The International Journal of Oral & Maxillofacial Implants, 01/2015

Purpose: The success of an implant-supported prosthesis is dependent on the passive fit of its framework fabricated on a precise cast. The aim of this in vitro study was to digitally compare the three-dimensional accuracy of implant impression techniques in partially and completely edentulous conditions. Materials and Methods: The master model simulated two clinical conditions. The first condition was a partially edentulous mandibular arch with an anterior edentulous space (D condition). Two implant analogs were inserted in bilateral canine sites. After elimination of the teeth, the model was converted to a completely edentulous condition (E condition). Three different impression techniques were performed (open splinted [OS], open unsplinted [OU], closed [C]) for each condition. Six groups of casts (DOS, DOU, DC, EOS, EOU, EC) (n = 8), totaling 48 casts, were made. Two scan bodies were secured onto the master edentulous model and onto each test cast and digitized by an optical scanning system. The related scans were superimposed, and the mean discrepancy for each cast was determined. Results: The statistical analysis showed no significant difference in the accuracy of casts as a function of model status (P = .78, analysis of variance [ANOVA] test), impression technique (P = .57, ANOVA test), or as the combination of both (P = .29, ANOVA test). The distribution of data was normal (Kolmogorov-Smirnov test). Conclusion: Model status (dentate or edentulous) and impression technique did not influence the precision of the casts. There is no difference among any of the impression techniques in either simulated clinical condition. Keywords: accuracy, dental implant, impression technique, three-dimensional optical scanning

Purpose: Success of orthodontic miniscrews in providing stable anchorage is dependent on their stability. The purpose of this study was to assess the effect of insertion method and postinsertion time interval on the removal torque of miniscrews as an indicator of their stability. Materials and Methods: Seventy-two miniscrews (Jeil Medical) were inserted into the femoral bones of three male German Shepherd dogs and assigned to nine groups of eight miniscrews. Three insertion methods, including hand-driven, motor-driven with 5.0-Ncm insertion torque, and motor-driven with 20.0-Ncm insertion torque, were tested. Three time intervals of 0, 2, and 6 weeks between miniscrew insertion and removal were tested as well. Removal torque values were measured in newton centimeters by a removal torque tester (IMADA). Data were analyzed by one-way analysis of variance (ANOVA) followed by the Bonferroni post hoc test at a .05 level of significance. Results: A miniscrew survival rate of 93% was observed in this study. The highest mean value of removal torque among the three postinsertion intervals (2.4 ± 0.59 Ncm) was obtained immediately after miniscrew insertion with a statistically significant difference from the other two time intervals (P .001). Insertion method did not have any effect on the removal torque, and no significant differences were observed in this regard (P = .46). Conclusion: The stability of miniscrews was not affected by the insertion method. However, of the postinsertion time intervals, the highest removal torque values were obtained immediately after insertion. Keywords: insertion method, insertion torque, miniscrew, postinsertion interval, removal torque

Purpose: Implant dentistry has revolutionized the treatment of partially and completely edentulous patients. The aims of this study were to explore what made patients choose implant treatment and their prior knowledge and expectations of this treatment option. Materials and Methods: A study population of 117 subjects was selected from 248 referred possible candidates for implant therapy. The subjects answered a questionnaire regarding implant dentistry prior to professional consultation at two hospital/university-based centers and one private implant center. Results: In most cases, the choice of treatment was motivated by expectations of improved chewing/function (46.0%), appearance (19.5%), or both (18.6%). Improved chewing/function and improved appearance were rated "very important" by 96.5% and 86.1% of patients, respectively. Surprisingly, 57.4% reported that the cost of treatment did not play a role in their decision. Only 6.0% claimed to have much prior knowledge about the treatment and 33.6% had a realistic perception about the length of anticipated service. Patients first received implant-related information primarily (62.9%) from dentists, and 75.2% thought their dentist gave the most useful information. Significant positive associations were found between knowledge about the treatment, the need for periodic professional oral health maintenance, and expected treatment time. Conclusion: Patients seek implant therapy primarily to improve chewing function and esthetics, whereas cost seems to be less important. Prior to treatment, many patients lack precise information on the importance of necessary implant-related hygiene measures and implant longevity. The general dentist is the primary source of information. Keywords: dental crowns, dental health services, dental implantation, dental implants, dental prostheses, dental restoration, dentist-patient relations, implant-supported dentures, interprofessional relations, patient expectations

Purpose: The aim of this study was to examine the effect of an alternative surgical technique on endosseous dental implant stability parameters in Class D4 bone. Differences between insertion torque (IT) and implant stability quotient (ISQ) produced by a conventional osteotomy versus a modified stepped osteotomy were examined. Correlations between IT, density in Hounsfield units (HU), and ISQ were also examined. Materials and Methods: Computed tomographic scans were taken of 16 cadaver heads to determine bone density at maxillary implant recipient sites, which ranged from 173.4 to 312.1 HU. Twenty-two implants were placed in sites with Misch Class D4 bone; control sites received 11 conventional osteotomies and test sites 11 modified stepped osteotomies. Maximum IT was recorded with an implant motor and confirmed with a torque driver, and ISQs were measured. Significant differences were analyzed with a Wilcoxon signed rank test, and correlations were analyzed with the Pearson test. Results: The mean IT in the control group was 15.91 Ncm, and in the test group it was 26.82 Ncm. The modified stepped osteotomy had a significantly greater mean IT than the conventional osteotomy, but no significant difference in ISQ was found between groups. Pearson correlations showed a significant positive correlation between IT in the control and test groups. Significant correlations were found between ISQ and HU in the test group. No other significant correlations between HU, IT, and ISQ were found. Conclusion: Within the limits of this cadaver study, the modified stepped osteotomy resulted in significantly greater implant stability in terms of IT than the conventional osteotomy in soft bone. Significant correlations were found between the IT produced in the modified stepped osteotomy and bone density. No significant correlations were found between IT and ISQ. Keywords: bone density, computed tomography, dental implant, modified surgical technique, primary stability

Purpose: To evaluate the accuracy of two digital impression systems based on the same technology but different postprocessing correction modes of customized software, with consideration of several clinical parameters. Materials and Methods: A maxillary master model with six implants located in the second molar, second premolar, and lateral incisor positions was fitted with six cylindrical scan bodies. Scan bodies were placed at different angulations or depths apical to the gingiva. Two experienced and two inexperienced operators performed scans with either 3D Progress (MHT) or ZFX Intrascan (Zimmer Dental). Five different distances between implants (scan bodies) were measured, yielding five data points per impression and 100 per impression system. Measurements made with a high-accuracy three-dimensional coordinate measuring machine (CMM) of the master model acted as the true values. The values obtained from the digital impressions were subtracted from the CMM values to identify the deviations. The differences between experienced and inexperienced operators and implant angulation and depth were compared statistically. Results: Experience of the operator, implant angulation, and implant depth were not associated with significant differences in deviation from the true values with both 3D Progress and ZFX Intrascan. Accuracy in the first scanned quadrant was significantly better with 3D Progress, but ZFX Intrascan presented better accuracy in the full arch. Conclusion: Neither of the two systems tested would be suitable for digital impression of multipleimplant prostheses. Because of the errors, further development of both systems is required. Keywords: accuracy, dental implant, digital impression, implant angulation, implant depth, intraoral scanner

Purpose: This study compared the volume stability and bone-forming capacity of biphasic calcium phosphate (BCP) with a high versus a low ratio of β-tricalcium phosphate (β-TCP) relative to hydroxyapatite (HA), ie, 70:30 vs 30:70, in the rabbit sinus model. Materials and Methods: Bilateral sinus windows were created in eight adult New Zealand white rabbits (2.5 to 3.5 kg); each sinus in each rabbit was assigned to one of two experimental BCP groups according to the HA:β-TCP ratio. One sinus was grafted with BCP with a high ratio of β-TCP (30:70; TCP70), and the contralateral sinus was grafted with BCP with a low ratio of β-TCP (70:30; TCP30). The animals were sacrificed after 2 weeks (n = 4) or 8 weeks (n = 4) of healing. Biopsy specimens were harvested and evaluated histologically, histomorphometrically, and with microcomputed tomography. Results: The bone volume did not differ significantly between the two groups at each healing point, or between 2 and 8 weeks of healing in both groups. The amount of new bone increased significantly between 2 and 8 weeks of healing in both groups, and it did not differ significantly between the TCP30 and TCP70 groups. The residual material was significantly more resorbed in the TCP70 group than in the TCP30 group at both 2 and 8 weeks. In the TCP70 group, a greater number of multinucleated giant cells were observed at both weeks. The bone-to-residual material contact ratio did not differ significantly between the two groups. Conclusion: The volume stability and osteoconductive capacity of BCP with an HA:β-TCP ratio of 30:70 was comparable to that with an HA:β-TCP ratio of 70:30. Thus, within the limitations of this study, it can be argued that BCP with an HA:β-TCP ratio of 30:70 can be successfully used for sinus augmentation. Keywords: biphasic calcium phosphate, bone regeneration, rabbit sinus model, sinus augmentation

Purpose: The purpose of this systematic review was to identify studies in which either orthodontic extrusion or bone grafting was used prior to single implant placement in the maxillary esthetic zone and to compare the biologic, functional, and esthetic outcomes of these two approaches. Materials and Methods: An electronic MEDLINE search was conducted by three independent reviewers to identify English-language articles, published in dental journals between January 1992 and August 2013, reporting on single-implant site development accomplished by orthodontic forced eruption of nonrestorable teeth or by bone grafting procedures. The search terms were categorized into four groups comprising a PICO (problem, intervention, comparison, outcome) question. Supplementary manual searches of published full-text articles and related reviews were also performed. Results: The initial database search produced 301 relevant titles. After careful examination and discussion, 32 studies were selected for inclusion. No study directly comparing the two implant site development methods was identified. The observation periods of the available studies were either short or not stated Conclusion: There is a substantial lack of evidence to determine which method for implant site development is better. Definitive conclusions cannot be drawn, since no clinical trials have directly compared these two methods. All included studies reported separately on the two implant site- development methods and used different protocols. According to the literature reviewed, it seems that both methods of implant site development are effective and neither method is superior. Multicenter studies and randomized clinical trials should be performed to evaluate the efficacy of these two methods. Keywords: anterior maxilla, bone grafting, implant site development, orthodontic extrusion, single implant

Purpose: The probability of survival of implant-supported prostheses may be affected by the interplay between different implant diameters supporting screwed or cemented crowns. The purpose of this study was to investigate the effect of implant diameter and prosthesis retention system on the reliability and failure modes of single crowns. Materials and Methods: Internal-hexagon implants were divided into six groups (n = 21 each) according to implant diameter (3.3, 4.0, or 5.0 mm) and crown retention system (screwed or cemented). Abutments were torqued to the implants, and crowns were then fixed and subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and reliability for missions of 50,000 cycles at 100, 150, and 200 N were calculated. Failure analysis was performed. Results: Cemented systems presented higher reliability than screwed ones, except between 3.3-mm-diameter cemented and screwed systems at a load of 100 or 150 N. Failure modes were restricted to the abutment screw and varied with implant diameter only in the cement-retained groups. Conclusion: Higher reliability was observed for cementretained crowns and implants of larger diameter compared to screw-retained and smaller diameter. Failure modes differed between groups. Keywords: dental implant, fatigue, fractography, reliability, step-stress accelerated life testing, Weibull analysis

Purpose: The purpose of this research was to compare the accuracy of definitive casts created with digital and conventional methods for implants with internal-octagon connections placed parallel or at different angles (15, 30, or 45 degrees). Materials and Methods: Four customized epoxy resin master casts were fabricated with two-implant analogs placed in the posterior mandible with different degrees of divergence. For the conventional (control) group, 10 traditional impressions were taken on each master cast with custom trays, open-tray impression copings, and polyvinyl siloxane; definitive stone casts were poured with type IV dental stone. For the digital group, 10 digital impressions were taken on each master cast with two-piece scannable impression copings and an intraoral digital scanner; definitive milled polyurethane casts were fabricated by the manufacturer. All four master casts and 80 control and test casts were scanned and digitized, and the data sets were compared. Any deviations in measurements between the definitive and corresponding master casts were analyzed statistically. Results: The amount of divergence between implants did not affect the accuracy of the stone casts created conventionally; however, it significantly affected the accuracy of the milled casts created digitally. A decreasing linear trend in deviations for both distance and angle measurements suggested that the digital technique was more accurate when the implants diverged more. At 0 and 15 degrees of divergence, the digital method resulted in highly significantly less accurate definitive casts. At 30 and 45 degrees of divergence, however, the milled casts showed either no difference or marginal differences with casts created conventionally. Conclusion: The digital pathway produced less accurate definitive casts than the conventional pathway with the tested two-implant scenarios. To ensure passive fit of definitive prostheses, verification devices and casts may be used when materials are produced digitally. Keywords: dental implants, dental impression technique, digital impression, implant divergence, parallel confocal technology

Purpose: To identify the influence of fixed prosthesis type on biologic and technical complication rates in the context of screw versus cement retention. Furthermore, a multivariate analysis was conducted to determine which factors, when considered together, influence the complication and failure rates of fixed implant-supported prostheses. Materials and Methods: Electronic searches of MEDLINE (PubMed), EMBASE, and the Cochrane Library were conducted. Selected inclusion and exclusion criteria were used to limit the search. Data were analyzed statistically with simple and multivariate random-effects Poisson regressions. Results: Seventy-three articles qualified for inclusion in the study. Screw-retained prostheses showed a tendency toward and significantly more technical complications than cemented prostheses with single crowns and fixed partial prostheses, respectively. Resin chipping and ceramic veneer chipping had high mean event rates, at 10.04 and 8.95 per 100 years, respectively, for full-arch screwed prostheses. For "all fixed prostheses" (prosthesis type not reported or not known), significantly fewer biologic and technical complications were seen with screw retention. Multivariate analysis revealed a significantly greater incidence of technical complications with cemented prostheses. Full-arch prostheses, cantilevered prostheses, and "all fixed prostheses" had significantly higher complication rates than single crowns. A significantly greater incidence of technical and biologic complications was seen with cemented prostheses. Conclusion: Screwretained fixed partial prostheses demonstrated a significantly higher rate of technical complications and screw-retained full-arch prostheses demonstrated a notably high rate of veneer chipping. When "all fixed prostheses" were considered, significantly higher rates of technical and biologic complications were seen for cement-retained prostheses. Multivariate Poisson regression analysis failed to show a significant difference between screw- and cement-retained prostheses with respect to the incidence of failure but demonstrated a higher rate of technical and biologic complications for cement-retained prostheses. The incidence of technical complications was more dependent upon prosthesis and retention type than prosthesis or abutment material. Keywords: cement, complication, dental implants, fixed dental prostheses, multivariate analysis, screw

Purpose: There is limited evidence available on the influence of location on bone density in the maxilla. Therefore, this study was aimed at comparing the microarchitecture of bone harvested from different nonatrophic maxillary locations. Materials and Methods: A total of 37 partially edentulous subjects (aged 48.15 ± 15.85 years) were included in the study. A bone core biopsy specimen was obtained from one site per patient at the planned implant surgery location. Thirty-four specimens were used for microcomputed tomography (micro-CT) analysis. Mann-Whitney U tests (independent samples) were performed to determine whether the distributions of the six bone-related parameters showed significant differences between sexes and site locations. Study sites were categorized as either anterior (incisors and canines) or posterior (premolars and molars). The possible associations among variables (bone volume fraction [BV/TV], age, and five bone-related parameters) were examined using the Spearman rank correlation test. Results: The mean BV/TV values showed no significant difference between the maxillary anterior (46.93 ± 26.2) and posterior (51.90 ± 28.42) locations. Statistically significant positive correlations were identified between BV/TV and trabecular thickness (Tb.Th) (r = 0.6, P .001) and between BV/TV and trabecular number (Tb.N) (r = 0.49, P = .006). Statistically significant negative correlations were found between BV/TV and trabecular spacing (Tb.Sp) (r = -0.65, P .001), between BV/TV and trabecular pattern factor (Tb.Pf) (r = -0.7, P .001), and between BV/TV and the structural model index (SMI) (r = -0.68, P .001). However, no correlations between BV/TV and age or sex were found. Conclusion: Bone density was independent of the anatomical location, assessed by micro-CT in the pristine nonatrophic maxillary bone. Studies with a larger sample size and different population should be conducted to validate the findings of the current project. Keywords: alveolar ridge augmentation, bone, dental implant, grafting, maxillary ridge augmentation

Purpose: This study evaluated the stability and histologic proof of osseoincorporation of Trabecular Metal (TM) dental implants, which feature a tantalum-based porous midsection. Materials and Methods: A total of 48 TM implants (test group) and Tapered Screw-Vent implants (control group) were immediately placed bilaterally into mandibular extraction sockets in dogs. Resonance frequency analysis was performed at weeks 0, 2, 4, and 12 after implant placement. Histologic and histomorphometric evaluations of the implant interface were performed. Results: Changes in mean implant stability quotients (ISQ) revealed no statistical differences between the test and control groups. Histologic analysis showed bone ingrowth into the porous tantalum structure of all test group implants. Histomorphometric analysis revealed an increased percentage of bone-to-implant contact between 4 and 8 weeks in both test and control groups. The porous sections of the test group exhibited significantly more new bone inside the pores at week 12 in comparison to weeks 2 and 4. No correlation was observed between ISQ and histomorphometric parameters. Conclusion: In a canine immediate extraction socket model, both test and control implants demonstrated comparable implant stability and bone-to-implant contact. Bone ingrowth was evident within the tantalum porous section of the test implants during the early healing. Keywords: bone ingrowth, osseoincorporation, porous tantalum, trabecular metal dental implant

Purpose: Ridge expansion is used to widen narrow ridges with adequate height for implant placement. This human case series presents the clinical and histologic results of delayed expansion of mandibles by ultrasonic surgery. Materials and Methods: Patients with residual alveolar ridge width between 2.3 and 4.1 mm in the coronal area of the posterior mandible were included in the study. First, four linear corticotomies were carried out by ultrasonic surgical device. Four weeks later, adequate bone expansion with a combination of scalpels, thin chisels, and threaded osteotomes that did not compromise cortical vascularization was performed, and two implants per ridge were inserted. Any gaps were filled with corticospongious porcine biomaterial. Three months after implant placement, healing caps were inserted, and bone cores were harvested from the regenerated areas for histologic analysis. Crestal width was recorded at each surgery. Results: The postoperative course was uneventful in all 32 patients (64 implants) who took part in the study, and the implant success rate was 96.88% at 3 months. The mean increase in ridge width was 5.17 ± 0.86 mm. The histologic specimens showed a mixture of new bone and particles of biomaterial, as well as newly formed bone. Histomorphometry demonstrated that 64% ± 3.1% of the specimen was composed of newly formed bone, 8% ± 0.8% was made up of marrow spaces, and 27% ± 2.6% comprised the residual grafted biomaterial. Conclusion: This study showed that mandibular ridge expansion using a delayed splitcrest technique by means of ultrasonic surgery and association with biomaterial led to good horizontal bone gain, with no fractures of the buccal plate, and a high implant success rate. The histologic specimens showed newly formed bone and good integration of the biomaterial. Keywords: alveolar bone loss, alveolar ridge augmentation, bone regeneration, bone resorption, piezosurgery

Purpose: The aim of this study was to analyze the patient pool referred to a specialty clinic for implant surgery over a 3-year period. Materials and Methods: All patients receiving dental implants between 2008 and 2010 at the Department of Oral Surgery and Stomatology were included in the study. As primary outcome parameters, the patients were analyzed according to the following criteria: age, sex, systemic diseases, and indication for therapy. For the inserted implants, the type of surgical procedure, the types of implants placed, postsurgical complications, and early failures were recorded. A logistic regression analysis was performed to identify possible local and systemic risk factors for complications. As a secondary outcome, data regarding demographics and surgical procedures were compared with the findings of a historic study group (2002 to 2004). Results: A total of 1,568 patients (792 women and 776 men; mean age, 52.6 years) received 2,279 implants. The most frequent indication was a single-tooth gap (52.8%). Augmentative procedures were performed in 60% of the cases. Tissue-level implants (72.1%) were more frequently used than bone-level implants (27.9%). Regarding dimensions of the implants, a diameter of 4.1 mm (59.7%) and a length of 10 mm (55.0%) were most often utilized. An early failure rate of 0.6% was recorded (13 implants). Patients were older and received more implants in the maxilla, and the complexity of surgical interventions had increased when compared to the patient pool of 2002 to 2004. Conclusion: Implant therapy performed in a surgical specialty clinic utilizing strict patient selection and evidence-based surgical protocols showed a very low early failure rate of 0.6%. Keywords: bisphosphonates, complications, dental implants, early failure, guided bone regeneration, indications

Purpose: The aim of this study was to investigate implant survival and the reactions of the bone and mucosa of the maxillary sinuses in patients treated with fixed dental prostheses supported by multiple zygomatic implants. Materials and Methods: Between 2001 and 2007, patients with extensive resorption of the basal bone of the maxilla received multiple zygomatic implants without grafts. In 2012, the maxillary sinuses were examined with cone beam computed tomography. Neo-osteogenesis at the posterior wall of the sinus was considered to be a sign of osteitis and classified as mild (3 to 4 mm), moderate (4 to 5 mm), or severe (> 5 mm). The maxillary ostium was examined and accessory ostia were registered. The sinus mucosa was evaluated according to the Lund-Mackay staging system, and the sinus was checked for fluid level and atelectasis. Patients reported any nasal- and sinus-related symptoms. Results: Fourteen patients who had received 58 zygomatic implants and 13 standard implants were examined. The mean follow-up was 9.3 years, and the implant survival rates were 97% and 92% for zygomatic and standard implants, respectively. Osteitis was found in all but one patient and classified as severe in 17 of the 27 investigated sinuses. The infundibulum was obstructed in nine sinuses, and an accessory ostium was present in seven. The mucosa of the maxillary sinus showed signs of chronic rhinosinusitis in all but one patient. No fluid levels were observed. Atelectasis occurred in 15 sinuses. Twelve patients reported unaltered nasal and sinus status. Conclusion: Patients with extensive bone resorption in combination with voluminous maxillary sinuses and nasal cavities can experience long-term success with prostheses supported by multiple zygomatic implants. Asymptomatic chronic rhinosinusitis with osteitis and gradual collapse of the maxillary sinus cavity can be anticipated. Keywords: chronic rhinosinusitis, dental implant, osteitis, zygomatic implants

Purpose: This study evaluated the retrospective outcomes of implant-borne dental rehabilitation in patients with mandibular defects reconstructed with a fibula free flap. Materials and Methods: Patients with segmental mandibular defects were enrolled in this cohort study. Defects in these patients were caused by oral neoplasm, trauma, and osteoradionecrosis. The patients were treated with a fibula free flap procedure and dental implant-borne prostheses between 1988 and 2010. Clinical and radiographic data were evaluated; Kaplan- Meier survival analysis and Poisson regression analysis were used to evaluate implant survival parameters. The statistical significance (α = .05) of the results was determined. Results: Seventy-four patients were selected in this study. All patients were available for continuous follow-up. Nine patients (12.1%) developed fibular graft complications postoperatively: 3 in donor sites and 6 in recipient sites. One hundred ninety-two implants were inserted, and 18 implants failed (9.3%). Overall implant survival in patients was 90.1%, 83.1%, and 69.3% after 5, 10, and 20 years, respectively. In 152 implants, probing depth (PD) ranged from 2 to 3 mm. In 31 implants, PD was greater than 5 mm. In 9 implants, PD was greater than 7 mm. The highest implant failure rates were expected for men (odds ratio [OR] = 2.948; 95% confidence interval [CI], 1.10 to 7.85; P = .031), patients receiving primary fibula free flap reconstruction (OR = 3.696; 95% CI, 1.16 to 11.73; P = .027), and patients receiving radiotherapy (OR = 5.269; 95% CI, 1.40 to 19.7; P = .014). Conclusion: Fibula free flap procedures and implant-borne prostheses proved to be reliable approaches for rehabilitation of mandibular defects and oral function. The overall postoperative fibula free flap and peri-implant complication rates proved to be low. Regular follow-up visits and proper oral hygiene maintenance contributed to the long-term successful treatments. Keywords: dental implant, fibula free flap, follow-up studies

Purpose: Implants can be inserted simultaneously during sinus floor elevation (SFE), or 6 months later, for posterior maxillary rehabilitation. The residual bone height (RBH) is a major factor that affects the type of surgical procedure that will be performed. The aim of this study was to compare the survival rates of implants inserted during one-stage SFE with two different RBHs ( 5 mm and ≥ 5 mm). Materials and Methods: This study consisted of implants inserted into an RBH of either 5 mm or ≥ 5 mm, and the survival of the implants was assessed according to the clinical symptoms of the patients: pain or tenderness during function (or spontaneously), mobility, depth of probing, exudation history, and radiographic bone loss at the final follow-up appointment. The survival rates of the two groups were statistically compared using the Fisher exact test. Results: Fifty-nine consecutive patients (29 women and 30 men) undergoing a onestage sinus elevation procedure simultaneously with implant insertion were included in this study. Fifty-one implants were placed in the study group (RBH: 1 to 4.9 mm), and 31 implants were placed in the control group (RBH: 5 to 8 mm). The survival rate of the implants in the study group was 94.2% at the 5.4-year follow-up and 95.8% in the control group at the 7.9-year follow-up. There was no statistically significant difference between the groups in terms of the implant survival rate (P = .785). Conclusion: The results of this study suggest that SFE with simultaneous implant placement in patients with an RBH 5 mm can be accomplished, and that the survival rate is similar to that of the one-stage SFE protocol with an RBH of > 5 mm. Keywords: atrophic maxilla, lateral sinus elevation, one-stage sinus elevation, sinus floor augmentation, sinus floor elevation

Purpose: The purpose of this study was to evaluate prospectively the clinical effectiveness of immediate loading of implants with complete-arch fixed prostheses in edentulous maxillae after the implants were placed with flapless guided surgery. Materials and Methods: Patients with edentulous maxillae who visited a single dental clinic during the recruitment period (April 2011 to May 2012) were selected by consecutive sampling and predetermined selection criteria. Four to six implants were placed in each patient with flapless guided surgery. The outcome measures were insertion torque, surgical time, postoperative pain (100-mm visual analog scale), marginal bone level change, implant survival, and oral health-related quality of life. Patients were followed for up to 1 year. Results: Fifty patients received 290 implants. All implants were immediately loaded 2 hours after placement with prefabricated fixed provisional prostheses. Two patients dropped out of the study. Hence, analyses were conducted for 278 implants in 48 patients (26 men, 22 women; mean age 56.0 ± 8.3 years; age range, 34 to 74 years). The average insertion torque was 57.7 ± 16.6 Ncm, the average surgical time was 22.9 ± 4.7 minutes, and the average score for postoperative pain was 14.7 ± 9.3. One year after immediate loading, the implant survival rate was 98.6%. Four implants showed mobility early after implant placement and were lost. Mean marginal bone level changes were -0.32 ± 0.43 mm. Scores on the Oral Health Impact Profile-54 (Japanese version) improved significantly after prosthetic treatment. Conclusion: The results of this study indicate that this treatment method for edentulous maxillae is predictable, with a high implant survival rate and a clinically reasonable improvement in oral health-related quality of life. Keywords: alveolar bone loss, computer-aided surgery, dental implants, edentulous jaw, immediate dental loading implant, survival rate

Purpose: The study was conducted to evaluate the effect of mineralized freeze-dried bone allograft (FDBA), alone or in combination with growth factors in extraction sockets, on subjective assessment of bone quality during implant placement. Materials and Methods: Forty-one patients whose treatment plan involved extraction of anterior or premolar teeth were randomized into four groups: Group 1, collagen plug (control); Group 2, FDBA/β-tricalcium phosphate (β-TCP)/collagen plug; Group 3, FDBA/β-TCP/platelet-rich plasma (PRP)/collagen plug; Group 4, FDBA/β-TCP/recombinant human platelet-derived growth factor BB (rhPDGF-BB)/collagen plug. After 8 weeks of healing, implants were placed. The clinicians assessed bone quality according to the Misch classification. A benchtop calibration exercise test was conducted to evaluate agreement and accuracy of operators in recognizing different bone qualities. Differences were analyzed using one-way analysis of variance (ANOVA) or chi-square tests for continuous and categorical data. Pairwise comparisons were tested using least squares means (LS means). Spearman correlation coefficients were used to evaluate the relationship of bone growth with potential confounders. P .05 was considered statistically significant. A simple (not weighted) kappa statistic was used to assess the agreement between raters. To assess accuracy in identifying bone quality, a chi-square test was used to compare the percent correct for each rater. Results: The benchtop calibration exercise test demonstrated agreement among clinicians (0.75 and 0.92 between raters 1 and 2 and raters 1 and 3, respectively). Raters were more likely to identify the correct bone quality (P > .05). Inclusion of bone grafting is associated with a shift from D4 quality to D3 quality bone. Inclusion of PRP in bone grafting eliminates the incidence of D4 bone, establishing D3 and D2 quality bone as prevalent (56% vs 42%, respectively). Inclusion of rhPDGF-BB and β-TCP in combination with the bone grafting has the same effect, although D2 quality is less prevalent. When compared to sockets grafted with FDBA/β-TCP/collagen plug alone, the sockets with growth factors demonstrated fewer residual bone graft particles. Conclusion: (1) Inclusion of bone grafting enhanced bone quality as assessed during implant placement. (2) Overall inclusion of PRP and rhPDGF-BB enhanced subjective bone quality, eliminating incidence of D4 quality in human extraction sockets. (3) The use of PRP or rhPDGF-BB may enhance healing within extraction sockets and decrease the healing time prior to dental implant placement. Keywords: bone quality, extraction socket, freeze-dried bone allograft, platelet-rich plasma, recombinant human platelet-derived growth factor BB

Purpose: This retrospective study evaluated the use of a composite graft of recombinant human bone morphogenetic protein-2 (rhBMP-2) and particulate mineralized bone allograft protected by a titanium mesh for vertical bone augmentation. Materials and Methods: A review of data on patients from four oral and maxillofacial surgery practices in the United States who required vertical augmentation prior to implant treatment was conducted. Vertical augmentation was accomplished with rhBMP-2 in an absorbable collagen sponge (ACS) carrier and particulate allograft. Cone beam computed tomography was used to measure vertical bone gains using this technique. Results: Sixteen vertical ridge augmentation procedures were performed in 15 patients. The maximum vertical bone gains ranged from 4.4 to 16.3 mm. The average maximum vertical bone gain was 8.53 mm. The procedure allowed implant placement in all patients. Forty implants were inserted into the grafted ridges after a minimum of 6 months of healing. All implants integrated and were used for prosthetic support. Conclusion: This study suggests that rhBMP-2/ACS and particulate mineralized bone allograft protected by a titanium mesh offers favorable vertical bone gains to allow dental implant placement. Keywords: cone beam computed tomography, recombinant human bone morphogenetic protein-2, titanium mesh, vertical bone augmentation

Purpose: The aim of this study was to evaluate bone healing after the use of a xenograft scaffold enriched with bone marrow mesenchymal stem cells (BM-MSCs), an autogenous bone graft, or the scaffold without BM-MSCs. Materials and Methods: Eighteen rabbits were used for this study; bilateral 12-mm-diameter defects were created in the animals' parietal bones. The bilateral defects were filled with a xenograft enriched with BM-MSCs (test group [TG]), with autogenous bone graft (positive control group [PCG]), or with a xenograft alone (negative control group [NCG]). In all groups, randomly, one defect was covered with a collagen membrane. The rabbits were sacrificed 8 weeks after surgery, and their parietal bones were harvested and analyzed histomorphometrically. Results: Within the PCG and the NCG, the defects covered with the barrier membrane showed better bone healing. In the TG, the defects covered with the barrier membrane did not show better bone healing (intragroup comparisons by Wilcoxon and Friedman tests for paired data). TG showed percentage of mineralized tissue (MT) of 56.03% ± 3.49% with membrane and 57.71% ± 5.31% without membrane. PCG showed MT of 55.13% ± 4.83% and 49.69% ± 3.81% with and without membrane, respectively, and NCG showed MT of 26.77% ± 7.29% and 19.67% ± 2.66% with and without membrane, respectively. Conclusion: Both autogenous bone graft and a xenograft enriched with BM-MSCs were equally effective for bone reconstruction and better than the xenograft alone. The use of a barrier membrane seemed to have a synergistic effect on bone healing in PCG and NCG but not in TG. Keywords: bone marrow, bone repair, cell transplantation, osteogenesis, stem cells

Purpose: The aim of this study was to assess the effect of characterized uncultured omental adipose-derived stromal vascular fraction (SVF) on bone regeneration in a circular mandibular bone defect. A chitosan scaffold was used to maintain the cells in situ. Materials and Methods: Seventy-five healthy male white Wistar rats were randomized into three experimental groups. In the control group, a surgical bone defect was created in the body of the mandible. In the scaffold group, a chitosan scaffold was placed into the defect. In the scaffold/ SVF group, a scaffold was implanted and seeded with 10-μL SVF aliquots (2.19 ± 0.43 × 107 cells). Results: Microscopic and histomorphometric analyses showed improved and earlier regeneration of bone defects in the scaffold/SVF group compared to the scaffold-only group. Conclusion: In this animal model, the use of a chitosan scaffold with SVF aliquots resulted in significantly earlier regeneration of bone than the use of the scaffold alone. Keywords: bone regeneration, chitosan scaffold, mandible, stromal vascular fraction

Purpose: There is a controversial body of evidence regarding optimal insertion angulation of an orthodontic miniscrew as a mean of skeletal anchorage. Materials and Methods: A bracket head-type 8-mm-long miniscrew (60-degree symmetrical trapezoid thread, 0.1-mm thread fillet, 0.2-mm thread height, with 0.5-mm thread pitch) was designed and monocortically inserted at 30, 45, 55, 70, 90, 110, 125, 135, and 150 degrees of inclination to the surface of bone. A bilayer cortical (1.6 mm) and cancellous (8.5 mm) bone model was constructed, adopted from a 22-year-old male patient's cone beam computed tomography (CBCT) image of his anterior hard palate area. A horizontal force of 2 N was applied parallel to the bone surface. Bone material was simulated as normal and osteoporotic bone. The maximum equivalent von Mises stress and microstrain values were separately calculated for the miniscrew, cortical bone, and cancellous bone. Deflections of the whole bone and miniscrew were also reported. Results: A significant lower stress was found in the cancellous bone compared to the cortical bone. Osteoporotic bone displayed higher strain values. Overall, 30-degree models exhibited the lowest von Mises stress and strain values for the cortical layer and miniscrew in both normal and osteoporotic models. Meanwhile, 90-degree models displayed the lowest strain values in the osteoporotic and normal cancellous bones. Minimum bone and miniscrew deflection values were related to the model of 30-degree insertion angulation. Conclusion: These results showed that, within the limitations of the study, the 30-degree angulation of miniscrew insertion toward the direction of applied force could lower the cortical bone stress and strain. Keywords: angulation, finite element analysis, miniscrew, stability, stress

Purpose: The primary objective of this study was to investigate the fracture resistance of experimental mini-implants with a reduced abutment height. The secondary objective was to assess the effects of implant diameter and bone level on the load limit, using finite element simulations. Materials and Methods: Two Ti-6A1-4V 1.8-mm-diameter implants were subjected to monotonic bending testing and fatigue tests incorporating 5 × 106 cycles (ISO 14801): a commercially available implant (c18), and an experimental implant with a reduced abutment height (e18). The load limit was estimated using the finite element models based on the maximum stress at failure in the experiments. For simulations, implants with increased diameters of 2.1 and 2.4 mm were also modeled, and the load limit was estimated for all models in a bone model. Results: In the bending test, e18 revealed a higher mean load at yield stress than c18, and this was attributed to the reduced height of the former. An endurance limit of 140 N was detected for both c18 and e18 in the fatigue test, while the load limit of e18 was higher than that of c18. The estimated load limit increased as the implant diameter or the bone level increased, with the highest value of 510 N observed at a diameter of 2.4 mm. Conclusion: A higher load limit was evident in the experimental mini-implant with a reduced abutment height. The simulations indicated that the load limit increased with increased implant diameter and higher bone levels. Keywords: fatigue, finite element analysis, implant, prosthodontics, stress, titanium

Patients missing portions or all of the maxillary alveolar bone who are restored with zygomatic implants frequently have threads exposed that can be a mucosal irritant. If such irritation is reported, covering the threads with a highly polished titanium sleeve is recommended. The technique of placing said custom sleeve is described. This adjunctive treatment method has eliminated mucosal irritation. Keywords: maxillectomy, oral mucosal irritation, osseointegration, zygoma, zygomatic implant

Technical complications in implant prosthetic cases represent a major challenge in dentistry. This case report describes minimally invasive management to recover an implant with a fractured remnant of a zirconia abutment, including provisional rehabilitation during a sequential treatment protocol in the esthetic zone. A patient was treated with a screw-retained one-piece implant-supported reconstruction made of a customized zirconia abutment with direct ceramic veneering in the maxillary right central incisor position. During the prosthetic try-in, a fracture in the apical portion of the abutment was evident. The first rescue attempt led to fracture of the retrieval instrument. Immediately, an individualized wired construction was applied to bond the existing fractured reconstruction to the neighboring teeth to maintain the peri-implant mucosal architecture. Because the implant screw canal was blocked, a customized round bur had to be manufactured and was placed in the implant axis with a specific bracket tool from the service set to protect the interior implant threads. Then, the drills of the service set were guided by the newly created access to remove the fractured remnants. The implant screw was retapped and the area rinsed with chlorhexidine solution. All remnants were removed without the need for surgical intervention. Neither the implant connection nor the bone-to-implant interface was damaged. The stepwise treatment approach with the customized round bur combined with the system-specific drills of the service set saved the blocked implant so that the patient could be successfully rehabilitated with a new implant reconstruction. Keywords: abutment fracture, dental implants, implant-abutment interface, technical complications, zirconia