The International Journal of Oral & Maxillofacial Implants, 01/2020

Purpose: To examine the effect of controlled progressive orthodontic loading on bone around implants subjected to overloading forces. Materials and Methods: Bilateral edentulous alveolar ridges were created in the posterior maxilla of five beagle dogs and left to heal for an 8-week period, after which 40 implants were placed. In the overloading group (OL), 16 implants were inserted and left to osseointegrate for 16 weeks; impressions were made, and metal crowns were mounted on with supraocclusal contacts with the antagonist teeth. Implants were exposed to dynamic overloading for 16 weeks. In the progressive loading + overloading group (PL+OL), 16 implants were left to osseointegrate for 8 weeks, and custom abutment cores were fabricated and coupled by pairs with Ni-Ti orthodontic springs. Ascending static forces of 100g, 200g, and 300g were each applied for a 3-week period, for a total 9-week progressive loading period. Thereafter, metal crowns with supraocclusal contacts were adapted, and a 16-week overloading protocol for implants was followed as for the overloading group. In the unloaded control group (UL), eight implants were inserted and left uncovered and unloaded for 32 weeks, that is, until the end of the experimental period, at which point all 40 implants were removed with the surrounding bone. Histologic, histomorphometric, and statistical analysis followed. Results: Higher bone-to-implant contact percentage was reported for the OL group (P = .006) and PL+OL group (P .001) compared with the UL group. Between the OL and PL+OL groups, the addition of progressive loading did not increase the bone-to-implant contact percentage (P = .225). Bone density 1 mm and 2 mm distant to the threads did not differ significantly between the three groups. Significantly lower crestal bone resorption was detected around OL group implants (P = .006) and PL+OL group implants (P = .004) compared with the UL group implants. The implant success rate was 87.5% for the UL group, 67.5% for the OL group, and 87.5% for the PL+OL group. Conclusion: The application of controlled progressive orthodontic loading on osseointegrated implants preceding overloading forces did not increase bone-to-implant contact. When applied, overloading significantly increased bone-to-implant contact compared with the unloaded implants. A significantly higher implant success rate was reported in the PL+OL group compared with the OL group. Keywords: bone remodeling, crestal bone resorption, occlusal load, overload, progressive load, static load

Purpose: This study evaluated a novel injectable, self-setting, osteoconductive, resorbable adhesive that provides immediate implant stabilization. Materials and Methods: Twenty-six large canines had the mandibular second through fourth premolars and the first molar removed bilaterally. After 3 months, oversized osteotomies were prepared with only the apical 2 mm of the implant engaging native bone. One site had a novel resorbable, self-setting, mineral-organic adhesive (TN-SM) placed around the implant, a second site received bone graft, and a third site received only blood clot. Removal torque, standardized radiography, and histology were used to evaluate implant stability and tissue contact after 24 hours, 10 days, and 4 months. Results: Mean removal torque values after 24 hours were 1.4, 1.3, and 22.2 Ncm for the control, bone graft, and mineral-organic adhesive, respectively. After 10 days, these values were 5.7, 6.2, and 45.7 Ncm and at 4 months increased to 88.7, 77.8, and 104.7 Ncm, respectively. Clinical, radiographic, and histologic evaluations showed a lack of inflammatory reaction. Control defects were initially radiolucent in the coronal area; grafted sites revealed particles in the gap, with both conditions gradually filling with bone over time. At 10 days, histologic evaluation demonstrated excellent biocompatibility and intimate contact of mineral-organic adhesive to both the implant and bone, providing an osseointegration-like bond; control sites revealed no bone contact in the defect area, while the bone-grafted sites revealed unattached graft particles. At 4 months, much of the mineral-organic adhesive was replaced with bone; the control and grafted sites had some bone fill, and many of the defects demonstrated no bone-to-implant contact and were filled with soft tissue or isolated graft particles. Conclusion: The mineral-organic adhesive provides immediate (osseointegration-like) and continued implant stabilization over 4 months in sites lacking primary stability. Experimental sites demonstrated maintenance of crestal bone levels adjacent to the mineral-organic adhesive and soft tissue exclusion without the use of membranes in this canine model. These results demonstrate that this novel mineral-organic adhesive can enable implant osseointegration in a site where insufficient native bone exists to allow immediate implant placement. Keywords: bone adhesive, calcium phosphate, dental implants, integration, phosphoserine, resorbable, stability

Purpose: Among all previous studies, history of periodontitis (HP) has been regarded as a negative indicator for peri-implant health. However, the role of HP under regular supportive post-implant treatment (SPT) has not yet been evaluated. The aim of this review was to evaluate whether HP remains a negative indicator even under regular SPT in terms of clinical outcomes. Materials and Methods: Two independent reviewers conducted electronic and manual searches of the literature in English from January 2003 to May 2018. Human clinical studies including both patients with and without HP under SPT with more than 1-year followup and complete information about peri-implant conditions were included. Risk ratio (RR) for implant survival rate, weighted mean difference (WMD) for radiologic marginal bone loss, pocket depth, bleeding on probing, and Plaque Index were analyzed to compare the outcomes in patients with and without HP. Results: Thirteen human studies fulfilling the inclusion criteria were selected. Based on the results of meta-analyses, in implants with a rough surface, even under the regular SPT, the HP group showed a lower implant survival rate (RR: 0.96, 95% confidence interval [CI]: 0.94 to 0.98, P .001) and more radiologic marginal bone loss (WMD: 0.34 mm, 95% CI: 0.20 to 0.48, P .001), pocket depth (WMD: 0.47 mm, 95% CI: 0.19 to 0.74, P .001), and bleeding on probing (WMD: 0.08 mm, 95% CI: 0.04 to 0.11, P .001) than the non-HP group. In implants with a machined surface, HP also showed a negative effect on bone loss (WMD: 0.88 mm, 95% CI: 0.65 to 1.11, P .001). However, in implants with a machined surface, no statistical significance in survival rate was found between HP and non-HP patients (RR: 0.98, 95% CI: 0.92 to 1.04, P = .895). Conclusion: Within the limitations of this review, HP remains a negative indicator for implant survival even under regular supportive post-implant treatment coverage in rough-surfaced implants. Keywords: dental implants, history of periodontitis, meta-analysis, peri-implantitis, supportive treatment, systematic review

Purpose: To compare the connection microgaps and the bacterial infiltration of implant-abutment interfaces of two extraoral implant models. Materials and Methods: Two implant models were used: the inner connection and the flush connection types. The implant-abutment microgaps of five sets of each extraoral implant were evaluated with scanning electron microscopy. Eleven additional sets of each model design were immersed in Staphylococcus aureus cultures for 24 hours, and samples were obtained from the external surface and from the implant's internal chamber to quantify the colony-forming units. Results: Scanning electron microscopy analysis showed that microgaps of the flush connection were smaller compared with the inner connection (P .0001), and that bacterial counts were higher at the inner connection compared with the flush connection (P .0001). Conclusion: Within the limitations of this experimental study, it can be concluded that the flush connection model presented a smaller microgap and fewer bacterial colonies compared with the inner connection model. Keywords: extraoral implants, implant-abutment interface, microbial leakage

Purpose: The purpose of this study was to evaluate bone repair with two bone substitutes, deproteinized bovine bone and biphasic calcium phosphate ceramics, associated with autogenous bone. Materials and Methods: The experimental groups were as follows: autogenous bone only (AB), autogenous bone/deproteinized bovine bone (1:1), and autogenous bone/biphasic calcium phosphate ceramic (1:1). After 30, 60, and 90 days, animals were euthanized and samples were collected for microcomputed tomography (micro-CT), histologic, histomorphometric, and expression analyses of VEGFA, RUNX2, ALP, COL1A1, OCN, PHEX, RANKL, and OPG genes by real-time polymerase chain reaction (PCR) array. Results: Histomorphometric analysis showed no difference in the amount of immature bone between AB and AB/biphasic calcium phosphate ceramic at 30 and 60 days. There was less mature bone formation in the AB/deproteinized bovine bone at 60 days compared with AB/biphasic calcium phosphate ceramic and AB, and a lower amount of immature bone in the AB/deproteinized bovine bone at 30 and 60 days compared with the AB (P ≤ .05). Micro-CT analysis showed higher immature bone volume (BVI) in the AB/biphasic calcium phosphate ceramic at 60 days and lower BVI at 90 days (P ≤ .05). Molecular analysis showed a lower expression of all genes in the AB/deproteinized bovine bone and AB/biphasic calcium phosphate ceramic compared with AB at all time points. A greater expression of RANKL was found in the AB/deproteinized bovine bone compared with AB/biphasic calcium phosphate ceramic at 30 days (P ≤ .05), and a lower expression of the OC, RUNX2, and ALP genes in AB/deproteinized bovine bone and AB/biphasic calcium phosphate ceramic was found compared with AB at all time points (P ≤ .05). Conclusion: The use of biphasic calcium phosphate ceramic resulted in greater immature bone formation than deproteinized bovine bone at an early assessment. The studied bone regeneration genes were downregulated in comparison to the control. Keywords: autogenous bone, biomaterials, bone formation, bone substitutes, deproteinized bovine bone, hydroxyapatite

Purpose: The aim of this study was to compare tissue-engineered bone using mesenchymal stem cells (MSCs) and conventional bone grafts in terms of histomorphometric outcome, bone gained, and implant failure in the atrophic maxilla. Materials and Methods: A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted. An electronic search of several databases was performed. RCTs comparing tissueengineered bone using MSCs to bone graft alone in rehabilitation of the atrophic maxilla were included. The outcome variables were a mean percentage of new bone formation, residual graft particles, and connective tissue. Bone gained and implant failure rate were also assessed. Risk ratio (RR) or standardized mean differences (SMD) were statistically analyzed. Results: A total of 190 augmented sites enrolled in 12 RCTs were included in this study. Nine of the 12 RCTs included 153 maxillary sinuses that underwent sinus elevation, and three RCTs included 28 patients with onlay bone grafting. There was no significant increase in new bone formation between the two groups at 3 to 4 months (SMD = -0.232%, CI: -0.659 to 0.195, low-quality evidence). However, at 6 months postgrafting, a statistically significant increase in new bone formation was found in favor of the tissue-engineered bone using the MSC group (SMD = 0.869%, CI: -1.98 to 9.310, moderate-quality evidence). No substantial difference was found between the two groups with respect to residual graft particles, connective tissue, bone gained, and implant failure rate (RR = 2.8, CI: 0.517 to 16.6, P = .226, very low- quality evidence). Conclusion: There is moderate- to very low-quality evidence supporting the use of tissueengineered bone using MSC therapy in maxillary alveolar bone regeneration compared with conventional bone grafting without MSCs. Keywords: histomorphometric analysis, maxillary sinus augmentations, mesenchymal stem cells, randomized controlled trial, systematic review, tissue-engineered bone

Purpose: To compare and evaluate maxillary sinus perforation repair, bone regeneration, and membrane degradation with cross-linked and non-cross-linked collagen membranes in rat sinuses at 2, 4, and 10 weeks, respectively. Materials and Methods: Fifty-one Sprague-Dawley rat models were included in the study. Bilateral maxillary sinus perforations were made with a straight bur. In the control site, cross-linked collagen membrane (Ossix Plus) was placed, and in the test site, non-cross-linked collagen membrane was used (Pro-Tiss). Euthanasia was carried out under carbon dioxide asphyxia where 17 rats were sacrificed at weeks 2, 4, and 10. Histologic evaluation of the specimens was subsequently done. Results: At 2 (P = .001), 4 (P = .031), and 10 (P = .024) weeks, there was a significant regeneration of maxillary sinus lining in sites treated with non-cross-linked collagen membrane over the cross-linked collagen membrane. No significant differences were observed in measures of bone regeneration (P = .92; 10 weeks) and membrane degradation (P = .06; 4 weeks) at the end of the study period between the two groups. Conclusion: The non-cross-linked collagen membrane appears to be more beneficial in maxillary sinus repair. However, it does not seem to confer additional benefits in bone regeneration or membrane degradation over cross-linked collagen membranes. Keywords: cross-linked collagen, guided tissue regeneration, maxillary sinus, non-cross-linked collagen, soft tissue injuries

Purpose: To test a novel implant metal-acrylic prosthesis design in comparison to a conventional prosthesis design through simulation of cyclic masticatory loading. The novel design involved digital designing and fabrication of the framework and the matched veneering acrylic resin material. Materials and Methods: Ten prostheses were fabricated for each group. All the prostheses exhibited a similar external design on two implants with a distal cantilever. The conventional group comprised a milled metal framework with mechanically retained acrylic denture teeth via vertical pins. The digital prosthesis group incorporated an inverted T-shape bar and a monolithic milled acrylic resin veneer. The resin veneer was subsequently adhesively attached on the bar. All prostheses were thermally aged and subjected to laboratory cyclic loading at the cantilever region. The load-to-failure and the number of cycles until failure were collected. Furthermore, failed specimens were analyzed to determine the mode of failure. Results: The digital prostheses failed at significantly greater load-to-failure (1,570.0 N ± 116.0 N) and number of cycles (124,857 ± 21,608) than the conventional prostheses (load-to-failure = 1,015.0 N ± 47.4 N; number of cycles = 28,452 ± 6,559). The conventional prostheses failed by fracturing of the acrylic teeth and veneering material that led to exposure of the metal framework. Half of the digital prostheses failed by superficial chipping of the veneering material, while the other half failed by the deformation and fracture of screws. Conclusion: Within the limitations of this study, the digital prostheses with the novel design and monolithic veneering material showed significantly higher strength compared with the conventional prostheses. The mode of acrylic failure of the digital prostheses was more favorable. Keywords: CAD/CAM, edentulous, full-arch, hybrid prosthesis, implant-fixed prosthesis, implants

Purpose: A systematic review was performed of the dimensional changes in facial cortical bone following implant placement into healed ridges, with the aim of establishing a minimum bone thickness that limits such changes. The influence of such bone remodeling upon the soft tissues and implant survival was also evaluated. Materials and Methods: A search was done of two electronic databases (MEDLINE via PubMed and CENTRAL), complemented by a manual search and lists of references. The risk of bias and methodological quality were assessed using the Cochrane Collaboration tool, the Methodological Index for Non-randomized Studies (MINORS), and the Quality Appraisal Checklist for Case Series. Results: The search yielded 536 publications, of which 11 (four randomized clinical trials, two non-randomized clinical trials, and five case series) were entered in the review. All the included studies reported vertical and horizontal implant facial bone resorption. Decreased facial bone thickness was correlated with increased vertical bone resorption, which in turn was associated with slight soft tissue retraction. A meta-analysis could not be performed, due to the heterogeneity of the study designs and measurement sites. Conclusion: No minimum facial bone thickness was seen that would completely avoid peri-implant bone loss and maintain soft tissue stability. However, a thickness of approximately 2 mm was associated with diminished vertical bone resorption and less peri-implant mucosal recession. Keywords: dental implants, facial bone resorption, facial bone thickness, implant success, marginal bone loss, soft tissue recession

Purpose: This study aimed to biomechanically evaluate the effects of cantilever length and implant inclination on the stress distribution of mandibular prosthetic restorations constructed from monolithic zirconia ceramic. Materials and Methods: Mandibular full-arch prostheses supported by four implants constructed from monolithic zirconia were designed using either a 5-mm or 9-mm cantilever length and a 15-degree or 30-degree distal tilt for the posterior implants. A simulated static load of 600 N was applied from the right side at a 45-degree angle. Von Mises and principal stress values in superstructures were analyzed using the Mesh VR Studio program. Results: When the effects of cantilever length were examined, in the models with the 15-degree implant tilt, stress values for posterior implants, porcelain, and cortical bone were lower when the cantilever length was shorter (5 mm). In the models with the 30-degree implant tilt, stress values in all implants (except for the anterior implant on the right) and in the porcelain superstructure were lower when the cantilever length was shorter; however, stress values for cortical and spongious bone were lower with the longer (9 mm) cantilever. When the effects of implant inclination were examined, in the models with a 5-mm cantilever, stress values for posterior implants and cortical bone were lower when the implant tilt was more severe (30 degrees). In the models with a 9-mm cantilever length, stress values for the right anterior implant, posterior implants, and cortical bone were lower when the implant tilt was less severe (15 degrees). Conclusion: Cantilever length and posterior implant inclination affected the distribution of force. Increasing the cantilever length led to a reduction in stress values in distally tilted posterior implants. Moreover, increasing the distal inclination led to a reduction in stress values in both the distally tilted posterior implants and cortical bone tissue in the model with a short cantilever. The monolithic zirconia fullarch porcelain superstructure was not affected by implant angulation, but was affected by cantilever length, with lower stress values observed with a longer cantilever. Keywords: All-on-4, cantilever length, implant, implant inclination, stress distribution, zirconia

Purpose: Proton pump inhibitors (PPIs) are prescribed for the treatment of gastric reflux disease, but such medications might also influence bone metabolism. Therefore, the primary goal of this study was to determine if bone loss severity at dental implants could be associated with PPI use. Materials and Methods: Dental, medical, and radiographic history records of patients receiving dental implants at the University at Buffalo, School of Dental Medicine from 2000 to 2017 were reviewed in this retrospective clinical study. Bone loss around each implant was evaluated radiographically by direct measurement of crestal bone loss and by counting the number of radiographically evident exposed threads. PPI use was confirmed by medical record examination. The effects of systemic factors were assessed. Confidence intervals (CI) and P values of mean differences between PPI and non- PPI groups were computed via IBM SPSS Statistics v.25. Results: A total of 1,480 implants from 635 patients were used in this study. Greater crestal implant bone loss was associated with patients with a history of PPI medication use. Mean crestal bone loss of 1.60 mm was noted at implants from PPI patients, in contrast to 1.01 mm of crestal implant bone loss at implants from the non-PPI group (group difference = 0.59 mm, 58.40% increase, P = .024, CI [95%] = 0.08 to 1.09 mm). Following adjustment for systemic factors, those effects persisted, with crestal implant bone loss of 1.87 mm from PPI patients, in contrast to 1.04 mm from non-PPI patients (group difference = 0.83 mm, 79.80% increase, P = .028, CI [95%] = 0.09 to 1.56 mm). Similarly, 0.63 exposed threads per implant were found in the PPI group, in contrast to 0.38 supracrestal implant threads in the non-PPI patient group (mean difference = 0.25 exposed threads, 65.8% increase, P = .039, CI [95%] = 0.01 to 0.50 mm). After excluding systemic factors, a similar pattern was observed with 0.79 vs 0.36 threads exposed from subjects taking PPIs, compared with those not taking PPIs, respectively (mean difference = 0.43 exposed threads, 119.4% increase, P = .014, CI [95%] = 0.09 to 0.77 mm). Conclusion: The data suggest that PPI medications are related to more loss of crestal bone at implant sites. Patients receiving implant therapy might require more frequent periodontal maintenance. Keywords: bone loss, dental implants, proton pump inhibitor

Purpose: Capturing implant position in impression-making procedures commonly involves transfer devices, such as implant impression copings and laboratory analogs. These components are intricately machined, including the lumen, and often include additional features for prevention of screw dislodgment. The Centers for Disease Control and Prevention recommends all surfaces in contact with human bodily fluid be disinfected with hospital-grade disinfectant. The ability of these components to harbor biologic contaminant material has not yet been determined, especially with regard to internal configuration, combined with the knowledge that many clinicians and laboratories use a spray disinfectant, which may limit disinfectant contact. The aim of this study was to determine the site and extent of contamination occurring on implant components following clinical impressions and laboratory procedures. Materials and Methods: The study design included forensic staining and subsequent analysis of 60 used impression copings, 10 used laboratory analogs, and 10 new components as controls. Results: Staining was found on 100% of impression copings used in vivo, indicating that biologic material had reached multiple sites on both internal and external surfaces of the components. Staining was also found on the internal aspect of used implant analogs, indicating transfer of biologic material from the impression coping and screw. None of the new control components presented staining at any site. Staining highlighted difficult areas to debride, particularly components with difficult or impossible access for cleaning and disinfection. Conclusion: Phloxine B staining indicated the ability of biologic material to reach all areas of the implant components. Having demonstrated the difficulty, sometimes impossibility, of accessing areas of these implant components, there is a need to develop protocols to reduce risk of potential transmission of infective material via implant components. Further study is warranted to determine the potential for transmission of infective material due to inadequate disinfection processes of implant componentry. Keywords: biologic contamination, disinfection, implant components, implant impression

Purpose: Autogenous bone grafts are considered a "gold standard." The success of autografts mainly depends on their ability to promote an osteogenic response. The aim of this study was to collect autogenous bone during implant osteotomy preparation using two different drilling protocols and to evaluate and compare the proliferation and differentiation ability of the collected bone particles. Materials and Methods: Autogenous bone particles were harvested from 20 patients during implant osteotomy preparation using two different drilling protocols: (1) standard drilling protocol with saline irrigation (according to the manufacturer's recommendation) and (2) low-speed drilling protocol without saline irrigation (speed 200 rpm). Collected bone samples were cultured in growth medium, and after 2 to 3 weeks, cells that grew out from bone grafts were cultured in the normal medium as well as in osteogenic medium for days 0, 4, 7, and 20. Scanning electron microscopy, alizarin red/toluidine blue staining, DNA, ALP, and calcium content measurements were performed. Repeated measures analysis of variance (ANOVA) with Bonferroni's test was employed to analyze the data of this study. Results: The total DNA content was significantly higher for the low-speed drilling samples compared with the standard drilling on day 4 (P .05), day 7 (P .01), and day 20 (P .001) in the normal medium and on day 7 (P .01) and day 20 (P .01) in the osteogenic medium. Besides, calcium measurements and mineralized matrix formation observed with alizarin red/toluidine blue staining were significantly higher for the low-speed drilling group compared with the standard drilling group. Conclusion: Osteogenic efficacy (differentiation and proliferation) of autogenous bone particles collected using low-speed drilling was superior compared with standard drilling samples. Keywords: bone graft(s), bone remodeling/regeneration, cell differentiation, dental implants, mineralized tissue/development, osteoblast

Purpose: To clinically evaluate a recently developed, standardized, three-implant-supported full-arch treatment concept for fully edentulous mandibles. Materials and Methods: This ongoing multinational prospective cohort study is evaluating the performance of the treatment concept over 5 years in patients who were fully edentulous or had failing dentition of the mandible. The primary outcome was the cumulative survival rate of implants (CSRI). Secondary outcomes included the cumulative survival rate of the prostheses (CSRP), marginal bone level change, soft tissue outcomes, impact on quality of life, and patient and clinician satisfaction. The 1-year report is presented here. Results: In total, 110 patients (330 implants) were included. Prostheses underwent immediate loading in 76.4% of cases and early loading in 23.6% of cases. The mean surgical time was 1.60 ± 0.78 hours, and the mean laboratory time was 3.99 ± 1.74 hours. At 1 year, eight implants and three prostheses failed, yielding an implant-level CSRI of 97.5% and a CSRP of 97.3%. All prosthetic failures were due to loss of two implants in the patient. The mean marginal bone level change at 1 year was -0.62 ± 1.39 mm. Among soft tissue outcomes, the Bleeding Index improved significantly between the 6-month and 1-year follow-up, and 242 implants (75%) were surrounded by keratinized mucosa by the 6-month follow-up. Patients reported a significant improvement in quality of life between prosthesis placement and the 6-month follow-up based on the Oral Health Impact Profile for Edentulous 21 questionnaire. Both patient and clinician satisfaction with function and esthetics were high throughout treatment. Conclusion: This novel treatment concept using a passively fitting standardized framework with simplified surgical and prosthetic workflow demonstrated high survival and excellent outcomes at 1 year while reducing chair and fabrication time. This concept may offer patients a safe and efficient option for fullarch mandibular prostheses. Keywords: dental implants, edentulous, efficient, failing, mandible, terminal dentition, Trefoil

Purpose: To assess the efficacy and safety of bone-anchored dental implant placement at the same time as orbital exenteration compared with delayed implant placement. Materials and Methods: A retrospective comparative study was conducted in a single tertiary care center between December 2003 and December 2017. Patients who underwent bone-anchored implant placement at the same time as orbital exenteration were included (group 1) and compared with patients who underwent delayed implant placement (group 2). The main outcome was the 1-year success rate of implant osseointegration. The secondary outcomes were the 5-year success rate of osseointegration, postoperative complications, and time between orbital exenteration and prosthesis placement. Results: Ten and 11 patients (21 and 22 implants) with a mean follow-up of 50.2 and 48.5 months were included in groups 1 and 2, respectively. Patients in group 1 were significantly older (69.7 vs 61.2 years, P = .026). No significant differences were found between both groups regarding tumor type and location, prior treatments, smoking status, and postoperative radiation beam radiotherapy. The 1- and 5-year success rates of osseointegration were 95.5% and 93.3% in group 1, and 100% and 100% in group 2, respectively (P = .488 and P = .450 between both groups). One implant did not osseointegrate in group 1 due to osteitis. Ethmoidal fistula was the most common postoperative complication found in both groups (P = .670). The mean time between orbital exenteration and episthesis placement was 8 (3 to 14) vs 11 (3 to 15) months in groups 1 and 2, respectively (P = .467). Conclusion: Placing implants at the same time as orbital exenteration is a viable procedure. It reduces surgical morbidity and allows placement of implants in a nonirradiated area. Keywords: episthesis, implant placement, one step, orbital exenteration, osseointegration

Purpose: To identify whether or not immediate loading yields different clinical outcomes from conventional loading of single-tooth implants in the esthetic zone. Materials and Methods: Various databases (MEDLINE/ PubMed, Cochrane [CENTRAL], and Embase) were searched electronically to find articles published in the English language from January 2000 to April 2018. Only randomized controlled clinical trials (RCTs) that compared conventional and immediate implant loading with a minimum follow-up period of 1 year or more were considered. Available data were pooled for meta-analysis using the Review Manager software. Results: Seven RCTs were included. There was no significant difference between immediate and conventional loading protocols on implant survival at the 1-year follow-up (risk ratio [RR] = 0.99; 95% confidence interval [CI]: 0.95 to 1.02). The differences regarding marginal bone loss between the two protocols were statistically insignificant (mean difference [MD] = 0.03 mm; 95% CI: -0.09 to 0.15 mm at the 1-year follow-up, and MD = -0.01 mm; 95% CI: -0.16 to 0.15 mm at the 2-year follow-up). Soft tissue changes following different loading protocols revealed no significant differences in the mesial papillae (MD = 0.30 mm; 95% CI: -0.25 to 0.85 mm), the distal papillae (MD = -0.00 mm; 95% CI: -0.42 to 0.42 mm), and the midfacial mucosa (MD = -0.33 mm; 95% CI: -1.17 to 0.50 mm) at the 1-year follow-up. The esthetic outcomes and patient satisfaction were reported in two and three RCTs, respectively. Conclusion: A short-term follow-up of single-tooth implants in the esthetic zone showed that the loading protocols (conventional or immediate loading) are not likely to influence the clinical outcomes, including implant survival and peri-implant stability of soft and hard tissues. Keywords: esthetic zone, immediate loading, peri-implant, single implant, stability

Purpose: The aim of this investigation was to compare the chewing efficiency after immediate and delayed loading of mini-implants that served as supplementary support for removable partial dentures (RPDs). Materials and Methods: In this four-center randomized trial, patients who had RPDs in arches with unfavorable tooth distributions, ie, no canine and at most two posterior teeth in one or both quadrants, received strategic mini-implants with ball abutments. The mini-implants in group A were loaded immediately either by housings with O-rings (insertion torque ≥ 35 Ncm) or by soft relining material (insertion torque 35 Ncm). In group B, the RPDs were only hollowed over the balls. After 4 months, the soft relined RPDs and all RPDs of group B received the housings. Masticatory efficiency was evaluated with a validated mixing ability test of two-colored chewing gum before surgery and 14 days, 4 months (before housing pickup), 4.5 months, and 12 months after surgery. The circular variance of hue was the measure of mixing. Results: From 76 participants with 79 RPDs, 38 each were randomly allocated to group A or B. In group A, the housings in six participants were picked up immediately, and the remaining RPDs were primarily soft relined. There was a significant group difference only after 4 months. The mixing ability was better after immediate loading than after delayed loading (P .0001). In group B, the chewing efficiency was notably deteriorated after the RPDs were hollowed over the ball abutments. However, immediately after all housings were picked up, the chewing efficiency in both groups was substantially improved, and the variance of hue values after 1 year were very similar in the groups. Conclusion: The chewing performance can be improved by inserting supplementary mini-implants under existing RPDs with unfavorable tooth support. This improvement occurred faster by immediate loading than by delayed loading. Keywords: chewing function, dental, mini-implant, randomized controlled clinical trial, removable partial denture, strategic

Purpose: To evaluate histomorphometrically early healing at implants placed in sites prepared with either a sonic device or conventional drills. Materials and Methods: Sixteen volunteer patients were recruited. Two titanium mini-implants were placed in the distal segments of the maxilla in recipient sites prepared with either a sonic device or conventional drills. Biopsy specimens containing the mini-implants were retrieved after 2 weeks in eight patients, and after 6 weeks in the other eight patients. Histomorphometric analyses were performed. Results: Histologic slides were available from seven patients for both 2-week and 6-week periods. After 2 weeks of healing, small amounts of new bone were found in contact with the implant surface, with 5.5% ± 7.3% and 3.8% ± 10.0% at the sonic and drill groups, respectively. After 6 weeks of healing, new bone was 46.9% ± 15.5% at the sonic group, and 46.4% ± 14.9% at the drill group. None of the differences was statistically significant. Conclusion: The percentage of new bone in contact with the implant surface was similar in the sonic and drill groups. Keywords: bone density, bone-to-implant contact, dental implants, histology, histometry, sonic device

Purpose: Numerous approaches have been proposed for the treatment of peri-implantitis, but to date, none has been identified as the most effective. This study compared the efficacy of implantoplasty and glycine air polishing for the surgical treatment of peri-implantitis. Materials and Methods: This prospective, randomized, parallel-group trial included 31 patients presenting with 42 implants with peri-implantitis. Patients underwent surgical treatment by implantoplasty (test group, n = 22) or glycine air polishing (control group, n = 20). Clinical parameters (Plaque Index), bleeding on probing (BOP), suppuration on probing (SOP), probing pocket depth (PPD), relative attachment level (RAL), and mucosal recession were assessed before surgery (baseline), and at 3 months and 6 months after surgery. Bone loss was recorded at baseline and 6 months. Two composite outcomes were also evaluated, according to the following definitions: (1) mean PPD reduction ≥ 0.5 mm + no further loss of bone; (2) PPD ≤ 5 mm, absence of BOP/SOP, and no additional mean bone loss ≥ 0.5 mm. Results: Plaque Index remained low ( 0.5) in both groups for the duration of the study. Mean BOP, SOP, PPD, and RAL were greatly reduced at 3 months in both groups, and remained low between 3 months and 6 months. Bone loss was stable in the implantoplasty group, and slight bone gain (0.5 mm) was observed in the glycine airpolishing group. There were no significant differences between the two groups in any parameter, and composite treatment outcomes were similar in both groups, irrespective of the definition. Conclusion: Within the limitations of this 6-month follow-up study, implantoplasty is as effective as glycine air polishing for the surgical treatment of peri-implantitis. Keywords: clinical research, oral infection, peri-implantitis, periodontology, surgical procedure, treatment, wound healing

Purpose: To prospectively evaluate the survival at 1 and 4 years of short implants retaining removable partial dentures (RPDs) in Kennedy Class I and II edentulism. Materials and Methods: Twenty patients (Kennedy Class I and II) rehabilitated with RPDs were selected for the insertion of one short implant in the distal edentulous ridge, connected to the RPD with a Locator attachment after osseointegration. The following data were recorded at the 1- and 4-year follow-up: bone loss, bleeding on probing (BOP), probing depth (PD), implant mobility, and survival. Results: Thirty-five implants were placed from September 2012 to April 2014. At the 4-year follow-up, 12 implants showed BOP, and for PD, 15 implants showed 2 mm, 16 implants showed 3 mm, and 2 implants showed 4 mm. One implant showed mobility, and two were lost (survival rate: 94.3%; 95% CI: 80.84 to 99.30). The mean bone loss was 1.04 ± 1.88 mm. Conclusion: Within the limitations of this study, the implant survival rate and the mean bone loss values reported are comparable with those reported by other authors. The use of short implants for retaining RPDs may be considered a viable treatment option for patients with distal edentulism and contraindications for more complex implant rehabilitation. Keywords: bone loss, implant survival rate, removable partial denture, short implants

Purpose: The purpose of this study was to analyze the projects submitted to the ITI International Team for Implantology for funding and the scientific publications ensuing from these projects, over a period of 30 years. Materials and Methods: This analysis was performed based on information available in the database of the ITI. For each project, data related to institution, country of origin, and grant status (financed or rejected) were extracted. For the financed projects, the grant amount and number of publications were recorded. Publications were searched independently by two investigators. For all publications, the study topic, study design, and citation number were recorded. Results: From a total of 1,372 submitted projects from 51 different countries and 308 different institutions, 514 (37.46%) were financed by the ITI. This amounts to more than CHF 52 million invested in favor of implant dentistry and related fields. A total of 552 publications (including original research and reviews) were identified related to these projects, with the majority being in vitro studies (n = 198), and the most common topic researched was implant surface modification (n = 134). The United States was the country and the University of Bern was the institution with the largest number of financed projects and published papers. Conclusion: This analysis revealed that the ITI has been actively supporting research in the field of implant dentistry and related areas globally. Several concepts in present-day implantology are based on literature from ITI-funded projects. Keywords: bibliometrics, dental implants, evidence-based dentistry, funding, implant dentistry, publications, research projects

This case report describes a digital workflow for a computer-aided design/computer-assisted manufacturing (CAD/CAM) healing abutment used in immediate implant placement in the esthetic zone. The design of the healing abutment was based on the existing tooth anatomy in order to provide anatomical support to the gingival tissues and to preserve the gingival contours of the natural tooth. This approach enhances the esthetic outcome of the definitive implant restoration. The surgical procedure including the guided bone regeneration is simplified, postoperative morbidity is reduced, and excessive occlusal loading during healing is limited. Keywords: CAD/CAM healing abutment, computer-guided surgery, immediate implant placement