The International Journal of Oral & Maxillofacial Implants, 05/2018

Purpose: To test the hypothesis if a novel single-chamber experimental dental implant allows in vivo the quantitative assessment of osseointegration over time and as a function of different surface properties (physical, chemical, geometric, biologic [osteoconductive or osteoinductive]) in a biologically unfavorable environment (local osteoporosis). Materials and Methods: Three prototypes of a novel experimental implant with different chamber sizes (small, medium, and large) were compared with each other to find out the minimum size of bone chambers needed to allow a discriminative quantification of osseointegration over time. For the comparison of low and high surface osteoconductivity properties, conventional sandblasted, acid-etched chamber surfaces (low surface osteoconductivity) were compared with biomimetically (calcium phosphate) coated ones (high surface osteoconductivity). The implants (4 implants per animal; 88 implants per time point) were inserted into the edentulous maxillae of a total of 66 adult goats with a physiologically osteoporotic masticatory apparatus. Two, 4, and 8 weeks later, they were excised and prepared for a histomorphometric analysis of the volume of neoformed bone within the chamber space and of the bone-to-implant contact (BIC) area. Results: The implants with small chambers did not show significant differences in bone coverage (BIC) nor bone volume (relative and absolute volume), neither as a function of time nor as of implant surface property (low versus high surface osteoconductivity). However, medium and large chambers revealed significant differences respecting both of these parameters over the 8-week postoperative time period. Conclusion: The new implant model permits a discriminative quantification of osseointegration in vivo in an osteoporotic bone environment for implants with medium-sized and large-sized chambers. Quantitative assessment of osseointegration is possible, both over time and as a function of low and high surface osteoconductivity properties. Keywords: animal experiments, bioactive surface, experimental implant, osseointegration, quantification, surface chemistry

Purpose: Alveolar ridge preservation procedures have been advocated to minimize postextraction dimensional loss. There is a need for systematic analyses of clinical factors affecting the outcomes of these procedures in order to improve their clinical outcomes. This systematic review and meta-analysis aimed to assess the efficacy of alveolar ridge preservation procedures in terms of hard tissue dimensional changes and to determine clinical factors affecting outcomes of these procedures. Materials and Methods: Studies comparing alveolar ridge preservation procedures with tooth extraction alone that reported quantitative outcomes for hard tissue dimensional changes were included. The primary outcome variable was horizontal dimensional changes of alveolar bone. Subgroup analyses evaluated effects of wound closure, flap elevation, type of grafting materials, use of barrier membranes, use of growth factors, socket morphology, and the position of teeth on outcomes of alveolar ridge preservation procedures. Results: Twenty-one studies were included, and quantitative analyses were performed for seven outcome variables. Significant differences between alveolar ridge preservation and control sites were found for six outcome variables, all favoring alveolar ridge preservation procedures. The magnitude of effect for the primary outcome variable (horizontal dimensional changes of alveolar bone) was 1.86 mm (95% CI = 1.44, 2.28; P .001). This magnitude of effect for the primary variable (as determined by subgroup analysis) was also significantly affected by type of wound closure (P = .033), type of grafting materials (P = .001), use of barrier membranes (P = .006), use of growth factors (P = .003), and socket morphology (P .001). Conclusion: Alveolar ridge preservation procedures are effective in minimizing postextraction hard tissue dimensional loss. The outcomes of these procedures are affected by morphology of extraction sockets, type of wound closure, type of grafting materials, use of barrier membranes, and use of growth factors. Keywords: alveolar ridge augmentation, alveolar ridge preservation, bone augmentation procedures, dental implants, evidence-based dentistry, meta-analysis, socket healing, tooth extraction

Purpose: To evaluate the mean amount of intrasinus bone obtainable with the osteotome technique for transcrestal maxillary sinus elevation combined with simultaneous implant insertion, with and without the use of grafting materials. Materials and Methods: A review was conducted on PubMed, Scopus, and Cochrane central databases. Only human studies in which implant placement was contextual to the sinus elevation procedure, without additional crestal regenerative procedures and with a minimum 1-year followup, were selected. Seventeen studies were found to meet the selection criteria. Results: No statistically significant difference between the two procedures was detected. The mean intrasinus bone gain at 3 years after surgery was 2.99 mm in cases where no grafting material was used and 4.24 mm in cases in which grafting materials were used. The mean percentage of crestal height increase at the implant site at 3 years after surgery, referring to a selection of studies with initial bone height > 4 mm, was 47.28% in procedures without grafting material and 62.68% in procedures with grafting material. A different dimensional behavior of the newly formed bone during the first 3 years after surgery was found: a slight volumetric shrinkage in grafting procedures and a slight bone increase in procedures without grafting material. No statistically significant difference in implant survival rate was found. Conclusion: Both osteotome transcrestal sinus elevation procedures seem to guarantee predictable short- and medium-term results with reference to the intrasinus bone gain. However, the use of grafting materials, compared with their nonuse, does not seem to have substantial advantages in the short and medium term as far as mean intrasinus bone gain is concerned. Keywords: bone substitute, dental implant, maxillary sinus floor augmentation

Purpose: Intermittent parathyroid hormone (PTH) is the commonly used therapeutic approach for patients with severe osteoporosis. The goal of this study was to elucidate the effect of the intermittent PTH treatment on guided bone augmentation (GBA) in the calvarium of ovariectomized (OVX) rats. Materials and Methods: Surgical ovariectomy on 14 rats and sham surgery on 7 rats were conducted on all rats as the first surgery. GBA surgery was conducted 8 weeks following the first surgery in the rat calvarium by placing 5-mm-diameter cylindrical plastic caps. Following surgery, rats were treated with 40 μg/kg PTH (OVX-PTH) or saline (Sham-Saline, OVX-Saline) via intraperitoneal injection three times per week during the all-observational period. Longitudinal microcomputed tomography (micro-CT) imaging was performed every 2 weeks following the GBA surgery without euthanasia, and the amount of newly generated bone volume (BV) was calculated. All rats were euthanized 12 weeks after GBA surgery, and histology was obtained. Sections stained with hematoxylin and eosin were used for the quantitative analysis of newly generated tissue, and immunohistology was used to visualize Runx2-positive cells and TRAP-positive cells. Results: Throughout the monitoring period, the BVs of OVX rats without PTH treatment (OVX-Saline) were significantly lower than that of the other two groups at weeks 8 and 12 in micro-CT analysis. During all experimental periods, the BV was highest in the OVX rats that were treated with PTH (OVX-PTH). Histologic analysis confirmed the result of micro-CT, and determined that the OVX-PTH presented a greater number of Runx2-positive cells. The number of TRAP-positive multinucleated osteoclasts was highest in OVX-PTH rats; there were no significant differences between the other two groups. Conclusion: The results of this study suggest that treatment with intermittent PTH was associated with increased newly regenerated bone volume in ovariectomized rat calvarial bone augmentation, which may have important clinical implications. Keywords: bone augmentation, GBR, osteoporosis, systemic disease

Purpose: To develop a TiOx film with high wettability using plasma oxidation methodology and to evaluate the effect of such surface modification on new bone formation and early osseointegration. Materials and Methods: Twenty sandblasted and acid-etched (SLA) titanium implants layered with a TiOx film layer were modified by plasma oxidation using a Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RFPECVD) system. Twenty SLA implants without any treatment were employed as the control group. Scanning electron microscopy was used to evaluate surface morphology of the coating. X-ray photoelectron spectroscopy (XPS) was utilized to identify the chemical composition of the implant surface, and the wettability was tested with the help of the contact angle calculation. All implants were randomly inserted into the proximal tibia of 20 rats with a split-plot design. Four weeks after implantation, early osseointegration of the two groups was analyzed by a removal torque test and histologic analysis. Results: The surface characteristics showed that both SLA and plasma oxidization-treated SLA (PO-SLA) surfaces displayed similar typical isotropic irregular indentations. As revealed by the XPS analyses, both TiO₂ and Ti₂O₃ were coexistent in the PO-SLA surface. The contact angle measurement revealed that the super-hydrophilic surface was created out in the PO-SLA surface. Four weeks after implantation, a higher removal torque value was observed in the group of implants with the PO-SLA surface compared with the control group (12.68 ± 1.07 vs 9.95 ± 1.42 Ncm, P .05), and a higher rate of bone-to-implant contact was also detected in the same group of implants with the PO-SLA surface (47.79% ± 9.59% vs 39.41% ± 9.00%, P .05). The bone area ratio was also higher in the PO-SLA surface group than the control group (39.10% ± 10.01% vs 29.01% ± 7.24%, P .05). Conclusion: It was indicated that the PO-SLA surface has combined the effect of high wettability and micro/nano-structures to notably increase early bone apposition.

Purpose: Decontamination of the rough surfaces of dental implants is a challenge in the treatment of peri-implantitis. An acceptable cleaning technique must be able to debride and detoxify the surface without traumatizing it. This study assessed the possible implant surface alterations following decontamination with laser, photodynamic therapy (PDT), and application of chlorhexidine (CHX). Materials and Methods: Of 16 dental implants with sandblasted, large-grit, acid-etched surfaces, Aggregatibacter actinomycetemcomitans was cultured on the surfaces of 15 implants for 48 hours. These 15 implants were divided into five groups of three and were subjected to erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation, 630 nm light-emitting diode and toluidine blue O photosensitizer, 810 nm diode laser, and indocyanine green-based photosensitizer, 2% CHX, and control group (no treatment). One implant remained intact. The morphology and element/phase identification of the implants were studied using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS), respectively. Results: The SEM images and EDS maps revealed that the decontamination methods did not alter the surface quality of the implants. However, in photodynamic therapy, sodium chloride that remained from rinsing liquid can make an adhesive layer on the surface of the treated implants. Conclusion: Er:YAG laser irradiation and PDT did not alter the surfaces of sandblasted, large-grit, acid-etched implants. Keywords: EDS, implant surface, implant surface alteration, laser, SEM, surface roughness

Purpose: This study compared the vertical misfit of fixed implant-supported titanium (Ti6Al4V) and yttria-stabilized tetragonal zirconia frameworks milled using the computer-aided design/computer-aided manufacturing (CAD/CAM) Zirkonzahn system. Materials and Methods: An aluminum mandibular master cast was used, and four analogs of the Regular CrossFit implant for straight multibase titanium alloy abutments (Institut Straumann) were fixed with self-curing acrylic resin in mandibular canine and second premolar tooth locations with the aid of a parallelometer. Scan abutments were placed over the four straight multibase Regular CrossFit abutments to determine their correct three-dimensional (3D) positioning in the virtual model. Implant frameworks were designed virtually, and five frameworks of each material (titanium alloy or yttria-stabilized tetragonal zirconia) were milled using the CAD/CAM system. Scanning electron microscope (SEM) images, with magnifications of 50×, 250×, and 1,000×, were obtained from three points on the buccal surface, three points on the lingual surface, and three points on the mesial surface of each abutment. The measurements were performed in the center of each of the thirds, thus defining points one, two, and three. The degree of vertical misfit at the framework-abutment interface was determined using ImageJ software and analyzed using the Student t test (P = .05). Results: The mean misalignment value was 6.011 ± 0.750 μm for the titanium group and 9.055 ± 3.692 μm for the zirconia group. Conclusion: Within the limitations of this study, there was no significant difference in vertical misfit between the titanium and zirconia implant frameworks produced using the CAD/CAM system. Regardless of the material used, the CAD/CAM frameworks achieved an adequate vertical fit. Keywords: computer-aided design, dental implants, dental materials, prostheses and implants, restorative dentistry

Purpose: This in vivo study used control variable implants to compare early bone responses in fluoride-modified (F-mod) and hydrophilic, sandblasted, large-grit, acid-etched (modSLA) surface implants that differed in implant design. Materials and Methods: Four different types of implants (n = 24) were prepared: F-mod surface with Astra Tech implant design; modSLA surface with Straumann implant design; sandblasted, large-grit, acid-etched (SLA) surface with Astra Tech design; and SLA surface with Straumann implant design. Scanning electron microscopy, confocal laser scanning microscopy, and x-ray photoelectron spectroscopy were performed to assess implant surface characteristics. Four implants from each implant type were inserted in the tibiae of four rabbits that were sacrificed 10 days after surgery. Bone-to-implant contact (BIC) and bone area (BA) were measured to evaluate early bone responses. Analysis of variance with Tukey's multiple comparison method was used for the histomorphometric data to find any significant difference. The surface characteristic-related data were analyzed using the Kruskal-Wallis test. The level of significance was .05 in statistical analyses. Results: No significant differences in BIC and BA were found among the modified surfaces (P > .05), whereas significant differences were found in surface topography and surface chemistry. The different designs showed no significant effects on early bone responses when identical surface modifications were applied (P > .05). Conclusion: F-mod and modSLA surfaces showed no significant differences in early bone responses. Furthermore, the implant design had no influence on the bone response. This in vivo experimental model will help improve the evaluation of surface modification factors by allowing an independent estimation of one variable (surface modification) against a constant (implant design). Keywords: control variable, fluoride-modified, hydrophilic SLA, implant design, SLA

Purpose: The forces needed to detach zirconia copings from titanium inserts of two-piece abutments were evaluated for implant platforms of different diameters (4.8 and 6.5 mm) and different luting strategies. Materials and Methods: Eight specimens (four for each platform diameter) were prepared to simulate two-piece zirconia implant abutments with prefabricated titanium inserts and computer-aided design/ computer-aided manufactured (CAD/CAM) zirconia copings. Half of the copings were luted to their titanium inserts by use of composite cement; the others were luted after additional bonding treatment of the titanium and zirconia surfaces. All specimens were subjected to tensile forces up to failure. Samples were used with or without artificial aging. Each specimen was luted and subsequently debonded 12 times; thus, a total of 96 tests were conducted. Results: All debonding forces exceeded approximately 600 N. Larger platform diameters (P .001) and additional bonding treatment (P = .021) resulted in significantly better retention; artificial aging had no effect (P = .165). Conclusion: Forces for debonding of titanium bases from zirconia abutments were favorable. The use of these abutments might be a viable prosthetic treatment option in specific clinical cases. Keywords: debonding forces, implant, titanium, zirconia abutment

Purpose: The objective of this study was to review the available literature regarding the use of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) in human alveolar ridge augmentation and to assess its effectiveness for this specific use. Materials and Methods: Three electronic searches of the MEDLINE database were performed. Results: This review noted a wide range of study protocols, carrier systems, study periods, and outcome measures. Conclusion: Within the limits of this literature review, the use of rhPDGF-BB and bone regeneration/ridge augmentation led to greater clinical attachment level gain and bone regeneration prior to implant placement. More controlled clinical studies are needed to establish the effectiveness of rhPDGF-BB in alveolar ridge augmentation. Keywords: alveolar ridge augmentation, bone regeneration, recombinant platelet-derived growth factor BB, rhPDGF-BB

Purpose: The purpose of this study was to examine the volumetric alterations and osseointegration properties in the augmented area of the ring technique using different types of bone graft material in sheep mandible bone. Materials and Methods: Three different materials (columnar forms, 7-mm diameter, 3-mm height) were stabilized using dental implants with a turned surface in the mandible bone of Finnish Dorset cross-bred sheep: group A, autogenous bone; group B, bovine bone; group C, biphasic bone substitute. Animals were euthanized after 5 weeks (N = 6). Three-dimensional image data by digital oral scanner were taken at the surgery and sacrifice, and the volume alteration of the material was calculated. The bone samples were fixed in formalin and dehydrated in ethanol. Resin-embedded samples were subjected to non-decalcified ground sectioning, and histologic and histomorphometric analysis (bone and material area alteration, bone-to-implant contact [BIC]) were done. Results: In three-dimensional (3D) image analysis, group A showed a statistically higher percentage of remaining materials compared with groups B and C. The histologic observation showed no new bone formations around the implants in all groups, especially at the maxillary site of the implant in the augmented area. In histomorphometric analysis, group A showed a statistically higher percentage of bone area (BA) compared with groups B and C; however, in all groups, bone-to-implant contact (BIC) showed low values, and there were no statistical differences between groups. Conclusion: The results of this study suggested that the autogenous bone maintained bone volume around the dental implant using the ring technique, and the impact of surface properties was of some importance; osseointegration with the turned surface in the augmented area showed low BIC values in all groups. Keywords: autogenous bone, biphasic bone substitute, bone regeneration, bovine bone, dental implant, ring technique

Purpose: The ideal digital cement space value for the fabrication of provisional computer-aided design/ computer-aided manufacturing (CAD/CAM) crowns with clinically acceptable marginal adaptation is not well known. The aim of this study was to evaluate the effect of different simulated cement space settings on the marginal fit of poly(methyl methacrylate) (PMMA) provisional CAD/CAM restorations. Materials and Methods: An extracted premolar tooth was prepared using ceramic crown preparation guidelines and represented both natural teeth and/or custom implant abutments. The prepared tooth abutment was scanned with a three-dimensional (3D) laboratory scanner (D900, 3Shape). CAD design software was used to subsequently design a premolar crown core with three different simulated cement space settings (20 to 40 μm, 20 to 50 μm, 20 to 60 μm). PMMA blocks were used to mill the specimens (n = 9, N = 27). Using a stereo zoom microscope, a total of 36 images for each of the 3 groups (9 crowns per group, 4 sites per crown) were captured to measure the mean vertical marginal discrepancy for every group. One-way analysis of variance (ANOVA) was used to analyze the data, and the post hoc Tukey multiple comparison test was performed. Results: The marginal gap values of the PMMA cores fabricated using the three cement space settings were significantly different from each other (P .001). The marginal gap was smaller with a 20- to 60-μm setting compared with 20 to 50 μm and 20 to 40 μm, and the 20- to 50-μm setting allowed for smaller marginal gaps compared with 20 to 40 μm (P .001). Conclusion: Within the limitations of this study, the marginal gaps of CAD/CAM-fabricated PMMA cores were smaller when the cement space was larger. The smallest marginal gaps were achieved when a 20- to 60-μm cement space was used (P .001). Keywords: CAD/CAM, cement space, implant abutments, marginal fit, natural teeth

Purpose: The aim of this study was to compare the bacterial leakage of conical internal connection implants with different taper angles (5.4, 12, 45, and 60 degrees) and examine the efficiency of a disinfectant agent and a silicone sealant agent in the prevention of bacterial leakage under loaded conditions. Materials and Methods: Twenty-one implant-abutment connections were studied from each implant system (Ankylos Implants, Dentsply; Bego Semados S Implants, Bego; Trias Implants, Servo-Dental; DTI Implants, DTI), for a total of 84 implants. Each system's implants were divided into three groups as follows: unsealed (control), 2% chlorhexidine gel-sealed, or silicone-sealed (n = 7 for each group). The insertion torque was applied to each abutment screw according to the manufacturers' recommendation. The specimens were partially immersed in an 8-mm E faecalis suspension. A cyclic load of 50 N was applied for a total of 500,000 cycles at 1 Hz to the specimens. Following disconnection of dental implants and abutments, microbial samples were taken from the inner threaded surface of the implants, plated, and counted under appropriate conditions. Results: There were no statistically significant differences in frequency of bacterial leakage and leaked bacterial counts among the four types of connections in all groups (P > .05). The statistically significant differences were found between sealant agents and control groups in four different connection types in terms of the amount of leaked bacteria (P .05). There was no significant difference between the amount of leaked bacteria for four connection types when comparing the chlorhexidine and silicone sealant agents (P > .05). Conclusion: Differences in taper angles in the internal conical connections had no significant effect on leaked bacterial counts or the frequency of bacterial contamination under dynamic loading. The application of 2% chlorhexidine gel or a silicone sealant can reduce the leaked bacterial counts and reduce the frequency of bacterial leakage. Keywords: bacterial leakage, dynamic loading, implant-abutment connection, sealant

Purpose: The aim of this study was to compare the retentive properties of an attachment with a nylon insert and an attachment with a polyetherketoneketone (PEKK) insert on two-implant mandibular overdentures during simulated masticatory loadings and insertion/removal cycles. Materials and Methods: Two attachment systems with nylon inserts or PEKK inserts were investigated, including nylon/ low, nylon/medium, nylon/high, PEKK/x-low, PEKK/low, PEKK/medium, and PEKK/high. The canine region of edentulous mandibular overdenture models was retained with two implant analogs through two different stud attachments at interimplant angulations of 0 and 20 degrees. The simulated mastication and insertion/ removal cycles were 400,000 cyclic loadings and 1,080 times of insertion/removal. Wear patterns and deformations on the attachment surface were analyzed with scanning electron microscopy. Results: At 0 and 20 degrees, initial retentive force was highest in nylon/high and lowest in PEKK/x-low. Final retentive force was highest in PEKK/high and PEKK/medium at 0 and 20 degrees, respectively, and PEKK/x-low was lowest at both angulations. At 0 degrees, nylon/low, nylon/medium, PEKK/x-low, and PEKK/low displayed a significant increase in retention (P .05), and nylon/high and PEKK/medium showed a significant decrease in retention (P .05), except PEKK/high, which exhibited no significant decrease (P > .05). At 20 degrees, nylon/low and PEKK/x-low increased retention significantly (P .05), and nylon/medium, nylon/high, PEKK/ low, PEKK/medium, and PEKK/high decreased retention significantly (P .05). Patrices of both attachment systems barely showed detectable abrasion, while matrices revealed severe wear and surface deformation. Nylon inserts particularly displayed more noticeable wear and deformation than PEKK inserts. Conclusion: Within the limitations of this investigation, the attachment system with a PEKK insert indicated less abrasion and retention change than the attachment system with a nylon insert on both paralleled implants and axially tilted implants under 400,000 cyclic loadings and 1,080 insertion/removal cycles for 1 year. Keywords: attachments, implant overdentures, nylon, retention, PEKK

Purpose: Sinus floor elevation using the lateral approach and bone window repositioning and a xenogeneic bone substitute (Cerabone) has been well documented clinically. The purpose of this histologic and histomorphometric study was to determine the fate of the window, its contributing role in the healing process, and the osseoconductivity and resorption potential of the high-temperature sintered bovine bone used, as well as to correlate the histomorphometric results with sinus depth and lateral wall thickness as determined on cone beam computed tomography (CBCT). Materials and Methods: Thirty biopsy specimens were harvested from the lateral side of the maxilla of patients operated on for sinus floor elevation and implant placement at two postoperative periods: early, group 1 (mean: 5.73 ± 0.44 months); and late, group 2 (mean: 8.68 ± 1.76 months). Sinus depth and lateral wall thickness were determined on CBCT and correlated to graft maturation. Results: The repositioned bone window was microscopically detectable in both study groups and looked well integrated. Bone was found growing out of the repositioned window toward the center of the graft, most often forming a trabecular network independently from the bone matrix, which is in favor of osteogenic potential of the window. Also, newly built bone was found directly attached to the surfaces of the window, indicating bone growth via osseoconduction. Repositioned window sides showed signs of low-grade inflammation. Active osteoclasts were only found to be associated with the newly built bone matrix, hinting at an active bone remodeling process. No signs of biodegradation or remodeling of the window were detected using the tartrate-resistant acid phosphatase (TRAP) technique. The histomorphometric analysis of the tissue distribution showed similar values of newly formed bone in group 1 (22.77% ± 5.89%) and in group 2 (26.15% ± 11.18%) and connective tissue values in both study groups (42.29% ± 8.98% for group 1 vs 46.03% ± 5.84% for group 2). No significant differences were found between group 1 (34.94% ± 7.10%) and group 2 (27.82% ± 11.97%) for xenogeneic bone substitute values. Statistically significant differences were only found between connective tissue values and newly built bone values (P .01 and P .001, respectively). Furthermore, a significant difference was found between connective tissue values and that of bone substitute up to 12 months (P .01). No significant correlation was found between sinus depth and lateral window thickness and histomorphometric results. Conclusion: The re positioned window technique appears to be a good osteoconductive barrier for bone formation. Its osteogenic potential needs to be confirmed immunochemically. High-temperature sintered bovine bone proved to be an effective slowly resorbing osseoconductive material. Keywords: bone window repositioning, Cerabone, histomorphometry, sinus floor elevation, xenogeneic bone substitute

Purpose: This study retrospectively evaluated the effects of bone density, staging strategy, implant stability, healing process, implant length, surface type, and photofunctionalization on early implant failure. Materials and Methods: Consecutive study samples at Yokohama City University Hospital were analyzed for their early implant failure potentially influenced by patient-, surgical protocol-, and implant-related factors. Through the screening process using univariate analysis for those factors, candidate influential factors such as bone density, staging strategy, the level of initial implant stability, postoperative wound breakdown, the length of implants, the surface type of implants, and use or nonuse of photofunctionalization were selected as independent variables in forward multivariate logistic regression analysis. The odds ratio (OR) for candidate factors was calculated. Results: A total of 563 implants placed in 219 patients from 2005 to 2017 were analyzed for their early implant failure. Stepwise logistic regression analysis finally identified postoperative wound breakdown (OR = 0.21) and the use of photofunctionalization (OR = 0.30) that significantly reduced the risk of early implant failure (P .01 and P .05, respectively). The implant failure rate was 10.0% with postoperative wound breakdown and 1.0% without it, whereas it was 4.3% without photofunctionalization and 1.3% with it. Conclusion: Among various patient-, surgical protocol-, and implant-related factors, the absence of postoperative wound breakdown and use of photofunctionalization significantly reduced the risk of early implant failure. It was notable that photofunctionalization, a unique, chairside measure to improve implant surfaces, was effective exclusively among implant-related factors. Keywords: dental implant, early failure, osseointegration, photofunctionalization

Purpose: The aim of this study was to evaluate the clinical and radiographic peri-implant tissues of bar, Locator, and resilient telescopic attachments for two-implant stabilized overdentures in subjects with mandibular atrophied ridges. Materials and Methods: Ninety edentulous individuals with mandibular ridge atrophy were randomly assigned into three equal groups and received two implants in the canine areas. Mandibular overdentures were constructed and attached to implants with Dolder bar attachments (BOD), resilient telescopes (TOD), and Locators (LOD). Plaque scores, gingival scores, pocket depths, implant stability, width of keratinized mucosa, vertical bone loss, and horizontal bone loss were evaluated at the time of prosthesis delivery and 6 months and 12 months after delivery. Results: With the exception of pocket depth and implant stability, all parameters showed a significant increase from prosthesis delivery to 6 months. BOD recorded the highest plaque scores, gingival scores, and pocket depths followed by LOD, and TOD recorded the lowest values. No significant difference in implant stability and keratinized mucosa was observed between groups. TOD and BOD recorded the highest vertical and horizontal bone losses, respectively. LOD recorded the lowest vertical and horizontal bone losses. There was no difference in implant survival rate between groups. Conclusion: Bar, resilient telescopic, and Locator attachments can be used successfully for two-implant stabilized overdentures in subjects with mandibular atrophied ridges after a 1-year follow-up period. Telescopic attachments were associated with improved clinical peri-implant soft tissues compared with other attachments. However, Locator attachments may be advantageous in terms of peri-implant bone preservation. Keywords: attachment, bar, implant, Locator, overdentures, telescopic

Purpose: To examine cone beam computed tomography (CBCT) anatomical findings, such as the concavity of the ridge and angulation of the tooth and alveolar ridge, either facial or palatal, in order to assess the potential clinical risks of performing flapless implant surgery. Materials and Methods: CBCT images that met the inclusion criteria were examined. All images in maxillary anterior areas (canine to canine), facial bone thickness at 3 and 5 mm from the cementoenamel junction (CEJ), angulation of the tooth and alveolar ridge (Angle T: the angulation between the long axis of the tooth and the palatal plane; Angle D: the angulation between the long axis of the tooth and the midline of the ridge), the deepest point of facial concavity, the distance from the deepest point of facial concavity to the apex of the tooth and alveolar bone crest, nasopalatine canal, dehiscence, and fenestrations were measured and statistically analyzed. Results: In total, 21 patients (12 women and 9 men) with a mean age of 55.9 years who met the inclusion criteria were included in the analysis. Data from 21 patients, 6 image sections per patient (total of 126 CBCT images) were analyzed. The mean value of facial bone thickness was 0.99 mm and 0.60 mm at 3 and 5 mm from CEJ, respectively. The distance from the deepest point of facial concavity to the apex of the tooth and alveolar bone crest was 2.79 and 11.29 mm, respectively. In canine areas, the mean values of facial bone thickness were larger at 3 mm but thinner at 5 mm. Also, canines were found to have a larger Angle D and a higher incidence of fenestration and dehiscence. Conclusion: Based on the findings, fenestration and a larger Angle D were associated with thinner facial bone thickness at 5 mm, and the tooth types also had an impact. Hence, for immediate implant surgery without flap elevation, besides anatomical structures, both angulation of the tooth and the alveolar ridge also need to be assessed. Keywords: angulation of tooth and ridge, concavity, cone beam computed tomography, flapless implant surgery, immediate implant placement, nasopalatine canal, occlusion

Purpose: The esthetic outcome of dental implants can be compromised when some degree of bone loss occurs around the implant. This may particularly affect the tissue-level (TL) design. Therefore, bone-level (BL) design implants may be preferable if a natural emergence profile is important. Notwithstanding the implant design, the gingival biotype has been identified as a crucial factor in the stability of crestal bone. The objective of this study was to investigate bone loss in patients with different gingival biotypes at TL and BL implant sites in the esthetic zone. Materials and Methods: In 41 patients, 20 TL and 22 BL implant procedures were carried out. Intraoral radiographs of all of the 42 sites were taken immediately after implant insertion as well as during the follow-up examination. The analysis of bone height was conducted using a computerized technique. The TRAN method was used to determine the gingival biotype. Results: After a mean in situ period of 4.9 years in the TL group, 12 implants with a thick biotype had a mean bone loss of 0.21 mm (SD: 0.43 mm). The eight implants with a thin biotype had a loss of 0.05 mm (SD: 0.47 mm; P = .31). After a mean in situ period of 1.9 years, the 14 BL sites with a thick biotype showed a mean bone change of -0.03 mm (SD: 0.38 mm). In the eight implants with a thin biotype, a change of +0.09 mm (SD: 0.32 mm; P = .84) was noted. Conclusion: Analysis of the obtained results did not reveal a dependency of bone height on implant design or on gingival biotype. However, prior to choosing an implant design, it may nevertheless be beneficial to screen for transparent soft tissues, where the BL design offers a more natural emergence profile. For this purpose, the TRAN method is clearly the fastest and easiest. Keywords: biotype, bone-level design, esthetic zone, peri-implant bone loss, radiographic analysis, tissue-level design

Purpose: To evaluate the influence that three different implant-abutment interface designs had on periimplant mucosal outcomes as assessed by the pink esthetic score (PES) 3 years after delayed implant placement and immediate provisionalization. Materials and Methods: Adult subjects (n = 141) requiring replacement of a bounded single tooth in the anterior maxilla as well as first premolar sites were randomized to receive one of three unique implant-abutment interface designs (conical interface [CI]; flat-to-flat interface [FI]; or platform-switch interface [PS]). Treatment included immediate provisionalization with prefabricated titanium abutments, followed by custom computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia abutments and cement-retained, all-ceramic crowns delivered after 12 weeks. Bilateral (anterior sites) or unilateral (premolar sites) digital clinical photographs were made at 1, 3, 6, 12, 24, and 36 months post-implant placement. Five calibrated faculty evaluators who previously scored the 1-year PES image dataset scored the 24- and 36-month photographs using a digital, cloud-based tablet interface. Results: Six hundred ten clinical photographs were evaluated, resulting in a total of 3,050 sum PES values and 21,350 individual PES values. Faculty evaluator intrarater and interrater reliability were found to be "substantial," with intraclass correlation coefficient (ICC) values of 0.76 and 0.77, respectively. All three implant-abutment interface groups demonstrated acceptable esthetics at 3 years (mean sum PES = 10.1 ± 1.9, 4.0 to 13.2), with no single group demonstrating significantly greater mean sum PES values than another at the 3-year follow-up or at any recall interval in between. Conclusion: No significant differences were observed in mean sum PES scores for subjects randomized to one of three different implant-abutment interface geometries. Within the limitations of this study thus far, the first 6 months following definitive prosthesis delivery appear to still be the most significant with regard to improvement in PES outcomes for all three treatment groups. Keywords: esthetics, immediate provisionalization, implant-abutment interface, peri-implant mucosa

Purpose: This observational study was based on a series of clinical cases in which failure of sinus augmentations occurred in patients who received prophylactic clindamycin therapy. Materials and Methods: Between the years 2006 and 2010, a retrospective observational study was performed. The study consisted of 1,874 patients (723 males and 1,151 females) in whom sinus augmentations were performed prior to placement of dental implants. Results: In nine (0.48%) patients (four males and five females), infection of the graft material inside the sinus floor occurred, and six patients developed an abscess in the site of surgery, 4 to 6 weeks postoperatively. In three patients, a buccal fistula with pus draining was observed 5 to 8 weeks postoperatively. In all patients, the source of infection was from the grafted material within the sinus. A common manifestation in all nine patients was that they had self-reported penicillin allergy and had been prescribed clindamycin (300 mg every 6 hours for 10 days). Conclusion: Prophylactic clindamycin therapy following sinus augmentation procedures seems to be a risk factor for infections and loss of grafting material following these surgical techniques. Keywords: allergy, amoxicillin, clindamycin, infection, penicillin, resistance, sinus augmentation

Purpose: The objective of this study was to use patient-reported outcome to explore patient characteristics that influence the oral health-related quality of life of post-implant patients. Materials and Methods: The study design was a nested case-control study. The target population was patients who had undergone implant treatment at the Department of Oral Implantology, Osaka Dental University, with a superstructure fitted ≥ 3 months previously. The survey period was from April 2014 to the end of October 2016. Oral health-related quality of life was evaluated using the General Oral Health Assessment Index (GOHAI). The relationship between patient characteristics and oral health-related quality of life was investigated by binomial logistic regression analysis. The Japanese GOHAI norm for the 50s and 60s age groups was used as the dependent variable for comparison with this study population. Explanatory variables were age, sex, time of survey, implant site, type of superstructure, pre-implant number of molar occlusal support zones, pre-implant deficit status, and number of missing teeth. Results: Of the total of 1,967 subjects, data were missing for 176 subjects, the time of survey was 3 months since fitting of the superstructure for 1,021 subjects, and 123 subjects did not meet the inclusion criteria. Therefore, 647 subjects were finally analyzed. As a result of implant treatment, 64.5% of subjects exceeded the Japanese GOHAI norm for the same age group (52.2). From logistic regression analysis, patient characteristics that were extracted as influencing oral health-related quality of life were age 65 years (odds ratio: 1.8); women (odds ratio: 1.8); and 1 preimplant molar occlusal support zone (reference value of 4 zones) (odds ratio: 2.5). Conclusion: This study showed that implant treatment is an effective method for dental prosthetic treatment from the perspective of patient-reported outcome. In addition, patient characteristics that influence the oral health-related quality of life of post-implant patients were shown to be age 65 years, women, and one pre-implant molar occlusal support zone. This study may help to predict posttreatment oral health-related quality of life and determine treatment plans. Keywords: dental implant treatment, General Oral Health Assessment Index, GOHAI, logistic regression analysis, oral health-related quality of life, patient-reported outcome

Purpose: To evaluate the sinus membrane perforation and implant survival rate after crestal minimally invasive sinus floor augmentation using hydraulic pressure and vibrations. Materials and Methods: In this retrospective single cohort study, all patients who underwent minimally invasive sinus floor augmentation between 2007 and 2015 using hydraulic pressure and vibrations were included. The sinus membrane is elevated by physiologic saline at 1.5 bar. The fluid is then set into vibration to further separate the sinus membrane from the bony floor. The endpoints were sinus membrane perforation and the survival rate of implants. Results: The hydraulic pressure and vibration technique was applied in 156 patients. Seven patients with perforations of the sinus membrane were treated with the lateral window approach and excluded from the follow-up analysis. In the remaining 149 patients, 184 crestal sinus floor augmentations were performed and 184 implants were placed. In 10 of these 184 cases, a perforation was suspected in the postoperative computed tomography (CT) scan. In total, the perforation rate was 8.9% (17/191). Nineteen implants were lost during the follow-up period ranging from 0.2 to 8.4 years with a median of 2.3 years. The cumulative implant survival rates after 1, 3, and 5 years were 94.4%, 87.7%, and 87.7%, respectively. No severe perioperative complications were noted. Conclusion: The hydraulic pressure and vibration technique allows a minimally invasive crestal sinus augmentation with a perforation rate less than 10% and implant survival rates of approximately 90%. Keywords: crestal, flapless, minimally invasive, sinus augmentation, sinus elevation, transalveolar

Purpose: Mild to moderate pain is common following dental implant surgeries, although severe pain is reported in some patients. This randomized, open-label trial was designed to determine the efficacy and safety of an opioid-sparing postsurgical pain management protocol with or without local infiltration of liposomal bupivacaine for full-arch implant surgery. This procedure is used in edentulous and/or failing dentition patients and involves securing four or more implants to the maxilla and/or mandible to serve as anchors for dental prostheses. Materials and Methods: Patients scheduled to undergo full-arch implant surgery were randomly assigned to receive an opioid-sparing postsurgical pain management protocol with or without liposomal bupivacaine 266 mg at the end of surgery. All patients received infiltration with ≤ 40 mL lidocaine 2% with epinephrine at the beginning of surgery and bupivacaine 0.5% with epinephrine near the end of surgery and oral opioid or nonopioid analgesics (oxycodone 5 mg tablets or ibuprofen 600 mg), as needed, postsurgically. Pain severity at the surgical site was assessed using a verbal 0 to 10 numeric rating scale (0 [no pain] to 10 [worst pain imaginable]). Patients separately assessed pain in their mandible and maxilla. Reports of treatment-emergent adverse events were collected. Results: Sixty-nine patients were randomized to the liposomal bupivacaine 266 mg (n = 34) or control group (n = 35). At all time points postsurgery for both the mandible (all P ≤ .0112) and the maxilla (all P ≤ .0083), the liposomal bupivacaine group reported significantly less cumulative pain than the control group. At the conclusion of the 7-day follow-up, patients in the liposomal bupivacaine group experienced one-third less cumulative postsurgical pain than patients in the control group. Seventy-seven percent of patients in the liposomal bupivacaine group and 80% in the control group experienced a treatmentemergent adverse event. A higher percentage of patients in the liposomal bupivacaine versus control group reported itching (15% vs 9%) and constipation (38% vs 23%). Conclusion: Patients receiving an opioidsparing postsurgical pain management protocol with liposomal bupivacaine 266 mg experienced a statistically significant reduction of postsurgical pain and clinically relevant reduction in opioid consumption. The overall incidence of treatment-emergent adverse events was comparable in patients receiving an opioid-sparing postsurgical pain management protocol with or without liposomal bupivacaine. Keywords: bupivacaine, dental implantation, liposomes, local anesthetics, non-opioid analgesics, oral surgery, pain management, postoperative pain

Purpose: The aim of this study was to analyze and compare the stress distribution patterns of different implant and restorative materials in the supporting tissue and implants. Materials and Methods: Twelve different implant/bone models were created using SolidWorks 2015 software (SolidWorks Corp) and analyzed using the finite element method. Straumann Bone Level implants with zirconia abutments and single-piece Straumann PURE Ceramic implants (Institute Straumann) restored with lithium disilicate glass-ceramic and zirconia ceramic cement-retained crowns were evaluated. A 118.2-N load was applied to the coronal aspect of the buccal cusp at a 75.8-degree angle in relation to the occlusal plane. Principal stress values for cortical and trabecular bone and the equivalent von Mises stress values for implants and frameworks were calculated. Results: Zirconia (ZrO₂) implant models showed lower principal stress values than the commercially pure titanium (cpTi) and titanium-zirconium (TiZr) implant models in cortical bone. All models showed similar principal stress values in trabecular bone. Von Mises stress values at the cpTi and TiZr implants were similar; however, values observed of ZrO₂ implants were higher. TiZr implants of 3.3 mm diameter showed similar strength to 4.1-mm-diameter cpTi implants. Both zirconia and lithium disilicate glass-ceramic frameworks transferred similar von Mises stress values in the supporting tissue of implant-supported prostheses. Conclusion: Narrow-diameter TiZr implants may be preferred for patients who have insufficient bone volume without bone augmentation procedures due to the material's enhanced biomechanical properties. ZrO₂ implants may be a suitable alternative for esthetic regions. Further clinical studies are recommended to investigate the long-term performance of TiZr and ZrO₂ implants. Keywords: lithium disilicate glass-ceramic, three-dimensional finite element analysis, TiZr implants, zirconia, zirconia implants

Purpose: This study aimed to evaluate and compare the retention and stability of rigid telescopic and milled bar attachments for implant-supported maxillary overdentures. Materials and Methods: An acrylic resin model of the edentulous maxilla without alveolar undercuts was fabricated, and four implants were inserted in the canine and second premolar areas of the model. Two experimental overdentures were constructed and connected to the model with either rigid telescopic (RTA) or milled bar (MBA) attachments. Resistance of overdentures to axial and nonaxial (anterior, posterior, and lateral) dislodging forces was measured to represent retention and stability, respectively. Measurements were made at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (retention after wear simulation). Results: After wear simulation, MBAs recorded significantly higher retention (P .001) and stability against anterior dislodging (P .001) than RTAs. RTAs recorded significantly higher stability against posterior (P = .022) and lateral (P .001) dislodging than MBAs. Initial stability of RTA against anterior (P .001) and posterior (P .001) dislodging was significantly higher than stability after wear simulation. Retention of RTAs (P = .020) and stability of MBAs against posterior (P = .038) and lateral (P = .020) dislodging after wear simulation were significantly higher than initial values. Conclusion: MBA was associated with increased retention of maxillary implant overdentures compared with RTA, while RTA was associated with increased stability compared with MBA. Keywords: attachments, implant overdentures, milled bar, retention, stability, telescopic

Purpose: To review potential complications that may occur using the zygoma implant published in the literature as well as complications encountered by the primary author. Solutions for prevention as well as the management of such complications are also discussed in detail. Materials and Methods: The authors have reviewed and outlined reports discussing the etiology as well as the management of potential complications associated with the use of the zygoma implant and have offered recommendations for the management of these complications. Results: Predictable clinical solutions are offered for the identification of the cause as well as the management of complications, including orbital involvement, intracranial involvement, paresthesia of V2, subperiosteal infections, overextended apical extension, vestibular dehiscence, failed zygoma implant, fractured implant, and management of sinus infections. Conclusion: A comprehensive knowledge of the specific steps for the proper execution of this complex procedure will allow for a predictable outcome as presented by the systematic reviews of the zygoma implant, which have reported a cumulative survival rate of 96.7% to 97.8%. Understanding the cause, the prevention, as well as the management of potential complications is imperative for the contemporary surgeon using the zygoma implant. Keywords: ad modum Brånemark, biomechanics, complications, extra-sinus, implant, maxillary reconstruction, zygoma, zygomatic

Alveolar bone resorption has been a major challenge for implant placement in regions limited by anatomical structures. New alternatives have been introduced with the inclusion of extra-short implants in dentistry. The association of guided bone regeneration (GBR) with the use of extra-short implants might be a viable alternative for regions with limited bone height. This case report aimed to present the rehabilitation of a patient with severe mandibular bone resorption in the posterior region. The association of GBR with the use of extra-short implants was a viable alternative after a 3-year follow-up. Keywords: extra-short implants, prosthetic rehabilitation, resorbed mandible