The International Journal of Oral & Maxillofacial Implants, 03/2020

Purpose: The aim of this study was to investigate the effect of implant and surgical characteristics on the mucosal vertical dimension components. Mucosal vertical dimension consists of the sulcular epithelium and the supracrestal tissue attachment, which can be clinically measured from the gingival margin to the bone-to-implant contact. Connective tissue attachment is measured from the apical border of attached epithelium to the first bone-to-implant contact, while epithelial vertical dimension is measured from the mucosal margin to the apical border of attached epithelium. Materials and Methods: An electronic and manual search for relevant articles published from January 1980 to May 2019 was performed. Animal studies of ≥ 10 implants followed by histometric analysis were included. Quality assessment was performed using the ARRIVE guidelines, and risk of bias assessment was performed using SYRCLE guidelines. Subgroup meta-analysis was performed to analyze the influence of different surgical approaches and implant design. Results: A total of 38 articles were included. The mean value and corresponding standard error of mucosal vertical dimension, supracrestal tissue attachment, connective tissue attachment, and epithelial vertical dimension were 3.39 ± 0.07 mm, 2.9 ± 0.12 mm, 1.35 ± 0.04 mm, and 2.0 ± 0.06 mm, respectively. Supracrestal and subcrestal bone-level implants had significantly higher mucosal vertical dimension than equicrestal bone-level implants. Platform-switching implants demonstrated significantly lower mucosal vertical dimension compared with non–platform-switching implants. Conclusion: Within its limitations, this review showed that equicrestal implants had a smaller mucosal vertical dimension than subcrestal and supracrestal implants, and platform-switching implants possessed a smaller mucosal vertical dimension. Keywords: dental implant, dental implant-abutment design, dental implantation, evidence-based dentistry

Purpose: This in vitro study evaluated the effectiveness of a sealing agent on vertical misfit of the implant-abutment interface in an external hexagon implant system before and after mechanical cyclic loading. Effects on preload maintenance of retaining screws after mechanical cycling were also assessed. Materials and Methods: External hexagon implant systems were divided into two groups (n = 12) according to the presence of an anaerobic sealing gel (control group-no sealing gel; experimental group-sealing gel applied). A prefabricated UCLA abutment was attached to the external hexagon implant with a digital torque wrench in accordance with the recommendations of the manufacturer. Specimens were tested through mechanical cyclic loading (1 × 10⁶ cycles, 2 Hz, and 130 N). Vertical misfit of the implant-abutment interface was analyzed using a stereomicroscope, and reverse torque values were obtained using a digital wrench. Misfit and reverse torque data were measured and analyzed via analysis of variance (ANOVA) and the Tukey least significant difference test (α = .05). Results: The sealing gel promoted lower vertical misfit values in the test group after mechanical cycling compared with before cycling (P = .009). The control group showed lower reverse torque values for retaining screws compared with the initial torque after mechanical cyclic loading (P .0001). However, sealing gel application promoted higher reverse torque values in the test group postcycling (P = .0003). Conclusion: Anaerobic sealing agent application improved vertical misfit of the implant-abutment interface and preload maintenance of screw-retained implant-supported prostheses post-mechanical cycling. Keywords: abutment, implant-supported prosthesis, preload, screw

Purpose: The aim of this systematic review was to estimate if an antibiotic prophylaxis regimen reduces implant failure and postoperative infection in healthy patients who are going to receive dental implants. Materials and Methods: An electronic database search (MEDLINE/PubMed, Scopus, Web of Science, Cochrane Library) until June 30, 2019, for randomized controlled trials (RCTs) was performed. The Cochrane Handbook for Systematic Reviews of Interventions to assess the risk of bias in individual studies was used. Patient- and implant-level data were extracted for the analyzed outcomes. The risk ratio (RR) and the 95% confidence interval were calculated as meta-analytic effects. A fixed- or a random-effect model was employed on the basis of the presence/absence of heterogeneity (I2 > 50%). Differences between groups were analyzed using the inverse of variance test. The Higgins Index and chi-square test were used to assess the studies' heterogeneity. Additionally, in order to evaluate the power of evidence and to adjust the meta-analytic findings for type 1 and 2 errors, a trial sequential analysis (TSA) was performed. Results: Nine studies including 1,984 patients and 3,588 implants were selected. Eight hundred eighty-five patients (1,617 implants) received no antibiotics or a placebo therapy before the implant surgery; 1,971 implants (1,099 patients) were treated with an antibiotic therapy. The meta-analysis at the patient level showed a statistically significant reduction in the rate of early implant failure associated with the use of antibiotics (I2 = 0%) (RR = 0.32 [0.20, 0.51], P > .001). Similar results were obtained after pooling the implantlevel data with the fixed-effect model (RR = 0.33 [0.22, 0.51], P > .001). Such results were also confirmed by the TSA after adjusting for type 1 and 2 errors. Conclusion: The results of this systematic review with meta-analysis indicate that an antibiotic prophylaxis prevents early implant failures in the case of healthy patients. No information can be provided on peri-implant infections. Keywords: antibiotics, chemotherapy, epidemiology, meta-analysis, prophylaxis, review (systematic)

Purpose: The purpose of this paper is to present evidence that supports the notion that the primary reason behind marginal bone loss and implant failure is immune-based and that bacterial actions in the great majority of problematic cases are of a secondary nature. Materials and Methods: The paper is written as a narrative review. Results: Evidence is presented that commercially pure titanium is not biologically inert, but instead activates the innate immune system of the body. For its function, the clinical implant is dependent on an immune/inflammatory defense against bacteria. Biologic models such as ligature studies have incorrectly assumed that the primary response causing marginal bone loss is due to bacterial action. In reality, bacterial actions are secondary to an imbalance of the innate immune system caused by the combination of titanium implants and ligatures, ie, nonself. This immunologic imbalance may lead to marginal bone resorption even in the absence of bacteria. Conclusion: Marginal bone loss and imminent oral implant failure cannot be properly analyzed without a clear understanding of immunologically caused tissue responses. Keywords: biomaterials, failure analysis, immunologic reactions, peri-implantitis, review (narrative)

Purpose: Abutment soft tissue integration in the transmucosal area supports the peri-implant tissues, improves esthetics, ensures a soft tissue seal against microorganisms, and preserves crestal bone level. The aim of this systematic review was to systematically analyze the cellular response of fibroblasts on different abutment materials and surface modifications in in vitro studies with a score-based reliability evaluation. Materials and Methods: A protocol aiming to answer the following focused question was developed: "What is the effect of different abutment materials and different surface modifications on in vitro cellular response of fibroblasts?" A search through three electronic databases (Medline/PubMed, EMBASE, and Web of Science) was performed using the following search terms: fibroblast, implant, abutment used as the main keywords, with AND/OR as Boolean operators. Only in vitro studies using machined titanium as control surface were included. A quality assessment of the selected studies was performed following the SciRAP method. Results: Out of a preliminary pool of 97 articles, 21 relevant articles were identified for final evaluation. Cellular response evaluation was investigated as follows: 10 studies compared two or more different materials, 7 assessed mechanical surface modification, 14 weighed chemical or biochemical surface modification, and 3 evaluated surfaces modified by a biophysical procedure. Rather than abutment bulk material, external surface features (collagen coating, electropolishing, plasma cleaning, and laser dimpling) were demonstrated to positively affect cell response (cell attachment, morphology and proliferations, expression of adhesion-related proteins and cytokines), mostly at the early stage. While sandblasting, acid etching, composite coating, nitride coating, and vitamin D presented lower results compared with machined, controversial results were demonstrated by anodization. The mean reporting quality SciRAP score was 78.17 ± 11.89, while the mean methodologic quality SciRAP score was 84.13 ± 12.35. Intrastudy comparison highlighted that the time after seeding chosen to evaluate the fibroblast response varies significantly and seems to deeply influence the response. In fact, due to heterogeneity in the study designs, statistical methods, and reported results, meta-analysis of the data was not possible. Conclusion: Within the limitation due to the design and heterogeneity of the included studies, it can be speculated that abutment material and its mechanical, physical, and chemical modification influence fibroblast response in vitro, especially in the earlier phases of contact with the abutment surface. Keywords: biomaterials, laser, microsurface, microtexture, review (systematic)

Purpose: To evaluate the resistance to fracture in cantilevered fixed dental prostheses (cFDPs) of single implant-supported zirconia cantilevers in the anterior region. Materials and Methods: Thirty-two cemented and solely screw-retained cFDPs consisting of an implant-supported crown replacing the central incisor and an attached cantilever unit in the position of the lateral incisor in the maxilla were constructed by computer-aided design (CAD) and machined by computer-aided manufacturing (CAM). For the cemented solution, a cFDP was designed on top of a customized abutment luted to an adhesive base. For screw-retained cFDPs, abutment, cement gap, and restoration of the cementable design were combined. All cFDPs were veneered manually on the facial side. Half of the samples underwent artificial aging (thermocycling and chewing simulation) before fracture tests were conducted with loads applied to the pontic either parallel to the implant axis (axial loading on the pontic) or tilted lingually by α = 45 degrees (oblique loading on the pontic). Thus, there were eight groups differing in cFDP design, artificial aging, and load application (n = 8/group). If fracture (F_u,total) occurred within the implant components, the adhesive base was replaced by a cast CoCr base, and the cFDP's fracture resistance (F_u,cFDP) was also determined. Using statistical analyses (SPSS 24, IBM), factors affecting fracture resistance were identified. Results: F_u,total was mainly correlated to screw fractures and therefore not affected by cFDP design. Oblique loading on the pontic (F_u,total = 231 N - 352 N), however, led to a significant (P .001) decrease in ultimate load compared with axial loading on the pontic (F_u,total = 611 N - 815 N). In relation to F_u,total, F_u,cFDP was approximately twice as high for both loading conditions. Conclusion: When relating the results to maximum occlusal forces exerted in the maxillary anterior region, single implant-supported cFDPs can be a viable restorative treatment option. Keywords: CAD/CAM, extension bridge, fracture load, implant-supported, zirconia

Purpose: Strontium has shown a positive effect on osseointegration in experiments. This study compared surface characterization and osseointegration of a strontium-incorporated implant with four commercial implants with different surface treatments. Materials and Methods: A strontium-oxide layer was created by hydrothermal treatment on the surface of the implant (SLA-Sr). Surface characterizations were observed using a scanning electron microscope, threedimensional (3D) optical microscope, and x-ray energy-dispersive spectrometry. Implants of different surface treatments including resorbable blasting media (RBM), sandblasting with large grit and acid etching (SLA-1, SLA-2), sandblasting and thermal acid etching (STA), and SLA-Sr were implanted into the proximal tibiae and femoral condyles of rabbits. Biologic effects were evaluated by removal torque testing and histomorphometric analysis after 3, 6, and 12 weeks of implantation. Results: Nanostructures were observed on the surface of SLA-Sr and STA. Calcium (Ca) was detected on the surface of RBM. Sr was detected on the surface of SLA-Sr. SLA-1 and STA had greater surface roughness than SLA-2, SLA-Sr, and RBM (P .05). In vivo, SLA-Sr achieved better removal torque value (RTV) than that of RBM and SLA-2 at 3 weeks (P .05), as well as increased bone area ratio (BA%) in cortical bone compared with RBM at 3 weeks (P .05). STA showed higher bone-to-implant contact ratio (BIC%) in cortical bone than RBM at 3 and 6 weeks (P .05). Compared with RBM, SLA-1 had better RTV at 6 weeks and higher BIC% in cortical bone at 12 weeks (P .05). Conclusion: In vivo, compared with SLA-2 and RBM, the implant with the strontium-oxide layer displayed slight advantages in new bone formation and osseointegration in the early healing stage. In the later osseointegration stage, the results of SLA-Sr were comparable with other implants. Keywords: dental implant, osseointegration, rabbit model, surface treatment, strontium

Purpose: The purpose of this study was to evaluate the influence of implant inclination on retention and peri-implant stresses of stud-retained implant overdentures during axial and nonaxial dislodgments. Materials and Methods: Mandibular acrylic models (n = 4) received two implants in the canine areas with 0-, 5-, 10-, and 20-degree lingual inclinations. Dentures were attached to the implants with stud connectors. Four strain gauges were bonded at buccal, lingual, mesial, and distal surfaces of each implant to monitor strains around implants. Retention values (Newton) and peri-implant stresses (microstrains, μs) were recorded during axial (vertical) and nonaxial (anterior, posterior, and lateral) dislodging. A general linear model was used to compare retention forces and implant stresses between implant inclinations and dislodging direction. In addition, a linear regression model was used to test correlation of implant stresses with confounding factors. Results: The highest retention and implant stresses were noted with 0 degrees, followed by 5 and 10 degrees (without difference), and the lowest values were noted with 20 degrees. Anterior dislodging was associated with the highest retention and implant stresses, followed by vertical dislodging, then lateral dislodging, and posterior dislodging. Peri-implant stresses significantly correlated with dislodging direction and retention forces. Every 1 N of increase in retention forces causes 19.17 μs increase in implant stresses. Anterior dislodging was associated with the highest predicted stress values (846.0 μs), and the lowest stress values (143.41 μs) were associated with posterior dislodging. Conclusion: Retention forces and peri-implant stresses decreased as lingual implant inclination increased during axial and nonaxial dislodging of stud-retained implant overdentures. Peri-implant stresses were significantly correlated with dislodging direction and retentive forces. Keywords: dislodgment, implant, inclination, overdentures, retention, stresses

Purpose: Diabetes mellitus has been shown to delay osseointegration of titanium dental implants. This study tested the hypothesis that serum derived from diabetes negatively affects osteoblast adhesion to polystyrene and titanium surfaces, partly through the presence of advanced glycation end products (AGEs). Materials and Methods: Twenty-four Sprague- Dawley rats were divided into three groups: normoglycemic control, streptozotocin-induced diabetic group, and diabetic group treated with the AGE inhibitor aminoguanidine. Polystyrene or titanium disks were preincubated in serum derived from each group. Human osteoblasts transfected with green fluorescent protein (GFP) were cultured, and the number of adherent osteoblasts was quantified. High-pressure liquid chromatography (HPLC) was used to fractionate eluates, which were further characterized by western blot with AGE antibody and adhesion assays. In parallel, sera derived from healthy patients, patients with controlled diabetes, and patients with uncontrolled diabetes were utilized for osteoblast adhesion assay and western blot. Results: Diabetic serum significantly reduced the number of adherent osteoblast and osteoblast aggregates on titanium disks, whereas aminoguanidine-treated serum rescued the effect of diabetes on the number of adherent osteoblast aggregates. Fractionated diabetic serum revealed distinct AGE bands at ~100 kDa and 44 kDa, whereas healthy serum did not express any. In human serum samples, both controlled and uncontrolled diabetes led to a significant reduction in the number of adherent osteoblasts on polystyrene and titanium surfaces compared with normoglycemic serum. This correlated with presence of AGEs in western blot in diabetic but not in healthy serum. Conclusion: Osteoblast adhesion on the titanium surface was greatly reduced by the exposure of serum derived from diabetic rats or humans. Recovery of osteoblast aggregates by aminoguanidine treatment suggests that AGEs played a role in this negative effect. The correlating presence of AGEs from the fractionated sera of diabetic rats or humans and impaired osteoblast adhesion on the titanium surface further supports this role. Keywords: bone healing, dental implant, diabetes mellitus, hyperglycemia, metabolism, osseointegration, osteoblast, streptozotocin, wound healing

Purpose: While primary stability still constitutes an important factor for implant success, high levels of insertion torque resulting from bone compression are controversial and may constitute a co-factor in peri-implant bone loss. Materials and Methods: Adhering to the manufacturers' protocols for medium-quality bone, implant surgery was performed in polyurethane foam blocks equipped with strain gauges attached to the buccal aspect. Following insertion and attachment of provisional abutments, oblique loading was performed. The following parameters were recorded for three different implant types (Straumann Bone Level Tapered [BLT], MIS V3 [V3], Dentsply Sirona ASTRA TX [ASTRA]): maximum insertion and removal torque, maximum strain during insertion and loading, and implant stability before and after loading (resonance frequency analysis [RFA]). Statistical analysis was based on analysis of variance (ANOVA), Tukey honest significant difference test, and Pearson's product moment correlation (α = .05). Results: Maximum insertion torque (59.9 ± 4.94 Ncm) was recorded for BLT followed by V3 and ASTRA (P .01 for all comparisons). Maximum removal torque (43.7 ± 9.69 Ncm) was also recorded for BLT, but the pairwise comparisons reached significance only for BLT vs ASTRA (P .01) and V3 vs BLT (P = .03). Implant stability differed among groups only after loading, where the pairwise comparison between BLT and ASTRA reached significance (P = .02). Maximum strain during insertion was caused by BLT reaching 19,482.62 μm/m, whereas ASTRA implants only caused 6,169.84 μm/m. Strain development during insertion differed significantly among groups (P .05 for all comparisons). Maximum strain during loading was observed in V3 (646.44 ± 204 μm/m), while only a nonsignificant difference existed between ASTRA and BLT. Insertion torque correlated significantly with strain development (r = 0.68; P .01), implant stability after loading (r = 0.46; P = .01), and removal torque (r = 0.54; P .01). Also, implant stability after loading correlated with removal torque (r = 0.86; P .01). Conclusion: Different implant designs and surgical protocols result in varying levels of bone compression. Implants with a triangular shape do not seem to solve this problem. Keywords: implant insertion torque, removal torque, resonance frequency analysis, strain development

Purpose: Socket augmentation decreases the magnitude of alveolar ridge resorption, but the literature is limited in respect to quantifying soft tissue remodeling. The aim of this study was to determine the volumetric and linear dimensional changes at the buccal surface for both hard and soft tissues after socket augmentation treated with a xenogeneic collagen matrix in combination with bone grafting. Materials and Methods: Twenty-four individuals indicated for tooth extraction were enrolled in this investigation. Each participant was randomly assigned to one of two groups: (1) deproteinized bovine bone + collagen plug, or (2) deproteinized bovine bone + xenogeneic collagen matrix. A cone beam computed tomography scan was taken prior to extraction and at 6 months postextraction. Intraoral scanning images were taken at baseline, 3 months, and 6 months postextraction. Hard and soft tissue analyses were performed to compare linear ridge remodeling and volumetric changes by noncontact reverse-engineering software. Results: Both groups showed bone and soft tissue remodeling. For hard tissue remodeling, there was no significant difference between the collagen plug and collagen matrix groups. For soft tissue remodeling, the collagen matrix group showed a reduced soft tissue loss compared with the collagen plug group. The volumetric analysis demonstrated that the mean buccal soft tissue volume loss for the collagen matrix group was 68.6 mm3 compared with 87.6 mm3 found in the collagen plug group (P = .009) over a 6-month period. Conclusion: This clinical investigation provides early evidence of using the total tissue volume to compare soft and hard tissue remodeling after socket augmentation. The results of this study demonstrated that the use of a xenogeneic collagen matrix reduced the buccal soft tissue loss after tooth extraction, but additional studies are necessary to evaluate the clinical significance of soft tissue augmentation after tooth extraction. Keywords: 3D, biomaterials, bone graft, bone substitute, randomized controlled clinical trial

Purpose: The purpose of this study was to compare success and outcomes among implants positioned either in grafted or ungrafted alveoli during 10 years of follow-up. Materials and Methods: This retrospective analysis was conducted on data of subjects who underwent tooth extraction and alveolar ridge preservation. Sites, one per patient, were ranked into three groups: postextraction ungrafted alveoli, and postextraction grafted alveoli with either synthetic magnesiumenriched hydroxyapatite or porcine bone. An absorbable collagen sheet was used to completely cover all the sockets. A secondary intention healing was sought for all procedures. Data regarding implant survival and marginal bone loss around implants were gathered until the 10-year follow up. Pairwise comparisons were performed with nonparametric tests, and statistical significance was set at .01. Results: Sixty-three subjects were included: 42 implants (19 and 23 in the magnesium-enriched hydroxyapatite and porcine bone groups, respectively) placed in grafted sites and 21 in nongrafted sites. The success rate of the grafted groups was 88.1% (CI: 78.3% to 97.9%) at the 10-year follow-up. On the other hand, in the ungrafted group, the overall success rate was 85.7% (CI: 70.8% to 100%). Peri-implant marginal bone loss at the 10-year follow-up for the magnesium-enriched hydroxyapatite group was 1.2 (0.7) mm, while for the porcine bone group, it was close to 0. The behavior of the ungrafted group appeared to be significantly different compared with both grafted groups; however, marginal bone levels ranging from 0.1 to 0.4 mm were observed from 3 to 10 years. Conclusion: A difference in terms of long-term success rates between grafted and ungrafted sites was not revealed. Bone loss was significantly higher in the magnesium-enriched hydroxyapatite grafted group compared with those in the other groups (without or with other bone substitute material). Keywords: bone graft, bone substitute, soft tissue management

Purpose: The aim of this study was to compare the percentage of tissue types and assess the presence/absence of odontoblasts or preodontoblasts in granulation tissue harvested from lesions associated with teeth extracted due to endodontic and periodontal reasons. Materials and Methods: Histologic reports of cases with a confirmed diagnosis (ie, endodontic or periodontal diseases) were included. These should include a semiquantitative analysis of the percentage of tissue types per sample (ie, epithelium, subepithelial connective tissue, bone or chronic inflammation/ deep connective tissue). The overall percentage of tissue type per diagnosis was calculated. Quantitative variables were summarized with means and standard deviations. Normal distribution was tested by the D'Agostino-Pearson omnibus normality test. The level of P .05 was adopted for statistical significance. Finally, an analysis of the salient findings was summarized. Results: The reports from 19 patients were included, 9 of endodontic and 10 of periodontal origins. The granulomatous tissue of endodontic and periodontal disease origin was similar, and consisted mainly of chronic inflammation (endodontic 40%, periodontal 41.7%), followed by epithelium (endodontic 25.7%, periodontal 29.2%), subepithelial connective tissue (endodontic 18.6%, periodontal 20.8%), and bone (endodontic 15.7%, periodontal 8.3%). No significant differences were found when comparing the groups regarding the percentage of tissue types (P ≥ .05). No osteoblasts or preosteoblasts were reported. Conclusion: Within the limitations of the study, the granulomatous tissues associated with chronic infection of endodontic or periodontal origin are comparable and consist primarily of chronic inflammatory cells. Keywords: granuloma, healing, histology, osteoblasts, periapical periodontitis, periodontitis

Purpose: To evaluate the osseointegration of mini-implants placed in grafted sinuses with lateral windows of two different dimensions. Materials and Methods: Sinus floor augmentation was performed in volunteers using a lateral window. The antrostomy was systematically prepared with a height of either 8 mm (large group) or 4 mm (small group). After 6 months of healing, mini-implants were placed in the grafted region. Biopsy specimens including the mini-implants were harvested 3 months after placement. Results: Twenty biopsy specimens, 10 from each group, were suitable for the histologic analysis. Similar amounts of new bone-to-implant contact were obtained in both the large (41.1% ± 19.5%) and the small (42.8% ± 13.2%) groups (P = .940). Small percentages of residues of xenograft were found in contact with the implant surface, with 0.6% ± 1.1% in the large group and 5.9% ± 9.5% in the small group (P = .098). The new bone density around the implants was 31.7% ± 8.2% and 34.0% ± 7.9% in the large and small groups, respectively (P = .623). Conclusion: The dimensions of the antrostomy did not influence the histologic healing of implants placed 6 months after sinus floor augmentation. Keywords: bone grafting, dental implants, osseointegration, sinus floor augmentation

Purpose: To compare the masticatory efficiency of an All-on-4 prosthesis with complete dentures on a Class I ridge with a color-mixing analysis test. Materials and Methods: Ten patients with fixed complete dentures on implants and an additional 10 patients with conventional complete dentures on a Class I ridge (Atwood) chewed a bicolor chewing gum (Hubba Bubba) for different numbers of cycles (5, 10, 15, and 20). The chewed gum was retrieved, scanned, and weighted to quantify masticatory efficiency. Results: This study showed higher values for implant-supported fixed complete dentures than conventional complete dentures. These findings were significant with the color-mixing test in cycles 5 and 10 between both groups. The reduction in weight was not significantly different between the two groups but was noteworthy in intercycle comparison. Conclusion: Implant-supported fixed complete dentures showed superior masticatory efficiency compared with conventional complete dentures constructed over well-formed ridges in the early chewing cycles. Keywords: complete denture, implant-fixed denture, masticatory efficiency, mixing ability test

Purpose: The goal of this study was to evaluate the cumulative survival rate and marginal bone loss (MBL) of extra-short (5- and 6-mm-long) and short (6.5-mm-long) implants inserted into severely atrophic, partially edentulous posterior maxillae and mandibles that were immediately restored with provisional fixed dental prostheses. Materials and Methods: Between October 2013 and December 2017, partially edentulous patients with severe vertical bone atrophy in the posterior area in need of replacement of premolars and/or molars with fixed prostheses were enrolled in the study. Analysis of cumulative survival rate and MBL was determined with respect to implant length at the longest, biannual follow-up period (38 ± 10 months; range: 25 to 48 months). Results: Fifty-five patients were included in the study. A total of 62 extra-short (5 and 6 mm), 15 short (6.5 mm), and 69 standard-length (≥ 10 mm) implants were immediately placed and loaded. Cumulative survival rates were similar for all implants (99.3%). One mandibular extra-short implant failed and was removed but was replaced 2 months later with another implant of the same length and diameter and successfully reloaded. Implant length did not impart any significant differences in MBL, though the presence or absence of platform switching was influential. Conclusion: The cumulative survival rate and MBL reported in this study encourage the use of short and extra-short implants to immediately restore with fixed prostheses partially edentulous patients with severe vertical bone atrophy in posterior areas. Thus, it could be an alternative treatment to vertical bone augmentation. Keywords: immediate restoration, implant-supported prosthesis, occlusal loading, posterior edentulism, short implants

Purpose: This study was designed to test the hypothesis that compression-resistant (CR) scaffolds augmented with recombinant human bone morphogenetic protein-2 (rhBMP-2) at clinically relevant doses in a nonhuman primate lateral ridge augmentation model enhances bone formation in a dose-responsive manner without additional protective membranes. Materials and Methods: Defects (15 mm long × 8 mm wide × 5 mm deep) were created bilaterally in the mandibles of nine hamadryas baboons. The defect sites were implanted with poly(ester urethane) (PEUR)/ceramic CR scaffolds augmented with 0 mg/mL rhBMP-2 (CR control), 0.75 mg/mL rhBMP-2 (CR-L), or 1.5 mg/mL rhBMP-2 (CR-H). The primary outcome of ridge width and secondary outcomes of new bone formation, cellular infiltration, and integration with host bone were evaluated using histology, histomorphometry, and microcomputed tomography (micro-CT) at 16 weeks following implantation. Results: New bone formation in the mandible was observed in a dose-responsive manner. CR-H promoted significantly greater new bone formation compared with the CR control group. In all groups, ridge width was maintained without an additional protective membrane. Conclusion: CR scaffolds augmented with a clinically relevant dose of rhBMP-2 (1.5 mg/mL) promoted significant new bone formation. These results suggest that a CR PEUR/ ceramic composite scaffold without a protective membrane may be a potential new rhBMP-2 carrier for clinical use. Keywords: bone graft, bone morphogenetic proteins, compression-resistant, histology, nonhuman primate, polymer, ridge augmentation

Purpose: To investigate the prevalence of interproximal contact loss between implant-supported fixed prostheses and adjacent teeth and its impact on marginal bone loss and to identify potential risk factors. Materials and Methods: Patients who received implant-supported fixed prostheses at Saint-Joseph University between the years 2011 and 2017 and met the inclusion/exclusion criteria were eligible to participate in this retrospective study. Interproximal contacts were evaluated with a 70-μm dental floss and confirmed visually and by periapical radiographs. Contact was considered open if the floss passed without resistance. Plaque Index and bleeding on probing were assessed, and radiographic bone loss around implants was measured at recall. Results: Eighty-three patients (183 interproximal contact points) were evaluated. Interproximal contact loss between implant-supported fixed prostheses and adjacent teeth occurred in 32.8%; among mesial contact points, 42.1% had interproximal contact loss, whereas 14.5% had interproximal contact loss on the distal side. In interproximal contact loss sites, a mean marginal bone loss of 0.73 mm was noted; the difference was statistically significant compared with marginal bone loss at sites with interproximal contact (P = .017). Age, sex, smoking status, periodontal status, implant sites, and the type of restoration were not significantly associated with interproximal contact loss or marginal bone loss. Sites with interproximal contact loss were 2.24 times more likely to present bleeding on probing than others. Conclusion: Interproximal contact loss occurred in 32.8% of implant-supported fixed prostheses, and a positive relationship between interproximal contact loss and marginal bone loss was found, which suggests that interproximal contact loss should be included as a prosthetic implant complication. Future research aiming at identifying the causative factor for interproximal contact loss is necessary. Keywords: implant complications, implant prosthesis, interproximal open contacts, marginal bone loss

Maxillary sinus augmentation is a procedure commonly performed in patients in need of posterior maxillary implants with limited vertical ridge height and sinus pneumatization. However, minimal information has been presented to evaluate the complexity of the sinus elevation procedure via a lateral window approach based on patient examination, including extraoral findings, anatomical factors, and the possible influence from the surgeon's experience. Therefore, this article presents a new scheme of maxillary sinus floor elevation difficulty score based on comprehensive patient- and surgicalrelated factors. The proposed scoring tool aims to aid surgeons in performing a comprehensive presurgical evaluation prior to the lateral wall sinus augmentation surgery and also enhance communication between clinicians and patients regarding the complexity of the case. Keywords: intraoperative complications, maxillary sinus, postoperative complications, risk factors, sinus floor augmentation

Titanium remains the material of choice in the manufacturing of dental implants because of its exceptional biologic and mechanical properties. However, cases of allergy to titanium have been reported in the literature causing skin, mucosal reactions, systemic symptoms, and eventually implant exfoliation. Although the frequency of these cases varied between 0.6% and 5%, undiagnosed or misdiagnosed cases may possibly increase this percentage significantly. Epicutaneous, intradermal inoculation of the allergen or blood tests (LTT, MELISA, IL1β, IL-6, TNF-α, IL-10) have been used with various degrees of sensitivity and specificity to assess Ti allergy. This case report demonstrated that titanium dental implant allergy caused rapid implant loss following an acute inflammatory reaction and its successful replacement by a one-piece zirconium implant. Keywords: osseointegration, titanium allergy, zirconium implants

A number of significant advances (omics and bioengineering) now enable seamless stratification of patients according to their individual genotypes. This allows for more precise diagnoses coupled with patient phenotypes and improved treatment planning and predictable outcomes. Collectively, these advances are designated as "personalized dental medicine." To become an essential part of personalized dental medicine, this term will have a robust impact on dental implant practice. This narrative review elucidates the importance of utilizing advanced bioengineering techniques and biotechnologies in the realm of dental implants, aiming to understand gene expression profiles controlling endosseous wound healing and promoting bone formation. Thus, the first objective of the review was to present the state of the art of conceptualizing osseointegration as a phenomenon. The second objective was to pave the way for personalized dental implant therapy and to introduce "implantogenomics" for the first time. Keywords: bioengineering, dentistry, implantogenomics, omics, osseointegration, personalized dental implant therapy

Purpose: Short implants are increasingly being used in posterior regions to avoid grafting procedures and their related risks, costs, and morbidity. However, studies focusing on implants measuring less than 6 mm long remain scarce, and the literature does not yet have a definition of the limits inherent with their use. This study attempts to investigate whether extra-short 4-mm implants are capable of receiving a maxillary single crown. Materials and Methods: This study evaluates, through the finite element method, the stress distribution generated at implant lengths of 4 mm and 10 mm caused by different crown heights (10, 12.5, and 15 mm) in the posterior maxilla region when submitted to axial (200 N) and oblique (100 N) loads. Results: The 4-mm implant showed a similar level of performance as that of the 10-mm implant when submitted to the axial load. However, the oblique load proved to be highly detrimental to both implants, inducing stresses of up to three times higher than those achieved in conjunction with the axial load, especially in the surrounding bone and the abutment. Conclusion: The use of 4-mm short implants to support single crowns in the posterior maxilla region may be feasible in habitual conditions; however, the risk associated with significant oblique loads should be mitigated by adopting a mutually protected occlusion approach and using acrylic occlusal devices if necessary. Keywords: biomechanics, dental implants, finite element analysis

Purpose: This study aimed to assess the stability and survival rate of dental implants inserted with different site preparation techniques—piezoelectric inserts versus traditional rotary instruments. Materials and Methods: Correlative research was located by searching articles in PubMed, EMBASE, and the Cochrane Library. This was accomplished independently by two different reviewers and supplemented by a manual search. Only prospective studies evaluating piezoelectric vs conventional implant site preparation in dental implantation were included in this review. A meta-analysis was performed on the stability and survival rate of implants. Results: One thousand fifty-five articles were identified following the search strategy, of which five studies were finally included in this meta-analysis. With regard to the survival rate of implants, there was no statistically significant difference between piezoelectric and conventional implant site preparation (RR = 0.98, 95% CI: 0.94, 1.03; I2 = 0%, P = .86). On the other side, the piezoelectric group had better stability in the eighth week (MD = 4.24, 95% CI: 1.36, 7.12; I2 = 0%, P = .80) and 12th week (MD = 3.33, 95% CI: 0.59, 6.08; I2 = 0%, P = .87) compared with the conventional group. Conclusion: Within the limitations of this study, it suggests that the survival rate of implants may not be influenced by the site preparation techniques (piezoelectric vs conventional), but the piezoelectric group may achieve better stability than the conventional group. Keywords: piezosurgery, site preparation, stability, survival rate