The International Journal of Oral & Maxillofacial Implants, 03/2014

Purpose: Because the maxilla and its alveolar process are prone to resorption after tooth loss, it is often necessary to perform a bone augmentation procedure to successfully carry out implant treatment in that region. The aim of this study was to determine the adhesive force between the sinus membrane and the osseous sinus floor that occurs during sinus floor elevation with a balloon lift system. Materials and Methods: Twenty-two ex vivo pig heads were used for this study. Access to the maxillary sinus was gained via the lateral sinus wall. Sinus elevation was performed using an inflatable balloon, which was consecutively filled with 3 mL of a radiopaque fluid. Pressure was monitored directly and continuously during the elevation procedure with an electronic pressure gauge. The integrity of the membrane was checked microscopically and macroscopically. Results: The average adhesion force of the sinus membrane was found to be 748 ± 65.56 mmHg. On microscopic and macroscopic inspection, no mucosal tearing occurred during sinus floor elevation. Underwood septa, when present, did not significantly influence the adhesion forces. Conclusions: The balloon system allowed for reproducible real-time measurement of the elevation forces and soft tissue resilience of the sinus membrane during the elevation process in this animal model. No mucosal ruptures were caused with this technical setup, in which effective elevation pressure ranging from 660 to 880 mmHg was not exceeded. A possible transfer of this technical setup to clinical procedures in humans requires investigation. Keywords: balloon lift, elevation forces, resilience, sinus floor elevation, sinus membrane

Purpose: The objectives of this study were to systematically review the literature regarding sinus floor elevation using osteotomes with respect to the timing of implant placement, implant characteristics, grafting materials, and intraoperative and postoperative complications and to perform a meta-analysis to determine the influence of initial residual bone height (RBH) on implant success. Materials and Methods: A systematic search of articles was conducted on MEDLINE and manually to identify studies of sinus floor elevation using osteotomes. Strict inclusion criteria were applied. The mean observation period was ≥ 1 year after functional loading of implants. The quality of the included papers was assessed using the Newcastle-Ottawa Scale for observational studies and the PEDro Scale for randomized clinical trials, and the heterogeneity of the papers included in the meta-analysis was evaluated. The statistical accuracy was tested using the Cochran C test, and the relationship between initial RBH and implant success was analyzed using the Student t test Welch variant. Results: Twenty-five studies published over a period of 13 years met the inclusion criteria; 15 were retrospective, 9 were prospective, and 1 was a randomized controlled trial. The included articles comprised 3,092 inserted implants with a failure rate of 3.85%. Of the 25 included studies, 8 were selected for the meta-analysis. RBH > 4 mm did not influence implant success/failure; however, there was a significant difference between the success/failure rates of implants, inserted in combination with sinus floor elevation using osteotomes, when the initial RBH was 4 mm. Conclusion: Initial RBH of less than 4 mm influenced the success rates of implants inserted in combination with sinus floor elevation using osteotomes. Keywords: bone height, complications, dental implants, implant success, meta-analysis, osteotome technique, sinus floor elevation, systematic review

Purpose: The purpose of this study was to compare the three-dimensional accuracy of indirect plastic impression copings and direct implant-level impression copings from three implant systems (Nobel Biocare [NB], Biomet 3i [3i], and Straumann [STR]) at three interimplant buccolingual angulations (0, 8, and 15 degrees). Materials and Methods: Two-implant master models were used to simulate a three-unit implant fixed partial denture. Test models were made from Impregum impressions using direct implant-level impression copings (DR). Abutments were then connected to the master models for impressions using the plastic impression copings (INDR) at three different angulations for a total of 18 test groups (n = 5 in each group). A coordinate measuring machine was used to measure linear distortions, three-dimensional (3D) distortions, angular distortions, and absolute angular distortions between the master and test models. Results: Three-way analysis of variance showed that the implant system had a significant effect on 3D distortions and absolute angular distortions in the x- and y-axes. Interimplant angulation had a significant effect on 3D distortions and absolute angular distortions in the y-axis. Impression technique had a significant effect on absolute angular distortions in the y-axis. With DR, the NB and 3i systems were not significantly different. With INDR, 3i appeared to have less distortion than the other systems. Interimplant angulations did not significantly affect the accuracy of NBDR, 3iINDR, and STRINDR. The accuracy of INDR and DR was comparable at all interimplant angulations for 3i and STR. For NB, INDR was comparable to DR at 0 and 8 degrees but was less accurate at 15 degrees. Conclusions: Three-dimensional accuracy of implant impressions varied with implant system, interimplant angulation, and impression technique. Keywords: accuracy, implant impression, plastic coping, three-dimensional

Purpose: To evaluate and compare the reliability of implant-supported single crowns cemented onto abutments retained with coated (C) or noncoated (NC) screws and onto platform-switched abutments with coated screws. Materials and Methods: Fifty-four implants (DT Implant 4-mm Standard Platform, Intra-Lock International) were divided into three groups (n = 18 each) as follows: matching-platform abutments secured with noncoated abutment screws (MNC); matching-platform abutments tightened with coated abutment screws (MC); and switched-platform abutments secured with coated abutment screws (SC). Screws were characterized by scanning electron microscopy and x-ray photoelectron spectroscopy (XPS). The specimens were subjected to step-stress accelerated life testing. Use-level probability Weibull curves and reliability for 100,000 cycles at 200 N and 300 N (90% two-sided confidence intervals) were calculated. Polarized light and scanning electron microscopes were used for fractographic analysis. Results: Scanning electron microscopy revealed differences in surface texture; noncoated screws presented the typical machining grooves texture, whereas coated screws presented a plastically deformed surface layer. XPS revealed the same base components for both screws, with the exception of higher degrees of silicon in the SiO2 form for the coated samples. For 100,000 cycles at 300 N, reliability values were 0.06 (0.01 to 0.16), 0.25 (0.09 to 0.45), and 0.25 (0.08 to 0.45), for MNC, MC, and SC, respectively. The most common failure mechanism for MNC was fracture of the abutment screw, followed by bending, or its fracture, along with fracture of the abutment or implant. Coated abutment screws most commonly fractured along with the abutment, irrespective of abutment type. Conclusion: Reliability was higher for both groups with the coated screw than with the uncoated screw. Failure modes differed between coated and uncoated groups. Keywords: abutment screw, biomechanics, dental implants, reliability, Weibull curves

Purpose: To compare linear measurements made on cone beam computed tomography (CBCT) images to direct measurements in ex vivo porcine mandibles. Materials and Methods: Six cross-sectional planes were defined by gutta-percha-filled cavities in seven mandibles. The mandibles were scanned in a CBCT apparatus and later sectioned, using a band saw, through the gutta-percha markers. Next, four direct (DIR) linear measurements were performed for each section with a handheld digital caliper, using the guttapercha markers as reference points. The corresponding radiographic (RAD) cross sections were then measured using dedicated software. A total of 168 sites were measured. Differences between RAD and DIR measurements [Δ(RAD - DIR)] were calculated for each pair individually. Results: Mean Δ(RAD - DIR) was -0.17 ± 0.53 mm (range, -1.42 to 1.09 mm). CBCT overestimated direct measurements at 36% of the sites; 8% of sites (95% confidence interval, 3.8% to 12.2%) showed errors between +0.5 and +1 mm, and 1.8% (95% confidence interval, -0.2% to 3.9%) showed errors greater than +1 mm. Conclusions: Good correlation was found between CBCT and direct measurements. However, the significant percentage of sites with overestimation of at least 0.5 mm indicates a need for safety margins to be maintained when CBCT is used to plan surgical interventions such as dental implant therapy. Keywords: accuracy, cone beam computed tomography, dental implants, dimensional measurement, ex vivo

Purpose: This study assessed the cost-effectiveness from a societal perspective of a dental implant compared with a three-unit tooth-supported fixed partial denture (FPD) for the replacement of a single tooth in 2010. Materials and Methods: A decision tree was developed to estimate cost-effectiveness over a 10-year period. The survival rates of single-tooth implants and FPDs were extracted from a meta-analysis of single-arm studies. Medical costs included initial treatment costs, maintenance costs, and costs to treat complications. Patient surveys were used to obtain the costs of the initial single-tooth implant or FPD. Maintenance costs and costs to treat complications were based on surveys of seven clinical experts at dental clinics or hospitals. Transportation costs were calculated based on the number of visits for implant or FPD treatment. Patient time costs were estimated using the number of visits and time required, hourly wage, and employment rate. Future costs were discounted by 5% to convert to present values. Results: The results of a 10-year period model showed that a single dental implant cost US $261 (clinic) to $342 (hospital) more than an FPD and had an average survival rate that was 10.4% higher. The incremental cost-effectiveness ratio was $2,514 in a clinic and $3,290 in a hospital for a prosthesis in situ for 10 years. The sensitivity analysis showed that initial treatment costs and survival rate influenced the cost-effectiveness. If the cost of an implant were reduced to 80% of the current cost, the implant would become the dominant intervention. Conclusion: Although the level of evidence for effectiveness is low, and some aspects of single-tooth implants or FPDs, such as satisfaction, were not considered, this study will help patients requiring single-tooth replacement to choose the best treatment option. Keywords: cost-effectiveness analysis, dental implant, economic evaluation, partial denture, single-tooth loss

Purpose: The objective of this study was to review all biomechanical investigations that have evaluated the implications of implant framework misfit with fixed prostheses. Materials and Methods: A detailed electronic search was conducted of PubMed (MEDLINE), Google Scholar, and Cochrane Library with the aid of Boolean operators to combine relevant key words. The search was confined to articles published in English through April 2013. The literature search was enlarged by manual searches of the peer-reviewed literature and the reference lists of the selected articles. Results: A total of 633 articles were retrieved from the initial search; however, only 28 articles met the determined inclusion criteria of the review. According to the study design, the selected articles were classified into two categories: laboratory studies (finite element analyses, actual model analyses, and screw stability analyses) and animal studies. The studies evaluated the effects of alterations in the magnitude and configuration of misfit, framework rigidity, type of retaining screws, and implant loading time. In addition to a lack of clear criteria of what constitutes an accurate implant framework fit, the biomechanical implications of framework misfit are unclear. Conclusions: Although implant framework misfit alters the biomechanical situation, negative biomechanical sequelae could not be confirmed from the included studies. Biologically, bone resorption cannot develop as a result of framework misfit. From a mechanical perspective, the framework stresses and screw stresses and instability increase with misfit, but the clinical significance of this remains unclear. Keywords: biologic complications, framework fit, mechanical complications, stress, strain

Purpose: To assess the relationship between mandibular cortical bone status as determined with panoramic radiography and insertion torque (IT) in implant treatment. Materials and Methods: Using panoramic radiographs, two dental radiologists assessed patients' mandibular cortical bone status and classified them into two groups-normal or abnormal (mildly, moderately, or severely resorbed)-based on morphologic features of the mandibular cortical bone margins. Kappa coefficients between the two dental radiologists were calculated to determine interexaminer variability. Included patients underwent implant placement and surgery, during which IT was measured. Patients were classified into three groups based on these measurements: 15 Ncm or lower, between 15 and 35 Ncm, and 35 Ncm or higher. Correlations between mandibular cortical bone morphology and measured IT were assessed and analyzed statistically. Results: Ninety-six patients (34 men, 62 women; mean age 59.1 years) were included in this study; 73 (76.0%) displayed a normal cortex and 23 (24.0%) had an abnormal cortex. In patients with a normal cortex, 13 (8.6%) had IT measurements of 15 Ncm or lower, 42 (27.6%) between 15 and 35 Ncm, and 97 (63.8%) of 35 Ncm or higher. In patients with an abnormal cortex, 3 (4.9%) had IT of 15 Ncm or lower, 35 (57.4%) between 15 and 35 Ncm, and 23 (37.7%) of 35 Ncm or higher. IT values were significantly lower in patients with an abnormal cortex compared to those with a normal cortex. A significant correlation between morphology of the mandibular cortex and IT was observed. Conclusion: The mandibular cortical bone status assessed on panoramic radiographs correlates with implant IT, suggesting that panoramic radiographs may be used effectively to determine bone density before implant treatment. Keywords: bone mineral density, image evaluation, insertion torque, panoramic radiography, primary stability

Purpose: The aim of this study was to suggest a clinical guideline to properly position immediate implant placement in the anterior maxillary area. Materials and Methods: The computed tomography (CT) records of 250 patients (125 males, 125 females; mean age 49.5 years) were evaluated, and the relationship of the sagittal root positions of the maxillary central incisor teeth to their respective alveolar bony housing was classified as buccal (B), medial (M), or palatal (P). Then, the clinical guideline was suggested based on the implications derived from the classification. In the second investigation, the validity of the clinical guideline was confirmed by CT analysis. First, a reference line was defined using soft tissue landmarks. Then, a virtual rectangle representing the dental implant was created and merged on the CT image, symbolizing the space where the dental implant would be positioned. The rectangular frame was positioned on the image in accordance with the guideline. The frame on the image was thoroughly assessed to detect the possibility of perforation of the labial plate. The location of the initial drilling access on the respective crown was determined by extending the longitudinal axis of the frame in a coronal direction. Results: Of the 250 samples, 94.0% were classified as type B. Type M and P represented 5.6% and 0.4% of the samples, respectively. In 82.0% of the samples, the frame was safely positioned, not contacting the labial or palatal cortical plate in the alveolar bony housing. Moreover, when a frame representing a tapered implant form with an apical diameter of 3.5 mm was applied, 98.8% of samples were positioned safely in the alveolar bony housing. The longitudinal axis of the frame crossed the respective crown at the incisal tip in 54.4% of the cases. It crossed the labial side of the crown and cingulum of the crown in 42.0% and 3.6% of the cases, respectively. Conclusions: The root of the maxillary central incisor teeth tended to be positioning labially in the alveolar bony housing. The result of the CT analysis confirms the clinical guideline as a dependable clinical reference in immediate implant placement. Keywords: clinical guideline, computed tomography, immediate implant, maxillary central incisor, sagittal root positions

Purpose: This prospective study aimed to examine postoperative dimensional changes in the buccal bone and mucosa around single-stage implants placed in the posterior region. Materials and Methods: The dimensions of peri-implant tissue around screw-type implants placed in the posterior region were examined at surgery (baseline) and 6 months and 1 year after surgery. The lateral contour of the buccal bone and mucosa was horizontally measured at five vertical heights at 1-mm intervals (+1 to -3 mm from the implant platform) using custom-designed instruments. Bone resorption on the proximal sides was assessed on radiographs. Mucosal recession was measured on plaster casts of the dentition. Results: Sixty-six implants placed in 30 patients were examined. All implants were clinically osseointegrated and stable throughout the study period. The buccal bone exhibited horizontal resorption throughout the study period, even at the most apical height measured. Assessed at each height, thicker bone (> 2 mm thick) tended to exhibit horizontal resorption during the first 6 months after surgery. However, the bone resorbed horizontally by approximately 0.4 mm during the final 6 months, irrespective of its contour. Vertical resorption of the buccal marginal bone was approximately 1 mm during the period from 6 months to 1 year. The bone-retaining group at the 1-year time point was found to have thicker bone walls at baseline compared with the bone-loss group. The thickness of the buccal mucosa showed little change. There was no obvious correlation between buccal bone resorption and mucosal recession. Conclusions: The buccal bone exhibited both horizontal and vertical resorption over the year after surgery. The initial contour of the bone was significantly associated with bone retention or loss at 1 year. However, mucosal recession was not directly affected by buccal bone resorption. Keywords: buccal bone resorption, dental implants, mucosal recession, prospective study

Purpose: Immediate loading of implants in the edentulous maxilla has previously been successfully performed and reported. Severe resorption of the maxillary alveolar crest presents a more demanding situation for the restorative team. Thus, it would be valuable to assess outcomes for this immediate loading treatment protocol in subjects with marked maxillary alveolar crest atrophy. This study evaluated the 3-year results of dental implants that were immediately restored with provisional fixed prostheses in atrophic maxillae without previous augmentation. Materials and Methods: Two centers enrolled subjects with resorbed edentulous maxillae (Lekholm and Zarb quality 3 or 4 and quantity C, D, or E). Six implants were placed in each subject and restored with screw-retained fixed provisionals within 24 hours. Impressions were taken for definitive restorations, which were placed 20 to 24 weeks later. Radiographs were used to analyze marginal bone level changes throughout the study. Results: Fifty-one patients received 306 implants. Forty-five patients remained in the study at the 3-year follow-up visit and successfully used their definitive prostheses. Sixtytwo percent of the implants were placed in bone quantity C and quality 3 or 4, and 38% were placed in quantity D and quality 3 or 4 bone. Thirteen implants in six subjects were lost, resulting in a cumulative survival rate of 96% after 3 years. The mean marginal bone loss during the first year was -0.4 ± 0.8 mm (255 implants); at 3 years it was -0.6 ± 1.1 mm (253 implants). Conclusion: Data from the first 3 years of this study revealed good clinical outcomes. Careful selection of patients and planning by the restorative team can enable successful treatment outcomes for patients presenting with marked resorption of the edentulous maxilla. Keywords: atrophic maxilla, dental implants, edentulous maxilla, immediate loading

Purpose: The purpose of this study was to identify retrospectively the predictors of implant survival when the flapless protocol was used in two private dental practices. Materials and Methods: The collected data were initially computer searched to identify the patients; later, a hand search of patient records was carried out to identify all flapless implants consecutively inserted over the last 10 years. The demographic information gathered on statistical predictors included age, sex, periodontal and peri-implantitis status, smoking, details of implants inserted, implant locations, placement time after extraction, use of simultaneous guided hard and soft tissue regeneration procedures, loading protocols, type of prosthesis, and treatment outcomes (implant survival and complications). Excluded were any implants that required flaps or simultaneous guided hard and soft tissue regeneration procedures, and implants narrower than 3.25 mm. Results: A total of 1,241 implants had been placed in 472 patients. Life table analysis indicated cumulative 5-year and 10-year implant survival rates of 97.9% and 96.5%, respectively. Most of the failed implants occurred in the posterior maxilla (54%) in type 4 bone (74.0%), and 55.0% of failed implants had been placed in smokers. Conclusion: Flapless dental implant surgery can yield an implant survival rate comparable to that reported in other studies using traditional flap techniques. Keywords: dental implants, flapless technique, implant dentistry, implant survival, outcomes

Purpose: To retrospectively compare the outcomes of implants placed in posterior mandibles vertically regenerated with onlay autogenous block bone grafts and short dental implants. Materials and Methods: Consecutive patients with vertical bone atrophy in edentulous mandibular posterior regions (7 to 8 mm of bone above the inferior alveolar nerve) were treated with either implants placed in regenerated bone using autologous block bone grafts (group 1) or short implants (with 5.5-mm intrabony length) in native bone (group 2) between 2005 and 2010 and followed for 12 months after loading. The procedure used was the established treatment protocol for this type of patient at the Oral Surgery Unit (University of Valencia, Spain) at the time of surgery. All grafts were obtained using piezosurgery. The outcomes assessed were: complications related to the procedure, implant survival, implant success, and peri-implant marginal bone loss. Statistical analysis was done using the Fisher exact test and the Mann-Whitney test. Results: Thirtyseven patients were included, 20 (45 implants) in group 1 and 17 (35 implants) in group 2. In group 1, 13 implants were less than 10 mm long (2 were 7 mm and 11 were 8.5 mm), and 32 were 10 mm or longer; the diameter was 3.6 mm in 6 implants, 4.2 mm in 31, and 5.5 mm in 8. In group 2 all implants were 7 mm long; the diameter measured 4.2 mm in 14 implants and 5.5 mm in 21 implants. Complications related to the block bone grafting procedure were temporary hypoesthesia in one patient, wound dehiscence with graft exposure in three patients, and exposure of the osteosynthesis screw without bone graft exposure in one patient. After 12 months, implant survival rates were 95.6% in group 1 and 97.1 % in group 2; success rates were 91.1% and 97.1%, respectively. The average marginal bone loss was 0.7 ± 1.1 mm in group 1 and 0.6 ± 0.3 mm in group 2. Conclusions: When residual bone height over the mandibular canal is between 7 and 8 mm, short implants (with 5.5-mm intrabony length) might be a preferable treatment option over vertical augmentation, reducing chair time, expense, and morbidity. Keywords: atrophied mandible, block bone graft, short dental implants

Purpose: The study evaluated the diagnostic performance of computed tomography (CT) bone density measurements (in Hounsfield units [HU]) in assessing the osteoporotic status of edentulous subjects (21 men, 40 women) scheduled to receive mandibular implant-supported overdentures. Materials and Methods: Density (in HU) of 61 left and 61 right mandibular canine sites was measured. Each subject was also subject to body bone mineral density measurements (dual-energy x-ray absorptiometry). Bone density T-score values of total hip, femoral neck, spine (L1 to L4), and total body were assessed. Pearson correlations were conducted between HU of each mandibular bone site and the subject's T-score values. Sensitivity/specificity and receiver operating characteristic curve analyses were used to assess the diagnostic performance of HU in detecting subjects who were, based on each of the four T-scores: (1) "not osteonormal", ie, with a T-score at or below -1.0; or (2) osteoporotic, ie, with a T-score at or below -2.5. Results: HU measurements of mandibular bone sites were found to have modest but significant correlations with each bone density T-score value (total hip, femoral neck, spine, total body). CT mandibular site HU measurement has diagnostic value in detecting a "not osteonormal" condition when total hip, spine, or total body T-scores were used, but not when femoral neck T-score was used. Conclusions: Based on the limited sample size, optimal HU cutoff values of ~530, ~600, and ~640 HU for total hip, spine, or total body T-scores, respectively, were proposed. CT mandibular site HU measurement had diagnostic value in detecting osteoporosis when spine T-score was used but not when total hip, femoral neck, and total body T-scores were used. An optimal HU cutoff value of ~460 HU for spine T-score was proposed. Keywords: bone density, computed tomography, dental implant, dual-energy x-ray absorptiometry, Hounsfield unit, osteoporosis

Purpose: To assess the response of soft tissues around two different abutment designs in healed sites in the esthetic zone. Materials and Methods: Twenty-six subjects received two endosseous implants in healed, bilateral implant sites in the esthetic zone in the maxilla or the mandible. After 17 to 19 weeks and left/ right randomization, the implants were restored with either a conventional (control) or curved (experimental) titanium abutment and a provisional crown. Eight weeks after abutment placement, definitive crowns were cemented (T0). Soft tissue development was assessed based on peri-implant bone loss, Pink Esthetic Score (PES), and probing depths immediately after placement of the definitive crown and after 1 year (T12) and compared between sites. Possible confounding variables (abutment angle, plaque presence, gingival bleeding, width of attached mucosa) were also documented at T0 and T12. Results: The mean peri-implant marginal bone loss from T0 to T12 was 0.00 ± 0.37 mm in the experimental group and 0.12 ± 0.27 mm in the control group. Differences were not statistically significant (P = .25). At T12, the curved abutment scored a mean PES of 10 ± 2.3 and the straight abutment scored 9.7 ± 2.3. The difference was not significant (P = .46). Probing depths were also not significantly different between the two groups (P = .85). Correlation and regression analysis showed no hints of predictive behavior for the possible confounding variables. Conclusion: A titanium abutment with a circumferential curved design is of no additional benefit to soft tissue development and preservation of marginal bone compared to a conventional straight abutment design for the restoration of single-tooth implants in the esthetic zone. Keywords: abutment design, clinical study, esthetic zone, peri-implant bone loss, randomized clinical trial, soft tissue response

Purpose: To determine the effect of crown height space, crown-to-implant ratio, and offset placement of a prosthesis on implant survival, crestal bone loss, and prosthetic complications; and to determine whether detrimental values for crown height space and crown-to-implant ratio exist for implant-supported restorations. Materials and Methods: Extra-short implants (length ≤ 6.5 mm) supporting a fixed denture in the posterior mandible and followed for at least 12 months were analyzed. Radiographic and clinical examinations were conducted to retrieve data about patients' dental and medical history, prosthetic complications, antagonist type, crown height space, crown-to-implant ratio, offset placement of the prosthesis, crestal bone loss, and implant failure. Results: Thirty-four patients (mean age, 60 ± 10 years) with 45 extra-short implants participated in this study. Patients were followed for up to 4 years (mean, 2 years) and no implants were lost. The mean crown-to-implant ratio was 2.4 (range, 1.5 to 3.69). Mean crown height space was 17.05 ± 3.05 mm, and 65.4% of the implants had a crown height space in the range of 15 to 20 mm. About 90% of the implants had a distal or mesial offset placement greater than 1 mm. The type of antagonist significantly affected marginal bone loss around extra-short implants: bone loss was greatest for implants opposing a partial denture (mean, 1.28 ± 1.09 mm) and was lower for implants opposing a natural dentition (mean, 0.73 ± 0.60 mm) or a complete denture (mean, 0.89 ± 0.60 mm). Analysis of marginal bone loss and the factors crown-to-implant ratio, crown height space, and offset placement according to antagonist dentition indicated a significant positive correlation only between bone loss and crown height space. Conclusions: When an increased crown-to-implant ratio is present, crown height space may influence crestal bone loss more significantly. Keywords: biomechanics, bone loss, crown height space, crown-to-implant ratio, short implants

Purpose: To compare patient satisfaction and postoperative pain and swelling for immediate versus conventional loading in partially edentulous patients requiring extraction of the remaining maxillary dentition and rehabilitation with fixed full-arch prostheses. Materials and Methods: This prospective, controlled, nonrandomized study with 12-month follow-up included 30 consecutive patients scheduled for fixed full-arch implant-supported maxillary rehabilitation. Fifteen patients were treated with conventional loading (control group) and the next 15 with immediate loading (test group). Ten-centimeter visual analog scales were used as assessment tools. Patient overall satisfaction and specific satisfaction with esthetics, chewing, speaking, comfort, self-esteem, ease of cleaning, and treatment duration were assessed preoperatively and at 3 and 12 months postoperatively. Postoperative pain and swelling levels were recorded daily during the first week. Statistical analysis was performed using Mann-Whitney and Wilcoxon rank sum tests, α = .05. Results: One test group patient was excluded, so the final sample included 29 patients. Between baseline and 3 months, in the test group general satisfaction and all specific satisfactions increased significantly with the exception of speech; in the control group overall satisfaction and self-esteem did not change, satisfaction with esthetics increased significantly, and satisfaction with speech, chewing, and comfort decreased significantly. After 12 months, satisfaction was significantly higher in the test group with the exception of ease of cleaning. Between 3 and 12 months, satisfaction improved in both groups but to a greater degree in the control group. After 12 months, there were no differences in satisfaction. No differences were found in either mean postoperative pain/swelling or maximum pain/swelling at the studied time points. Conclusions: Patient satisfaction for immediate loading was significantly higher than for conventional loading during the osseointegration period. After 12 months, when final prosthetic rehabilitations had been in function for some time, differences had disappeared. No differences were found between loading protocols in postoperative pain or swelling. Keywords: immediate dental implant loading, loading protocols, patient outcomes assessment, patient satisfaction

Purpose: The aim of this clinical study was to assess horizontal width changes in grafted and ungrafted sites after bone expansion and implant placement. Materials and Methods: Twenty-three patients were included in this prospective study. Each patient required extraction of two teeth and replacement with implants. After dental extraction in 23 alveoli (group 1), a collagen sponge was used to cover fresh sockets, and the remaining 23 alveoli (group 2) were grafted with corticocancellous porcine bone. Three months after extraction, bone expansion was performed in each site, and 46 dental implants were placed. To evaluate tissue volume changes, the variations in width of the buccal ridge were recorded with a periodontal probe immediately after tooth extraction, 3 months later (before implant placement), and 3 months after implant placement. Results: In group 1, at 3 months after implant placement, mean volume changes of +1.6 ± 0.8 mm for incisors and canines, +1.4 ± 0.5 mm for premolars, and +0.8 ± 0.5 mm for molars were seen. In group 2, mean changes of +1.5 ± 0.8 mm for incisors and canines, +1.3 ± 0.3 mm for premolars, and +2.8 ± 0.6 mm for molars were observed. Statistically significant differences were found only for molars. Conclusions: In both groups, incisor, canine, and premolar sites showed no differences in volume changes, but statistically significant differences were found between molars in the two groups; the biomaterial graft prevented collapse of the large defects and significant volume loss. Keywords: biomaterial, bone remodeling, fresh socket

Purpose: The aim of this paper is to present a large-scale long-term follow-up of dental implants placed simultaneously with nasal floor augmentation using osteoconductive bovine bone substitutes. Materials and Methods: Patients who received dental implants combined with nasal floor elevation in three dental centers between 2006 and 2012 were included in this report. Preoperative available bone height was measured on computed tomographic scans. Implant parameters as well as implant survival rates were recorded. The cohort consisted of long-term follow-up of this previously reported cohort, combined with a cohort of newly treated patients. Results: Overall, 67 patients were included in this study. Cigarette smoking was reported by 16 patients. Two hundred three implants were inserted in combination with nasal floor elevation. No nasal mucosa perforations were observed. The mean follow-up periods were 65.93 ± 13.2 months (range, 33 to 86 months) for the original cohort and 23.14 ± 9.4 months (range, 7 to 44 months) for the newly treated patients. The available bone height prior to bone augmentation was 8.89 ± 1.1 mm (range, 5 to 11.2 mm) and a mean of 3.65 ± 0.9 mm (range, 1.1 to 7 mm) of additional height was achieved with nasal floor elevation. During the follow-up period, no implants were lost, resulting in a 100% survival rate. Conclusion: Nasal floor augmentation, as shown in this report, might serve as a reliable method for reconstruction of the anterior atrophic maxilla when residual height is insufficient. Keywords: alveolar bone, anterior teeth, bone augmentation, dental implants, maxilla, success, survival

Purpose: This 5-year prospective multicenter study compared implant survival and success, peri-implant health and soft tissue responses, crestal bone level stability, and complication rates following immediate loading of single OsseoSpeed implants placed in anterior maxillary healed ridges or extraction sockets. Materials and Methods: Individuals requiring anterior tooth replacement with single implants were treated and immediately provisionalized. Definitive all-ceramic crowns were placed at 12 weeks. Implant survival, bone levels, soft tissue levels, and peri-implant health were monitored for 5 years. Results: One hundred thirteen patients received implants in fresh sockets (55) and healed ridges (58). After 5 years, 45 and 49 patients remained for evaluation, respectively. During the first year, three implants failed in the extraction socket group (94.6% survival) and one implant failed in the healed ridge group (98.3% survival); this difference was not significant. No further implant failures were recorded. After 5 years, the interproximal crestal bone levels were located a mean of 0.43 ± 0.63 mm and 0.38 ± 0.62 mm from the reference points of implants in sockets and healed ridges (not a significant difference). In both groups, papillae increased over time and peri-implant mucosal zenith positions were stable from the time of definitive crown placement in sockets and healed ridges. Compared to flap surgery for implants in healed ridges, flapless surgery resulted in increased peri-implant mucosal tissue dimension (average, 0.78 ± 1.34 mm vs 0.19 ± 0.79 mm). Conclusion: After 5 years, the bone and soft tissue parameters that characterize implant success and contribute to dental implant esthetics were similar following the immediate provisionalization of implants in sockets and healed ridges. The overall tissue responses and reported implant survival support the immediate provisionalization of dental implants in situations involving healed ridges and, under ideal circumstances, extraction sockets. Keywords: dental implants, extraction socket, immediate loading, marginal bone level, soft tissue

Purpose: To analyze the frequency of perforation of the sinus membrane during maxillary sinus floor elevation (SFE) and to assess possible risk factors. Materials and Methods: Seventy-seven cases of SFE performed with a lateral window approach were evaluated retrospectively. Clinical and radiographic variables potentially influencing the risk of sinus membrane perforation were evaluated and divided into patient-related factors (age, sex, smoking habit); surgery-related factors (type of surgical approach, side, units, sites, and technique of osteotomy); and maxillary sinus-related factors (presence and height of septum, height of residual ridge, thickness of lateral sinus wall, width of antrum, and thickness and status of sinus membrane). Results: The following factors presented with at least a 10% difference in rates of perforations: smokers (46.2%) versus nonsmokers (23.4%), simultaneous (32%) versus staged (18.5%) approach, mixed premolar-molar sites (41.2%) versus premolar-only sites (16.7%) versus molar-only sites (26.2%), presence of septa (42.9%) versus no septa (23.8%), and minimum height of residual ridge ≤ 4 mm (34.2%) versus > 4 mm (20.5%). These same parameters, except minimum height of residual ridge, also showed an odds ratio above 2. However, none of the comparisons reached statistical significance. Conclusion: The present study failed to demonstrate any factor that statistically significantly increased the risk of sinus membrane perforation during SFE using the lateral window approach. Keywords: radiographic analysis, retrospective study, risk factors, sinus floor elevation, sinus membrane

Purpose: The purpose of the study was the evaluation of possible cytologic effects of taurolidine to fibroblasts and osteoblast-like cells. Materials and Methods: Human gingival fibroblasts and SaOS-2 cells were seeded on samples with sand-blasted and acid-etched surfaces. Both groups were treated with taurolidine, chlorhexidine, and pure water with three different treatment times. Three dates of measurements were set to evaluate cell viability, cytotoxicity, and apoptosis. Results: Highest cytotoxicity was measured in both cell lines in the groups treated with chlorhexidine, while cell viability was lower than in the corresponding taurolidine and pure water groups; on days 3 and 6 these differences were significant. Taurolidine showed similar results to the pure water groups. Conclusion: The results of this study indicate that taurolidine is biocompatible and gentle to the tested human cells for the application time of a mouthrinse. Keywords: peri-implantitis, cell culture, antiseptic treatment

Purpose: A low direct current can be used to disinfect dental titanium implants in simulated physiologic environments. The aim of this study was to determine whether this treatment affects implant surface structure and cytocompatibility. Materials and Methods: Titanium test disks with a sandblasted, acidetched, large-grit (SLA) surface were placed as anodes in an electrolytic bath with physiologic saline and treated with 15 mA of current for 15 minutes. Surfaces were analyzed by light and electron microscopy and contact angle measurement. Depth profile analyses of SLA disks were run at subsurface levels from 0 to 1,000 nm. The proliferation and viability of preosteoblastic cells and human foreskin fibroblasts on implant surfaces were assessed. Alkaline phosphatase (ALP) activity was determined with and without exposure to bone morphogenetic protein-2 (BMP-2). Mineralization was determined after 4 weeks. Results: A blue discoloration was observed after treating the SLA disks, but no damage was recognized microscopically. An oxidation layer formed on the surface and the wettability of the disks increased significantly. Cell proliferation and initial maturation were not affected by the treatment. Mineralization and ALP activity of BMP-exposed cells, however, were slightly but significantly reduced on test disks. Conclusions: The current study showed that the alterations in implant color after electrochemical treatment did not reflect significant surface changes, which would preclude cell adhesion and growth or have a major impact on osteoblastic differentiation or maturation. Keywords: cytocompatibility, electrolytic disinfection, peri-implantitis, surface, titanium

Maxillary sinus surgery has been shown to be a reliable procedure for increasing vertical bone height prior to implant placement. A variety of grafting materials have been proposed, with particulate bone substitutes showing similar clinical results to autogenous bone when rough surfaces implants are used. A barrier membrane is usually placed external to the grafted sinus, covering the antrostomy. In this technical report, the membrane is placed over the window and its borders gently tucked between the inner side of the bony wall and the graft material. This procedure stabilizes the membrane without tacks and prevents graft dislodgement through the antrostomy. Keywords: maxillary sinus augmentation, maxillary sinus grafting complications