The International Journal of Oral & Maxillofacial Implants, 04/2022

Purpose: This review aimed to summarize the current literature on the oral biofilm formation on alternative abutment materials compared with titanium (Ti) or Ti alloy in clinical and in situ conditions. Materials and methods: An electronic database search was conducted in PubMed, Cochrane Library, EMBASE, Scopus, Web of Science, LIVIVO, BVS, ProQuest, and OpenGrey up to November 2020. Clinical and in situ studies evaluating the biofilm formed on metallic, ceramic, or polymeric abutment materials compared with Ti or Ti alloy were included. Outcome measures were microbial counts/profile, cell viability, and biofilm coverage/thickness. Clinical parameters were deemed secondary outcomes. Risk of bias was assessed by RoB 2 and ROBINS-I tools. Results: A total of 10 clinical and 9 in situ studies were included. Meta-analysis was not performed due to heterogeneity across studies. The abutment materials polytetrafluoroethylene, gold alloy, gold-platinum alloy, cobalt-chromium, alumina, and zirconia were reported. Six out of ten clinical studies (60%) and four out of nine in situ studies (44%) found no qualitative or quantitative microbiologic differences between tested materials. When significant differences were detected, conflicting results were reported. Clinical outcomes were consistent with healthy conditions for all investigated materials. Conclusion: There is not enough evidence to support the existence of relevant microbiologic differences in the biofilm formed on alternative abutment materials over Ti and its alloys in oral conditions. No evident relationship between microbiologic results and clinical outcomes were found. In situ studies and polymicrobial analyses showed a higher tendency to find significant differences between materials. Schlagwörter: biofilms, dental abutments, dental implants, microbiology

Purpose: The purpose of this systematic review and meta-analysis was to evaluate the effects of splinting impression copings on the accuracy of conventional impressions for two-unit nonparallel implant restorations. Materials and methods: MEDLINE via PubMed, Embase, and Web of Science databases were searched with no publication year or language limits, and studies comparing the accuracy of conventional impressions for two-unit nonparallel implant restorations made using splinted impression copings and nonsplinted impression copings were identified. A meta-analysis was performed using Review Manager software. The mean difference (MD) with 95% confidence interval (95% CI) for the framework strain and marginal gap of the implant-framework connection between impressions using splinted and nonsplinted copings were statistically analyzed (α = .05). Results: Initially, 142 articles were identified after the removal of duplicates. Five in vitro studies were included in the systematic review, and four in vitro studies were included in the meta-analysis. All the included studies were focused on internal-connection implants and implant-level impressions. The implant angulation in the included studies ranged from 8 to 30 degrees. Impressions using splinted impression copings exhibited significantly smaller marginal gaps than those using nonsplinted impression copings (P = .02; mean difference [MD] = -13.34; 95% CI = -24.31 to -2.36). Moreover, with respect to the framework strain, no significant differences were found between impressions using splinted impression copings and nonsplinted impression copings (P = .47; MD = -12.64; 95% CI = -47.32 to 22.03). Conclusions: Significantly larger marginal gaps were found in the impressions using splinted impression copings, but the clinical significance was low. Based on the limited number of studies included, splinting copings is unnecessary when making conventional impressions for two-unit nonparallel implant restorations. Schlagwörter: accuracy, conventional impression, implant, meta-analysis, nonparallel, splinting copings

The goal of this overview was to systematically verify the best available literature on surgical and nonsurgical treatments of peri-implantitis to determine evidence-based treatment protocols for peri-implantitis. Three databases (MEDLINE/PubMed, Web of Science, and Cochrane Library/Evidence) were searched by two independent reviewers, including systematic reviews (SRs) that involved randomized controlled trials (RCTs). The search was limited to articles between January 2014 to January 2021 with an English language restriction. In total, 437 articles were initially found, of which only 34 were selected for full-text reading. Nine SRs were included in this study, enrolling 59 different RCTs. Some studies investigated both surgical and nonsurgical techniques, while others focused on only one approach or the other. In total, six of the studies included nonsurgical techniques, and eight included surgical techniques (ie, augmentative, regenerative, and corrective/resective techniques). Nonsurgical interventions appeared to offer some degree of clinical improvements, especially in bleeding on probing levels, but they were not enough to fully treat peri-implantitis. Whereas surgical techniques seemed to be more effective in improving overall clinical parameters, especially probing depth, bleeding on probing, and to some extent, marginal bone level, no specific surgical technique or material (graft or membrane) had a clear advantage over others. Therefore, resective surgical and implantoplasty techniques demonstrated significant improvements in clinical parameters. Although surgical interventions are more indicated to treat peri-implantitis than nonsurgical procedures, the predictability is still a concern due to titanium particles scattered within the local tissue. Schlagwörter: nonsurgical, outcomes, peri-implantitis, surgical, systematic review, treatment

Purpose: To compare the fracture resistance of a press-on ceramic custom implant restoration with pressed and cemented restorations. Materials and methods: Thirty-two (32) lithium disilicate (IPS e.max Press) custom hybrid abutment restorations were fabricated. The restorations were divided into two groups (n = 16) according to the construction technique: the commercial control group (C) and the press-on group (P). For the control group, lithium disilicate restorations were pressed and cemented on titanium bases. For the press-on group, lithium disilicate pressable ceramic (IPS e.max Press) was pressed on the titanium bases with injection molding. Each group was further divided according to the restoration design, either screw- or cement-retained, into two subgroups of eight specimens each. Specimens of C group were divided into screw-retained (cemented hybrid abutment crown, CHAC) or cement-retained (cemented hybrid abutment, CHA). Specimens of the P group were also divided into screw-retained (pressed hybrid abutment crown, PHAC) and cement-retained (pressed hybrid abutment, PHA). The specimens were subjected to static loading until failure with a universal testing machine. Two-way analysis of variance (ANOVA) was used to assess the effect of different techniques and designs on the fracture resistance of the samples (P < .05), followed by one-way ANOVA and Tukey honest significant difference (HSD) test (α = .05). Results: C group showed higher mean fracture resistance (812.443 ± 129.14 N) than P group (596.71 ± 108.83 N), and the difference was statistically significant (P < .05). Regarding restoration design, HA groups showed higher mean fracture resistance (742.621 ± 153.82 N) than HAC (666.53 ± 163.07 N) groups with no statistically significant difference. CHA showed the highest mean fracture resistance (817.65 ± 161.76 N), while PHAC showed the lowest mean fracture resistance values (525.83 ± 47.29 N). Conclusion: The commercial cemented lithium disilicate restorations showed higher fracture resistance than the press-on restorations, although both showed a maximum load capacity that was greater than physiologic incisal force in the anterior region, and both hybrid abutments and hybrid abutment crowns were equally efficient in withstanding occlusal loading forces. Schlagwörter: abutment design, dental implants, fracture resistance, IPS e.max Press, lithium disilicate, pressable ceramics

Purpose: A new tissue-level implant design with angulations of 17, 30, and 45 degrees has been introduced to allow the use of the existing bone while maintaining the restorative platform at an angle to ensure an optimal functional and esthetic result for treatment of edentulous patients. The aim of this study was to measure implant survival, bone loss, and peri-implant health of the novel tissue-level angled-head dental implant system. Materials and methods: A retrospective analysis of cases from three private offices that were using the new implant system was performed. Data regarding patients' demographics, number and location of implants, restoration type, bone loss, implant failure, bleeding, and pocket depths were collected and analyzed. The data collected were analyzed using mainly descriptive statistics. Results: A total of 29 participants were selected, and 185 dental implants were placed. The average patient age was 61 ± 7 years, and 52% were female. Some of the patients were medically compromised; 7% were diabetic, 20% were smokers, and 7% had osteoporosis. The average time from dental implant placement to the placement of the screw-retained crowns was 6 ± 5 months. Four implants failed with an average time to failure of 18 ± 8 months. Implant survival rate was 97.8%. The average bone loss was 0.014 ± 0.082 mm at 1 year, 0.133 ± 0.306 mm at 5 years, and 0.426 ± 0.903 mm at 10 years. Overall, 18.9% of implants were associated with bleeding, and only one implant had a pocket depth greater than or equal to 5 mm. Conclusion: The new tissue-level implant design with angulations of 17, 30, and 45 degrees has demonstrated predictable survival and success rates with minimal bone loss. The long-term follow-up seems highly promising; however, further studies are warranted to validate the results. Schlagwörter: alveolar bone, bone loss, peri-implantitis, success, survival

Prosthetic design is a critical step in implant treatment planning that must synchronize with implant positioning to promote a state of peri-implant health. Improperly designed prostheses may not only hinder patient (or professional) hygiene measures but also impact the ability of clinicians to examine the peri-implant supporting tissues for diagnostic purposes. The purpose of this review was to discuss the current state of the evidence surrounding prosthetic factors associated with peri-implant diseases. Following the chronologic order of implant treatment, key prosthetic variables were discussed in relation to peri-implant disease pathogenesis. Specific concepts including the impact of implant spatial positioning, abutment height, residual cement, and implant splinting were found to be associated with peri-implant disease pathogenesis. Excessive occlusal forces were found to play a role in susceptibility to prosthetic complications with limited evidence to suggest a role in peri-implant disease progression. An intimate prosthetic-biologic connection exists, which must be respected to promote an environment for long-term peri-implant stability and health. Schlagwörter: dental implants, dental prosthesis designs, etiology, peri-implantitis

Purpose: To compare frameworks manufactured by selective laser melting (SLM) and electron beam melting (EBM) with frameworks manufactured by milling, regarding dimensional precision after veneer layering and spark erosion for the all-on-six implant concept. Materials and methods: Frameworks (n = 5/group) were manufactured by milling, SLM, and EBM. Dimensional precision of the frameworks was evaluated by marginal fit, screw loosening torque, and strain. Marginal fit was assessed by the single screw protocol. The screw-loosening torque was measured for the evaluation of screw stability. Tension distribution was analyzed with strain gauges. All frameworks received veneer layering followed by the marginal fit, screw-loosening torque, and strain gauge tests. Subsequently, the frameworks were subjected to the spark erosion process. The analyses were repeated after each stage (baseline, veneer layering, and spark erosion). Data was explored by two-way repeated-measures analysis of variance (ANOVA) with the Bonferroni test (α = .05). Results: At baseline, the highest (worst) marginal fit values were displayed by SLM frameworks (mean ± standard deviation [SD]: 186.13 ± 21.27 μm), while the milling group (83.30 ± 12.03 μm) showed the lowest (best) values (P < .05). After veneer layering, EBM presented the worst marginal fit values (222.55 ± 52.56 μm; P < .05) among the groups. Over time (from the baseline to veneer layering), the marginal fit values increased (became worse) for milling (P = .002) and EBM (P < .001), while for SLM (P = .002) the values decreased (improved). Compared with veneer layering data, spark erosion improved the marginal fit values only for EBM (P = .005). Irrespective of time, the screw-loosening torque for the milling group showed higher values. The lowest strain was found for the SLM at baseline (P < .05), but it increased after veneer layering (P = .015) and after spark erosion (P = .028). Conclusion: Additive technologies are promising for dental applications. In addition, all technologies demonstrated accuracy in the manufacturing of implant-supported frameworks, especially the EBM technology, which demonstrated biomechanical behavior similar to the milling technology after the intervals (baseline, veneer layering, and spark erosion) assessed in the study. Schlagwörter: ceramics, computer-aided design, dental marginal adaptation, prostheses and implants, stress, mechanical

Purpose: To examine the stress distribution in the maxillary All-on-4 treatment concept supported by implants of different diameters under two different loading forces using finite element analysis. Materials and methods: Two distinct All-on-4 designs were prepared in a fully edentulous maxilla, supported by 3.3- and 4.1-mm-diameter implants. Posterior implants were tilted distally, approximately 30 degrees to the occlusal plane, and anterior implants were placed axially. Bone, implant, and prosthetic components were modeled separately and were tightly connected to each other. Under two distinct loading conditions representing the occlusal forces of healthy and bruxist individuals, the stresses on peri-implant bone, implant, and prosthetic components were evaluated using finite element analysis. Results: There were higher stresses on cortical bone than on trabecular bone. The stresses on bone and implant components were concentrated around the posterior implants, whereas stresses on the prosthesis were concentrated anteriorly. With increasing implant diameter, the stresses on trabecular bone, abutments, and crowns increased, whereas the stresses on cortical bone, implants, and frameworks decreased. Compressive stresses in the cortical bone and von Mises stresses in the frameworks exceeded the overload limit in both models under bruxist loading. Conclusion: The stresses on the cortical bone, implants, and frameworks were slightly higher in the model with 3.3-mm-diameter implants, whereas the stresses on the trabecular bone, abutments, and crowns were slightly higher in the model with 4.1-mm-diameter implants. Schlagwörter: All-on-4 treatment, bruxism, edentulous maxilla, finite element analysis, implant diameter, overload

Purpose: The aim of the present retrospective clinical study was to evaluate the outcome of a maxillary sinus lateral window augmentation protocol, which sought to shorten the treatment time. Materials and methods: This protocol entailed sinus augmentation with deproteinized bovine bone minerals (DBBM) and simultaneous implant placement in patients with minimal residual bone height. A total of 89 sinus augmentation procedures were performed in 74 patients, in whom 160 implants were placed between 2005 and 2013. The mean residual bone height was 2.6 ± 0.6 mm. The healing time before loading was 4.18 ± 0.63 months. Results: In a first evaluation in 2014 the early implant survival rate (EIsR) was 96.8% after a mean period of 5.4 ± 2.2 years. A second evaluation in 2019 after a mean period of 10.4 ± 2.2 years showed a late implant survival rate (LIsR) of 83.1%. The failures after 2014 were all caused by peri-implantitis, which affected 14.6% and 16.8% of patients and implants, respectively. This prevalence of peri-implantitis does not appear to be higher than that usually observed in nonaugmented sites. Conclusion: This reduction in the duration of treatment compared to the usual duration of 9 to 12 months does not seem to affect the predictability of the technique. Schlagwörter: atrophic sitres, lateral approach, long-term complications, maxillary sinus augmentation, reduction treatment time

Purpose: To evaluate the effect of six scan patterns on the accuracy and speed of digital impressions with two different intraoral scanners for complete-arch implant rehabilitation. Materials and methods: A master model containing six parallelly placed implant analogs was fabricated, and six scan bodies were connected to the analogs. Reference scan was obtained with a laboratory scanner. Test scans were obtained by intraoral scanning with six scan patterns using 3Shape TRIOS 3 and Carestream CS 3600 intraoral scanners. Scanning time was recorded. Trueness and precision were assessed with an inspection software. Two-way analysis of variance (ANOVA) was performed to examine the effect of scan pattern, scanner, and their interaction on accuracy and scanning time. Differences between the six scan patterns with each scanner were tested by one-way ANOVA. Differences between the two scanners were evaluated by t test. The level of significance was set at α = .05. Results: For trueness, the effects of scanner, scan pattern, and their interaction were significantly different in both linear and angular discrepancy. For precision, the scanner and scan pattern each had a significant effect on linear discrepancy independently, while their interaction did not. Only the effects of scanners were significantly different in angular discrepancy. For each of the two scanners, significant differences were detected in accuracy and speed between the patterns. Conclusion: Scan pattern significantly influenced the accuracy and speed of digital impressions for complete-arch implant rehabilitation. Schlagwörter: dental implants, digital impression, edentulous, intraoral scanner, scan pattern

Purpose: Titanium-zirconium (Ti-Zr) alloy has been developed to strengthen the implant body, but clinically relevant information is still limited. The aim of this in vitro study was to compare the rotational load fatigue performance of implant-abutment connections in narrow-diameter (3.3-mm) and regular-diameter (4.1-mm) implants made with commercially pure grade 4 titanium alloy (CPTi-G4) and Ti-Zr. Materials and methods: Narrow-diameter (N) and regular-diameter (R) implants with CPTi-G4 (Ti) or Ti-Zr (Tz) materials were tested. This resulted in four test groups: NTi, NTz, RTi and RTz. Five specimens were made for each group (n = 5). Abutments used were milled from titanium-aluminum-niobium alloy abutment blanks. A rotational load fatigue machine applied a sinusoidally varying load at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz in air at 20°C. The number of cycles to failure was recorded. The upper limit was set as 5 million cycles. Results were evaluated using analysis of variance (ANOVA) and Tukey post hoc tests. Failure locations and patterns were evaluated with scanning electron microscope (SEM). Results: All regular-diameter test groups reached the upper limit of 5 million cycles without failure. All narrow-diameter test groups failed within the range of 402,530 cycles to 3,374,353 cycles. It could be observed that NTz showed a higher mean cycle count as compared to NTi. NTi test group recorded two implants damaged, one implant fracture, five abutment fractures, and four screw fractures. NTz test group showed only abutment fractures at the level of implant platform, with no damage to the implant bodies. Significant difference was found between implants of different diameters. There was no significant difference between implants of different materials. Conclusion: Regular-diameter implants performed significantly better than narrow-diameter implants, regardless of material, while no significant difference in cyclic load to failure was found between groups of different alloys. All NTz failures were at the abutment only, without damage to the implant. This failure pattern can potentially be clinically advantageous in terms of retrieval and subsequent replacement of a failed prosthesis. Schlagwörter: implant fracture, implant-abutment connection, load fatigue, narrow diameter implant, titanium-zirconium

Purpose: To evaluate the mechanical stability of highly translucent zirconia (Zr) cantilevered fixed dental prostheses (cFDPs) and to investigate the influence of the number of implants (one versus two) supporting cFDPs with different restorative materials on their mechanical stability and load-bearing capacity. Materials and methods: Thirty-two specimens consisting of implant-supported prostheses embedded in resin blocks were fabricated. Sixteen specimens received one implant (bone-level implant, 4.1-mm diameter, 13-mm length; Straumann) to support two-unit cement-retained cFDPs with one extension unit and the other 16 received two implants (bone-level implant, 4.1-mm diameter, 13-mm length; Straumann) positioned corresponding to the missing maxillary central incisors to support three-unit cement-retained cFDPs with one extension unit. Two different prosthetic materials, chromium-cobalt (Cr-Co; Wirobond C+, Bego) and highly translucent Zr (Lava Plus, 3M ESPE) were selected to fabricate the two- and three-unit cFDPs. Standardized twoand three-unit Cr-Co frameworks (CC-I, n = 8; CC-II, n = 8) and highly translucent Zr frameworks (Zr-I, n = 8; Zr-II, n = 8) with a 6-mm cantilever extension were fabricated using CAD/CAM (EOS M 290). Following thermomechanical fatigue loading, the specimens were tested for fracture resistance under static loading. The influence of restoration material and number of supporting implants on fracture resistance were tested using two-way analysis of variance (ANOVA). The level of statistical significance was set below 5% (α < .05). Results: All specimens survived aging. The mean (± standard deviation) fracture resistance values were 416.25 (± 42.71) N for Zr-I, 548.75 (± 75.41) N for Zr-II, 601.0 (± 41.51) N for CC-I, and 664.5 (± 37.59) N for CC-II. CC and Zr group specimens showed significantly different fracture resistance results (P < .001). The number of implants significantly influenced the fracture resistance of Zr groups (P = .001), whereas the influence was not significant for CC groups (P = .089). Conclusion: Within the limitations of this in vitro study, highly translucent zirconia cFDP frameworks demonstrated the potential to withstand reported physiologic occlusal forces applied in the anterior region. The increase in the number of implants supporting zirconia cFDPs significantly contributed to achieving higher fracture resistance values. Schlagwörter: dental implants, fixed dental prosthesis, cantilever, zirconia, highly translucent zirconia

Purpose: The aim of this study was accuracy assessment of placed implants in full-arch cases using specific software and hardware to perform static computer-assisted implantology and immediately loaded prostheses. The degree of deviation existing between planned and achieved implants was carried out by a new noninvasive measurement procedure of the implant position performed on stone casts. Materials and methods: Fourteen stone casts retrieved from 14 full-arch fully guided implant treatments were selected to perform the study. Each cast, manufactured for the surgical treatment by using a specific laboratory kit, was obtained from the respective surgical guide. A sleeve for each implant was embedded into the guide, which helped the examiners to manufacture a stone cast per guide containing the implant analogs, which was used to recover the final position of the planned implants. A total sample of 60 implants were assessed. The postoperative casts, poured to produce the immediate prostheses, were then processed by a contact (or tactile) scanner, and the generated standard tessellation language (STL) files were overlapped (best-fit alignment) using engineering software that revealed all the measured discrepancies. In terms of accuracy, differences relating to arch, assessed bone quality, implant length, and drill length (prolongation short or long) were reported. Results: The use of a noninvasive tactile scanner revealed mean entry point horizontal deviations of 0.30 mm (SD: 0.39 mm), mean entry point vertical deviations of 0.20 mm (SD: 0.25 mm), mean apical horizontal deviations of 0.50 mm (SD: 0.73 mm), and mean apical vertical deviations of 0.24 mm (SD: 0.28 mm). The frontal and lateral angular deviations were investigated, and corresponding mean values of 1.99 degrees (SD: 2.30 degrees) and 1.80 degrees (SD: 2.44 degrees) were detected. Conclusion: The reported results demonstrate that the contact tactile scan is a viable and biologic way to assess implant deviations. Schlagwörter: 3D, CAD/CAM, computer-guided surgery, data accuracy, dental implant, guidance, immediate loading, osseointegrated implants, surgery, surgical guide, surgical procedure

Purpose: To find out the difference in the stresses induced by one-piece monophasic and two-piece dental implants supporting All-on-4 implant-supported prostheses using finite element analysis. Materials and methods: Two finite element maxillary models were designed: In the two-piece model, two-piece dental implants were used, and in the one-piece model, one-piece dental implants were used. The dental implants were placed according to the All-on-4 treatment concept. The anterior implants were axially placed; however, the posterior implants were placed with a distal inclination of 15 degrees. In each model, the prosthetic superstructure was designed to be a titanium implant prosthesis with zirconia crowns. Three loading scenarios were applied in this study. The first scenario simulated biting function with a total load of 250 N. The second scenario simulated incision function in which 90-N horizontal static load was applied to the palatal surface of central incisors. The third scenario simulated biting in the presence of a cantilever. Results: In the three loading scenarios, the stresses were higher in the two-piece model. Higher stress values were recorded posteriorly rather than anteriorly in both models. Conclusion: One-piece dental implants induce lower stress values compared with two-piece dental implants when used in All-on-4 implant-supported prostheses. Schlagwörter: All-on-4, biomechanics, finite element analysis, one-piece dental implant, screw-retained prosthesis

Purpose: Acceleration of the bone healing period and/or increasing the quality of newly formed bone still have great importance in the field of oral and maxillofacial surgery. The aim of this study was to evaluate the effect of isolated liquid Mecsina (herbal extract) and its combination with xenogeneic graft material (bovine bone graft) on bone regeneration. Materials and methods: Full-thickness critical-size defects with 10-mm diameter and 2-mm depth were created on the calvarial bone region in 28 Sprague Dawley male rats. Four groups were generated: Mecsina Hemostopper, Mecsina Hemostopper + graft group, only graft group, and empty control group. On the 28th day following surgery, all animals were sacrificed. The calvarial samples were evaluated both histopathologically and histomorphometrically. Results: According to the histopathologic evaluation result, vascular proliferation was significantly higher in the groups in which Mecsina Hemostopper was used as a single material or in combination with graft material (P < .05). Histomorphometric evaluation showed that trabecular and osteoid thickness were significantly higher in all Mecsina application groups (P < .05). Conclusion: Mecsina Hemostopper was found to be an effective agent in increasing cell proliferation and providing more qualified bone formation. The combination of Mecsina and xenogeneic bone graft was found to be one of the most effective augmentation options for critical-size defects in rats. Mecsina Hemostopper could be used to get more qualified bone formation clinically, but more clinical research is needed in the future. Schlagwörter: bone formation, herbal blood stopper, histomorphometric analysis, Mecsina Hemostopper, xenogeneic bone graft

Purpose: To primarily evaluate the dimensional changes of bone and soft tissue following ridge augmentation in compromised molar regions. The secondary objective was to evaluate the histologic composition of augmented sites. Materials and methods: The study included 27 patients who underwent augmentation of extraction sites with grafts covered by a collagen membrane. CBCT was taken immediately after augmentation (T2) and after 8 months of healing, before implant placement (T3). The width and height of the extraction sites were recorded at extraction (T1) and reentry surgery (T4). A histomorphometric analysis was performed. Data were evaluated in terms of bone crest level, implant survival rates, and change in mucogingival junction. Results: According to clinical measurement, horizontal and vertical bone gain was 10.15 ± 1.00 mm and 8.80 ± 1.86 mm, respectively. Radiographic measurement showed that the horizontal width changes were 1.46 ± 0.52 mm, 0.98 ± 1.29 mm, and 1.29 ± 0.82 mm, respectively, at 1, 3, and 5 mm apical to the crestal level. Vertical bone change was 2.34 ± 0.90 mm in the center of the socket. Histomorphometric analysis showed that percentages of mineralized bone, nonmineralized tissue, and bone substitute were 32.31% ± 13.25%, 25.36% ± 12.24%, and 42.34% ± 9.54%, respectively. The mucogingival junction shift was 0.6 ± 1.1 mm. Implant survival rates and crestal bone resorption were 100% and 0.78 ± 0.58 mm, respectively, after 1 year of loading. Conclusion: Ridge augmentation can be performed successfully to manage extraction sockets. Membrane coverage combined with primary wound closure could be conducive to new bone regeneration and peri-implant tissue health. Schlagwörter: bone regeneration, ridge preservation, tooth extraction

Purpose: Immediate dental implants revolutionized the field of implant dentistry with significant advantages over conventional implants. The lack of adequate bone in the extraction socket raises the question of the appropriate timing of implant loading. Platelet concentrates have been used widely to accelerate bone regeneration in the maxillofacial region. This study evaluates the effect of platelet concentrates on bone healing and implant stability in the maxillary and mandibular molar regions. Bone regeneration is regulated by several growth factors, particularly vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1); therefore, quantification of these factors in platelet concentrates and its correlation with bone healing has been assessed in this study. Materials and methods: The primary aim of this randomized clinical trial was to compare the stability of immediate dental implants in the maxillary and mandibular molar regions treated with platelet-rich fibrin (PRF) versus concentrated growth factors (CGF) using resonance frequency analysis (RFA). The secondary objectives were to evaluate the bone regenerate around implants with the use of PRF and CGF and to quantify growth factors VEGF and TGF-β1 in the prepared CGF and PRF and their correlation with bone healing, if any. A total of 36 patients were randomized into three groups (12 each): control, PRF, and CGF. In all patients, immediate implants were placed either with or without platelet concentrate (PRF or CGF). Implant stability was measured using RFA immediately postoperatively and at 4, 8, and 12 or 16 weeks (12 weeks for mandible and 16 weeks for maxilla) postoperatively. Radiodensity and the bone gap (horizontal/vertical) were measured on intraoral periapical radiographs immediately postoperatively and at 8 weeks and 12 or 16 weeks postoperatively. Results: On comparing the implant stability quotient (ISQ), radiodensity/grayscale (GS), and horizontal and vertical bone gap (HG and VG), there was no significant difference noted between the three groups at any point in time. On ISQ analysis at 8 weeks, the control group showed a significant improvement (P = .04), whereas at 12 or 16 weeks, significant improvement was seen in PRF (P = .03) and CGF groups (P = .02). In GS assessment, only the control group showed significant improvement at 12 or 16 weeks (P = .009). In horizontal and vertical bone gap analysis all three groups showed significant improvement at 8 weeks (control [P < .001], PRF [P = .001], CGF [P = .01]) as well as 12 or 16 weeks (control [P < .001], PRF [P < .001], CGF [P = .006]). The enzyme-linked immunosorbent assay (ELISA) quantification of VEGF and TGF-β1 showed significant concentration of VEGF in PRF as compared to the plasma, while concentration of TGF-β1 was found to be comparable in both groups. Conclusion: The application of platelet concentrates seems to enhance stability of implants, but intergroup results were nonsignificant at all time points. There was no statistically significant difference between the three groups when comparing quality (radiodensity/grayscale) and quantity (horizontal and vertical gap reduction) of bone regenerate. Studies with larger sample sizes are required to make conclusive assertions regarding efficacy of platelet concentrates in dental implants. Schlagwörter: concentrated growth factors, dental implant, immediate implant, implant stability quotient, osseointegration, platelet-rich fibrin

Purpose: The aim of this study was to introduce and evaluate a modified one-and-a-half-barrel fibular technique guided by occlusion for functionally reconstructing mandibular defects. Materials and methods: Fifteen patients underwent mandibular reconstruction with the modified one-and-a-half-barrel technique and simultaneous insertion of dental implants. A vascularized fibular segment was used to reconstruct the alveolar ridge of the neomandible with dental implants loaded simultaneously. The inferior border was reconstructed with a nonvascularized segment. Panoramic radiographs were taken 1 week, 6 months, and 12 months after the surgery to measure the vertical height of the fibular segment, calculate the bone resorption rate at different time points, and observe the implant marginal bone loss and crown-to-implant ratio. The OHIP-14 questionnaire was employed to evaluate the perceived outcomes of oral rehabilitation. Results: The vertical height of the vascularized and nonvascularized fibular segments 1 week, 6 months, and 12 months after the surgery was 14.51 ± 1.93, 14.19 ± 1.88, and 13.81 ± 1.78 mm; and 8.65 ± 0.98, 7.72 ± 0.94, and 7.25 ± 0.93 mm, respectively. The bone resorption rate of vascularized and nonvascularized fibular segments was 2.20% ± 1.04% and 10.69% ± 5.73%, respectively, in the first 6 months, and 2.67% ± 1.44% and 6.16% ± 2.75%, respectively, in the latter 6 months, showing a significantly higher resorption rate in the nonvascularized segment (P < .05). The implant marginal bone loss after functional loading was significantly greater than that before dental rehabilitation (P = .001). The OHIP-14 total scores were 20.07 ± 10.24, 19.00 ± 7.82, and 3.93 ± 1.87 before surgery, at 6 months, and at 12 months after surgery, respectively (P = .000). Conclusion: The proposed technique not only guarantees the esthetic appearance of patients but also achieves a suitable vertical height to facilitate the placement of the implant at the same time. Schlagwörter: bone resorption, dental implant, esthetics, fibula, free tissue flaps, mandibular reconstruction

Purpose: In recent years, ceramic implants made of zirconia have secured a niche position next to established titanium implants, due partly to new scientific findings and positive clinical experience with the handling of ceramic implants. The aim of this study was to assess the clinical and radiographic data for monotype ceramic implants that have remained in place for 60 months under masticatory loading. Materials and methods: In 2011, this prospective clinical study included patients with a single-tooth gap in the maxilla and mandible. Monotype ceramic implants (Straumann) were used according to a standard protocol. Provisional prostheses were placed after 3 months, followed by final prostheses 3 months later. Patients were invited for a 60-month follow-up. Implant survival was analyzed from lifetime data. Success rates and crestal bone levels were evaluated from implant placement to 6, 12, 36, and 60 months after surgery. Results: From the initial 44 patients recruited, 36 were analyzable for the 60-month follow-up. With one implant lost before the 6-month followup, the survival rate after 60 months was 97.7%, and the mean survival time was 58.7 months. Sixty months after implant placement, the success rate was 97.2% (95% confidence interval = 84.6% to > 99.9%). Mean bone loss after 60 months was 0.99 (± 0.59) mm. Conclusion: After 60 months, monotype ceramic implants made of zirconia achieved success and survival rates comparable with those reported for titanium implants in selected patient populations. Ceramic implants can be used as an alternative to titanium implants at the request of patients and if specifically indicated, for example, due to titanium intolerance. Schlagwörter: ceramic implants, clinical investigation, ceramic implants, success rate, survival rate, zirconium oxide

Purpose: To observe whether the initial implant stability, evaluated by two different methods-the insertion torque value (ITV) and implant stability quotient (ISQ)-may be influenced by different clinical conditions as well as to understand whether it is possible to establish an overall positive correlation between both methods and whether the obtained correlation is maintained for each clinical variable under scope. Materials and methods: The initial implant stability was evaluated by assessing and recording the ITV and the ISQ for each implant included in the study. The independent evolution of each method was observed considering clinical conditions grouped by gender (male or female), age (≤ 60 or > 60 years), arch (mandible or maxilla), location (incisors, canines and premolars, or molars), implant geometry (aggressive tapered or traditional parallel), diameter (3.5, 3.75, 4.3, or 5 mm), length (≥ 10 or < 10 mm), and immediate implantation (yes or no). The Mann-Whitney-Wilcoxon and Kruskal-Wallis localization tests were used to identify intragroup differences. To determine the level of correlation between both methods, the Spearman rank correlation was used. Results: The intragroup comparisons showed that the mandible (P = .03), short implants (P = .03), and delayed implantation (P = .07) subgroups exhibited higher ITVs. The other groups did not show significant differences. The higher ISQ measurements were obtained in the mandible (P = .0002), younger patients (P = .02), diameters of 3.75 mm and 4.3 mm (P = .04), and delayed implantation (P < .0001) subgroups. No differences were found for the other groups. A strong overall correlation (rho = 0.541; P = 8.023e-06) was found between both methods for ITVs up to 40 Ncm once they were accompanied by a linear increase in the ISQ to a value up to 78. From this value, the overall correlation decreased (rho = 0.237; P = .0055). Regarding the clinical conditions, different levels of significant correlations were found for both genders, older patients, maxilla, molar area, aggressive tapered implant geometries, diameters of 4.3 mm, diameters of 5 mm, lengths ≥ 10 mm, and implants placed in healed bone. The other clinical conditions under scope did not exhibit an important correlation between both methods. Conclusion: When analyzed separately, clinical conditions such as the arch, implant length and diameter, patient age, and timing of implantation showed an influence on the ITV and the ISQ. An important overall correlation between both methods was found for ITVs of ≤ 40 Ncm. This correlation was maintained for several of the clinical conditions studied. Schlagwörter: immediate loading, implant initial stability, implant stability quotient, insertion torque

Purpose: Since flap advancement is a prerequisite for tension-free primary closure and successful regenerative procedures, the aim of this study was to test the efficacy of six surgical approaches for flap advancement in an ex vivo porcine model. Materials and methods: A total of 60 fresh mandibles from pigs were randomized into one of six groups: (1) trapezoidal full-thickness flap design with two vertical releasing incisions (control), (2) trapezoidal flap with linear periosteal scoring, (3) mucosal detachment technique, (4) mucosal detachment with horizontal extension, (5) mucosal detachment with horizontal and vertical extension, and (6) mucosal detachment with horizontal vertical and cutback extension. Coronal advancement of the flap was recorded as the primary variable; the surface area of exposed mucosa and the tear strength were recorded as secondary variables. Results: Homogeneity existed among groups for preoperative keratinized tissue width and tissue thickness. Mucosal detachment with horizontal, vertical, and, cutback extensions achieved the highest amount of advancement. All remaining groups achieved a statistically higher advancement compared with the trapezoidal full-thickness flap (control). Pairwise comparison demonstrated statistical significance between any two groups (P < .001). A positive correlation was noted between exposed mucosa and flap advancement; the advancement increased 0.62 mm for each 10 mm2 of increase in the exposed mucosal surface. Strength at tear stress was the highest in the trapezoidal full-thickness flap (control) and mucosal detachment with horizontal-vertical-cutback incisions (P < .001). Conclusion: Coronal flap advancement was maximized in the mucosal detachment techniques and positively correlated with the area of exposed mucosa. Schlagwörter: bone regeneration, oral surgical procedures, plastic surgery, surgical flaps