The International Journal of Prosthodontics, 03/2020

Purpose: To evaluate the influence of facial type and anteroposterior skeletal discrepancy of complete denture wearers on residual ridge height, masticatory performance, oral health–related quality of life (OHRQoL), and satisfaction levels. Materials and Methods: A total of 56 edentulous patients (mean age of 67.1 years) were radiographically evaluated prior to rehabilitation to determine residual ridge height in the maxilla and mandible, facial type, and anteroposterior skeletal discrepancy. Masticatory performance tests with 40 chewing cycles were applied. The Dental Impact on Daily Living questionnaire was used to measure OHRQoL and satisfaction. Data were analyzed with Kruskal-Wallis test and logistic regression. Results: Dolichofacial participants presented with significantly higher bone height than mesofacial and brachyfacial types in the anterior region of the maxilla and mandible and had more mandibular bone than mesofacial types in the premolar region. Class II patients presented significantly higher bone height than Class I participants in the anterior maxilla. Dolichofacial patients performed significantly better than brachyfacial patients in the masticatory performance test. Class I patients achieved more homogenous artificial food trituration than Class III patients (P .05). High OHRQoL scores were reported in appearance and general performance irrespective of facial type or anteroposterior skeletal discrepancy. Conclusion: Dolichofacial patients had superior masticatory performance compared to brachyfacial patients. Class III patients showed a reduced capacity to homogenize the food bolus. Mesofacial, dolichofacial, and Class III patients reported the best perceptions of their OHRQoL. Anteroposterior skeletal discrepancy seems to be the main factor contributing to mastication impairments in totally edentulous patients.

Purpose: To analyze the clinical behavior of screw-retained monolithic lithium disilicate (LDS) implantsupported single crowns (ISSCs) over a 1-year follow-up. Materials and Methods: A total of 28 patients were restored with 45 screw-retained monolithic LDS (press-fabricated) ISSCs bonded to titanium bases in posterior sites. Modified United States Public Health Service criteria and Kaplan-Meier survival and success rates were evaluated. Results: A total of 27 patients with 44 ISSCs were evaluated 12 months (mean ± standard deviation: 13.02 ± 2.28) after prosthesis delivery. No implant or crown failures occurred. The Kaplan-Meier survival and success rates were each 100% after 1 year. Minorly increased surface roughness was noted in the occlusal contact point areas of 9 ISSCs (20.5% Bravo rating). Marginal adaptation, color match, and anatomical form stayed favorable over time. Conclusion: Press-fabricated LDS monolithic screwretained implant crowns appear to be a promising treatment option for posterior implants under short-term observation.

Purpose: To visually and spectrophotometrically determine the differences in the shades of maxillary anterior implant crowns and peri-implant soft tissues compared to a natural teeth control group. Materials and Methods: A total of 44 patients restored with single implant–supported restorations were assessed after at least 6 months in function. Images of the implant crowns, peri-implant soft tissues, and their controls were captured using a spectrophotometer (SpectroShade Micro, Medical High Technologies). Visual assessment of shade differences between the implant crowns and peri-implant soft tissues and their controls were performed by the patients and four dental professionals using a visual analog scale (VAS). Analysis of variance was applied to detect differences between groups. Results: The mean color differences (ΔE) between the implant crowns and peri-implant soft tissues and their respective controls were 4.8 ± 2.6 and 6.6 ± 2.7, respectively. A significant difference (P = .025) in mean ΔE values was observed only at the cervical third of the implant crowns. The patient group showed the highest mean VAS scores for shade matching of the implant crowns (8.4 ± 1.2) and peri-implant soft tissues (7.8 ± 1.6) with their respective controls. Conclusion: Spectrophotometric analysis showed significant shade differences at the cervical third of the implant crowns. The patients were more satisfied with the shade matching of their implant restorations than the dental professionals.

Purpose: To determine the prevalence of possible tooth grinding (TG) and possible sleep bruxism (SB) and to examine their impacts on oral health–related quality of life (OHRQoL) among Asian adults. Materials and Methods: A total of 3,072 subjects (18 to 65 years of age) from 12 dental centers were invited to complete a self-administered questionnaire on TG/SB and OHRQoL, and 2,417 were included in the study. Participants were subsequently categorized into three groups (no TG/SB, possible TG, and possible SB) based on the International Classification of Sleep Disorders. The 14-item Oral Health Impact Profile (OHIP-14) severity, extent, and prevalence scores were subsequently computed and compared. Data were examined using Kruskal-Wallis and Mann-Whitney U tests, Spearman correlation, and univariate regression analysis (P .05). Results: Of the 2,417 subjects (mean age 24.79 ± 7.49 years), 42.82% reported either possible TG (n = 921; 38.11%) or possible SB (n = 114; 4.72%). Significant differences in global and domain OHIP-14 scores were found between the groups, except for the extent scores in functional limitation and physical disability. Mean global severity scores of the possible SB group (9.36 ± 9.45) were 1.5- and 2.2-fold larger than the possible TG (6.39 ± 7.61) and no TG/SB (4.22 ± 6.15) groups, respectively. A significant but weak correlation (r = 0.14 to 0.19) was found between the number of positive responses for TG/SB and OHIP-14 severity scores. Conclusions: A high prevalence of possible TG and SB was found among the Asian cohort studied. Possible TG and SB were significantly associated with poorer OHRQoL. The physical pain, psychologic discomfort, and psychologic disability domains were most influenced by TG/SB. More epidemiologic studies on the functional, physical, and psychosocial influences of SB are required.

Purpose: To assess the 10-year clinical retention and survival rates of metal-ceramic (MC) and all-ceramic (AC) cantilever resin-bonded fixed dental prostheses (CRBFDPs). Materials and Methods: Forty CRBFDPs constructed from either cobalt-chromium ceramic (MC group; n = 20) or glass-infiltrated alumina ceramic (AC group; n = 20) were placed in 40 patients between August 2007 and December 2009. After baseline recordings, the patients were followed up using modified United States Public Health Services (USPHS) criteria after 6 months and thereafter annually for 10 years. Data were statistically analyzed using Kaplan-Meier estimation with log-rank (Mantel-Cox) test. Results: The 10-year clinical retention rate was 95.0% in the MC group and 70% in the AC group. The difference was statistically significant (P = .02, log-rank test). Three all-ceramic CRBFDPs fractured at 6, 12, and 84 months after insertion. No statistically significant difference in survival rate was observed between the MC and AC groups over the 10 years of clinical observation (MC: 100%; AC: 85%; P = .075) (Kaplan-Meier method, confidence interval = 92.5% to 97.5%). Conclusion: Although glass-infiltrated alumina ceramic anterior CRBFDPs exhibited a lower clinical retention rate compared to metal-ceramic CRBFDPs, the debonded prostheses were recemented and continued in function over the observation period. Additionally, an acceptable 10-year clinical longevity was recorded.

Purpose: To evaluate the effect of different abutment morphologies on peri-implant hard and soft tissue behavior. Materials and Methods: The focus question for this literature search was: What are the effects of different abutment morphology (concave vs convex) on peri-implant hard and soft tissue behavior? Randomized clinical trials (RCTs) with a minimum sample size of 20 implants (10 per group) and a follow-up period of at least 3 months after implant loading were considered eligible for this study. This review excluded studies comparing different abutment heights or surfaces and different implant shapes. Two different metaanalyses were performed: one for marginal bone loss (MBL) to evaluate hard tissue changes, and one for Pink Esthetic Score (PES) as an indicator of soft tissue modifications. Results: Four publications from 12 full texts analyzed were included. The meta-analysis (data from 117 patients and 173 abutments) indicated that a statistically significant difference (P .00001) was detected from the data regarding MBL between the two groups (mean difference = –0.21 [95% CI: –0.25, –0.16]), but not considering the PES (mean difference = –0.69 [95% CI: –2.08, 0.70]) after a minimum period of 3 months after implant loading. All such evidence was confirmed by the trial sequential analysis on both MBL and PES. Conclusion: The results demonstrate that abutment design may have an influence on MBL but no impact on soft tissues. However, the existing evidence is moderate, as few RCTs were conducted and follow-up periods were short.

Purpose: To analyze the impact of different veneering techniques on the fracture load of telescopic secondary crowns made of a high-performance polymer (Ultaire aryl ketone polymer [UAKP]). Materials and Methods: Zirconia primary crown models (taper of 0 degrees) were prepared (N = 48), polished, scanned, and divided into four veneering groups (n = 12 each): premanufactured, digital, full anatomical, and vestibular. For all groups except vestibular, a standardized telescopic secondary crown (thickness: 0.6 mm, circular margin: 1 mm) was constructed, adapted to the corresponding primary crown, milled from UAKP, and veneered. The veneered master crown was developed based on the premanufactured group. After surface polishing, all specimens were artificially aged in a chewing simulator (1.2 million cycles, 50 N, 1.1 Hz, between 5°C and 55°C). Fracture load was tested in a universal testing machine with a piston (Ø = 6 mm, 1 mm/minute). Fracture patterns were analyzed. For statistical analysis, Kolmogorov-Smirnov test and descriptive statistics followed by one-way ANOVA with post hoc Scheffé test were conducted (P .05). Results: Significant differences in fracture load were found between different veneering techniques (P .001), with the highest values for the vestibular and digital groups, followed by the premanufactured group. Full anatomical veneering showed the significantly lowest fracture load (1,885 ± 397 N). For all specimens, cohesive brittle fractures with similar fracture patterns occurred, irrespective of the veneering technique. Conclusion: The veneering technique of telescopic secondary crowns made of high-performance polymer affects overall stability. All veneering techniques provided sufficient fracture load values for telescopic secondary crowns made of UAKP. Digital veneers seem the most recommendable.

Purpose: To evaluate the antimicrobial activity of effervescent tablets on the surfaces of cobalt-chromium (Co-Cr) and heat-polymerized resin. Materials and Methods: From a metal matrix, 55 circular wax patterns (Ø 12 × 3 mm) were obtained and cast in Co-Cr alloy. Muffles for acrylic resin were prepared from circular wax patterns (Ø 20 × 5 mm). The metal specimens were positioned in the muffle, and the resin was pressed into its surroundings to simulate the composition of a removable partial denture (RPD). The mixed specimens were sterilized and contaminated with Streptococcus mutans, Staphylococcus aureus, Candida albicans, and Candida glabrata, composing a multispecies biofilm, and subsequently immersed according to the manufacturer's instructions in four cleansing solutions: Polident 3 Minute denture cleanser (P3M), Polident for Partials (PP), Corega Tabs (CT), and NitrAdine (Ni); as well as distilled water (positive control) and no contamination (negative control). After cleansing, viable microorganisms were quantified by counting the number of colony-forming units (CFU/mL). From the CFU values, log10^{(CFU + 1)} values were calculated for statistical analysis. Kruskal-Wallis test with Dunn post hoc test were performed (α = .05). Results: There was a significant reduction (P = .001) of S mutans after immersion in Ni (median [95% CI] 3.27 [2.92; 3.45]) compared to the CT (3.86 [3.75; 4.01]) and control (4.08 (3.73; 4.22]) groups, while the PP (3.63 [3.28; 4.11]) and P3M (3.83 [3.61; 4.04]) groups presented an intermediate action. The effervescent tablets did not present antimicrobial action against S aureus (P = .537), C albicans (P = .795), or C glabrata (P = .519). Conclusion: Ni exhibited moderate antimicrobial action. The effervescent tablets did not promote reduction of multispecies biofilm, and their daily use should be carefully considered.

Purpose: To assess the influence of ferrule thickness on the fracture resistance and failure mode of endodontically treated bovine incisors and to predict the long-term prognosis, as well as choose the most suitable clinical treatment, for teeth with different ferrule thicknesses. Materials and Methods: A total of 50 endodontically treated bovine incisors were restored with quartz fiber posts and metal crowns and separated into five groups (n = 10 each): no ferrule (group A); 0.5-mm–thick ferrule (group B); 1.0-mm–thick ferrule (group C); 1.5-mm–thick ferrule (group D); and 2.0-mm–thick ferrule (group E). All specimens were subjected to a fatigue loading test (2.33 Hz, 50 N, 300,000 cycles). Survived specimens were loaded until fracture on a universal testing machine at an angle of 135 degrees and a crosshead speed of 0.5 mm/minute. Failure modes and fracture resistance were recorded. Data were analyzed using one-way ANOVA and least significant difference tests. Results: A significant increase (P .05) was detected in fracture resistance with increase in ferrule thickness. Group D (1.5 mm) and group E (2.0 mm) showed significantly higher fracture resistance than the other three groups. All failures belonged to restorable fracture patterns. Conclusion: Ferrule thickness contributed significantly to the fracture resistance of endodontically treated bovine incisors restored with quartz fiber posts and metal crowns. Teeth with ferrule thickness of ≥ 1.5 mm can achieve higher fracture resistance and have a better long-term prognosis.

Purpose: To examine microwave heating for the purpose of ceramic glazing as an alternative to conventional methods in terms of color stability. Materials and Methods: Thirty disk-shaped specimens (11 × 2 mm) of VITA VM 9, VITA VM 13, VITA VMK 95, and IPS e.max Ceram veneers were prepared (n = 30 each). The specimens were further divided into three subgroups according to surface finishing procedure (polishing, conventional oven glazing, or microwave glazing [n = 10 each]). The related surface finishing procedure was applied according to the manufacturers' instructions. Color differences (ΔE) of the ceramic samples stored in a coffee solution at 37°C for 168 hours were determined using spectrophotometry. Data were analyzed using two-way ANOVA. The group differences were analyzed using Tukey HSD test. Results: Microwave-glazed specimens showed similar ΔE values to conventionally glazed specimens for the tested ceramics (P > .05). Polished specimens showed higher ΔE values than glazed specimens for the investigated ceramic materials, and the difference was significant for VITA VMK 95 and Vita VM9 (P ≤ .05). Conclusion: Microwave glazing has the advantage of decreasing glazing time to a few minutes and could be considered as an alternative method to conventional oven glazing and polishing with respect to color stability.

This report presents a digital technique for the fabrication of a two-piece hollow bulb maxillary obturator prosthesis. The procedure described resulted in an accurate prosthesis while avoiding the discomfort associated with analog impressions. The manipulation of a routine postoperative CT scan in conjunction with a 3D printer allowed for the fabrication of a 3D-printed anatomical cast, from which the two-piece hollow bulb obturator was fabricated. The obturator prosthesis framework was digitally designed and milled from a modified PEEK material, resulting in a lightweight prosthesis with excellent biocompatibility. The clinical and laboratory steps involved are described.

Children affected by dentinogenesis imperfecta (DI) require restorative techniques or prosthodontic management to minimize the functional and psychosocial impacts of the condition. In cases of excessive wear of the deciduous dentition and moderate cooperation from the child, removable complete overdenture prostheses are the most suitable treatment option. However, limited restorative space is a technical challenge for the placement of such prostheses. Advances in digital technologies can help assist in the fabrication of monolithic prostheses with reduced thickness. The present clinical report describes the management of a moderately cooperative 7-year-old patient suffering from DI with severe tooth wear, reduced restorative space, and a high smile line. The design and fabrication of complete overdentures were performed using a digital workflow. This innovative monochromatic monolithic approach combined with the use of gingivashade composite resin respected the available restorative space while obtaining a natural esthetic appearance. Such a strategy requires regular denture replacement according to the child's growth and loss of deciduous dentition. An additional aim is to obtain the cooperation needed for a future global fixed rehabilitation over time.

Microstomia is a clinical condition of reduced mouth opening that can be acquired or congenital in origin. Problems associated with microstomia can be related to function, esthetics, or both. Management of microstomia due to facial burns is complex due to the presence of hypertrophic and contracture scars. Available treatment options can be broadly classified as surgical, nonsurgical, or both. Splints can be used to prevent the contraction of perioral musculature or to recuperate lost mouth opening. Various intraoral or extraoral, tooth-borne or tissue-borne, and static or dynamic appliances are in clinical use, but their designs are case specific. This case report explains the management of microstomia secondary to facial burns by using a dynamic splint in combination with intralesional injections of triamcinolone acetonide and hyaluronidase.