The International Journal of Oral & Maxillofacial Implants, 05/2014

Purpose: The purpose of this study was to evaluate and compare the strain development at different occlusal heights of an implant prosthesis and adjacent teeth through the use of strain gauges. Materials and Methods: A test model was constructed using autopolymerizing polyurethane resin, artificial composite resin teeth, and an implant gold crown in the mandibular first molar area. The resin block containing the implant and the gold crown was sectioned, and two expansion screws were attached perpendicular to the bottom of the resin block on the buccal and lingual sides. The expansion screws were turned to create a gap. Four groups were created based on the occlusal height of the implant gold crown. Three strain gauges were attached to the buccal surfaces of the mandibular right second premolar, implant gold crown, and second molar. Beef jerky, carrot, and bread were used as test foods. A universal testing machine was used to apply compressive forces of 300 N (beef jerky), 250 N (carrot), and 50 N (bread), and the occlusal force was measured in each group. Results: With 300 N, occlusal forces were concentrated on the adjacent teeth when the occlusal height of the implant prosthesis decreased. With 250 and 50 N, when the occlusal height of the implant prosthesis increased, the occlusal force applied to the implant prosthesis increased, but alterations in the implant crown height had little effect on the adjacent teeth. Conclusion: Different amounts of strain in the implant prosthesis and adjacent teeth were recorded depending on the occlusal height of the prosthesis. With 250 or 50 N of force, an increased prosthesis height affected the implant itself. With 300 N of force, decreased occlusal height of the prosthesis resulted in increased force on the adjacent teeth. Keywords: bite force, dental implants, dental stress analysis, pressure transducers, vertical dimension

Purpose: The purpose of this in vitro study was to determine whether there is a correlation between the speed of sound (SOS), as measured by quantitative ultrasound (QUS), and bone quality, as expressed in Hounsfield units (HU) measured by spiral computed tomography in the mandible. Materials and Methods: Dry human mandibles (n = 23) with 69 regions of interest (ROIs) were selected for QUS and computed tomographic measurements of SOS and HU, respectively. The three ROIs defined in each mandible were the right canine, left canine, and central incisor regions. A time-of-flight approach was used to establish the SOS through bone. The mean HU value derived from scanned computed tomographic images of each ROI was evaluated for correlation with SOS. Results: The Spearman rho test revealed a modest but significant correlation between SOS and HU (R2 quadratic = 0.339, P .01). Conclusion: In this in vitro study conducted in dry human mandibles, a statistically significant correlation was identified between QUS and HU. Keywords: bone quality, Hounsfield units, quantitative ultrasound, speed of sound

Purpose: The aim of this study was to describe the average angulation and dimensions of the pterygomaxillary area in the atrophic maxilla to facilitate the orientation of pterygoid implants during their placement. Materials and Methods: A retrospective radiologic study was made. A virtual pterygoid implant, 13, 15, or 18 mm long, was placed in the pterygomaxillary area following the axis of the bone, with a distance of at least 2 mm maintained between the artery and palatine nerve and the implant. The long axis of the implant was inclined slightly toward the palatal to follow the cortical palatal bone. The angles between the long axis of the virtual implant and Frankfort horizontal were measured in both sagittal and frontal views. To calculate the average length of the pterygomaxillary area, the virtual long axis of the implant was measured from the alveolar crest to the pterygomaxillary suture. Results: The average anteroposterior axis inclination of the pterygomaxillary area was 72.5 ± 4.9 degrees relative to Frankfort horizontal. The average angulation of the palatal vestibule was 81.3 ± 42.8 degrees relative to Frankfort horizontal. The average length of the pterygomaxillary area was 22.5 ± 4.8 mm. Conclusion: Pterygoid implant placement requires thorough knowledge of each patient's anatomy and individual needs. The mean position of the pterygomaxillary buttress axis was 72.5 ± 4.9 degrees to the distal and 81.3 ± 2.8 degrees to the palatal relative to Frankfort horizontal. Placement of pterygoid implants in this inclination may increase accuracy of implant placement. The average length from the tuberosity to the most apical point of the pterygoid apophysis was 22.5 ± 4.8 mm. These results suggest that an implant 15 to 18 mm in length would fit in the pterygomaxillary area to reach the cortical bone. Keywords: atrophic maxilla, implant angulation, pterygoid implant, pterygomaxillary region, radiologic assessment, tilting

Purpose: The aim of this study was to evaluate the effects of different implant angulations and attachment configurations on the retentive forces of locator attachment-retained overdentures over a simulated time period of 6 months. Materials and Methods: Two acrylic resin models (models 1 and 2) were fabricated to represent an edentulous mandible. In model 1, the midline implant (in the central region) was vertical and the other two implants (in the canine regions) were 20 degrees divergent from the midline, reaching a total divergence of 40 degrees. In model 2, all three implants were vertically oriented, perpendicular to the occlusal plane and parallel to each other. Three-point vertical pull-out forces were employed in a universal testing machine at a constant crosshead speed of 50 mm/min after overdenture construction and a simulation of 6 months of repeated insertions/removals of the overdenture. Locator attachments with different male combinations and bar and clip attachments were tested in model 1. Clear locator attachments and bar and clip attachments were tested in model 2 and served as controls. Results: The initial retentive forces of all attachments in both models ranged from 26.58 to 62.05 N, whereas the initial retentive forces of the attachments for only model 1 ranged from 49.58 to 62.05 N. The highest retention value was recorded for clear green locator attachments and the lowest for hader bar yellow clip attachments. Locator attachments showed higher retention values than hader bar yellow clip attachments. Conclusion: All attachment systems demonstrated a decrease in retention over time. Locator attachments provided better retention than hader bar yellow clip attachments. The highest retention values were obtained when green male locators were used in combination with male attachments. Keywords: implant-retained overdenture, locator attachments, retention

Purpose: To determine the effect of increased torque of the abutment screw and retorquing after 10 minutes on implant-supported fixed prostheses. Materials and Methods: Two strain gauges (SGs) were attached to four implants stabilized on an acrylic resin mandible. Four implant-supported frameworks were constructed to represent passive fit (PF) and different amounts of misfit (MF1, MF2, and MF3). Vertical misfit was measured using a traveling microscope. Each framework was torqued to 35 Ncm (the manufacturer's recommendation) and 40 Ncm, and the preload was recorded immediately and again after retorquing 10 minutes later (torque stage). Results: The smallest gap was observed under the PF framework. Three-way analysis of variance revealed significant effects of the framework, torque value, and torque stage on preload. The PF showed the highest mean preload under both torque values. An independent-sample t test between the torque values revealed a statistically significant difference only for MF1 and MF2. A dependent-sample t test of the torque stage revealed a statistically significant difference at a torque value of 35 Ncm under the PF and MF3 frameworks. Conclusion: Increasing the torque value beyond the manufacturer's recommended amount and retorquing of the screws at 10 minutes after the initial torque did not necessarily lead to a significant increase in preload in full-arch implant-supported fixed prostheses, particularly under non-passively fitting frameworks. Keywords: dental implants, implant-supported prostheses, preload, screw loosening, tightening torque

Purpose: This study compared the vertical microgaps of milled zirconia and cobalt-chromium (Co-Cr) implantsupported fixed dental prosthesis frameworks to those seen in one-piece frameworks cast with different techniques. Materials and Methods: Two threaded implants were used to simulate the rehabilitation of a maxillary partially edentulous space from the second premolar to the second molar. Three-unit screwretained prosthetic frameworks were fabricated and divided into the following groups (n = 10 in each group): 1 = cast in Co-Cr using burnout cylinders; 2 = cast in Co-Cr using cast-on Co-Cr cylinders; 3 = onepiece cast in Co-Cr using a passive fitting technique; 4 = milled Co-Cr framework; 5 = milled zirconia framework. The microgap was measured under an optical microscope at ×25. Readings were made with one screw tightened and with both screws tightened. Data were submitted to statistical analysis to enable comparison between groups (α = .05). Results: All frameworks presented microgaps less than 70 μm under all reading conditions, except for group 1 with the readings made on the side opposite the tightened side (124.22 μm). With one screw tightened, the microgap on the tightened side was significantly smaller in groups 2, 3, and 4. On the opposite side, groups 3, 4, and 5 presented significantly smaller microgaps compared to the other groups. When both screws were tightened, the microgap was significantly smaller in groups 2, 3, and 4. Conclusion: One-piece cast frameworks associated with a passive fitting technique and milled Co-Cr frameworks presented smaller microgaps than the other fabrication methods and materials that were tested. Keywords: computer-aided design, computer-assisted manufacture, dental implants, implant-supported dental prosthesis, prosthetic fit, prosthodontics, screw retention

Purpose: The aim of this study was to evaluate the accuracy of implants inserted using a mucosa- supported stereolithographic surgical guide and to determine the influence of surgical management of the guide (fixed or unfixed), arch (maxilla or mandible), and smoking habit (normal or hyperplastic mucosa) on accuracy. Materials and Methods: In completely edentulous subjects, preoperative computed tomography (CT) was performed, and the images were used to plan implant positions. After the implants were placed, CT was performed again, and the presurgical and postoperative images were compared. With computer software, the jaw contours from the two CT scans were matched and the deviations between the planned and actual implant positions were evaluated. Surgical technique, arch, and smoking habit were examined as independent variables, and their influence on accuracy was evaluated with a t test. Results: Twenty-eight surgical guides (225 implants) were included in this study. Deviations between planned and actual positions were seen in the global coronal (mean ± SD: 1.68 ± 0.6 mm), global apical (2.19 ± 0.83 mm), and angular (4.67 ± 2.68 degrees) dimensions. Fixation of surgical guides (fixed: 4.09 degrees; not fixed: 5.62 degrees) and use of the guide in the maxilla (4.36 degrees; mandible: 5.46 degrees) resulted in statistically significantly less angular deviation (ie, better accuracy). Nonsmoking patients showed statistically significantly better accuracy in global coronal (nonsmokers: 1.54 mm; smokers: 1.83 mm) and global apical (nonsmokers: 2.08 mm; smokers: 2.27 mm) deviations. Conclusion: The greater supporting surface of the maxilla and fixation of the surgical guide improved the accuracy of the guides. The reduced mucosa thickness in nonsmokers decreased global coronal and global apical deviation. Keywords: accuracy, guide, computer-assisted image processing, dental implants, edentulous, stereolithography, surgical guide, three-dimensional imaging

Purpose: The aim of this study was to evaluate and compare the settling of abutments into implants and the removal torque values (RTVs) before and after cyclic loading. Materials and Methods: Five different implant-abutment connections were tested: Ext = external butt joint + two-piece abutment; Int-H2 = internal hexagon + two-piece abutment; Int-H1 = internal hexagon + one-piece abutment; Int-O2 = internal octagon + two-piece abutment; and Int-O1 = internal octagon + one-piece abutment. Ten abutments from each group were secured to their corresponding implants (total n = 50). All samples were tested in a universal testing machine with a vertical load of 250 N for 100,000 cycles of 14 Hz. The amount of settling of the abutment into the implant was calculated from the change in the total length of the implant-abutment sample before and after loading, as measured with an electronic digital micrometer. The RTV after cyclic loading was compared to the initial RTV with a digital torque gauge. Statistical analysis was performed at a 5% significance level. Results: A multiple-comparison test showed specific significant differences in settling values in each group after 250 N cyclic loading (Int-H1, Ext Int-H2 Int-O2 Int-O1). There were statistically significant decreases in RTVs after loading compared to the initial RTVs in the Int-H2 and Int-O2 groups. No statistically significant differences were found in the Ext, Int-H1, and Int-O1 groups. Conclusion: The results of this study demonstrated that the settling amount and RTV (loss of preload) after cyclic loading were specific to the abutment type and related to the design characteristics of the implantabutment connection. Keywords: axial displacement, dental implants, implant-abutment interface, torque

Purpose: The aim of this study was to undertake a systematic review with meta-analysis on randomized controlled trials (RCTs) to compare the rates of survival, success, and complications of short implants to those of longer implants in the posterior regions. Materials and Methods: Electronic literature searches were conducted through the MEDLINE (PubMed) and EMBASE databases to locate all relevant articles published between January 1, 1990, and April 30, 2013. Eligible studies were selected based on inclusion criteria, and quality assessments were conducted. After data extraction, meta-analyses were performed. Results: In total, 539 dental implants (265 short implants [length 5 to 8 mm] and 274 control implants [length > 8 mm]) from four RCTs were included. The fixed prostheses of multiple short and control implants were all splinted. The mean follow-up period was 2.1 years. The 1-year and 5-year cumulative survival rates (CSR) were 98.7% (95% confidence interval [CI], 97.8% to 99.5%) and 93.6% (95% CI, 89.8% to 97.5%), respectively, for the short implant group and 98.0% (95% CI, 96.9% to 99.1%) and 90.3% (95% CI, 85.2% to 95.4%), respectively, for the control implant group. The CSRs of the two groups did not demonstrate a statistically significant difference. There were also no statistically significant differences in success rates, failure rates, or complications between the two groups. Conclusion: Placement of short dental implants could be a predictable alternative to longer implants to reduce surgical complications and patient morbidity in situations where vertical augmentation procedures are needed. However, only four studies with potential risk of bias were selected in this meta-analysis. Within the limitations of this meta-analysis, these results should be confirmed with robust methodology and RCTs with longer follow-up duration. Keywords: complication, dental implant, failure rate, short implant, survival rate, systematic review

Purpose: The purpose of this report was to evaluate data from published articles to determine the success and effectiveness of advanced bone grafting and dental implant therapy in alveolar cleft patients. Materials and Methods: A MEDLINE (PubMed) search was conducted of articles published in English without limits regarding year of publication. Bone grafting, implant survival and success rates, marginal bone resorption, esthetic outcomes, and patient satisfaction were evaluated. Screening of eligible studies, quality assessment, and data interpretation were conducted by two reviewers independently. Results: Seven retrospective and four prospective clinical studies were selected and analyzed. In all, 484 dental implants in 377 participants were investigated. The mean survival rate was 91.5% ± 4.77% with a mean follow-up of 54.3 ± 24.7 months. One hundred eleven of the 257 patients (43.1% ± 31.6%) with inadequate bone volume following initial bone grafting received secondary and/or tertiary bone grafting. The donor sites included the tibia, iliac crest, mandibular symphysis, and mandibular ramus. After dental implant placement, studies showed a difference in marginal bone loss around implants ranging from a mean of 0.28 mm with a 40-month follow-up to a mean of 3.5 mm with a 76-month follow-up. There were few data reporting the esthetic outcomes of implants; these focused on the loss of papillae and longer definitive restorations. Conclusion: Differing levels of evidence were available for clinical outcomes of dental implants in alveolar cleft patients. Treatment with dental implant therapy and bone grafting for patients with a history of alveolar clefts seems to be a predictable treatment option in the short term ( 5 years). However, more long-term (> 5 years) data for implant success rates and peri-implant clinical parameters are needed. Keywords: alveolar bone grafting, alveolar cleft, cleft lip and palate, dental implants, secondary alveolar bone grafting

Purpose: To compare the retentive properties of ball and locator attachments during 5,000 insertionseparation cycles, corresponding to approximately 4.5 years of clinical use. Materials and Methods: Four dental implants (diameter, 3.8 mm; length, 12 mm) were inserted into the prepared beds of two polyethylene blocks. Twenty acrylic prosthetic components were fabricated and connected to the ball and locator abutments. Tensile force was applied to the prosthetic components until the attachments were separated from the abutments. All samples were subjected to 5,000 insertion-separation cycles. Retention forces were measured after 10, 100, 200, 300, 400, 500, 1,000, 1,500, 2,000, 3,000, 4,000, and 5,000 insertion-separation cycles. Additionally, the wear of the attachments was measured using scanning electron microscopy. Data were analyzed to determine statistical equivalence among the two different attachments using the Student t test procedure and the Mann-Whitney U test procedure (α = .05). Results: Ball attachments showed significant retention loss after 100, 200, 400, 500, 1,500, and 4,000 cycles, and the locator attachments showed significant retention loss after 100, 200, 300, 500, and 3,000 cycles as compared with the previous cycle (P .05). Retention loss after 5,000 cycles was detected significantly more often for ball attachments than for locator attachments (P = .049). No significant difference was detected between the retention losses of the two attachment systems during the other cycles as compared with the initial retention values (P > .05). No significant difference was detected between the wear on the two attachment systems after 5,000 cycles (P > .05). Conclusion: Both attachment systems showed decreased retentive forces after 5,000 insertion-separation cycles. However, after 5,000 insertion-separation cycles, locator attachments showed better retentive properties than ball attachments. Keywords: edentulous mandible, implant, impression, overdenture

Purpose: The purpose of this experimental study was to analyze radiographically in a dog model how different implant-abutment interface configurations influence alveolar crestal bone changes. Materials and Methods: Six different experimental implant-abutment connections were evaluated in six mixed-breed dogs. The following parameters were tested: absence of microgap, microgap proximal to bone crest, and microgap distant from bone crest. In addition, two different cervical abutment profiles, one straight and one featuring a supracrestal concavity, were evaluated. Implants were based on a cylindrical full-body screw design and made from coldworked grade IV commercially pure titanium. The diameter (at thread tips) measured 4.1 mm, whereas the inner diameter was 3.5 mm. Standardized periapical digital radiographs were obtained for comparative analysis at baseline and at 3, 4, 5, 6, 7, 8, and 9 months after implant placement. Radiographs were randomized and calibrated for linear measurements. For statistical analysis, mixed-model repeated-measures analysis of variance was used. Results: All implants integrated successfully and remained stable during the entire period of the study. Radiographically, when comparing groups with straight profiles, crestal bone remodeling in group C (one-piece design) was significantly less than in group A (matching diameters) and B (nonmatching diameters). In fact, implant group C showed the least crestal bone remodeling of all groups. When comparing groups with a concave profile but different microgap configurations, all three designs demonstrated bone loss with no significant differences among the three groups. Conclusion: A nonsubmerged one-piece implant design demonstrated the least amount of bone remodeling of all groups. Implant-abutment connections with a concave profile established crestal bone levels immediately apical to the concavity regardless of the microgap variable. Keywords: alveolar bone loss/etiology, dental implants, horizontal offset, platform switching, supracrestal concavity

Purpose: To determine the thickness of the facial bone wall and the sagittal angulation between the long axis of the teeth and the long axis of the associated alveolar bone in the maxillary esthetic zone using cone beam computed tomography (CBCT). Materials and Methods: A retrospective radiographic study of CBCT images was conducted in 300 patients. The distance between the cementoenamel junction (CEJ) and the facial bone crest, the thickness of the facial bone wall (4 mm apical to the CEJ and midroot), and the sagittal angle between the long axis of teeth and the long axis of the respective alveolar bone were measured. Descriptive statistics and frequency analyses were performed. Results: The sample included 133 men and 167 women (mean age, 36.9 years; range, 18 to 60 years). The distance between the CEJ and the facial bone crest varied between 0.1 and 4 mm and showed an overall tendency to increase with age. Almost 80% of anterior teeth and 40% of premolars exhibited a thin facial bone wall ( 1 mm), and nearly 30% of sites had a bone wall thinner than 0.5 mm. The sagittal angle at approximately 80% of central incisor and second premolar sites was 20 degrees, but the angle at more than 40% of canine sites was ≥ 30 degrees. There was a significant decrease in facial bone wall thickness from premolars to anterior teeth. Conclusion: The facial bone wall in most maxillary anterior teeth was very thin. There was a substantial sagittal angulation between the long axes of teeth and those of their respective alveolar bone in most esthetic zone positions. CBCT analyses of the facial bone wall and the sagittal angle are recommended to ensure the most appropriate dental implant treatment approach. Keywords: bone wall, cone beam computed tomography, dental implant, esthetics, maxilla, root

Purpose: The aim of this study was to evaluate the treatment outcome of implants placed in the maxillary anterior segment. Materials and Methods: Patients were treated with bone-level implants (Straumann Bone Level Implant, Institut Straumann) that supported all-ceramic single crowns and were followed for 2 to 4 years. Titanium or ceramic abutments were used according to the quality of the soft tissue at each site. Esthetic parameters were recorded to assess treatment outcomes. Pink esthetic scores (PES) and white esthetic scores (WES) were used to evaluate the esthetic outcome of anterior single-tooth implant-supported crowns. Patient satisfaction was also evaluated by means of a questionnaire. Results: Fifty-five implants were placed in 47 patients. At the recall examinations, all implants were confirmed to have successfully integrated and demonstrated healthy peri-implant soft tissues, as documented by generally accepted clinical parameters. Overall, the esthetic results were considered favorable, and there were no significant differences between restorations with ceramic or titanium abutments. WES values were slightly superior to PES values. None of the implants had mucosal recession. Conclusion: Objective and subjective evaluation of maxillary bone-level implants in the esthetic zone yielded satisfactory results. Pleasing esthetic outcomes and stable facial soft tissues were achieved.

Purpose: This study investigated whether the nonincision placement of miniscrews could lead to ectopic implantation of epithelium at the bone-implant interface and, if so, whether the epithelial cells could survive. The fate of grafted epithelial cells was also investigated. Materials and Methods: Ten healthy male beagle dogs were included in the study and were divided into three groups. Group 1 dogs (n = 3) were implanted with miniscrews without any other procedures. In group 2, epithelial cells were collected, infected by adenoassociated virus-2 containing green fluorescent protein (GFP), and injected into pilot holes drilled before miniscrew implantation in three dogs, and one dog was injected with epithelial cells as a negative control. In group 3, tiny gingival tissue pieces were injected into pilot holes drilled before miniscrew implantation. In group 1, hematoxylin-eosin and fluorescent immunohistochemical (IHC) staining of cytokeratin were performed on both undecalcified and decalcified slices. In groups 2 and 3, IHC staining of cytokeratin and apoptotic testing were performed. Results: No ectopically implanted epithelial cells were found at the boneimplant interface of the miniscrews in group 1. In group 2, fluorescence emitted by cytokeratin antibody and by GFP was observed in specimens at 0 days, had decreased by 3 days, and had disappeared by 7 days. In group 3, areas of fluorescent cytokeratin-positive tissues were much smaller at 7 days than at 0 days, and none were found at 28 days. In groups 2 and 3, there were many apoptotic epithelial cells at the boneimplant interface at 3 days and 7 days, respectively. Conclusion: There was little possibility of implantation of epithelium into alveolar bone though placement of miniscrews with a nonincision procedure. Furthermore, even when epithelial cells or tissue was ectopically implanted, it was soon cleared through an apoptotic process. Keywords: epithelium implantation, miniscrew, nonincision placement

Purpose: The aim of this study was to analyze the histologic quality and histomorphometric quantity of newly formed bone and the biologic properties after maxillary sinus floor augmentation with biphasic tricalcium phosphate (BCP) prior to dental implant placement. Materials and Methods: The selected alloplastic bone substitute, a blend of 60% hydroxyapatite and 40% β-tricalcium phosphate, was placed into the sinus cavity and covered with a bioresorbable membrane. Ten bone samples were harvested from the grafted sinuses of eight patients at 6 months postsurgery for histologic and histomorphometric analysis during implant placement at stage-two surgery. Results: Histologic analysis of the 10 biopsy specimens showed remaining BCP particles in intimate contact with the newly formed bone. Several areas of bone substitute resorption and new bone remodeling were observed. The mean composition of the bone samples harvested from the grafted sinuses was 26.1% ± 6.3% newly formed bone, 29.3% ± 9.1% remaining BCP particles, and 44.7% ± 7.7% connective tissue/bone marrow. Conclusion: BCP biomaterial was osteoconductive and biocompatible. This biomaterial scaffold promoted the formation of new bone, which was in intimate contact with the remaining bone substitute particles. Within the limits of this study, maxillary sinus floor augmentation using BCP bone substitute is a reliable procedure for dental implant placement. Keywords: beta-tricalcium phosphate, bone substitute, histology, histomorphometry, hydroxyapatite, sinus floor augmentation

Purpose: The purpose of this study was to evaluate and compare Oral Health-Related Quality of Life (OHRQoL), denture satisfaction, and masticatory performance in edentulous patients provided with mandibular implantsupported overdentures (ISODs) retained with telescopic attachments and those of conventional complete dentures (CCDs). Peri-implant soft tissue changes were also evaluated at various intervals during a 1-year observation period. Materials and Methods: Participating patients received new CCDs and later received two mandibular interforaminal implants and had their mandibular CCDs converted into ISODs with telescopic attachments. Questionnaires were used to assess OHRQoL (Shortened Oral Health Impact Profile-14, Malaysian version) and denture satisfaction at different stages of treatment with CCDs and ISODs. Objective masticatory performance with the CCDs and ISODs was recorded with a mixing ability test. Evaluations were carried out at 3 months with the new CCDs, 3 months after mandibular ISOD provision, and 1 year after receiving the ISOD. Peri-implant parameters were additionally assessed at specific intervals during the treatment period. The data obtained were statistically analyzed and compared. Results: In the 17 patients who completed the protocol, significant improvements were observed in OHRQoL and patient satisfaction when CCDs were modified to ISODs, after 3 months, and at 1 year. Significantly better mixing ability with the ISOD was noted, with the highest values observed at 1 year. Statistically insignificant differences were observed for all the peri-implant parameters, except for gingival recession, for which significant changes were observed 6 months after ISOD delivery (values had stabilized by 1 year). Conclusion: Telescopic crown attachment-retained mandibular ISODs improved OHRQoL, dental prosthesis satisfaction, and masticatory performance compared to CCDs. Peri-implant soft tissue response and implant stability were found to be favorable after 1 year. Keywords: denture satisfaction, implant-supported overdentures, masticatory function, peri-implant parameters, quality of life, telescopic crown attachments

Purpose: The aim of this study was to evaluate marginal bone levels, with cone beam computed tomography, on the buccal and lingual aspects of implants placed with the implant-abutment interface (IAI) at different positions in relation to the alveolar crest. Materials and Methods: Thirty patients in need of single-tooth rehabilitation were randomly assigned to three groups based on the position of the IAI in relation to the buccal aspect of the alveolar crest at the time of implant placement. Patients in groups 0, 1, and 2 had their implants placed level with the buccal crest or 1 or 2 mm apical to the buccal aspect of the alveolar crest, respectively. The implants were restored with screw-retained single crowns after 4 months. Marginal bone levels on the buccal and lingual aspects of the implants were evaluated at 12 months after implant placement. Results: All groups of implants demonstrated significantly different crestal positions. Group 2 implants maintained the greatest subcrestal position (1.33 ± 0.86 mm) compared to the implants of group 0 (-0.04 ± 0.18 mm) and group 1 (0.34 ± 0.44 mm). There were no differences between groups in the level of the first bone-to-implant contact relative to the implant platform. Implants of group 0 exhibited less buccal bone remodeling (-0.08 ± 0.25 mm) compared to group 1 (-0.65 ± 0.45 mm) and group 2 (-0.85 ± 0.75 mm) implants. For groups 1 and 2 implants, there was a significant negative correlation between buccal wall thickness following the osteotomy and the amount of buccal bone remodeling. Conclusion: In this study, different responses were seen in the buccal and lingual peri-implant bone for implants with platformswitched Morse taper connections placed with the IAI at different locations in relation to the alveolar crest. Keywords: bone loss, clinical study, dental implants, prospective study, radiology, subcrestal osseointegration, titanium

Purpose: To present a new technique for sandwich osteoplasty in the posterior mandible and to evaluate its feasibility as part of dental implant treatment. Materials and Methods: A retrospective study of sandwich osteoplasty in the posterior mandible was conducted. No osteosynthetic material was used to stabilize the osteotomy. Fixation was achieved with the interposition of two bone blocks harvested from the retromolar region. Results: Eighteen patients with 26 sites of severe atrophy of the posterior mandible were treated. After a healing period of 4 months, 53 dental implants were inserted into the augmented region. The implants were loaded with single crowns or fixed dental prostheses 3 months after placement. The mean vertical bone gain after 4 months of healing was 4.2 mm (standard deviation 1.4 mm). The average bone loss between augmentation and implantation was 2.3 mm (35.4%). All implants osseointegrated and showed no clinical signs of peri-implantitis. In three subjects, the elevated bony segment perforated the lingual mucosa near the adjacent teeth after excessive elevation (> 6 mm) but healed without any sequelae. Conclusion: An alternative method for vertical alveolar ridge augmentation of the posterior mandible is presented. No osteosynthetic material is required for fixation, and related complications can be avoided. Further prospective clinical studies are required to demonstrate the feasibility of this technique versus the conventional sandwich osteoplasty. Keywords: dental implants, mandibular augmentation, sandwich osteoplasty, vertical ridge augmentation

Purpose: This study evaluated overdentures retained by mini-dental implants (MDIs) as a treatment option for complete edentulism during a 3-year follow-up period. Materials and Methods: This observational clinical study included completely edentulous patients who were treated with MDI-retained overdentures. The MDIs were supplied by the manufacturer. Results: Twenty-three patients received 7 maxillary and 16 mandibular MDI overdentures retained by 110 MDIs. Of the 36 MDIs placed in the maxilla, 8 failed (in two patients), 2 had compromised survival, 3 displayed satisfactory survival, and 23 were successful. Of the 74 MDIs placed in the mandible, 11 displayed satisfactory survival and 63 were successful. The marginal bone loss was more pronounced for the MDIs placed mesially (intercalated), in areas of decreased ridge width and bone density, and with lower values of insertion torque. The overdentures fractured in seven patients; in 4 of them, this corresponded to the implant housing area. Self-reported reasons for patient dissatisfaction included occasional pain under the overdenture (n = 5) and instability of the maxillary antagonist complete denture (n = 4). Conclusion: Based on this research, considering its limitations, it is possible to conclude that survival rates and health status are better for MDI overdentures applied in the mandible than for those applied in the maxilla. The most severe prosthetic complications encountered were overdenture base fracture, matrix detachment, and instability of the maxillary antagonist denture. Keywords: denture, edentulous, mini-dental implants, overdenture

Purpose: The aim of the study was to analyze the characteristics of implant dentistry claims in Italy based on insurance company technical reports for malpractice claims. Materials and Methods: One hundred twenty-one technical reports of cases of professional malpractice in implant dentistry between 2006 and 2010 were included in the study. Data included the sex and age of the patient and dentist, the kind of negligence claimed, and the damages awarded as a consequence of the alleged misconduct. Results: Of the cases examined in this study, 9.9% went to court. The patients were female in 73.6% of the cases. Most of the technical errors were committed during implant insertion (82.6%). In 50.4% of cases, the technical error involved the surrounding structures, such as damage to the inferior alveolar nerve (32.2%) or the lingual nerve (2.5%), invasion of the maxillary sinus (9.1%), or pulpal dental necrosis in adjacent teeth (6.6%). Incomplete clinical documentation was apparent in 54.5% of cases. In 9.9% of cases, a civil suit had already been filed before a visit, and medicolegal advice from the insurance expert had been procured. Conclusion: The discrepancy between the total number of cases examined and those that went to court indicates that implant malpractice claims in Italy are most often settled out of court. The large number of intraoperative errors seen and the high proportion of injuries to surrounding structures suggest that implant dentists would benefit from further specific training. Also, clinical documentation vital to a defense against any claims relating to professional misconduct was incomplete or absent in more than half of the cases. Keywords: dental insurance, implant dentistry, Italy, malpractice, negligence

Purpose: To quantify the cement remnants on titanium and zirconia abutment analogs after cement removal by resin and steel scalers. Materials and Methods: Defined areas of titanium or zirconia cylindric samples were covered with thin cement rings of zinc oxide phosphate (ZOP), glass ionomer (GIC), carboxylate (CAB), zinc oxide-eugenol (ZOE), or zinc oxide-eugenol-free (ZOEF). The cements were mixed with liquid-to-powder ratios of 50%, 75%, 100%, and 150% of powder. After setting and aging by thermocycling, each specimen was scaled by a blinded, trained clinician. Standardized digital photos of the scaled areas were analyzed according to a four-point classification scheme for remnants, and the results were analyzed statistically. Results: The main effects of the independent variables "cement type," "abutment material," and "scaler" showed statistically significant differences for all variables. Such differences were also found with regard to the interactions of the variables "cement type" and "material" as well as for the type of cement and scaler. The extent of remnants after scaling differed significantly between titanium and zirconia. Steel scalers achieved statistically significantly better cleaning than resin scalers. The powder-to-liquid ratio of all luting agents significantly influenced the extent of cement surplus after scaling. ZOEF was the only type of cement that could be more successfully removed from titanium than from zirconia. Conclusions: Nearly complete removal of ZOE could be achieved. This luting agent was not as sensitive to aberrant mixing ratios or to resin or steel scaling as the other types of cement. With the exception of ZOEF, zirconia surfaces were easier to clean. After removal of most of the remnant, some cements showed a barely visible thin greasy or powdery layer. Keywords: cement, cement remnant, luting agent, scaler, titanium, zirconia

Purpose: Narrow-diameter implants have become popular, as bone augmentation procedures can frequently be avoided. In order to provide implants with sufficient strength, a titanium-zirconium (Ti-Zr) alloy has recently been introduced purportedly showing improved mechanical properties as compared to commercially pure titanium (cpTi). This paper reports on the clinical and fractographic aspects of a fractured Ti-Zr implant, generally considered a rare event. Materials and Methods: A narrow-diameter Ti-Zr implant was placed in a patient aged 66 years in the area of the maxillary right canine and used to support a removable partial denture retained by cylindrical telescopic crowns placed on the implant and on the maxillary left canine. Eleven months after successful osseointegration, the patient presented with a horizontally fractured implant. The fractured part was retrieved for fractographic analysis. Results: The implant fractured just apical to the abutment screw, where the wall thickness of the implant is minimal. Scanning electron microscopy (SEM) analysis revealed the starting point of the fracture at the palatal aspect of the implant. No fatigue striations could be observed, indicating a brittle fracture atypical for Ti-based alloys. Conclusions: The fractographic observations correlate with the given loading situation, which is characterized by high levels of moment loading being imposed on the implant by a rigidly retained cantilever prosthesis. Mechanical overload going beyond the approved indications for Roxolid implants (Straumann) has to be seen as primary cause for this fracture. Keywords: implant fracture, fractography, Roxolid, telescopic crown

To successfully rehabilitate edentulous patients using endosseous implants, there must be enough available bone. Several techniques have been proposed for augmentation of sites with insufficient bone volume. Although autogenous bone has long been considered the gold standard for such procedures, the limited availability of graft material and a high morbidity rate are potential disadvantages of this type of graft. An alternative is to use recombinant human bone morphogenetic protein 2 (rhBMP-2), which is able to support bone regeneration in the oral environment. These cases demonstrate the applicability of rhBMP-2 in maxillary sinus elevation and augmentation procedures in the maxilla to enable dental implant placement. The use of rhBMP-2 in alveolar augmentation procedures had several clinical benefits for these patients. Keywords: bone regeneration, bone transplantation, oral surgery, recombinant human bone morphogenetic protein 2

Purpose: This study investigated the effect of the absence of estrogen on the process of implant osseointegration in the jaws of beagle dogs. Materials and Methods: Of eight beagle dogs, four underwent bilateral ovariectomy (OVX), and the other four constituted a control group. Twelve weeks postsurgery, XiVE implants (Dentsply) were placed in the second premolar site in the mandible and in the canine site in the maxilla. Zero, 4, 8, 12, and 16 weeks after implant placement, implant stability quotients (ISQs) were measured by resonance frequency analysis (RFA). Results: The blood estrogen levels 12 weeks postsurgery were 5.8 ± 1.8 pg/mL in the OVX group and 37.0 ± 2.9 pg/mL in the control group, which represents a significant decrease (P .01). The ISQ of maxillary implants in the OVX group 12 weeks after implant placement was 64.5 ± 1.7, and in the control group it was 74.3 ± 1.5; the ISQ was significantly reduced in the OVX group (.01 P .05). Conclusion: The results of this study indicate that the absence of estrogen induced by OVX in beagle dogs could reduce osseointegration around maxillary implants but has little influence in the mandible. Keywords: beagle dog, dental implants, estrogen deficiency, osseointegration, ovariectomy

Purpose: Autografts are considered to support bone regeneration. Paracrine factors released from cortical bone might contribute to the overall process of graft consolidation. The aim of this study was to characterize the paracrine factors by means of proteomic analysis. Materials and Methods: Bone-conditioned medium (BCM) was prepared from fresh bone chips of porcine mandibles and subjected to proteomic analysis. Proteins were categorized and clustered using the bioinformatic tools UNIPROT and PANTHER, respectively. Results: Proteomic analysis showed that BCM contains more than 150 proteins, of which 43 were categorized into "secreted" and "extracellular matrix." Growth factors that are not only detectable in BCM, but potentially also target cellular processes involved in bone regeneration, eg, pleiotrophin, galectin-1, transforming growth factor beta (TGF-β)-induced gene (TGFBI), lactotransferrin, insulin-like growth factor (IGF)-binding protein 5, latency-associated peptide forming a complex with TGF-β1, and TGF-β2, were discovered. Conclusion: The present results demonstrate that cortical bone chips release a large spectrum of proteins with the possibility of modulating cellular aspects of bone regeneration. The data provide the basis for future studies to understand how these paracrine factors may contribute to the complex process of graft consolidation. Keywords: autograft, bone regeneration, conditioned medium, paracrine, proteomics, secretome, supernatant