mandibular first molar to receive three-unit fixed partial denture. Six groups of 10 samples each, 3-unit provisionals were fabricated using additional manufacturing at 0,45 and 90 degrees, heat polymerized polymethyl methacrylate, auto polymerizing resin and bis-acryl composites resins and tested for fracture load and surface roughness. One way ANOVA and Tukey tests were used to analyze the data. Results. For fracture load, lowest mean value was obtained for auto polymerizing bis-acrylic resin (464.9N) and highest value for 0 degree (596 N), while surface roughness values were lowest for heat polymerized polymethyl methacrylate (0.132μm), and the highest for auto polymerizing polymethyl methacrylate (0.836 μm). Significant differences were obtained between three build directions for fracture load and surface roughness (p=0.001); in all pairwise comparisons except between 0 and 90 degrees (p=0.502) for fracture load; and between all three build directions for surface roughness (p=0.01). On comparing with other provisional materials, significant difference (p=0.001) was observed between all groups. Conclusion- Build direction affected the mechanical properties of additively manufactured three-unit provisionals with 0 degree printed provisionals showing highest fracture load and lowest surface roughness. On comparing with other provisional materials, 0 degree showed highest fracture load, with surface roughness similar to heat polymerized provisionals.

Purpose: To determine whether digital training improves conceptual skills acquisition for custom tray fabrication and tooth arrangement in the preclinical curriculum for complete denture fabrication. Materials and methods: A crossover design study compared third-year student grades after conventional (manual) and digital training. Half the students were trained with conventional techniques prior to digital, while the other half were trained with digital techniques prior to conventional. The first part of the study (DP1) focused on custom tray fabrication and involved 154 students. The second part (DP2) focused on tooth arrangement with 204 students. The effect of preliminary digital training on conceptual skills was assessed by comparing the results of the students using a Student's t-test. Results were also analyzed by ranking on the students’ Perceptual Ability Test (PAT) score. Finally, students’ satisfaction with the training was investigated. Results: Students who completed the initial digital session achieved better custom tray fabrication and tooth arrangement in the subsequent manual sessions. For manual laboratory work, the most dexterous students (PAT1 group) demonstrated the best performance. However, PAT2 students had the best performance during the digital sessions during DP1, and PAT1 and PAT2 students had the best performance during the digital sessions during DP2. Additionally, 40% of DP1 and 12% of DP2 students expressed satisfaction with digital sessions. Conclusion: With complementary manual and digital teaching, digital tools may be useful for enhanced student learning. Digital training has contributed to improve results in manual sessions but did not affect student satisfaction and remained a limited tool to detect learning difficulties. Keywords: complete denture curriculum; digital dentistry; digital learning; preclinical simulation; custom tray; tooth arrangement; pedagogical study

Objective. Evaluate the roughness and color stability of different types of resins used to immerse denture bases in various denture cleansers overnight. Metodology. A total of 150 resin samples were made, which were divided into 3 groups of denture resin (conventional thermally activated, milled and 3D printed) (n= 50) and subdivided into 5 denture cleaners (Distilled water, Corega Tabs, Efferdent, NaOCl 1.0%, Listerine Cool Hint) (n= 10). The roughness properties (Ra) and chromatic difference (ΔE00) were evaluated during 90 days and 180 days of overnight cleaning. Data were evaluated by two-way ANOVA and Tukey's test for multiple comparisons (P<.05). Results. Listerine had significantly higher Ra and ΔE values (P<.001) compared to other solutions, being significant in conventional resin at 180 days (P<.001). Conclusions. The use of Listerine as an overnight cleaner presents greater damage to the optical and surface properties of denture base resins, mainly with conventional resin, with 1% NaOCl being a valid option in relation to cost-benefit. Keywords: Dentures; Denture cleaners; Disinfection; CAD/CAM.

Purpose: To compare the fracture load of two framework materials, zirconia and a new fiber-reinforced composite (FRC), for full-arch implant-supported rehabilitations using various cross- sections. Material and Methods: A cobalt-chromium metal model simulating the all-on-four concept and including 2 anterior straight and 2 posterior 45- degree angled multi-unit digital implant analogs was manufactured. 4 straight multi-unit abutments were screwed onto the implant analogs. The metallic model was scanned, and 18 frameworks were fabricated, consisting of 9 made of zirconia and 9 made of fiber-reinforced composite (FRC). The frameworks were then divided into 6 groups, with each group consisting of 3 frameworks  (n=3). Group division was based on material type (Zirconia or FRC Trilor) and framework cross-section: 3.5 x 6 mm2, 5.5 x 6 mm2, or 7.5 x 6 mm2. All specimens underwent thermocycling in 2 baths (5 ͦ c- 55 ͦ c for 2350 cycles). Subsequently, the frameworks were cemented to the abutments of the metal model and subjected to a load-to-failure bending test at 3 different points using a universal testing machine (crosshead speed: 1 mm/min) until complete fracture occurred (according to ISO/TS 11405:2015). Descriptive statistics were used to present quantitative variables as means ± standard deviations. To compare two means, Student's t-test or Mann-Whitney test was utilized, and for three means, ANOVA test was used. Results: The FRC group with a 7.5 x 6 mm2 cross-section exhibited the highest load-to-failure values (ranging from 1020 N to 2994N) , while the zirconia group with a 3.5 x 6 mm2 cross-section recorded the lowest values (ranging from 212 N to 1287 N). The material type and framework cross-section significantly affected the mean load-to-fracture values (p< 0.05). Regardless of the framework cross-section, the FRC group exhibited higher fracture loads than the zirconia group. In both materials, fracture load values were increased with larger framework cross-sectional areas, with the highest values observed at the inter-implant midpoint. Conclusion: The FRC Trilor demonstrated a fracture load that make it a suitable alternative to zirconia for all-on-four implant prosthetic frameworks.

Purpose: This study aimed to evaluate the prevalence of biological and technical/mechanical complications in edentate elders rehabilitated with complete removable dental prostheses (CDs) and overdentures [tooth-retained (ODs), implant-retained (IODs)]. Materials and Methods: Patient records of adults (>60y) rehabilitated with CDs, ODs, and IODs were included. Demographic information (age, sex), information on the prostheses type, number/type of biological/prosthetic complications, along with the number/time of the complications, were extracted.Kaplan-Meier model was used for the statistical analyses. Results: 162 patients (mean age: 74.5±9.45y; prostheses: n=224, CD=172; OD=21; IOD=31) were included. The average period of function in situ was 19.70±27.66, 32.72±27.84, and 31.73±32.67 months, for the CDs, ODs, and IODs, respectively. 5 prostheses failed. Survival analysis revealed an overall survival rate (SR) of 97.8%, with individual five-year cumulative survival probability of 96.1% for CDs, 94.1% for ODs, and 100.0% for IODs. There were no significant survival differences between maxillary and mandibular prostheses within each type of rehabilitation. In the maxilla, no significant differences were found in maintenance visit times due to prosthodontic complications among the different types of prostheses. Patients with mandibular CDs required maintenance visits earlier compared to mandibular ODs (p<0.001) and IODs (p<0.001). Patients with mandibular ODs also required maintenance visits earlier than those with mandibular IODs (p=0.005). Conclusions: Rehabilitation of the edentate jaws, whether with CDs, ODs, or IODs, is a predictable treatment modality with high survival rates. Differences in maintenance visit times were observed, with CDs and ODs in the mandible requiring earlier visits compared to IODs.

Purpose: The objective of the study was to determine the values of 15 craniofacial linear distances in the Serbian ethnic group and the correlations between them that are predictive or can serve as proxy for OVD using and compare two methods of face-anthropometric and digital 2D face-photogrammetric measurement. Material and methods: A total of 90 adults were selected. Facial distance as a tool to measure the OVD was Sn-Gn - distance between septum of the nose (Sn) and tip of the chin (Gn). Face-anthropometric measurements were made with a Boley Gauge (Buffalo Dental Manufacturing Co.NY,USA). Digital 2D photogrammetric facial measurements were performed using the computer program DrCeph (FYI Technologies, USA). Results: Determined mean value for the distance Sn-Gn by face-anthropometric was Sn-Gn(f) X=63.55 and by face-photogrammetric was Sn-Gn(ph) X=63.56. Multivariate regression analysis revealed that Sn-Gn(f) depended on ExL-ExR(f)  p<0.001, ZyL-ZyR(f) p=0.077, N-Sn(f) p=0.096, Sn-Sto(f)  p=0.043 and gender and that Sn-Gn(ph) depended on ExL-ExR(ph) p<0.001, EnL-EnR(ph) p=0.029, N-Sn(ph) p=0.013, Sn-Sto(ph) p=0.001 and gender. Conclusions: A comparison of facial anthropometry and digital 2D facial photogrammetry reveals no statistical significance differences in the values obtained and shows that facial photogrammetry could be a reliable method as a facial anthropometry.

Purpose: The aim of the current study is to evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intra-coronal preparation designs. Materials and Methods: An examination of the marginal adaption of two materials, lithium disilicate (IPS e.max CAD) (EX) and polymer infiltrated ceramic network material (PICN; Vita Enamic) (EN), and two preparation designs where D1 represents MOD inlay preparation with no cusp reduction and D2 in addition of the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. 4 sub-groups (EX-D1), (EX-D2), (EN-D1), (EN-D2) were  conducted. Forty (n=40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, standard deviation (Sd), minimum, maximum, and 95% confidence interval. Pair-wise comparisons using Tukey's Post-Hoc test were performed following a significant analysis of variance (ANOVA) P ≤ 0.05. Results: The results revealed that lithium disilicate (IPS e.max CAD) showed statistically significantly higher mean gap distance than polymer infiltrated ceramic network material (PICN; Vita Enamic) (61µm to 99µm). Pair-wise comparisons showed that D2 design has statistically significant higher mean gap values than D1. Conclusions: Both lithium disilicate (IPS e.max CAD) or polymer infiltrated ceramic network material (PICN; Vita Enamic) provided marginal adaptation within clinical accepted range. Polymer infiltrated ceramic network material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional Preparation. 

Purpose: To determine the average time it takes for patients to adapt to mandibular complete dentures and the factors associated with this critical period. Materials and methods: A total of 108 completely edentulous patients were rehabilitated using complete dentures. Adaptation was evaluated based on the following criteria: mastication, comfort, speech, and swallowing with dentures. Kaplan-Meier analyses were used to estimate the average time to adaptation. Log-rank test was used to assess the adaptation period and associated factors. Results: Of the 108 rehabilitated patients, 89 had adapted to mandibular complete dentures at the 6-month follow-up. The mean time to adaptation estimated from the Kaplan-Meier curve was 78.54 days (95% CI: 71.04 to 86.04). The factors associated with the adaptation period were previous experience with a mandibular denture (P = .032), the professional who made the previous complete dentures (P = .034), frequency of appearance of traumatic lesions after 15 days of rehabilitation (P = .023), posterior mandibular ridge height (P = .005), and regular use of the new dentures (P = .002). Conclusion: Most patients adapted to mandibular dentures after 2.6 months. No prior mandibular denture experience, use of old dentures made by a dental technician, occurrence of traumatic injuries 15 days after complete denture delivery, presence of a resorbed posterior mandibular ridge, and nonregular wear were associated with longer adaptation time to the new mandibular complete dentures.

Purpose: To report on the follow-up of two earlier published RCTs on the performance of screw-retained monolithic zirconia restorations on Ti-base abutments based on intraoral optical scanning or conventional impressions. Materials and Methods: A total of 54 patients receiving 89 restorations (44 single crowns [SC]), 21 splinted crowns [2-FDP], and 24 three-unit fixed partial dentures (3-FDP)] were included in the 1- to 3-year follow-up period. The restoration survival and technical complications were documented. Results: A total of 50 patients with 84 restorations completed the 3-year follow-up. One 3-FDP from the IOS group was lost. This resulted in survival rates of 97.9% for the test and 100% for the control restorations and an overall survival rate of screw-retained monolithic zirconia restorations on implants of 98.8% after 3 years. There was no statistically significant survival difference between the test and control groups (P = .362). When evaluated separately, a 100% survival rate for SCs and 97.7% rate for 2-FDPs was reported. One decementation and three occurrences of screw loosening occurred over the 1- to 3-year follow-up. The multiple-implant restorations showed higher (23.3%) complication rates at the restoration level than the SCs (4.9%) after 3 years of function (P = .026). Conclusion: Screw-retained monolithic zirconia restorations on Ti-base abutments show promising survival rates after 3 years of function. Restorative complications of screw-retained monolithic zirconia restorations on Ti-base abutments are more likely to happen in the first year of function and are more common in multiple-implant restorations than solitary crowns. The impression (IOS or conventional) does not seem to influence these results.

This case report describes a novel approach combining orthodontic and implant digital treatment planning workflows to enable prosthetically driven implant placement before orthodontic treatment is performed or completed. The computer-assisted implant placement is performed using a static surgical guide based on the future positions of the teeth after completion of orthodontic treatment. This innovative approach allows for select partially edentulous patients to undergo fixed prosthetic rehabilitation before orthodontic treatment is completed.

Purpose: To evaluate the effect of tooth brushing and dentifrice fluoride (F^-) concentration on changes in color and translucency (ΔE₀₀ and ΔT₀₀, respectively), surface gloss (GS), surface roughness (Sa), and microstructure of a glazed CAD/CAM ceramic. Materials and methods: Ceramic blocks (e.max/CAD) were sectioned into rectangular plates (14 x 12 x 1 mm), and one surface of each sample was glazed. Samples were divided into three groups according to the F- concentration in the dentifrice (0, 1,100, and 5,000 μg/g) and were then subjected to 60,000 tooth brushing cycles. Luminosity and color were measured using a spectrophotometer at baseline and after every 20,000 cycles to obtain their ΔE₀₀ and ΔT₀₀ values. Another set of samples was prepared to measure the GS with a gloss meter and the Sa with a confocal laser microscope. The GS and Sa results were subjected to analysis of variance, Tukey test, and Dunnett test (α = .05). Results: After 60,000 tooth brushing cycles, all of the variables were clinically acceptable, and there were no significant differences in the ΔE₀₀, ΔT₀₀, GS, or Sa among the fluoridated dentifrices. The GS values decreased significantly as the number of tooth brushing cycles increased. Conclusion: The ΔE₀₀, ΔT₀₀, GS, and Sa values were all clinically acceptable after the glazed e.max/CAD ceramic had been subjected to 60,000 tooth brushing cycles with dentifrices containing up to 5,000 μg/g of F^-.

Purpose: To compare the CIE L*a*b* values of two different dental shade guides using two shade-matching spectrophotometers. Materials and methods: SpectroShade Micro (MHT) and Easyshade (VITA Zahnfabrik) were tested. One calibrated operator performed 30 measurements of each tab from three batches of two guides, VITA Classical (VC) and VITA 3D-Master (VM). Receiver operating characteristic (ROC) curves and intraclass coefficients (ICC) between the different batches were calculated. Results were given as mean and SD of the L*a*b* values and the respective color differences according to the CIEDE 2000 formula (ΔE₀₀) for each of the shade tabs in the two spectrophotometers, then analyzed with independent student t test (α = .05). Results: A total of 1,440 and 2,610 measurements for VC and VM, respectively, were performed per spectrophotometer. There were statistically significant differences between the two devices for all L*a*b* values, with the exception of: L* for 3R1.5; a* for 2R1.5, 3L1.5, 2L2.5, 3M2, 3L2.5, 4L1.5, and 4L2.5; and b* for D3, 1M2, and 3M2. When assessing the same shade guide, differences in ΔE₀₀ were detected between devices above the acceptability threshold (ΔE₀₀ ≥ 1.8) for all shade tabs except for VC (C1, C2, D3, A3.5, C3, and A4) and VM (4M1, 3R2.5, 4L2.5, and 4M3). The overall mean of the inter-device ΔE₀₀ was 2.2 ± 1.0 for VC and 2.5 ± 1.0 for VM. Conclusion: The two dental spectrophotometers presented high ICC and ROC values, which validates their indication as auxiliary tools. However, there are discrepancies in the hues D (VC) and R (VM) with interdevice variability when evaluated for the L*a*b* component.

Purpose: To investigate the physical and mechanical behavior of polyether ether ketone (PEEK) before and after thermocycling and its potential use as a more durable prosthetic component for implant-supported and -retained removable dental prostheses (I-RDP). Materials and methods: Roughness and surface hardness were evaluated in specimens obtained using the subtractive method (n = 20) with Ø 9 mm and 2 mm of thickness, and retention force was measured in attachments with Ø 4 mm and 3 mm of height. For fatigue resistance test, a polyurethane matrix with two ball-abutment implants (MDL, Intra-Lock International) was used to simulate the mandibular alveolar ridge. A total of 40 attachments (n = 20 pairs) were captured in acrylic resin blocks using a technique analagous to the direct clinical pick-up of overdenture female attachments and submitted to 2,900 insertion/removal cycles to simulate 24 months of overdenture use. Physical analyses were performed by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and differential scanning calorimetry (DSC) before and after thermocycling (5° C to 55°C for 10,000 cycles). After normal distribution was verified by Shapiro-Wilk test, one-way analysis of variance (ANOVA) was applied to analyze the surface roughness and hardness, and two-way ANOVA with Bonferroni adjustment was used to assess the retention force (α = .05). Results: Thermocycling did not change the PEEK surface roughness or hardness (P > .05). As for the retention force, the highest average was observed after the thermocycling test (P = .006). Conclusion: Based on the FTIR, XRD, and DSC results, PEEK crystallinity decreased after thermocycling, and the physical and mechanical behavior of this polymer was compatible with the proposed application, attesting that it is a component of greater durability for I-RDPs.

Purpose: To evaluate the performance of fully (Celtra Duo, Dentsply Sirona) and partially (VITA Suprinity, VITA) crystallized zirconia-reinforced lithium silicate and partially sintered lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging. Materials and methods: Specimens of each glass-ceramic were subjected to polishing with rubber cups (POL), glazing (GL), or control (C; no treatment) and afterwards aged with 18,000 thermal cycles (5°C to 55°C). The average roughness (Ra), 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated by atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and flexural strength test (n = 10), respectively. Data were analyzed using two-way analysis of variance and Tukey test (α = 5%). Results: POL promoted lower Ra than glazing, and Celtra Duo presented higher Ra than IPS e.max CAD (P < .05). Surfaces without polishing promoted higher Ra than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glass-ceramic. Irrespective of the treatment, the contact angle was higher in Celtra Duo, and regardless of the material, there was higher biofilm formation and lower flexural strength of unpolished compared to POL or GL ceramics. Conclusion: Polishing with rubber cups promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the glazed surface. In general, Celtra Duo and VITA Suprinity showed similar behavior to IPS e.max CAD, which makes zirconia-reinforced lithium silicate glass-ceramics a good option for indirect restorations.

Purpose: To assess whether implant-retained prostheses produced with a laser-sintering technique present accuracy and passive fit comparable to their milled counterparts. Materials and methods: Two Regular Neck Straumann analogs were placed in a block of polymethyl methacrylate (PMMA) at 15 mm of distance and parallel to one another. The PMMA block was then scanned, and two groups of cobalt-chromium (Co-Cr) screw-retained, three-unit implant prostheses were fabricated using milling (control) and laser sintering (test) techniques. The prostheses were then screwed on the PMMA block, and the vertical marginal gap between the prostheses and the analogs at the implant-abutment junction was measured twice: (1) when only one screw was tightened, and (2) when both screws were fully tightened. The mean marginal gap measurements were compared to assess the difference in terms of passive fit between the laser-sintered and milled prostheses. Results: The mean marginal gap of the milled and laser-sintered groups was 23.18 μ (SD = 6.2) and 23.71 μ (SD = 19.5), respectively. Conclusion: Laser-sintered prostheses presented a marginal fit comparable to milled.

Purpose: To develop an instrument for the assessment of perception of orofacial appearance and psychologic issues that can affect peoples' judgments. Materials and methods: A panel composed of five members (one psychologist, two prosthodontists, one orthodontist, and one final-year dental student) generated 31 items that could draw specific hypothetical dimensions. The questionnaire was self-administered by individuals attending local high schools and university (N = 261; 26.4% men) in the 14- to 28-year age range. Internal consistency, construct validity, responsiveness, and temporal stability were assessed. Results: Factorial analysis and Cronbach's alpha identified four dimensions (self-esteem, perfectionism, body image, and smile appearance concern) that could be best fitted by 17 items. Internal consistency was good (α in the 0.70 to 0.80 range). The dimensions were correlated with existing instruments that measure similar constructs. In responsiveness testing, tooth whitening did not induce changes in perfectionism or body image; however, it did increase self-esteem and decreased esthetic concern (P < .05). Conclusion: The newly created questionnaire is a consistent and reliable short instrument that measures psychologic issues related to the perception of orofacial appearance.

Purpose: To assess the retention and adaptation of milled and printed denture bases and to compare them to conventional ones. Materials and methods: A total of 24 completely edentulous patients were selected. For each patient, three maxillary denture bases were constructed. Three groups were defined according to fabrication technique: group I = denture bases were constructed by a conventional technique; group II = denture bases were milled from prepolymerized blocks of polymethyl methacrylate; and group III = denture bases were fabricated by a 3D printing technique. A digital force gauge was used for measuring the retention of the denture bases intraorally, while Geomagic Control X 64 software was used to evaluate the adaptation of the denture bases with their corresponding master casts. Analysis of variance for repeated measures was used for comparison among the groups, followed by pairwise comparison with Bonferroni correction as a post hoc test. The significance level was set at α = .05. Results: Statistical analysis showed significant differences among the three groups regarding retention and adaptation. The highest values of retention and adaptation of denture bases were found in group II (milling group). Conclusion: Within the limitations of this study, the following could be concuded: milled denture bases demonstrated better retention and adaptation than the conventional heat-polymerized and the printed denture bases; and printed denture bases showed better adaptation but similar retention to conventional heat-polymerized denture bases.

Purpose: To measure the influence of postpolymerization condition (dry or submerged in water) and time (2, 10, 20, and 40 minutes) on the accuracy of additively manufactured model material. Materials and methods: A bar standard tessellation language file was used to manufacture the resin specimens (E-Model Light, EnvisionTEC) using a 3D printer (Vida HD, EnvisionTEC). Two groups were created based on the postpolymerization condition: dry (D group) or submerged in water (W group). Each group was divided into four subgroups (D1 to D4 and W1 to W4) depending on the postpolymerizing time (2, 10, 20, and 40 minutes; n = 20 each; N = 160). The specimen dimensions were measured using a low-force digital caliper (Absolute Low Force Caliper Series 573, Mitutoyo). The volume was calculated: V = l × w × h. Shapiro-Wilk test revealed that the data were not normally distributed. Data were analyzed using Kruskal-Wallis and pairwise Mann-Whitney U tests (α = .05). Results: Significant differences in length, width, height, and volume values were found among the subgroups (P < .0018). In all groups, the width dimension (x-axis) presented the worst accuracy compared to height (z-axis) and length (y-axis) (P < .0018). The D2 and D4 subgroups obtained the closest dimensions to the virtual design; additionally, no significant differences were found between the two subgroups (P < .0018). Dry condition showed higher manufacturing accuracy compared to the water-submerged condition. In the water-submerged subgroups, the highest accuracy was obtained in the W2 and W4 subgroups (P < .0018). Conclusion: Postpolymerization conditions and time influenced the accuracy of the material tested. Dry postpolymerization condition with a time of 10 and 40 minutes obtained the highest accuracy.

Purpose: To evaluate the efficacy of cleaning protocol in decontamination of organic compounds from polished zirconium oxide samples. Materials and methods: A total of 24 rectangular plate specimens were sintered from zirconium oxide. All samples were polished with commercially available polishers (course, fine, and superfine) and polishing paste. During the first step of the protocol, all specimens were cleaned with steam. After that, samples were randomly assigned to one of three groups (n = 8 each): A, B, and C. In group A, no additional cleaning was performed, while specimens of group B underwent an ultrasonic cleaning in distilled water. Group C specimens were cleaned in an ultrasonic bath with a special detergent solution. After washing, samples were subjected to energy-dispersive x-ray spectroscopy (EDX) and scanning electron microscope examination. In order to detect organic materials, the level of carbon atoms was measured. Results: EDX analysis revealed that samples in group A had the highest percentage levels of carbon atoms (9.57 ± 3.67) on the surface compared to the other cleaning protocols. The group B cleaning protocol resulted in lower carbon levels (4.73 ± 3.56), but the difference was not significant from only steam-blasted ones (P = .439). All specimens in group C had no detectable carbon atoms (0), which implies that all wax molecules had been removed (P < .05). Conclusion: Only following the group C cleaning protocol can total decontamination of the polished zirconium surface from organic compounds be expected. Therefore, it is advised to employ an ultrasonic bath with detergent solution for cleaning procedures of zirconium abutments before delivery.

Purpose: To evaluate the application of chitosan as a cleanser in the control of biofilm formation on cobalt-chromium (Co-Cr) alloy and acrylic resin surfaces. Materials and Methods: In total, 172 Co-Cr discs and 172 acrylic resin discs (14 mm x 3 mm) were contaminated with Streptococcus mutans, Staphylococcus aureus, Candida albicans, or Candida glabrata and incubated for 48 hours. Then, specimens were randomly divided into groups and immersed in the following solutions for 15 minutes: WC = solution without chitosan (control); CH = chitosan solution (5 mg/mL); CN = chitosan nanoparticle solution (3.8 mg/mL); and ET = effervescent tablet. Biofilm recovery rates (n = 9) were evaluated by counting the colony-forming units (CFU/mL). Biofilm morphology was evaluated using scanning electron microscopy. Data were compared with Kruskal-Wallis or analysis of variance followed by Tukey post hoc tests. Results: For acrylic resin, ET showed the lowest number of CFU for S aureus and S mutans (P < .001). CH exhibited intermediate values for S mutans, S aureus, and C albicans, and CN exhibited intermediate values for S mutans and S aureus. For C glabrata, there was no statistical difference between the solutions (P = .264). For Co-Cr, ET showed the highest level of antimicrobial action against all microorganisms (P < .001), and CH showed an intermediate level of action against S mutans and S aureus. Against C albicans and C glabrata, there was no significant difference among CH, CN, and WC. Conclusion: Although ET had a broader spectrum of antimicrobial action, the chitosan solution showed promise as a denture cleanser. Int J Prosthodont 2021.

Purpose: To clinically evaluate oral implant restorations placed by undergraduate students in the dental clinical curriculum at KU Leuven (Belgium) in terms of function and esthetics. Materials and methods: A retrospective observational cohort study was designed. The esthetic and functional evaluations of implant-supported restorations placed in the framework of the undergraduate implant dentistry clinical training program using White/Pink Esthetic Score (WES/PES) and visual analog scale (VAS) scoring was performed. Furthermore, complications were registered based retrospectively on the patient's medical file. The following research questions were stipulated: (1) How well do implant-supported restorations placed by undergraduate students perform esthetically? and (2) Which complications occurred and how were these managed? Results: Between August 2008 and July 2014 (6 academic terms), 251 implants (Brånemark System Mk III, Nobel Biocare) were placed in 113 patients by 155 students (> 40% of all students enrolled in the training program). Of these implants, 228 were restored in 101 patients by 118 students with varying restoration types. Esthetic scoring of the restorations in 83 of these patients revealed a satisfying mean WES of 8.14 ± 2.09 (out of 10) and PES of 9.56 ± 3.14 (out of 14). Complications were registered in 18.9% of the cases. Discussion: Clinical training in implant dentistry for undergraduates contributes to the development of advanced skills in the dental student's Master education. Overall, patients were satisfied with their implant-supported restorations. Implant and restoration success rates and complication incidence were confirmed by long-term data in the oral implant literature.

Purpose: To evaluate the dimensional discrepancy between the diagnostic wax-up and the resulting mock-up. Materials and methods: A maxillary model with misaligned teeth was scanned, and an initial cast was 3D printed. A total of 60 identical casts were 3D printed from the initial one after scanning, and based on a digital additive veneer wax-up on the 6 anterior teeth, 10 more casts were 3D printed. The specimens were allocated to seven groups (n = 10 each). Group 1: transparent silicone matrix with a flowable light-curing composite resin; group 2: same as group 1, with the addition of a prefabricated transparent tray; group 3: silicone impression putty (65 on the Shore A hardness scale) and light-body silicone impression material with a dual-curing bis-acryl resin; group 4: same as group 3 without light-body silicone; group 5: silicone laboratory putty (92 Shore A) with a dual-curing bis-acryl resin; group 6: silicone laboratory putty (92 Shore A) with PMMA; and group 7: wax-up casts (control). Scans from the mock-ups were co-registered, segmented, and superimposed with the scans from the wax-up. The difference of the mock-up compared to the wax-up was quantified using morphologic operations. The results were analyzed with Kruskal-Wallis test and Dunn post hoc test (P < .05). Results: All mock-ups were larger in size in comparison to the wax-up. Significant differences were found for every labial surface third. The incisal third was the most inaccurate third, while the middle third was the most accurate. The most accurate groups were 2 and 5, and the largest discrepancy was observed in group 6. Conclusion: The analog mock-up differed dimensionally from the wax-up, irrespective of the technique/materials used.

Purpose: To compare in a randomized controlled trial the 5-year clinical outcomes of (1) 3-unit fiber-reinforced resin-bonded fixed dental prostheses (RBFDPs) to 3-unit metal-ceramic RBFDPs; and (2) 3-unit fiber-reinforced RBFDPs to 2-unit cantilevered metal-ceramic RBFDPs. Materials and methods: A consecutive sample of 50 young adult patients with tooth agenesis or trauma in the anterior region was included. The recruitment period was from 2005 to 2009, during which a total of 62 RBFDPs were inserted. In group A, 27 participants were randomly treated with 18 metal-ceramic 3-unit RBFDPs and 15 3-unit fiber-reinforced RBFDPs. In group B, 23 participants were randomly treated with 16 metal-ceramic 2-unit RBFDPs and 13 3-unit fiber-reinforced RBFDPs. All patients were followed up at baseline registration and at 1, 3, and 5 years. The primary outcome parameter was survival rate of the RBFDPs, and the secondary outcome parameters were periodontal and technical/esthetic outcomes and patient-reported evaluation of the RBFDPs. Results: Seven patients dropped out of the study during the 5-year observation period. In group A, the fiber-reinforced RBFDPs had a cumulative survival rate of 23% after 5 years, which was significantly less than for the 3-unit metal-ceramic RBFDPs. In group B, the cumulative 5-year survival rate was 36% for the fiber-reinforced RBFDPs and 91% for the 2-unit cantilevered metal-ceramic RBFDPs. Conclusion: The 3- and 2-unit metal-ceramic RBFDPs had a significantly higher 5-year survival rate than the 3-unit fiber-reinforced RBFDPs. The accessibility for oral hygiene practice was better with 2-unit compared to 3-unit RBFDPs, and the degree of gingivitis was lower. The esthetic outcome was better for the RBFDPs with ceramic pontics than the composite ones.

Purpose: To evaluate the effect of cavity tapering on the marginal and internal adaptation of endocrowns fabricated from two different ceramic materials. Materials and methods: Two mandibular molar model teeth were prepared with two different cavity tapers (5 and 10 degrees). Forty endocrowns in four groups (n = 10 each) were milled using lithium disilicate and zirconiareinforced lithium silicate ceramics for each cavity taper. The marginal and internal adaptation were measured with a stereomicroscope (×30) at 18 different points. The data were statistically analyzed using independent t test (P < .05). Results: A statistically significant difference was shown among the tested groups at 10 degrees of taper (P < .001). At 5 degrees of taper, the difference was insignificant. The greatest internal gap was observed on the pulpal floor in all tested groups. Conclusion: All materials had clinically acceptable internal and marginal gaps; however, lithium disilicate ceramic had significantly better adaptation at 10 degrees of taper.

Purpose: To evaluate the fracture behavior of monolithic crowns made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent; and Initial LiSi Block, GC) and zirconia-reinforced lithium silicate (Celtra Duo, Dentsply Sirona; and Suprinity, VITA) materials before and after cyclic fatigue aging. Materials and methods: Four groups (n = 22 per group) of CAD/CAM-fabricated maxillary incisor crowns were produced. All crowns were luted on metal dies with an adhesive dual-curing resin cement (G-CEM LinkForce [GC]). Half of the crowns in each group (n = 11) were statically loaded to fracture without aging. The remaining half were subjected to cyclic fatigue aging for 120,000 cycles (F_max = 220 N) and then loaded statically to fracture. Fracture mode was then visually examined. Scanning electron microscopy and energy-dispersive spectroscopy were used to evaluate the microstructure of the CAD/CAM ceramic materials. The data were statistically analyzed with two-way analysis of variance followed by Tukey honest significant difference (HSD) test (α = .05). Results: Before cyclic aging, there was no statistically significant difference in load-bearing capacity among the four groups (P = .371). After cyclic aging, the load-bearing capacity significantly decreased for all groups (P = .000). While the e.max CAD blocks had significantly higher load-bearing capacity (1,061 ± 94 N) than both monolithic ceramic crowns (P < .05), no significant difference was obtained compared to the Initial LiSi Block group (920 ± 140 N) (Tukey HSD P = .061). Conclusion: The mechanical performance of monolithic ceramic crowns fabricated from lithium disilicate was better than zirconia-reinforced lithium silicate after cyclic fatigue aging.

Purpose: To evaluate the fracture strength of endodontically treated molars filled with different composite resins, with or without fiber reinforcement. Materials and methods: A total of 60 intact mandibular molars were selected and endodontically treated. A standardized mesio-occlusal-distal cavity was prepared with cervical margins 1 mm above the cementoenamel junction and oral and buccal walls with 1.5-mm remaining thickness. Universal adhesive was used in all specimens in etch-and-rinse mode. Specimens were divided into four groups (n = 15 each) according to restoration technique: CSM group, adhesive overlay with hybrid ceramic (CeraSmart, GC); EXP group, direct composite restoration (Essentia U, GC) and everX Posterior (GC) as core material; ESU group, direct composite restoration (Essentia U); and EST group, direct composite restoration (Essentia U) reinforced with horizontal bidirectional glass fibers placed over the pulpal chamber floor (everStick-Net, GC). After 7 days of water storage, samples were loaded until fracture using a universal testing machine. The maximum breaking loads were recorded in Newtons (N), and statistical analysis was then conducted with two-way analysis of variance and post hoc Tukey test. Fragments were analyzed using scanning electron microscopy. Results: Mean fracture resistance was: CSM = 1,428.9 ± 316.90 N; EXP = 1,874.57 ± 299.47; ESU = 1,557.44 ± 355.65; and EST = 1,870.27 ± 145.11. CSM and EXP showed the highest strength values when compared to the other groups. The variable "fiber insertion" did not significantly alter the fracture resistance. Origins of the fractures were always located on the occlusal surface, mainly from the major contact loading area. Conclusion: The use of everX Posterior showed great improvement in fracture resistance, similar to cuspal coverage restoration. However, only short fiber-reinforced composite resins showed a favorable fracture pattern.

Purpose: To investigate the influence of occlusal interference in dental prosthetics using finite element analysis (FEA). Materials and methods: The FEA model designed for this study centered on an all-ceramic, bi-layered, fixed partial denture (FPD) retained on the maxillary first premolar and molar, with the second premolar replaced by a pontic. The surrounding structures, such as the neighboring teeth, antagonists, and periodontium, were modeled. Four different load cases were designed at occlusal interferences of 0, 8, 12, and 24 μm, loaded by a simulated bite force of 300 N. Principal and von Mise stresses, as well as strain, were evaluated for all included structures. Results: For interferences of 12 and 24 μm, failure-relevant tensile stresses in the veneering layer were observed at the occlusal surfaces. Stress found in the zirconia FPD did not reach fatigue or flexural strength for any test load. Conclusion: Peak tensile stress was observed in close proximity to occlusal contact points, increasing with increasing occlusal interference. The FEA results suggested that the majority of occlusal stress is absorbed by the deformation of the periodontal ligament. Framework failure caused by the simulated interferences was not expected. Surface defects may ultimately lead to failure due to fracture or chipping, especially in cases of weaker ceramics or veneering.