The International Journal of Oral & Maxillofacial Implants, 04/2018

Purpose: To compare the suitability of a fused filament fabrication (FFF) consumer 3D printer with a professional digital light processing (DLP) printer for the production of surgical templates for guided oral implant surgery. Materials and Methods: Eight virtual templates were printed with two different 3D printers. These were optically scanned and the incongruences between virtual and printed templates were determined after alignment of the surface scans and the virtual data. Minimum, maximum, and mean incongruences were determined, and a t test between both groups was performed to determine statistically significant differences in accuracy. Results: Templates printed with the professional DLP printer showed statistically significantly less incongruence (P = .001) than those fabricated by the consumer FFF 3D printer. Conclusion: The accuracy of manufactured templates is strongly dependent on the printing device and method. At this time, the tested consumer 3D FFF printer is not suitable for the fabrication of templates for implant guided surgery. Minimum requirements regarding printers' features and 3D-printed templates need to be assessed in future studies. Keywords: accuracy, additive manufacturing, guided surgery, oral implantology, 3D printing

Purpose: The aim of this study was to evaluate the mechanical behavior of implant-supported cemented restorations placed on two types of abutment design, with and without a prosthetic finish line, evaluating fracture resistance and the type of fracture produced in the abutment-crown complex. Materials and Methods: Eighty zirconia restorations supported by tapered implants were divided into two groups: group I, with 40 zirconia crowns cemented onto individualized zirconia abutments with a chamfered finish line (1 mm deep); and group II, with 40 zirconia crowns cemented onto individualized zirconia abutments without a finish line. All specimens underwent thermocycling and dynamic loading before static load testing to evaluate their fracture resistance. Results: Fracture resistance values (N) and the type of fracture were analyzed. The mean fracture resistance was 462.1 ± 66.3 N in group I and 343 ± 40 N in group II. In group I, fractures were produced in the prosthetic fixation screw; in group II, all mechanical failures were produced in the transepithelial abutment's cervical area. Conclusion: Group I specimens showed greater fracture resistance than group II. The fracture type in group I occurred in the prosthetic screw. Group II fractures occurred in the zirconium oxide abutment. Keywords: BOPT, finish line, prosthetic cementoenamel junction, vertical preparation, zirconia implant

Purpose: Implant-retained mandibular overdentures are a proven treatment modality for edentulous patients. Low-profile stud attachments may allow divergence between the abutments up to 40 degrees. The purpose of this study was to investigate load transfer characteristics of various locations and nylon male configurations of low-profile stud attachment-retained overdentures. Materials and Methods: Three tapered dental implants were placed into three photoelastic mandibular models. The center implants were placed vertically onto the midline, and the distal implants were inclined 20 degrees corresponding to centralized implants. Three different distances (11, 18, and 25 mm) between the centralized and the distal implants were set on the models. Low-profile stud attachment (Locator)-retained mandibular overdentures were fabricated for each photoelastic model. Five different nylon male configurations of this stud attachment were established. The load transfer characteristics of the configurations were tested using a circular polariscope. Results: The observed stress levels for the tested configurations were moderate except for group 25C (photoelastic model with 25-mm interimplant distances and clear nylon male), which illustrated a high stress level. For the 11-mm photoelastic model, little or no discernible stress was noted around the dental implants for group 11R (red nylon male), group 11G (green nylon male), and configurations of clear and red or green nylon males (group 11CR [clear and red nylon males] and group 11CG [clear and green nylon males]). Conclusion: The applied loads were distributed to the supported dental implants and denture-bearing areas for tested designs. Equitable load distribution and less stress may be gathered using nylon males for angulated implants (red and green) when dental implants are placed inclined. Keywords: denture precision attachment, implant-supported dental prosthesis, overdenture, photoelastic

Purpose: To evaluate the bending strain exerted on a maxillary implant overdenture supported by rigid bar and nonrigid double crown connectors in models of high- and low-quality bone. Materials and Methods: Four implants were embedded in acrylic resin models of an edentulous maxilla simulating good- and poor-quality bone at the canine and second premolar regions bilaterally. A bar (cross-section dimension: 5 × 5 mm; bilateral distal extension: 10 mm) and double crown connectors with a metal framework (same morphology as the bar) were attached to these implants and placed under a constant 49 N vertical load at the anterior and cantilever regions of both superstructures. The bending strain on the implants was measured by strain gauges attached to the implant surfaces. Results: In good-quality bone with cantilever loading, the strain-which was highest near the load for both attachment systems-was highly concentrated in the rigid bar system but dissipated through the double crown connector. The directionality of the bending moment was homogenous on the two attachments. In poor-quality bone, strains were significantly lower and more variable, especially for double crown connectors, and there was heterogeneity in the directions of the bending moment. Conclusion: Within the limitations of this study, bar and double crown connectors have identical biomechanical features in good-quality edentulous maxillary bone, but have divergent properties in poor-quality bone. Keywords: bar attachment, bending strain, bone quality, double crown connectors, implant overdenture

Purpose: Recently, a torque-measuring micromotor that calculates the integral (I) of torque-depth curve at implant insertion was developed. This device was used to investigate the correlation between (I) and mechanical stress in photoelastic resin blocks with the density of D1 bone. Materials and Methods: Using the micromotor, 40 implants (3.75 × 12 mm) were placed in 40 D1 blocks that had been prepared in four different ways. Four groups of 10 blocks each were prepared according to tunnel length (12 or 14 mm) and debris removal (yes or no). After insertion, peri-implant mechanical stress and its correlation with (I) were assessed by photoelastic and linear regression analysis, respectively. Analysis of variance (ANOVA) and Kruskal-Wallis tests investigated differences in mechanical stress patterns and dynamic parameters among the groups. Results: (I) significantly correlated with mechanical stress in D1 resin under all conditions, except for 12-mm implant sites still containing debris. The correlation was significant concerning the whole dataset (r = 0.979) and separately for the coronal (r = 0.940), middle (r = 0.964), and apical (r = 0.948) portions of the implants. Peak torque did not correlate significantly with peri-implant mechanical stress. Longer implant sites and debris removal were significantly associated with lower peri-implant mechanical stress. Conclusion: (I) provides a reliable measure of mechanical stress in D1 bone during implant placement. Preparation of longer osteotomies and routine removal of all debris might reduce peri-implant bone stress significantly. Keywords: bone density, bone stress, implant osteotomy, photoelasticity, surgical protocol, torque-depth integral

Purpose: To compare the bone responses of chemically modified implants using the plasma immersion ion implantation and deposition method with those of blasted implants. Materials and Methods: The titanium implants were blasted with resorbable blasting media (RBM) and designated as controls. The ion-implanted implants were divided into two test groups, namely, calcium (Ca) and magnesium (Mg) implants. Six implants (two implants per group) were placed into the proximal tibias of 11 New Zealand white rabbits. Fluorochrome labeling was administered at 2 and 4 weeks after surgery. Resonance frequency analysis (RFA) was conducted immediately after surgery and at 6 weeks of healing. The removal torque was measured in half of the tibiae. The implants in another tibia were subjected to fluorescence analysis and histologic and histomorphometric evaluations. Results: The fluorescence analysis suggested that osteoconductivity was improved in the early osseointegration stages in the Ca and Mg implants. In the cortical region, the bone-to-implant contact in the Mg implants and the bone area % in the Ca and Mg implants were higher than those in the RBM implants (P .05). All groups demonstrated similar biomechanical strengths with respect to the RFA and the removal torque measurements. Conclusion: The osseointegration speed and the bone contact were positively affected by the Ca and Mg ion implantation, especially in the Mg implants, because of the synergistic effect. However, no remarkable differences were found in biomechanical strength in the later osseointegration stages. Keywords: calcium, ion implantation, magnesium, surface chemistry

Purpose: The aim of this study was to assess the effects of simulated axial loadings on the pull-out force required to disengage a two-piece conical connection abutment from an implant. Materials and Methods: Ten conical connection abutments (Ankylos Regular/X Abutment, Dentsply-Friadent) and 10 implants (Ankylos C/X Implant) were used. The implant-abutment assemblies were divided randomly into two groups: control group (C) and experimental group (E). For group E (n = 5), a cyclic load of 18 to 180 N at a frequency of 10 Hz to 10⁶ cycles was applied centrally and along the long axis of the implant, whereas for group C (n = 5), each sample was put on a workbench without cyclic loading at the same time during the testing period. Before mechanical loading, the initial torque values and the total lengths of tested samples of groups C and E were recorded. After cyclic loading, the postloading reverse torque value, the total length, and the pull-out force of tested samples of groups C and E were recorded. The difference between the initial torque value and the postloading reverse torque value was defined as the total torque loss. The difference between the initial total length and the postloading total length was defined as the axial displacement. The data were analyzed by independent t test. Results: The mean pull-out force of the experimental group was 77.60 N (SD = 6.16 N), which was significantly larger than that of the control group (mean = 55.28 N; SD = 9.41 N) (P .05). The mean total torque loss and the mean axial displacement of the experimental group were both significantly higher than those of the control group (P .05). Conclusion: Simulated axial loading increased the pull-out force of loaded abutments in comparison with unloaded abutments. Under simulated axial loading, the pull-out force of abutments tended to increase as the axial displacement of abutments and the total torque loss of abutment screws were both increased. Keywords: axial loading, conical connection, implant abutment, pull-out force

Purpose: To assess studies on edentulous patients rehabilitated using mandibular implant-supported profile prostheses and analyze the impact of different numbers of implants used on the implant survival rate, peri-implant bone loss, and prosthesis survival rate. Materials and Methods: This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement and was registered on PROSPERO. The PubMed/MEDLINE database was searched for articles published before July 18, 2016. The study attempted to answer the following PICO question: In edentulous patients, do full-arch fixed prostheses supported by three implants have a satisfactory implant survival rate, marginal bone loss, and prosthesis survival rate compared with those supported by different numbers of implants? Evidence levels of each study were evaluated using the Oxford Centre for Evidence-Based Medicine (OCEBM); methodologic quality was evaluated using the Methodological Index for Nonrandomized Studies (MINORS) scale and Cochrane Risk of Bias Tool. Descriptive statistics were performed when applicable. Implant survival curves were constructed using the Kaplan-Meier method, and marginal bone loss was analyzed using the Kruskal-Wallis, Dunn's, and Mann-Whitney tests. Results: This analysis included 21 published studies of 4,712 implants and 1,245 mandibular implant-supported profile prostheses in 1,245 patients. The patients were grouped by the number of implants used: group 1 (three implants) had an implant survival rate of 90%; group 2 (four implants) had a rate of 95%; and group 3 (five implants) had the lowest rate, 74%. Groups 1 and 3 had the lowest first-year bone losses (median: 0.73 and 0.70 mm, respectively), and were significantly different from group 2 (median: 1.31 mm; P .001). Conclusion: Despite the limitations in the studies with low levels of evidence and the methodology of MeSH term research, it was concluded that the implant survival rate and first-year bone loss of full-arch fixed prostheses supported by three implants were satisfactory. However, the prosthesis survival rate was inferior to that of other groups, which suggests a longer follow-up of these rehabilitations. Keywords: dental implants, implant-supported dental prosthesis, survival rate

Purpose: Central manufacturing of two-piece computer-aided design/computer-aided manufacture (CAD/ CAM) zirconia abutments may provide a higher accuracy of internal and external adaptation at the expense of delayed restoration delivery. The aim of this study was to compare the fit of two-part zirconia abutments that were either fabricated centrally with the DEDICAM system or at a local laboratory. The field of interest was the marginal, external, and internal luting gap between the titanium insert and CAD/CAM zirconia coping. Materials and Methods: Two groups of nine two-piece CAD/CAM zirconia hybrid abutments were subjected to scanning electron microscopy (SEM) to evaluate the precision of fit and thickness of the adhesive joint. Control specimens were fabricated with the CAMLOG DEDICAM system at the manufacturer's site; the test specimens were produced in a local laboratory. After embedding all samples (n = 18) in resin, they were sectioned, and the external, marginal, and internal luting gaps between the titanium base and zirconia coping were measured with SEM. Welch's t test was used for statistical analysis of the obtained data. Results: The overall range of measured gaps between the components of two-piece CAD/CAM zirconia abutments was 0 to 115.5 μm; the mean overall gap size and standard deviation was 45.61 ± 5.88 μm and showed no appreciable difference between the test and control groups. The mean sizes of the marginal/ external and internal gaps showed only negligible differences. The internal gap size was generally larger and showed a higher variability than the marginal/external gaps, albeit on a very low level. None of the reported differences between the test and control specimens were statistically significant. Conclusion: Luting-gap sizes of CAMLOG DEDICAM- and locally fabricated CAD/CAM zirconia hybrid abutments showed no appreciable difference. Both configurations of two-piece abutments provided a highly precise fit of hybrid components, overmatching the high-quality standards in CAD/CAM implant-based prosthetic dentistry. Keywords: full ceramic, hybrid abutments, internal fit, luting gap, marginal fit, two-piece CAD/CAM zirconia abutments

Purpose: To investigate if the presence of a cantilever influences the survival and success of partial fixed implant-supported prostheses, through a systematic review and meta-analysis, with additional analysis of the survival and marginal bone loss rates and prosthesis complications. Materials and Methods: The register protocol of the review in the PROSPERO database is CRD42016052008. The MEDLINE and Scopus databases were used for an electronic search of relevant studies up to November 2016, by means of two independent reviewers. The keywords included the combinations "fixed partial denture" with "dental implants", and with "extension" or "cantilever"; and "implant-supported dental prosthesis" with "extension" or "cantilever". The inclusion criteria were randomized clinical trials and prospective and retrospective clinical studies in English that addressed the comparison of success and survival of the use of implant-supported fixed prostheses, with and without cantilevers. Data from the selected studies were used to perform the statistical analysis. Results: Among the 408 articles identified, 4 articles met the eligibility criteria. The presence of a cantilever did not compromise marginal bone loss or the survival of the prostheses. However, minor complications were encountered for the group of partial fixed prostheses without cantilevers, with a statistical difference (P = .008). Conclusion: Cantilevers can be used in fixed prostheses and do not interfere negatively in the survival or success of the prosthesis or the marginal bone loss. However, there are minor complications when prostheses without cantilevers, or short cantilevers, are used. Keywords: cantilever, dental implants, extension, fixed partial denture, implant-supported dental prosthesis

Purpose: Primary implant stability represents the first step for successful osseointegration. The knowledge of the correlation between host bone density, insertion torque, and implant macrogeometry seems to be fundamental to achieve sufficient primary implant bone fixation in each clinical situation. The purpose of this study was to measure, in vitro, the impact of dental implant macrogeometry and insertion torque values on primary stability in relation to different bone densities, representing both the human mandible and maxilla. Materials and Methods: One hundred twenty 3.8 × 11-mm commercial dental implants were used. Forty implants had small threads with a machined neck, 40 implants had small threads with a microthreaded neck, and the last 40 implants had large threads with a reverse neck design. Fresh bovine ribs, representing a medium-dense bone density (D2-D3), and fresh ovine iliac crest, representing a soft bone density (D4), were used. Insertion torque and micromobility under lateral force data were recorded for each implant. Results: In the medium-dense bone type, the reverse neck implant design showed less primary implant stability than the conventional straight implant neck. In soft bone, both implants with the large thread design and microthreaded neck implants showed better implant stability than the implant with a small thread design with a straight machined neck. Implants with large and self-cutting threads showed significantly (P .05) lower micromobility values than other implants in postextractive sites in low-density bone. Conclusion: Implant geometries and bone density are the main factors involved in the degree of primary implant stability. Large-thread implant designs are highly desirable in cases of poor bone quality. Each implant geometry generates an insertion torque value, which is correlated to the stability of that specific implant in a specific bone quality, but the insertion torque is not an objective value to compare primary stability between different implant types. Keywords: bone density, implant geometry, insertion torque, osseointegration, primary implant stability

Purpose: The aim of this study was to evaluate the efficacy of photodynamic therapy (PDT) and light-activated disinfection (LAD) against a 3-day-old bacterial suspension prepared from three different bacterial species present on titanium dental implants, and to analyze the possible alterations of the implant surfaces as a result of the PDT and LAD. Materials and Methods: The study was conducted on 72 titanium dental implants contaminated with a bacterial suspension prepared from three bacterial species: Prevotella intermedia, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. The contaminated implants were incubated under anaerobic conditions for 72 hours and then were randomly divided into four experimental groups and two control groups (n = 12 each), according to the following treatment protocols: group 1 (PDT1): PDT (660 nm, 100 mW, 60 seconds) with toluidine blue; group 2 (PDT2): PDT (660 nm, 100 mW, 60 seconds) with phenothiazine chloride dye; group 3 (LAD): light-emitting diode (LED) with toluidine blue; group 4 (toluidine blue): treatment with only toluidine blue for 60 seconds. In the positive control group, the implants were treated with a 0.2% chlorhexidine-based solution for 60 seconds, and in the negative control group, no treatment was used. Results: The highest bacterial reduction was recorded in the PDT1 (98.3%) and PDT2 (97.8%) groups. The results of this study showed that there was a statistically significant reduction of bacteria in the PDT1 and PDT2 groups compared with the negative control group (P .05), individually for each bacterial species as well as for all three species together. LAD was less effective than PDT1 and PDT2, and did not show a statistically significant difference compared with the negative control or any other treatment group. Toluidine blue was the least effective treatment in terms of both the total bacterial count and the individual count for each bacterial species. Conclusion: Both PDT1 and PDT2 protocols showed a high efficacy against a 3-day-old bacterial biofilm on dental implants and were more effective compared with LAD. Keywords: decontamination, dental implants, LAD, laser, PDT, photodynamic

Purpose: To quantify the rate of maintenance interventions of mandibular prostheses: complete dentures and overdentures retained by two implants, with either internal hex or external hex connections. Materials and Methods: This study analyzed patients with edentulous mandibles treated with distinct treatment protocols: a control group received complete dentures; a second group received Locator-retained overdentures supported by two external hex connection implants; and a third group received overdentures supported by internal hex connection implants. All of the maintenance interventions associated with the prosthetic treatment after delivery were recorded (starting from 2000 until the final assessment in 2012). Moreover, patient satisfaction was assessed using a 0 to 10 visual analog scale. Results: The final sample was composed of 136 patients: 56 in the control group, 31 in the hex implant overdenture group, and 49 in the internal connection overdenture group followed over a period of 60 months (ranging from 3 to 144 months). Prosthetic adjustment was the most frequent intervention carried out, particularly within the control group (a mean rate of 1.1 ± 1.9 times/subject/year) in comparison with the internal connection (0.6 ± 0.8 times/subject/year) and hex implant overdenture groups (0.3 ± 0.2 times/subject/year). Relining was also frequently required, occurring on average every 4 years in the control group and every 7 years in the overdenture groups. Abutment loosening was more frequent in the hex implant overdenture group than in the internal connection overdenture group (8/31 versus 8/49), as well as abutment wear (5/31 versus 5/49). Gingival inflammation was significantly more common in the hex implant overdenture group (19/31 patients), as compared with the controls (16/56 subjects), and satisfaction was higher in patients in the two overdenture groups (mean Oral Satisfaction Scale [OSS] score of 8.1 ± 1.9 for external and 8.4 ± 1.6 for internal connections) than in the control group (5.3 ± 3.3). Conclusion: Locator-retained overdentures needed less than half the number of maintenance interventions when compared with the control group, and maintenance was required every 2 to 4 years. Keywords: gerodontology, Locator system, overdentures, prostheses complication, prostheses maintenance

Purpose: The primary objective of this study was to assess the accuracy of periapical radiographs in determining the peri-implant marginal bone level. The accuracy of the linear measurements on radiographs was considered as the absolute difference between the true, intraoperative or surgical marginal bone level measurements (direct bone measurements during surgical procedures) and the radiographic measured distances. The secondary aims were to identify the variables influencing the radiographic evaluation (arch: mandible/maxilla; implant location: anterior/posterior; timing of implant placement: "early delayed" and "prolonged delayed"). The influence of vestibular and palatal/lingual crestal bone levels was also investigated. Materials and Methods: STROBE guidelines were followed. As soon as the implant was inserted, the marginal bone levels were recorded using a straight periodontal probe (intraoperative or surgical measurements). At the same time, periapical radiographs were taken. To standardize the radiographic images, periapical radiographs were acquired using the long-cone parallel technique and film holding system. All radiographs were analyzed by two examiners blinded to the surgical measurements. Intraclass correlation coefficient (ICC) was employed to assess the intraobserver and interobserver variability. The descriptive statistics, t test, and multivariate statistics were used; the threshold for statistical significance was P ≤ .05. Results: Two hundred sixty-eight implants were inserted in 142 patients. The interobserver agreement was 0.980; the intraobserver variability was 0.990 and 0.993. The mean difference between the radiographic and surgical measurements was 0.45 mm (range: 0 to 8 mm; SD: 1.76). Comparing the radiographic and surgical measurements, a statistically significant difference (P = .000) was detected. None of the variables considered (arch, implant location, and timing of implant placement) significantly influenced the accuracy. Neither the vestibular alveolar edge (P = .908) nor the lingual/palatal (P = .485) significantly influenced the accuracy. Conclusion: The periapical radiograph statistically significantly overestimates the level of periimplant marginal bone compared with surgical measurements. The arch, implant location, timing of implant placement, and level of vestibular or lingual/palatal alveolar edge do not influence deviation between the intraoperative peri-implant marginal bone level measurements and the radiographically determined marginal bone levels. Keywords: alveolar bone loss, computer-assisted, dental implant, dental radiography, radiographic image interpretation

Purpose: The objective of this investigation was to assess the microbiologic contamination in the inner surface of titanium implants prior to prosthetic abutment placement. Materials and Methods: The study population consisted of partially edentulous individuals who had previously received at least one internal hexagon titanium dental implant. A bacterial sample of the inner surface of the individual dental implant was taken after surgical reopening for healing abutment placement. The samples were allocated in order to evaluate three distinctive variables as follows: (1) location (mandible vs maxilla), (2) early exposure of implants to the oral cavity (cover screw) throughout the healing stage (exposed vs not exposed), and (3) existence or lack of keratinized mucosa (KM). The microorganism species detected were examined by checkerboard DNA-DNA hybridization. Results: A total of 32 partially edentulous patients with 78 implants placed in both the maxilla and mandible were enrolled: 8 men and 24 women, ranging in age from 27 to 64 years (mean age: 47.7 years). Bacteria were detected in 20 patients, distributed in 41 implants. Spontaneous early implant exposure and absence of KM did not increase bacterial contamination in the inner surface of implants. A significant increase in the detection of 22 bacterial species was found in the mandible when compared with the maxilla. Conclusion: Microbial biofilm accumulation in the implant's internal surface might happen before healing abutment placement. Exposure of implants to the oral cavity and absence of KM were not directly related to a greater microbial biofilm count. The results suggested that submerged healing does not protect implants against bacterial colonization. Keywords: checkerboard DNA-DNA hybridization, dental implants, microbiology, peri-implantitis

Purpose: To investigate whether pretreatment patient-related factors are associated with the outcomes of dental implant treatment through multidimensional evaluations of oral health-related quality of life and health-related quality of life using the Oral Health Impact Profile (OHIP) and the 36-Item Short Form Health Survey (SF-36) developed from the Medical Outcomes Study, respectively. Materials and Methods: Oral health-related quality of life was evaluated using the Japanese version of the OHIP, and health-related quality of life was evaluated using scores for the mental component summary (MCS) and physical component summary (PCS) dimensions of the SF-36. Data were collected before treatment (baseline) and 1 month after delivery of the prostheses (follow-up). Stepwise multivariate regression analysis was used to explore the associations of posttreatment OHIP and SF-36 scores and changes in these scores after treatment (dependent variables) with age, sex, educational background, number of missing teeth, Eichner's classification, pretreatment state, site of the embedded implant, number of implants, types of definitive prostheses, and baseline OHIP and SF-36 scores (independent variables). Results: Data from 150 consecutive patients (mean age: 58.1 ± 11.5 years) who underwent dental implant treatment between April 2008 and April 2016 were analyzed. The mean OHIP summary score, OHIP dimension scores (oral function, orofacial pain, orofacial appearance, and psychosocial impact), and MCS score showed significant improvements after treatment (P .05). The baseline OHIP and SF-36 scores were consistently and significantly associated with the treatment outcome (ie, dependent) variables (P .05). Moreover, the site of the embedded implant was identified as a significant predictor of the posttreatment status and changes in the OHIP summary score, oral function and orofacial appearance dimension scores (OHIP), and MCS score. Conclusion: These results suggest that patient perceptions of health and oral health conditions may help in the prediction of the outcomes of dental implant treatment. Keywords: dental implants, quality of life, treatment outcome

Purpose: To present the different definitions of peri-implantitis proposed in the literature and to propose a new evidence-based etiology-driven classification of peri-implantitis to accurately and fully describe the etiology of peri-implantitis. Materials and Methods: Full-text papers on the selected topic were obtained for all abstracts and titles that appeared to meet the inclusion criteria. Additional papers were included from the reference lists of the selected studies. No methodologic and reporting quality of the included papers was applied in order to collect the greatest number of articles. Results: One hundred twenty-two studies were found according to the search criteria. After filter activation, abstract evaluation, and duplicate removal, 16 articles were deemed useful for the aim of the present narrative review. A manual search using personal contact and references of published works and contributions by the authors included another 16 articles, resulting in a total of 32 articles. After full-text article selection and reading, 15 articles were finally included. Conclusion: There is not a generally accepted classification system of the various degrees of peri-implantitis. An etiology-driven classification was proposed as a tool to assist the clinician in properly detecting and classifying etiology-based peri-implantitis. This classification may also support the assignment of prognosis, and if needed, therapy to arrest/prevent peri-implantitis. Keywords: classification, dental implants, peri-implant diseases, peri-implantitis

Purpose: Peri-implant bone thickness is an important local factor that could influence esthetic outcomes in immediate implant therapy. The aim of this study was to assess the thickness of the buccal bone overlying the anterior maxillary teeth in Kenyans. Materials and Methods: A total of 184 cone beam computed tomography (CBCT) scans that met the inclusion criteria were retrospectively studied. Buccal bone thickness of all maxillary anterior teeth was assessed, resulting in a total of 1,104 teeth. Measurements were taken on sagittal views at a point 4 mm below the cementoenamel junction (M1) and at the mid-root level (M2). The data were analyzed using SPSS software (version 20, IBM), and statistical significance was set at P ≤ .05. Results: Mean buccal bone thickness of the teeth studied was 0.55 ± 0.38 mm at M1 and 0.60 ± 0.30 mm at M2. Missing buccal bone wall was observed in 31.61% (349 teeth) of all teeth at M1 and in 21.38% (236 teeth) of all teeth at M2. The majority of the teeth had a thin buccal bone wall ( 1 mm) at M1 (56.34%) and at M2 (68.48%), whereas a thick buccal bone (≥ 1 mm) was only observed in 12.05% of teeth at M1 and in 10.14% of teeth at M2. Thin buccal bone was mainly found in central incisors, while thick buccal bone wall was found mainly in canines. The thickness of buccal bone at M1 decreased with an increase in age. Conclusion: Contour augmentation would be necessary in most of these cases, as the buccal bone was typically thin. The thickness at the cervical portion was inversely correlated with age. One in every four of the cases would not be ideal for flapless immediate implant placement due to a missing buccal bone wall. Preoperative CBCT analysis of the buccal wall is recommended for appropriate treatment planning. Keywords: bone resorption, dental implants, esthetics, tooth extraction

Purpose: The aim of this study was to evaluate volumetric stability of autologous and xenogeneic block grafts and primary stability of implants in maxillary grafted areas. Materials and Methods: Each patient received one autologous block and xenogeneic block, both covered with a membrane. Bone thickness measurements clinically and tomographically were made before, immediately, and 6 months postoperatively. After 6 months, identical implants were placed in each grafted area, and primary stability was measured. Results: Eight patients with anterior horizontal bone defects were selected. Clinical outcomes at 6 months postgrafting in the autologous block revealed a mean thickness of 7.4 ± 1.6 mm, with an initial mean measurement of 3.4 ± 1.7 mm and 2.6% resorption, whereas the mean in the xenogeneic block was 8.9 ± 1.5 mm, 3.3 ± 1.6 mm, and 7.3%, respectively. Tomographic evaluation of the thickness at 6 months postgrafting in the autologous block was a mean 7.8 ± 1.8 mm, with an initial mean of 3.7 ± 1.6 mm and resorption of 0%, while the mean in the xenogeneic block was 9.3 ± 1.6 mm, 3.6 ± 1.4 mm, and 2.1%, respectively. No significant difference in bone thickness was observed immediately or 6 months after the procedure. The mean implant placement torque was 32 ± 22 Ncm in the autologous block and 18 ± 9 Ncm in the xenogeneic block (P = .004). Conclusion: Xenogeneic block was shown to be a suitable alternative to reconstruct horizontal defects in the alveolar ridge that had undergone extensive resorption, though lower insertion torques were obtained during implant placement. Keywords: bone block graft, bone grafts, xenogeneic bone block graft

Purpose: To compare, by gene profiling analysis, the molecular events underscoring peri-implant mucosa formation at machined vs laser-microgrooved implant healing abutments. Materials and Methods: Forty endosseous implants were placed by a one-stage approach in 20 healthy subjects in nonadjacent sites for single-tooth restorations. In a split-mouth design, machined smooth and laser-microgrooved healing abutments were randomly assigned in each subject. Peri-implant mucosa adjacent to healing abutments was harvested by tissue punch biopsy at either 1, 2, 4, or 8 weeks following abutment placement. Total RNA was isolated from the peri-implant transmucosal soft tissues. A whole genome microarray using the Affymetrix Human Gene 2.1 ST Array was performed to describe gene expression profiles in relation to abutment topography and healing time duration. Data analysis was completed using GeneSpring software v.12.6. Results: Differential gene expression was revealed at all time points and among surfaces. Five hundred one genes were differentially expressed (fold change ≥ 2.0) at machined versus laser-modified abutments, and 459 of these were statistically significant (P ≤ .05). At 1 week, unique expression of IL-24 and MMP1 was observed in tissues from laser-treated surfaces. At 2, 4, and 8 weeks, mRNAs encoding keratins and protective proteins of cornified epithelium were upregulated in tissues from laser-modified abutments. At 4 weeks, upregulation (> 2-fold) of mRNAs encoding proteins associated with collagen fibril formation and function was observed in tissue from laser-modified abutments. In both tissues of machined and laser-modified abutments, mRNAs encoding junctional epithelium-specific proteins, ostogenic ameloblast associated protein (ODAM) and follicular dendritic cell secreted protein (FDCSP) were highly upregulated throughout weeks 2 to 8. Conclusion: Peri-implant abutment mucosal wound healing involves selective differentiation of epithelium and induction of the junctional epithelium. Laser-mediated alterations in abutment topography enhance collagen fibril-associated gene expression and alter epithelium/junctional epithelial gene expression. Clinically, shallower probing depths are measured at laser-mediated versus machined implant abutments. Keywords: dental implant abutment, junctional epithelium, laser, mucosal integration, titanium

Purpose: The aim of this study was to assess and compare the esthetic outcome of tissue-level (TL) and bonelevel (BL) implants that had been placed as single implants in the anterior maxilla. Materials and Methods: Between 2001 and 2008, patients were treated using TL implants (Straumann). From 2008 until 2012, patients received the newly developed BL implant (Straumann). All patients with a single anterior maxillary implant who came to check-ups regularly were contacted and invited to take part in the study. Standardized photographs were taken to conduct the evaluation. Five observers analyzed the esthetic outcome using the pink esthetic score (PES). For the purpose of statistical analysis, the Wilcoxon rank sum test was applied. Interobserver reliability was evaluated with Krippendorff's alpha. Results: Forty-six patients agreed to take part in the study. The study comprised 10 immediate (TL = 6, BL = 4), 21 early (TL = 6, BL = 15), and 15 delayed implantations (TL = 11, BL = 4). All implant sites were simultaneously augmented. The prosthetic restorations were delivered 6 to 24 weeks after implant placement in the TL group and 10 to 14 weeks after implant placement in the BL group. Esthetic evaluation was performed after a mean period of 9.5 years for TL implants (range: 5.5 to 12.0) and 3.7 years for BL implants (range: 2.6 to 7.1). The overall PES was 8.49 (SD: 2.35) for TL implants and 9.29 (SD: 1.90) for BL implants (P = .37). Comparison of single parameters was between P = .24 and P = .83, indicating no statistically significant difference between the two implant types. Conclusion: Within the limits of this study, it can be stated that both implant designs showed comparably satisfying esthetic results. Keywords: bone-level implant, esthetic zone, long-term esthetic outcome, pink esthetic score, single implant, tissue-level implant

Purpose: To compare the peri-implant radiographic crestal bone changes around implants placed at the subcrestal or crestal level. Materials and Methods: Systemically healthy patients with at least two missing teeth requiring implant-supported fixed prosthetic restorations were enrolled in the study. Implants were randomly placed either 1 mm subcrestally or at the bone crest level. Radiographic examination was performed using the long-cone parallel technique and customized film holders. Digital periapical radiographs were obtained at the time of implant placement (T₀), at the time of prosthesis delivery (T₁), and 12 months (T₂) after prosthetic loading. Marginal bone levels were measured at the mesial and distal aspects of each implant with digital image software. Results: A total of 54 implants were present for the radiographic analysis at the 12-month follow-up. No implant showed mechanical or biologic complications throughout the follow-up period. The implant survival percentage was 100%. After 1 year, the mean bone loss was 0.711 ± 0.721 mm in the subcrestal group and 0.224 ± 0.418 mm in the crestal group. Furthermore, only the subcrestal group showed statistically significant radiographic bone resorption at the end of the follow-up. Conclusion: Within the limitations of this study, implants placed at the crestal level showed greater peri-implant bone stability during the 1-year follow-up. Studies with larger samples and longer follow-up are needed to confirm the results of this investigation. Keywords: bone preservation, crestal bone level, dental implants, surgery

Purpose: To correlate the link between natural teeth located in esthetic regions of the arches before extraction with their definitive dental implant restorations, and to propose a new and contemporary esthetic index based on the natural dentition (EIND) preoperatively. Materials and Methods: Patients possessing a high smile line with teeth requiring implant replacement therapy in the maxillary anterior region were included. Clinical intraoral photographs and periapical digital radiographs taken before extraction and 10 ± 1.5 months (range: 9 to 12 months) after the delivery of implant-supported permanent restorations were used to make the measurements and evaluations according to the proposed index. Pink esthetic score (PES) parameters were analyzed. Statistical analyses of preimplant and postimplant parameters between tooth sites and implant sites were carried out with a computer software program. Results: The study included 51 patients (35 women, 16 men), with a mean age of 39.6 years, with a total of 83 dental implants placed in the maxillary anterior region. Of these, there were 6 right canines, 22 right lateral incisors, 11 right central incisors, 22 left central incisors, 17 left lateral incisors, and 5 left canines. Of the 83 included implants, 67 were immediately and 16 were delayed placed. Statistical analyses between tooth sites and implant sites showed significant differences in tissue contour (P = .001), texture (P = .001), alveolar deficiency (P = .001), and total PES (P = .007). No statistically significant difference was detected in mesial papilla, distal papilla, tissue margin, tissue biotype, and the amount of keratinized mucosa. Additionally, R2 value presented a higher variance and lower predictable values of peri-implant tissue parameters compared with those of the natural dentition. Conclusion: This study analyzed various periodontal and peri-implant soft and hard tissue parameters, and a new index system, EIND, was proposed. This index could be used to collect the esthetic-related parameters for pre-extraction treatment planning and provide valuable information for esthetic risk assessment. Keywords: dental esthetics, dental implants, gingiva, periodontium, risk assessment, tooth

Purpose: To compare changes in the prevalence of peri-implantitis when the unit of analysis is the subject and when the unit of analysis is the implant, by means of meta-analysis with subgroup and sensitivity analyses, according to the case definition and cutoffs. Periodontal probing depth (PPD) and bleeding on probing (BOP) were considered the primary variables. Materials and Methods: Electronic and manual searches of observational studies of implants with loading of more than 6 months were conducted. The quality of the studies was evaluated, and finally, a description (qualitative analysis) and a meta-analysis (quantitative analysis) of the available studies were performed. Results: Fifty-five studies were included in this systematic review, 32 of which met the criteria for evaluation of disease based on PPD and BOP. A total of 2,734 subjects and 7,849 implants were evaluated. The prevalence of peri-implantitis, defined by PPD and BOP, was 17% when the unit of analysis was the subject, and 11% when it was the implant. If the clinical criterion was PPD ≥ 4 mm, the prevalence by subject was 34% and by implant 11%. If PPD was ≥ 5 mm, the prevalence by subject was 12% and by implant 10%. Finally, if the clinical criterion was PPD ≥ 6 mm, the prevalence by subject was 18% and by implant 10%. Conclusion: The prevalence of peri-implantitis is influenced by the criteria used for the case definition, and the true prevalence may currently be incorrectly estimated. Keywords: dental implants, meta-analysis, peri-implantitis, prevalence, systematic review

Several studies have clearly shown that osseointegrated implants, when inserted in growing bone, such as in adolescents, do not follow the eruptive path of adjacent teeth; instead, they act like ankylosed teeth, remaining in a stationary position for the lifetime, thus developing a progressive infraposition of the implant-supported crown. However, further studies have demonstrated that similar changes also occur in adult patients, although mostly in a small amount and over long time spans. Here the case of a female patient aged 35 years is presented, in which infraposition of the maxillary central incisor developed in a very short time (15 months). The treatment provided was a combined orthodontic/prosthetic approach with a 4-year follow-up. Keywords: craniofacial growth, implant crown, infraposition, orthodontic intrusion

Inferior alveolar nerve repositioning is an option for treating the edentulous posterior mandible with insufficient bone height above the inferior alveolar canal. This report presents a case in which inferior alveolar nerve medialization was performed for placing dental implants. In the second postoperative week, mandibular fracture occurred after biting on a relatively solid piece of food, which was treated conservatively. Keywords: implants, inferior alveolar nerve medialization, mandible fracture, paresthesia