The International Journal of Oral & Maxillofacial Implants, 05/2019

Purpose: The purpose of this in vitro study was to evaluate the behavior of abutments attached to Morse taper connection implants, with and without internal index, against oblique cyclic loads. Materials and Methods: Twenty test pieces composed of abutments connected to Morse taper implants solely by friction action were subdivided into two groups (n = 10): group NI (no index) and group I (index). The test units were submitted to tensile tests, before and after cycling loads. Paired t tests were used for intragroup data at different times, and independent t tests were used for the comparisons between the groups. Results: There was a statistically significant difference in both the groups when the precycling and postcycling tensile values were compared. In the comparison between the no index and index groups, there was no statistically significant difference in precycling and postcycling tests. Conclusion: Within the limitations of this in vitro study, it can be concluded that the cyclic loads increased the tensile strength of abutments on Morse taper implants regardless of the index presence. On the other hand, the presence of an index did not significantly alter the values of tensile tests, before and after cyclic loads. Keywords: dental implant-abutment design, Morse taper dental implant-abutment interface, tensile strength

Purpose: To evaluate the bonding ability of self-adhesive and dual-cure resin cement systems applied to zirconia materials of different translucency in combination with each other and with titanium. Materials and Methods: Computer-aided design/computer-assisted manufacture (CAD/CAM) disks of three different zirconia materials (Zenostar MO 0 [medium opacity], MT 0 [medium translucency], and T 1 [translucent], Wieland Dental) were milled and hard sintered in order to obtain cylindrical samples of either 12 mm high × 12 mm diameter (used as a substrate) or 12 mm high × 8 mm diameter (to be bonded to the substrate). CAD/CAM disks of titanium (Starbond Ti4 Disc, S&S Scheftner) were milled in order to obtain a cylinder shape (12 mm high × 8 mm diameter to be bonded to the zirconia substrate). The bonding surfaces were sandblasted with alumina particles (70 μm/2 ATM). Two resin cement systems were tested in this study: a self-adhesive resin cement (SpeedCEM Plus, Ivoclar Vivadent) and a dual-cure resin cement (Variolink Esthetic DC, Ivoclar Vivadent) in combination with a primer (Monobond Plus, Ivoclar Vivadent). The smaller cylinders were bonded to the substrate following the manufacturer's instructions. After 24 hours at 37°C storage, each specimen was subjected to shear bond strength testing in a universal testing machine. The substrate was fixed to the machine, and shear force was applied to the small cylinder close to the bonding interface. Shear bond strength data were statistically analyzed by a three-way analysis of variance (ANOVA) followed by the Tukey test for post hoc comparison (P .05). Results: No significant differences were found between substrates in the shear bond strength test (P = .078). Variolink Esthetic DC showed a statistically significantly higher bond strength compared with the SpeedCEM Plus (P = .001) with the exception of Zenostar MT substrate (P = .014). Conclusion: The resin cement systems showed high shear bond strength values when zirconia was resin bonded to either titanium or the corresponding zirconia substrate. Different zirconia translucencies did not affect the bond strength. The use of MDP primer and a dual-cure cement showed statistically significantly higher strength compared with the self-adhesive resin cement system with the only exception being the bonding of the translucent zirconia Zenostar MT. Keywords: cubic phase, MDP, sandblasting, self-adhesive, shear bond strength test, titanium, translucent zirconia

Purpose: Several approaches for increasing peri-implant mucosal thickness have been proposed, including autogenous, allogeneic, and xenogeneic grafts. The objective of this meta-analysis was to analyze whether xenogeneic matrices are viable alternatives to autogenous soft tissue grafts in peri-implant soft tissue augmentation. Materials and Methods: A systematic search was performed to select randomized clinical trials that compared connective tissue grafts and xenogeneic collagen matrices. The primary outcomes were the mucosal thickness and keratinized mucosa changes, while the secondary outcomes were patient morbidity, painkiller consumption, and surgical time required for the procedure. Results: Seven randomized clinical trials were included for the final evaluation with a total number of 218 implant sites (108 in the connective tissue graft group, 110 in the collagen matrix group) with 3 to 12 months (mean: 6 months) followup period. Results showed mucosal thickness increase in both buccal and crestal sites, but it did not yield statistical significance. The keratinized mucosa gain difference was only -0.06 mm (95% CI [-30.0, 0.18]) between the treatments. The postsurgical discomfort, increased consumption of painkillers, and reduction of treatment time (15.46 minutes less) differed significantly in favor of the collagen matrix group. Conclusion: Within the limits of this study, it can be concluded that collagen matrix and connective tissue graft are equivalent in peri-implant soft tissue augmentation. Keywords: collagen matrix, connective tissue, dental implants, keratinized tissue, meta-analysis, soft tissue management

Purpose: This study was conducted to compare the bone cutting performance of the piezoelectric device with traditional drills in terms of cut execution time, environmental noise produced, surface morphology characteristics, and residual cell vitality of the bone samples. Materials and Methods: Two fresh pig jaws were obtained from a local slaughterhouse, and nine bone samples with a standard size (1 cm3) were harvested from each jaw: three using piezosurgery, three with a multiblade bur mounted on a surgical handpiece, and three with a diamond bur mounted on a high-speed handpiece, for a total of 18 samples. Two samples for each harvesting method were examined by scanning electron microscope (SEM), observing four surfaces per sample. For each surface observed, a count of the intertrabecular spaces was performed, and each space was evaluated as completely, partially, or unfilled by debris. Four samples per sampling method were examined by cell culture to evaluate residual cell vitality after cutting. The execution time of each osteotomy was measured with a stopwatch. The environmental noise was measured, at two different distances, with a phonometer. Results: At SEM analysis, piezosurgery osteotomies showed 66% of totally free intertrabecular spaces on the cutting surface, statistically significantly higher than those on the multiblade bur (33%) and diamond bur (12%) cutting surfaces (P .0005). Bone samples harvested with piezosurgery also demonstrated faster cell proliferation. Finally, piezosurgery generated less environmental noise, though it required longer cutting time. Conclusion: Piezoelectric technology is a valid alternative to rotating burs for osteotomy, demonstrating higher bone cell viability and a precise and silent, though slower, cut. Keywords: bone graft, histomorphometric, piezosurgery, surgery

Purpose: Optimal positioning of implant placement is difficult in several conditions. In cases of thin alveolar ridges or irregular alveolar crests, the dental implant thread is not always fully submerged in the alveolar bone. The response of surrounding bone to dental implants placed apically several days after the initial surgery has yet to be fully revealed. This study evaluated apically positioned dental implants with sandblasted with large grit and acid-etched (SA) surfaces 1 day after initial placement with treatment of saline or tetracycline. Materials and Methods: Twelve rabbits were used in this study, and the surgeries were performed on both sides of the mandibular bone. Twenty-four implants were placed and classified into three groups. In the control group, implant placement was performed following recommendations, with the SA surface submerged in the bone. In the saline and tetracycline groups, 1 mm of the SA surface was exposed above the cortical bone. On the following day, the implants were apically positioned after treatment using a cotton pellet soaked with sterile saline (saline group) or tetracycline solution (tetracycline group). The images from the nondecalcified tissue slide were compared with microcomputed tomography (micro- CT) images. The bone-to-implant contact ratio and bone area ratio were measured using micro-CT images 4 weeks after implant placement. Results: The bone-to-implant contact ratio (mean ± standard deviation, %) of the control group was 87.9 ± 13.7, and those of the saline and tetracycline groups were 83.7 ± 15.46 and 86.9 ± 18.5, respectively. No statistically significant differences were noted among the three groups (P > .05). The bone area ratio (mean ± standard deviation, %) was 90.1 ± 12.2, 96.6 ± 4.3, and 88.7 ± 22.3 for the control, saline, and tetracycline groups, respectively (P > .05). The results from the transverse plane showed no significant differences among the three groups. Conclusion: This study evaluated the effects of apically positioned dental implants with SA surfaces 1 day after initial placement, and uneventful healing was observed irrespective of treatment with saline or tetracycline. Apical positioning of the dental implant within a few days of initial placement may be acceptable without compromising osseointegration. However, further studies in large animal models with larger sample sizes may be necessary before clinical application is recommended. Keywords: apical positioning, dental implants, micro-CT, modified placement, osseointegration, replantation

Purpose: Stability of an implant-supported restoration is an ultimate measure of the success of the procedure. It has been recommended by some to retighten the abutment screw for maintenance of the crown on the implant. The purpose of this study was to evaluate the usefulness of two retightening protocols to maintain the clamping force. Materials and Methods: Three groups of slip-fit implants (MIS 4.3 by 10.5) were compared. The first group was only tightened once (group C). In the second group (group R10M), the screw was retightened after 10 minutes. The third group (group R2W) was retightened after 2 weeks of simulated functional loading. After completion of individual protocols, all specimens were loaded for 100,000 cycles. After the loading, all specimens had the remaining torque audited. Results: The mean torque loss for group C was 6.10 (± 5.13) Ncm. Group R10M was 2.03 (± 3.018) Ncm, and group R2W was 0.30 (± 0.483) Ncm. A one-way analysis of variance (ANOVA) recorded significant differences among the groups (P = .003). Multiple pairwise comparisons between groups by Tukey test recorded significant differences between group C vs group R10M (P = .035) and group C vs group R2W (P = .002). There was no significant difference in torque loss between groups R10M and R2W (P = .509). Conclusion: Within the parameters of this in vitro investigation, it was concluded that both retightening after 10 minutes (P = .035) and after 2 weeks (P = .002) was equally effective. Keywords: clamping force, embedment relaxation, preload, slip fit connection, torque

Purpose: To evaluate the bending moments and failure modes of zirconia meso-abutments bonded to titanium bases restored with different monolithic all-ceramic crowns after aging, and to compare them to titanium abutments restored with all-ceramic crowns. Materials and Methods: Forty-eight internal conical connection implants (CONELOG, Camlog Biotechnologies GmbH 4.3 mm diameter) were restored with four different computer-aided design/computer-aided manufacturing (CAD/CAM) abutment-crown combinations (n = 12). Thirty-six customized zirconia meso-abutments were bonded to titanium bases (CONELOG Titanium Base CAD/CAM crown, Camlog Biotechnologies GmbH) and divided into three groups according to the different crown materials: (T1) monolithic lithium disilicate (e.max CAD, Ivoclar), (T2) monolithic PICN (polymerinfiltrated ceramic network [Enamic, Vita]), and (T3) monolithic zirconia (Lava Plus, 3M ESPE). Twelve titanium customized abutments restored with monolithic lithium disilicate (e.max CAD, Ivoclar) crowns served as the control group (C). The crowns were equal maxillary central incisors and were adhesively bonded with a resinbased cement (Panavia 21, Kuraray). All samples were embedded in acrylic holders. After aging (1,200,000 cycles, 49 N, 1.67 Hz, 5°C to 50°C, 120 seconds), static load was applied until failure. Bending moments were calculated for comparison of the groups. Data were statistically treated with one-way analysis of variance (ANOVA) followed by Tukey post hoc test (P .05). Failure modes were analyzed descriptively. Results: The means of the bending moments were 356.4 ± 20.8 Ncm (T1), 357.7 ± 26.3 Ncm (T2), 385.5 ± 21.2 Ncm (T3), and 358.8 ± 25.3 Ncm (C). Group T3 revealed significantly higher mean bending moments than the other groups (P .05). No differences were found between zirconia meso-abutments supported by titanium bases and customized titanium abutments when lithium disilicate crowns were used (P > .05). No failures were identified during and after aging. After static load, failures occurred due to fracture of the abutment in the internal connection in all the groups. Conclusion: Zirconia meso-abutments bonded to titanium bases showed similar mechanical stability compared with customized titanium abutments. Regarding the crown material, all three tested ceramics (lithium disilicate, PICN, and zirconia) revealed very good stability when used in the monolithic state. Keywords: aging, bending moments, CAD/CAM, monolithic crowns, titanium base, zirconia abutments

Purpose: The purpose of this study was to evaluate axial displacement in cement-retained prostheses using computer-aided design/computer-aided manufacturing (CAD/CAM) abutments with three different types of implant-abutment connections. Materials and Methods: CAD/CAM abutments made with two types of titanium blocks (made by the same manufacturer as the implant manufacturer and by a manufacturer with a patent for CAD/CAM abutment fabrication) were connected with three types of implant connections: external, internal butt, and internal conical connection. Titanium custom abutments and zirconia prostheses were fabricated using the CAD/CAM system for each specimen. The geometries and surface morphologies of CAD/CAM abutments and ready-made abutments were comparatively evaluated using scanning electron microscopy. Cemented prostheses on abutments were mounted on a universal testing machine and subjected to 250-N sine wave cyclic loads. Cumulative axial displacement was measured at 3, 10, 100, and 106 loading cycles and analyzed by repeated measures analysis of variance (ANOVA). Results: Surface geometries and morphologies of CAD/ CAM abutments varied by the implant-abutment connections and manufacturers of the titanium block. The internal conical connection exhibited the greatest axial displacement, while the external connection showed the lowest axial displacement. The CAD/CAM abutment made with a compatible titanium block exhibited a greater axial displacement than that exhibited by the abutment fabricated using a titanium block made by the implant manufacturer. Conclusion: In implant connections with a vertical stop, axial displacement occurred primarily in the early loading period and was self-limited. However, long-term axial displacement can occur with internal conical connection implants. Therefore, in internal conical connection implants, axial displacement should be managed more carefully using a provisional restoration, with consideration of the abutment fabrication method. Keywords: axial displacement, CAD/CAM abutment, cement-retained prosthesis, cyclic loading, implant-supported dental prosthesis, internal conical connection

Purpose: Antibacterial dental implants and related prosthetic components could help to reduce infection and prevent peri-implantitis. The purpose of this study was to determine the effect of ultraviolet (UV) light treatment of titanium on biofilm formation of human oral bacteria. Materials and Methods: Machineprepared commercially pure titanium disks were treated with UV light for 12 minutes. Human oral bacteria were seeded onto untreated and UV-treated disks. Early bacterial attachment to titanium was assessed at 12 hours. Surface topography of initial biofilms was evaluated by 3D scanning electron microscopy at 24 hours. The quantity and morphology of subsequent colony development and biofilm formation were examined by confocal laser scanning microscopy for up to 7 days. Results: Throughout the time course, significantly fewer bacterial cells attached to UV-treated titanium surfaces compared with untreated ones. While biofilm developed rapidly to a final thickness of approximately 16 μm by day 3 on untreated titanium, on UV-treated surfaces it remained below 8 μm, even at day 7. Similarly, UV treatment resulted in 70% less exopolysaccharide (EPS) volume than on untreated surfaces at day 7. This is consistent with the finding that EPS production per cell was significantly lower on UV-treated surfaces. Untreated titanium surfaces covered with biofilm were fivefold rougher than the original machined surface, while UV-treated surfaces remained twofold rougher due to significantly less biofilm formation. Conclusion: UV treatment of titanium surfaces significantly reduces attachment of human oral bacteria and subsequent biofilm formation as well as EPS production for at least 7 days. UV treatment prevented the escalation of surface colonization, mitigating an unfavorable bacteriophilic cascade and environmental trigger for biofilm formation. Keywords: dental implants, peri-implantitis, titanium, ultraviolet

Purpose: This in vitro study assessed the artifact production related to titanium and zirconia implants in cone beam computed tomography (CBCT) and compared the effect of different protocol settings on image quality for both materials. Materials and Methods: A titanium implant and a zirconia implant were placed in a dry mandible. CBCT scans were obtained separately for each implant using the ProMax 3D (Planmeca) unit; 20 protocols were tested with varying kilovoltage (70 to 90 kVp) and resolution (high and low), and with and without a metal artifact reduction tool. Standard deviation and contrast-noise ratio were calculated in regions of interest adjacent and distant to the implant. Results: The zirconia produced more artifacts and its images were more affected by the different protocols than titanium. High kVps and an activated metal artifact reduction tool decreased the standard deviation values related to both implants. Activation of the metal artifact reduction tool also increased contrast-noise ratio values for both implants, whereas increasing kVp improved them only on titanium images. The standard deviation and contrast-noise ratio were not affected by resolution. Conclusion: The zirconia implant generated more image artifacts than the titanium implant. Increasing kVp and the metal artifact reduction tool are efficient in decreasing the CBCT artifacts for both implants, whereas resolution does not affect their production. Keywords: artifacts, cone beam computed tomography, dental implant

Purpose: To analyze the effect of crown-to-implant (C/I) ratio over survival rate, marginal bone loss, and prosthetic complications of dental implants. Materials and Methods: Electronic (PubMed [MEDLINE], Embase, and Cochrane Central) and manual searches for clinical trials with a minimum follow-up of 1 year were performed. Clinical and anatomical C/I ratios were obtained. Regression models were created to assess for potential correlation between C/I ratio (anatomical and clinical) and survival rate, marginal bone loss, or prosthetic complications. A subgroup analysis of 6-mm implants and a comparison of C/I ratios of > 1.5 vs ≤ 1.5 were also performed. The Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool For Randomized Controlled Trials were used to evaluate the risk of bias. Results: An overall moderate risk of bias was assessed among the selected articles. Linear regression analysis did not reveal a significant correlation between anatomical C/I ratios and survival rate (P = .905), marginal bone loss (P = .33), or prosthetic complications (P = .67). Similarly, no significant correlation to survival rate and marginal bone loss (P = .42, P = .84) was observed in the articles providing the clinical C/I ratios. Conclusion: Increased C/I ratio does not seem to be directly related with increased marginal bone loss and does not represent a biomechanical risk factor for the stability of the prosthesis and for the survival of dental implants. Keywords: crown-to-implant ratio, dental implants, evidence-based dentistry, peri-implant bone loss, short implants

Purpose: This study evaluated the efficacy of newly designed, laser-perforated pure titanium membranes for guided bone regeneration using beta-tricalcium phosphate (β-TCP), and compared them with the existing membrane. Materials and Methods: Bilateral acute lateral ridge defects were created in the mandibles of 12 dogs (four defects per animal), which were then randomly divided into two groups (six dogs each). The twenty-four bone defects in each group were then further divided into five groups. The groups were as follows: (1) F001M0, a prototype membrane without a frame plus β-TCP (n = 5); (2) F001M1, a prototype membrane with a frame plus β-TCP (n = 5); (3) FBS, an existing control membrane plus β-TCP (n = 5); (4) control 1, β-TCP without membrane and with covering flap only (n = 5); and (5) control 2, no treatment (no β-TCP and no membrane) (n = 4). In all groups where β-TCP was used, it was mixed with peripheral blood. The animals were necropsied at 6 or 12 weeks postoperatively (six dogs each), and samples were collected and processed for radiographic, histologic, and histomorphometric analyses. Results: Among the three membrane groups, regenerated tissue and bone volume was greatest in the F001M1 group at both 6 and 12 weeks postoperatively, although differences among groups were not statistically significant. Bone mineral density was similar among the membrane groups. Histologic analysis revealed that immature fibroblasts were present on the laser-perforated portion at 6 weeks, which induced vascularization. In addition, more calcified bone was replaced beneath the prototypes than beneath the FBS membrane at 12 weeks. Histomorphometric analyses revealed that the calcific osseous areas at 12 weeks after surgery were significantly greater in the F001M1 and F001M0 groups than in the FBS group (P = .021, P = .032). Furthermore, the fibrous tissue areas beneath the membrane at 12 weeks postoperatively were significantly smaller in the prototype groups than in the FBS group (P = .02, P = .02). Conclusion: The efficacies of both prototype membranes were not inferior to that of the FBS membrane, indicating that they may facilitate bone regeneration and maturation when β-TCP mixed with autologous blood is employed. Keywords: barrier membrane, beta-tricalcium phosphate, guided bone regeneration, mandible, titanium membrane, ultrafine microperforation

Purpose: There is a lack of studies reporting long-term prevalence of peri-implant diseases in patients rehabilitated with overdentures and not receiving maintenance, which is a common situation. The aim of this cross-sectional study was to evaluate the patient satisfaction and rate of biologic complications in patients rehabilitated at least 7 years before with mandibular/maxillary overdentures, who for personal or economic reasons decided not to participate in a structured supportive maintenance program. Materials and Methods: Each of the patients filled out a health and dental history and a visual analog scale (VAS)-based satisfaction questionnaire; additionally, the patients received a clinical examination and a panoramic radiograph. The prevalence of peri-implant diseases and the patient satisfaction were reported. Moreover, presumed risk indicators of peri-implant diseases and implant loss were tested through univariate analyses and multivariate, time-adjusted, logistic regressions. Results: A total of 52 patients who received 63 overdentures on 252 implants were included. The included patients showed a high degree of satisfaction (mean VAS = 6.3; SD: 2.1) and very low discomfort rates and would repeat the type of rehabilitation (mean VAS = 6.99; SD: 2.6). The prevalence of peri-implantitis was 30.8% at patient level and 19.4% at implant level, while 23.1% of patients experienced implant loss at any time. A clear tendency toward increased prevalence of biologic complications after the eighth year of loading was noted. In loading time-adjusted regression analyses, bone-level implants were associated with a higher prevalence of recession with no/minimal inflammation (OR = 3.37; 95% CI: 1.16 to 9.77; P = .025), while the maxillary arch was associated with both severe peri-implantitis (OR = 4.18; 95% CI: 1.03 to 16.97; P = .046) and implant loss (OR = 9.27; 95% CI: 3.41 to 25.14; P = .000). Conclusion: Despite high levels of satisfaction, patients rehabilitated with overdentures not participating in a structured supportive schedule show high rates of biologic complications. For this reason, they should be strongly motivated, at the time of prosthesis delivery, to participate in a structured maintenance program. Keywords: long term, patient satisfaction, peri-implant diseases, peri-implantitis, peri-implant mucositis, risk factors, supportive

Purpose: The aim of this retrospective case-control study was the evaluation of the split bone technique with regard to the occurrence of early complications, implant survival rate, and peri-implant bone resorption. The effect of patient-related factors (sex, age, tobacco consumption), implant location, and the implant system used on bone resorption was analyzed. Materials and Methods: Patients treated by means of the split bone technique with autologous bone blocks from the external oblique line in a two-stage grafting procedure were observed for up to 5 years after implant placement. The control group was a randomly selected group of patients with implants inserted without any augmentation procedures. Vertical bone resorption was measured radiographically, implant survival was calculated by means of the Kaplan-Meier procedure, and complications were recorded numerically. Results: A total of 194 augmentations in 164 patients were performed in the 10-year period. One graft was lost due to exposure and infection of the recipient site, and in four cases, severe resorption of the graft prior to implant placement made a second augmentation necessary. Eighty-seven patients with 100 grafts and 173 implants in the study group and 91 patients with 173 implants in the control group participated in the follow-up. Implant survival was 100% in the study group and 98.5% in the control group (P = .262; log-rank test). The median vertical peri-implant bone resorption after 5 years was 0.7 mm in the study group and 0.6 mm in the control group (P = .371; Mann-Whitney U test). In the study group, the difference between male (0.4 mm) and female (0.9 mm) patients was significant at the end of the follow-up period (P = .022). Significant differences were also found between smokers (2.8 mm) and nonsmokers (0.6 mm) after 5 years (P = .002). Conclusion: The split bone technique using autogenous bone represents a reliable therapy method with a very low complication rate and an implant survival rate of 100% after 5 years. The technique did not result in any increase in peri-implant bone resorption during the follow-up period. Smoking and gender may negatively influence peri-implant bone resorption when using this technique. Keywords: alveolar ridge augmentation, bone block graft, implant survival, peri-implant bone resorption, split bone technique

Purpose: To evaluate the clinical outcomes of aftermarket computer-aided design/computer-assisted manufacturing (CAD/CAM) titanium abutments supporting splinted prostheses and single crowns in the posterior region. Materials and Methods: This study retrospectively evaluated the records of patients who received posterior implant-supported splinted restorations and single crowns supported by aftermarket CAD/CAM titanium abutments. Recall and clinical examination of the patients were performed between January 2017 and February 2018. A logistic regression was conducted to evaluate the influence of variables on the occurrence of complications and success rates. Correlations between the bone-level change and variables were calculated using the Spearman correlation. Results: One hundred thirty-five patients with 287 implants (86 crowns and 97 splinted prostheses) were recalled and examined clinically and radiographically after a mean observation period of 6.3 ± 1.2 years (range 4.1 to 9 years). Failure of three implants led to a survival rate of 99.0%. Complications included 18 (9.8%) ceramic chippings, 15 (8.2%) screw loosenings, 8 (4.4%) decementations, 52 (38.5%) patients with peri-implant mucositis, and 9 (6.7%) patients with peri-implantitis. A significantly higher incidence of ceramic chipping occurred with bruxers (odds ratio [OR] = 3.939, 95% confidence interval [CI] = 1.28 to 12.09, P .05). All screw loosenings occurred in single crowns. All decementations were observed in restorations cemented with temporary cement. Marginal bone loss around implants was significantly correlated with smoking (r = -0.155, P .05). Hypertension was significantly associated with peri-implant mucositis (OR = 4.7, 95% CI = 1.65 to 13.39, P .05). The technical success rate was 80.1%. The biologic success rate was 57%. There was no association between the restoration type and the success rates of the restorations. Conclusion: Using aftermarket CAD/CAM titanium abutments to support posterior restorations yielded comparable survival and success rates after a mean observation period of 6 years. However, in light of the relatively high incidence of screw loosenings, especially in patients receiving single-implant crowns, informing patients of the additional chairside aftercare with this type of treatment option is recommended. Keywords: aftermarket CAD/CAM titanium abutment, biologic complications, dental implant, posterior fixed prostheses, radiographic measurement, technical complications

Purpose: The purpose of this retrospective clinical study was to evaluate the short-term performance of implants and implant-supported dental restorations (single crowns, fixed/removable dental prostheses, and overdentures) and to identify risk factors for prosthetic complications under the conditions of general dental practice. Materials and Methods: De-identified data extracted from electronic patient records were analyzed to clarify the research question. Patient-related variables and implant- and suprastructure-related variables were documented for each patient. The probability of complication-free survival after 1 and 2 years was evaluated using the Kaplan-Meier method. In addition, the prosthetic complications were analyzed using Cox regression models. Results: Eighty-four patients with 134 healed dental implants supporting 107 restorations were studied over a clinical period of up to 52 months (mean: 23.9 months). Of all implants placed (n = 186), nine (4.8%) failed during the healing phase. Of the healed implants, peri-implant bone loss occurred for two implants among two patients. Nonetheless, these two implants remained functional. Complications were as follows: peri-implantitis (1.5%), loss of retention (10%), loosening of the abutment screw (6%), and chipping of the veneer material (3.7%). The probability of complication-free survival for suprastructures alone was 92% (95% CI: 86% to 96%) after 1 year and 84% (95% CI: 75% to 90%) after 2 years of clinical service. Taking into consideration all complications/failures of implants and of restorations, complication-free survival was 86% (80% to 91%) and 79% (70% to 85%) after 1 and 2 years, respectively. Conclusion: Both healed dental implants and implant-supported restorations placed in general practice present high survival; the survival rates seen during the quite short observation period appear comparable to institutional study outcomes. However, technical prosthetic complications are not uncommon among restorations in general dental practice and probably occur more often than reported from university studies. Keywords: complications, dental implants, general practice, implant-supported restorations

Purpose: There is always a tension between allowing novice trainees to place implants independently and the need to achieve accurate functional and esthetic outcomes. The aim of this study was to measure the influence of surgeon experience on the accuracy of implant placement using a teeth-supported surgical guide via a partially guided surgical protocol. Materials and Methods: Twenty partially edentulous patients were randomly allocated to expert and novice surgeon groups. Implant drilling and placement for the two groups were performed through a flapless surgical technique using surgical guides following a partially guided surgical protocol. The study primary independent variable was the surgeon experience, while the outcome variable was the accuracy, which was measured based on the differences in implant angulations preoperatively and postoperatively. Two-way analysis of variance (ANOVA) was applied to find the influence of surgeon experience, implant size, and the interactive effect of surgeon experience and implant size on the angular deviation. Results: A total of 40 implants were inserted in 7 men and 13 women. There was no significant difference (P = .453) in the mesiodistal deviation between the expert and novice groups. In a buccolingual direction, the expert group performed more accurate implant placement (3.7 ± 3.35) compared with the novice surgeons (8.5 ± 6.3). Conclusion: The level of surgeon experience affects the accuracy of implant placement using a teeth-supported surgical guide; therefore, the use of computer-guided surgery via a partially guided protocol does not completely compensate for the level of operator experience. However, such surgical guide might be used in a whole task training of novice surgeons, as it can bridge the gap between simulation training in vitro and freehand surgery in a clinical setting. Keywords: computer-guided surgery, implant placement, surgeon experience, surgical guide

Purpose: This follow-up study evaluated the implant success rate and marginal bone response of submerged and nonsubmerged osteoconductive two-piece implants with a moderately rough implant neck in thick and thin gingival biotypes. Materials and Methods: The stability of the hard tissue surrounding the implants was evaluated, based on clinical and radiographic examinations performed after implant placement and every follow-up thereafter. The clinical data were processed via linear mixed-effects model statistics at the patient level. Results: Forty-three edentulous and partially edentulous patients were treated with a total of 97 implants with an osteoconductive surface. After 2 years in function, all the implants and dental prostheses reached a 100% success rate according to predefined criteria. Taking implantation as a baseline, the mean change in the marginal bone level (ΔMBLp) after 2 years in function was −0.36 mm (SD: 0.55), and bone resorption higher than 1 mm and less than 2.5 mm was observed for seven implants. Taking dental prosthesis placement as a baseline, the ΔMBLp after 2 years of loading was −0.13 mm (SD: 0.39), and bone resorption higher than 1 mm and less than 2.0 mm was observed only for two implants. Statistically significant differences in mean marginal bone loss were observed in the gingival biotype (P = .006) and submersion (P .05). Their influence on the dynamics of peri-implant bone loss during the process of biologic width restoration was analyzed. Conclusion: This study demonstrated the high stability of peri-implant hard tissue and the 100% success rate of the implant system with a moderately rough neck. The biotype and implant submersion were evaluated as factors having a significant influence on marginal bone loss. Keywords: biotype, dental implants, insertion depth, osteoconductive surface, peri-implant bone loss

Purpose: Sinus floor elevation (SFE) and simultaneous implant placement is predictable and reproducible. However, the graft material for the antral cavity remains a topic of debate. Considering the high osteogenic potential of the sinus membrane, most graft materials are generally accepted. This study aimed to assess the outcome of simultaneous SFE and implant placement, using leukocyte- and platelet-rich fibrin (L-PRF) as a sole graft material. Materials and Methods: This study was designed as a single cohort prospective study. Clinical and radiographic measurements (cone beam computed tomography [CBCT]) were performed immediately after implant placement and at abutment connection (6 months later). The amount of newly formed bone was linearly recorded on cross-sectional images. Four measurements (mesial, distal, buccal, palatal) were registered with the axis of the implant as reference. Results: Six lateral and 22 transalveolar SFEs were performed in 26 patients with simultaneous implant placement. Six months after surgery, 27/29 implants were clinically integrated. The mean vertical bone gain was 3.4 ± 1.2 mm and 5.4 ± 1.5 mm for transalveolar SFE and lateral SFE, respectively. The level of the new sinus floor was in all cases in continuation with the apex of the implant, and the peri-implant crestal bone height was stable. Conclusion: L-PRF as a sole graft material during simultaneous SFE and implant placement proved to be a practical, safe, and economical subsinus graft material, resulting in natural bone formation.

Purpose: Ridge preservation limits dimensional changes after tooth extraction. However, it is still unclear if using a membrane may be advantageous over a collagen wound dressing. Therefore, the goal of this report was to evaluate the outcomes of ridge preservation using freeze-dried bone allograft with a collagen wound dressing. Materials and Methods: This study included 21 patients who had one molar extracted, and the site received ridge preservation using freeze-dried bone allograft and a collagen wound dressing (test 2 group). Patients had two standardized cone beam computed tomography (CBCT) scans, taken within 72 hours and 3 months after extraction, to measure changes in ridge height and width, and buccal and lingual plate thicknesses. Changes in keratinized tissue width were recorded. Three-arm analyses were performed using historic data from a previous randomized controlled trial by the same study group, in which 20 molar sites received a collagen wound dressing alone (control) and 20 received ridge preservation with freezedried bone allograft and a dense polytetrafluoroethylene membrane (test 1) using the same methodology. Results: There was a statistically significant difference in mean buccal ridge height changes between the control group (2.6 ± 2.06 mm) and test 2 group (1.55 ± 0.93 mm) but no difference in ridge and keratinized tissue width changes between groups. No correlation was found between buccal plate thickness and ridge width change. Conclusion: Freeze-dried bone allograft with collagen wound dressing as a barrier was used successfully for ridge preservation in intact molar extraction sites ( 50% bone loss) and can be considered as a treatment alternative to freeze-dried bone allograft with a dense polytetrafluoroethylene membrane. Keywords: allografts, bone, cone beam computed tomography, dental implants, molar, tooth extraction

Purpose: The aim of this crossover study was to evaluate electromyographic (EMG) connectivity of masseter muscle with different attachments used to retain implant overdentures in patients with atrophied mandibular ridges. Materials and Methods: Twenty-four edentulous participants with atrophic mandibular ridges received conventional dentures (control). Three months after the adaptation period, two implants were placed in the canine areas of the mandible. After osseointegration, each participant was successively given the following prostheses in a crossover manner: (1) ball-retained overdentures, (2) bar-retained overdentures, and (3) Locator-retained overdentures. The EMG parameters (amplitude, chewing area, chewing rate, duration of chewing cycle, duration of chewing burst, and chewing time) were measured 3 months after wearing the following prostheses: conventional dentures, ball overdentures, bar overdentures, and Locator overdentures. Measurements were made during chewing of hard (carrot) and soft (cake) foods. Results: The highest EMG activity/amplitude, chewing area, duration of chewing cycle, and duration of chewing burst were noted with ball overdentures, followed by bar overdentures and Locator overdentures, and the lowest values were observed with conventional dentures. The highest chewing rate and masticatory time were noted with conventional dentures, and the lowest values were observed with ball overdentures. With the exception of chewing area, no significant differences in all tested parameters between bar overdentures and Locator overdentures were observed. Except for duration of chewing cycle, all tested parameters were significantly higher during chewing of hard food than soft food. Conclusion: Within the limitations of this study, twoimplant overdentures recorded higher muscle functions compared to conventional dentures regardless of the type of attachment used. For such overdentures, ball attachment may be recommended over bar and Locator attachments, as it was associated with improved muscle activity and function. Keywords: atrophied ridge, attachments, EMG activity, implants, overdentures

Purpose: To evaluate effects of preoperative virtual planning and jaw reconstruction guided by dental implant rehabilitation on dental prosthesis rehabilitation after jaw reconstruction. Materials and Methods: Patients indicated for segmental jaw resection and who agreed to receive jaw reconstruction procedures were enrolled in the study. Appropriate surgical procedures were determined by a maxillofacial surgeon and a prosthodontist before surgery. The virtual design was created according to preoperative computed tomography. Patients were divided into navigation and non-navigation groups. Implant surgery was performed 6 months after reconstruction surgery. After treatment completion, factors such as survival rate of implants, site of reconstruction, type of graft, and type of prosthesis were compared. Results: In total, 29 patients were included in the study, with 16 patients in the non-navigation group and 13 in the navigation group. A total of 101 implants were inserted, and the implant success rate was 98.02% (2 implants extracted due to peri-implantitis). All patients received prosthetic treatment. Of the 13 navigation group patients, 9 received fixed implant-supported prostheses, whereas the other 4 received removable dentures. Of the 16 non-navigation group patients, 9 eventually received fixed implant-supported prostheses and 7 received removable dentures. There were no significant intergroup differences in terms of prosthesis type (P = .702). However, the proportion of fixed implant-supported prostheses in the navigation group was higher compared with the non-navigation group. Conclusion: Preoperative virtual planning and dental implant rehabilitation- guided jaw reconstruction through preoperative designing can provide a good opportunity to achieve high rates of implant success and dental rehabilitation. This method can also benefit fixed implant-supported prosthetic restorations. Moreover, the use of navigation after virtual planning has no effect on the type of prosthetic reconstruction. Keywords: dental implants, dental rehabilitation, jaw reconstruction, surgical navigation, virtual planning

Purpose: The aim of this study was to evaluate the performance of implants placed for 5 years in grafted vs nongrafted sinuses in relation to crown-to-implant ratio. The measurements of crown and implant lengths took into account changes in both endo-sinus and crestal bone levels over 5 years. Materials and Methods: Enrolled patients required one or two implants in at least one sinus and presented a residual bone height of posterior maxilla ≤ 4 mm. Individual sinuses were randomly allocated either to be grafted or not before surgery. Implants of 8 mm in length were placed using osteotome sinus floor elevation (OSFE). After 10 weeks of healing, they were loaded functionally using definitive single crowns. Radiographic measurements were made on periapical radiographs taken at surgery, prosthetic steps, and 5 years. The implant length was measured between the most apical and coronal contact of bone and implant, and the crown length was measured between the most occlusal point of the crown and the crestal bone. Data were analyzed using mixed linear models. Results: Twenty implants were placed in grafted sinuses and 17 in native bone (12 patients). One of the 35 restored implants failed. Immediately after surgery, the mean lengths of the implants placed in grafted and nongrafted sites were 2.4 ± 0.8 and 2.7 ± 0.9 mm, respectively (P = .351). At loading, the mean crown-to-implant ratios were 3.8 ± 0.8 and 4.6 ± 2.0 (P = .033), respectively, whereas at 5 years, they were 2.0 ± 0.8 and 2.1 ± 0.4, respectively (P = .341). Conclusion: The use of grafting material is not necessary to restore posterior maxilla ≤ 4 mm with OSFE and simultaneous implant placement. Over 5 years, all restored implants but one were functional. Despite unfavorable conditions in terms of initial bone anchorage and height of single crown restoration, a high initial crown-to-implant ratio did not compromise the long-term survival of implants placed in grafted or nongrafted sinuses. Keywords: atrophic posterior maxilla, crown-to-implant ratio, dental implants, grafting material, osteotome sinus floor elevation, proximal bone-to-implant contact

Purpose: To show the clinical and radiographic results of intrabony peri-implantitis lesions treated nonsurgically with adjunctive systemic metronidazole with a mean follow-up of 50 months. Materials and Methods: Subjects diagnosed with peri-implantitis (probing depth ≥ 5 mm with concomitant bleeding on probing and/or suppuration) with radiographic evidence of intrabony defects > 2 mm were included in this study. Implants affected received one session of nonsurgical mechanical debridement with ultrasonic and steel curettes. Systemic metronidazole was immediately prescribed for 7 days. Clinical and radiographic variables were registered at baseline and at the end of follow-up. Results: Eighteen patients and 25 implants were included in this investigation. At baseline, the mean radiographic bone level and intrabony component were 4.52 ± 2.14 mm and 3.93 ± 1.51 mm, respectively. After a mean follow-up of 54 (range: 12 to 108) months, the mean radiographic bone level reduction was 2.6 ± 0.21 mm, and the intrabony component reduction was 2.85 ± 0.37 mm (P .05). A mean probing depth reduction of 4.66 ± 1.33 mm was observed (P .05). Conclusion: Within the limits of this study, nonsurgical treatment of peri-implantitis with the adjunctive administration of systemic metronidazole has shown potential effectiveness in terms of probing depth and radiographic defect reduction after a mean follow-up of 54 months. Keywords: metronidazole, nonsurgical peri-implant therapy, peri-implantitis, radiographic bone loss

The aim of this case report was to present clinical, radiologic, and histologic healing outcomes following functional endoscopic sinus surgery (FESS) to manage maxillary sinusitis after lateral sinus augmentation. Three patients who underwent lateral sinus augmentation developed maxillary sinusitis after 3 to 4 weeks. Pharmacologic interventions were performed, but the patients' symptoms did not resolve. The patients were referred to an otorhinolaryngologist and underwent FESS without the removal of bone substitute material or implants. The patients' symptoms disappeared completely after FESS. The implants were osseointegrated successfully and have functioned well to date (between 4 months and 7 years after definitive prosthesis delivery). No pathologic change was noted clinically or radiologically after FESS. However, biopsy specimens demonstrated some new bone formation with varying degrees of fibrotic change and tissue density, which is not compatible with the clinical and radiologic observations. FESS without intraoral debridement may be sufficient to resolve maxillary sinusitis after lateral sinus augmentation; this may not lead to favorable histologic healing in the augmented sinus. Keywords: case report, dental implant, endoscopic sinus surgery, sinus augmentation, sinusitis

Block anesthesia for the maxillary division (V2) of the trigeminal nerve is a suitable approach when an entire quadrant of teeth and/or associated structures are involved. The most effective approach to anesthetize the maxillary branch is intraorally via the greater palatine canal. This case report describes the use of a computer-aided design/computer-assisted manufacturing (CAD/CAM) implant surgical template designed with a guide channel to allow for the administration of maxillary nerve block through the greater palatine canal. Keywords: 3D, CAD/CAM, local anesthesia, sinus elevation, surgery, surgical guide

Purpose: Immediate replacement of a new implant for a failed implant has the benefit of reducing treatment time and increasing patient satisfaction. Limited studies have reported the outcome of implants placed in previously failed sites. It has been proposed that porous tantalum trabecular implants (TM implants) may offer superior integration due to their structure and may be beneficial in situations that normally present a clinical challenge. The purpose of this pilot study was to analyze dental implant survival in a series where failed implants were immediately replaced by TM implants. Materials and Methods: This pilot study assessed 16 implants in 14 patients where failed implants were immediately replaced by TM implants. All clinical procedures were performed by the same board-certified periodontist in a private practice setting. The implants were restored 8 to 10 weeks postoperatively with stock contour abutments and cemented crowns. Patients were recalled yearly for radiographs and clinical assessment of probing depth, bleeding on probing, and integration status. Data were collected on patient demographics, smoking status, periodontal health status, implant site and size, and the use of membranes and/or grafts. Descriptive statistics were used to describe the demographics of the study population and to calculate overall implant survival proportions. Results: The mean age at time of first implant placement was 54.4 years, with a range of 41 to 74 years. Distribution by sex was evenly split at 50% men and 50% women. The majority of patients were smokers (68.8%), and 75% of the patients had a history of moderate or severe periodontal disease. For the replacement TM implants, most were a larger size than the original implant, 6 × 10 vs 4.8 × 10. Sixteen implants were immediately placed into failed implant sites, and 15 had a successful outcome and continue to maintain function at 5 years post-implantation. Radiographs of the TM implant site showed excellent boneto- implant contact, and the patients did not show clinical signs or symptoms of pain, mobility, infection, or tenderness. Conclusion: Although the limited sample size limits comparisons to larger studies, this initial finding suggests that TM implants may be suitable for immediate placement into failed implant sites. Keywords: replacement implant, tantalum, trabecular implant