The International Journal of Oral & Maxillofacial Implants

Purpose: This study was conducted to examine the effects of coating poly(D,L-lactide-co-glycolide) (PLGA)/ recombinant human bone morphogenetic protein-2 (rhBMP-2) submicron particles by electrospray onto titanium (Ti) implants on the proliferation and differentiation capacity of mesenchymal stem cells. In addition, the duration of rhBMP-2 release was investigated. Materials and Methods: Ti disks were fabricated and divided into four groups as follows. Group C (control) was anodized at 300 V, group P was anodized and then coated with 0.2% PLGA, group B1 was anodized and then coated with PLGA/rhBMP-2 submicron particles at 200 ng per disk, and group B2 was anodized and then coated with PLGA/rhBMP-2 submicron particles at 600 ng per disk. The topography of the PLGA/rhBMP-2-coated Ti surfaces was examined, and proliferation assays, alkaline phosphatase activity tests, and rhBMP-2 releasing tests were conducted in vitro. Results: There was no difference in the roughness of control Ti disks and Ti disks coated with PLGA/rhBMP-2 submicron particles by electrospray. The proliferation of mesenchymal stem cells increased over time; at 7 days, cell proliferation on the Ti disks coated with rhBMP-2 was significantly higher than the other groups. Anodized Ti disks coated with PLGA/rhBMP-2 (groups B1 and B2) released rhBMP-2 for approximately 21 days. In accordance with the amount of rhBMP-2 released from the PLGA/rhBMP-2 construct, the differentiation capacity of mesenchymal stem cells on the PLGA/rhBMP-2-coated disks was increased significantly. Conclusion: Submicron PLGA/rhBMP-2 coating on Ti implants by electrospray facilitated cell proliferation and differentiation, which is important for early healing and integration of implants. Keywords: anodized implant, coating, differentiation, electrospray, mesenchymal stem cells, poly(D, L-lactideco- glycolide), proliferation, recombinant human bone morphogenetic proteins

Purpose: Many experts have proposed the treatment of titanium surfaces with plastic or nonmetal tips to prevent damage to implant surfaces by metal instruments during professional cleaning. It is also known that any material that is softer than titanium may leave remnants of itself on the treated surface. The aim of this study was to quantify the surface area covered by plastic remnants after instrumentation with various plastic instruments and to evaluate the efficacy of the removal of these remnants by confocal microscopy. Materials and Methods: Twenty-seven rough-surfaced titanium disks were used for quantification of plastic remnants. Nine disks each were cleaned with (1) a plastic tip on ultrasonic scaler A, (2) a carbon tip on ultrasonic scaler B, or (3) a plastic curette. Three disks from each group were cleaned with a three-way syringe for 10 seconds, and three other disks were cleaned with 0.2% chlorhexidine-soaked cotton pellets. Images were obtained at random areas on each disk with a confocal microscope, and a digital image analysis program was used to quantify the area with autofluorescence. Results: Approximately 10% to 20% of the surface was covered with plastic remnants of the instrument, irrespective of the instrument used. These remnants were not removed with a three-way syringe or chlorhexidine-soaked cotton pellets. Conclusion: Plastic remnants remained after instrumentation, regardless of the instrument used. Moreover, the study highlighted the difficulty of removing all remnants with water spray or a chlorhexidine-soaked cotton pellet. This study suggests that confocal microscopy is a reproducible method for quantification that may be applied for future comparisons of methods to remove plastic residue. Further research is warranted to evaluate the biologic effects of plastic remnants. Keywords: chlorhexidine, dental implant, dental scaling, microscopy, plastics, titanium

Purpose: Accurate torque application and determination of the applied torque during surgical and prosthetic treatment is important to reduce complications. A study was performed to determine and compare the accuracy of manual wrenches, which are available in different designs with a large range of preset torques. Materials and Methods: Thirteen different wrench systems with a variety of preset torques ranging from 10 to 75 Ncm were evaluated. Three different designs were available, with a spring-in-coil or toggle design as an active mechanism or a beam as a passive mechanism, to select the preset torque. To provide a clinically relevant analysis, a total of 1,170 torque measurements in the range of 10 to 45 Ncm were made in vitro using an electronic torque measurement device. Results: The absolute deviations in Ncm and percent deviations across all wrenches were small, with a mean of -0.24 ± 2.15 Ncm and -0.84% ± 11.72% as a shortfall relative to the preset value. The greatest overage was 8.2 Ncm (82.5%), and the greatest shortfall was 8.47 Ncm (46%). However, extreme values were rare, with 95th-percentile values of -1.5% (lower value) and -0.16% (upper value). A comparison with respect to wrench design revealed significantly higher deviations for coil and toggle-style wrenches than for beam wrenches. Conclusion: Beam wrenches were associated with a lower risk of rare extreme values thanks to their passive mechanism of achieving the selected preset torque, which minimizes the risk of harming screw connections. Keywords: complications, dental equipment reliability and validity, immediate dental implant loading, torque

Purpose: Peri-implantitis is a challenging situation that leads to tissue destruction and eventual implant failure. The purpose of this study was to evaluate and compare, clinically and histologically, the influence of ligature-induced peri-implantitis on two implant designs in a canine extraction socket model. Materials and Methods: Sixty-four implants (4.1 × 13 mm) were placed bilaterally in eight dogs immediately after extraction of the mandibular premolars (P3, P4) and molars (M1, M2). Thirty-two conventional threaded implants (group A) and 32 tantalum-based porous implants (group B) were placed. After 12 weeks of normal healing, experimental peri-implantitis was induced in four dogs via the placement of ligatures subgingivally around the implant necks in the treatment group; the control group remained ligature-free. Two dogs in each group were euthanized after 12 or 26 weeks of plaque accumulation (control group dogs received regular cleanings). Clinical evaluations were conducted during the observation period and histologic sections were obtained for histologic and histomorphometric assessments. Results: All the implants exhibited clinical and histologic osseointegration. The treatment group showed significant loss of peri-implant tissue from the induced peri-implantitis. Pocket probing depths for the treatment groups were significantly greater than those of the control groups. Mean bone-to-implant-contact values were not statistically different for control vs treatment groups or for group A vs group B. In the treatment group, group B implants exhibited mean bone ingrowth of 28.4% to 36.3% and achieved more bone formation along the length of the implant than group A implants in the treatment group. Conclusion: Implant design did not influence the tissue response or histomorphometric findings under induced peri-implantitis in the canine extraction socket. Keywords: bone ingrowth, peri-implantitis, porous tantalum

Purpose: All-ceramic abutments are employed increasingly often in implant dentistry for esthetic reasons. In vitro stress testing is required to evaluate the suitability of these constructions, especially in load-bearing posterior regions. The purpose of the study was to assess and compare the fatigue and fracture resistance of one- and two-piece computer-aided design/computer-assisted manufacture (CAD/CAM) zirconia implant abutments with an internal-hex connection and prefabricated commercially available zirconia stock abutments. Materials and Methods: Twenty-one abutment-crown specimens were prepared for three test groups. Control group 1 (SZ) included specimens with unprepared stock zirconia abutments, test group 2 (OP) included onepiece CAD/CAM zirconia abutments, and test group 3 (TP) included two-piece CAD/CAM zirconia abutments. All 21 specimens underwent thermocycling and fatigue testing. Finally, all specimens were tested for fracture resistance with a universal testing machine. The maximum load was applied to the tapered occlusal area of each crown at a 30-degree angle and a crosshead speed of 0.5 mm/min until the implant-abutment connection failed. Kolmogorov-Smirnov, Shapiro-Wilk, and post-hoc Scheffé tests were used for statistical analysis. Results: All abutments in groups SZ and OP fractured into two or more pieces after fracture resistance testing. None of the TP abutments displayed apparent disintegration, but failure was evidenced by bending of the retention screw. OP abutments (232.1 ± 29.8 N) and SZ abutments (251.8 ± 23.2 N) showed lower fracture loads than the TP abutments (291.4 ± 27.8 N). However, only the difference between the OP and TP groups was statistically significant. Further load-displacement analyses corroborated the higher mechanical stability of the TP abutments. Conclusion: Superior resistance was achieved for two-piece hybrid CAD/CAM zirconia abutments. These abutments might be clinically beneficial in high-load areas, such as premolar and molar regions. Keywords: ceramics, computer-aided design/computer-assisted manufacture, dental stress analysis, fracture load, hybrid abutments, elasticity, implant abutments, zirconia

Purpose: To evaluate the effect of cyclic disengagement on the retentive force and wear patterns of pairs of three Locator inserts (blue, pink, and clear) in vitro. Materials and Methods: Implant analogs (Astra Tech) were positioned into aluminum blocks parallel to each other and perpendicular to the horizontal plane, with one analog angulated mesially by 10 degrees (0/10), or with two implant analogs each angulated mesially by 5 degrees (5/5). Ninety Locator attachments, in 15 pairs of each standard retention strength (blue, pink, and clear), underwent 2,500 cycles of testing, lubricated with artificial saliva. Data were analyzed after 6, 12, and 18 months of simulated clinical use (720, 1,440, or 2,160 cycles). The wear patterns of the Locator inserts were examined before and after the cyclic dislodgments using scanning electron microscopy. Results: There were significant differences in retentive force between clear, blue, and pink inserts at baseline, with the clear insert being the most retentive in the 0/10 model. The lowest percentage reduction in retentive force from baseline to 2,160 cycles was the pink insert in the 0/10 model, and the highest was the blue insert in the 5/5 angled model. Conclusion: A rapid decrease in retentive force was observed in all three models after 720 cycles for all three inserts. The most retentive combination was the clear insert in the 0/10 model, and the least retentive was the blue insert in the 0/10 model. After 2,160 cycles, there was a significant reduction in retentive force of 59% to 70%. However, the values of retention were still higher than those claimed by the manufacturer. Keywords: implant angulation, retentive force, wear

Purpose: To conduct an in vitro comparison study on the primary stability of two different clinically used dental implant designs. Materials and Methods: Eighteen pairs of osteotomies were prepared in fresh bovine bone specimens. The control implant had a subtle tapering and was placed using straight drills. The test implant had a marked tapering and was placed using tapered drills. The bone density at the experimental sites was determined in Hounsfield units (HUs) by using cone beam computed tomography and imaging software. The implants were inserted during continuous registration of insertion torque. The bone blocks were embedded in plaster for firm fixation in a rig for displacement measurements. Resonance frequency analysis (RFA) measurements were taken. A lateral force of 15 N was applied to the RFA transducer and the displacement measured in micrometers. A flex constant (μm/N) was calculated for each measurement. Results: The test implants displayed statistically significantly higher primary stability than the control implants for all parameters. There was a marked difference in displacement and flex constant in low-density bone in favor of the test implant, but there was no obvious difference in higher-density bone. Conclusion: In this study, placement of a tapered implant design using tapered drills resulted in higher primary stability than a control implant with subtle tapering using straight drills. The results indicate that the novel implant may work particularly well in soft bone densities such as the posterior maxilla. However, clinical studies are needed to confirm this. Keywords: bone density, displacement, primary implant stability, resonance frequency analysis, in vitro study, Hounsfield units

Purpose: Whole saliva comprises components of the salivary pellicle that spontaneously forms on surfaces of implants and teeth. However, there are no studies that functionally link the salivary pellicle with a possible change in gene expression. Materials and Methods: This study examined the genetic response of oral fibroblasts exposed to the salivary pellicle and whole saliva. Oral fibroblasts were seeded onto a salivary pellicle and the respective untreated surface. Oral fibroblasts were also exposed to freshly harvested sterilefiltered whole saliva. A genome-wide microarray of oral fibroblasts was performed, followed by gene ontology screening with DAVID functional annotation clustering, KEGG pathway analysis, and the STRING functional protein association network. Results: Exposure of oral fibroblasts to saliva caused 61 genes to be differentially expressed (P .05). Gene ontology screening assigned the respective genes into 262 biologic processes, 3 cellular components, 13 molecular functions, and 7 pathways. Most remarkable was the enrichment in the inflammatory response. None of the genes regulated by whole saliva was significantly changed when cells were placed onto a salivary pellicle. Conclusion: The salivary pellicle per se does not provoke a significant inflammatory response of oral fibroblasts in vitro, whereas sterile-filtered whole saliva does produce a strong inflammatory response. Keywords: cytokines, fibroblasts, inflammation, microarray, saliva, salivary pellicle

Purpose: Achieving accelerated implant osseointegration could make immediate or early loading of implants more predictable. Platelet-rich fibrin (PRF) is frequently used to accelerate soft and hard tissue healing. The activated platelets in PRF release growth factors, resulting in cellular proliferation, collagen synthesis, and osteoid production. The aim of this study was to compare the stability of dental implants inserted in a onestage surgical protocol with or without PRF application. Materials and Methods: Twenty healthy patients with adequate alveolar bone and two or more adjacent missing teeth extracted at least 6 months previously were included in this study. A minimum of two tapered implants (Ankylos, Dentsply/Friadent) were placed in each patient. After surgical preparation of the implant sockets, PRF that had been prepared preoperatively was placed randomly into one of the sockets (PRF+). The acellular plasma portion of PRF was used to wet the implant placed into the PRF-coated socket. Resonance frequency measurements were made after implant placement and at 1 week and 1 month postoperatively. Results: Mean implant stability quotients (ISQs) of the PRF+ implants was 69.3 ± 10.5, and mean ISQs for the PRF- implants was 64.5 ± 12.2 at the end of the first week. The mean ISQs at 4 weeks postoperatively were 77.1 ± 7.1 for the PRF+ group and 70.5 ± 7.7 for the PRF- group. Conclusion: In this study, PRF application increased implant stability during the early healing period, as evidenced by higher ISQ values. Simple application of this material seems to provide faster osseointegration. Keywords: dental implants, immediate loading, implant stability, platelet-rich fibrin, platelet-rich plasma, resonance frequency analysis

Purpose: To verify whether the parts of dental implants can be contaminated by opportunistic pathogens. Materials and Methods: In this cross-sectional study, 38 individuals (52 implants) were investigated. Samples for microbiologic analysis (for a total of 180 sites) were obtained from each individual, from three types of sites in the following order: (1) the peri-implant sulcus of each implant, (2) the gingival sulcus of adjacent teeth, and (3) inside the implant-abutment connection and the abutment of each implant. Swabs from the oral mucosa (cheeks, tongue, and pharynx) were also collected. Quantitative real-time polymerase chain reaction was carried out for total bacterial counts of Enterococcus faecalis and Pseudomonas aeruginosa. Two-way analysis of variance (sites, species) and Holm-Sidak tests were used for statistical analyses. Results: No opportunistic bacteria were found in the gingival sulcus specimens (38 sites). E faecalis was detected in the peri-implant sulcus (3 of 52 sites) and the inner connection/abutment portion (3 of 52 sites). P aeruginosa was identified only in the oral mucosa swabs (1 of 38 sites) and represented the highest bacterial number (3.5 × 106). Statistically significant differences were only found between species and in the peri-implant sulcus. Conclusion: Within the limitations of this study, significant differences in the presence and levels of nosocomial bacteria were detected in the peri-implant environment of diseased implants. From a clinical point of view, data from this study might suggest that, in patients affected by peri-implantitis, prostheses should be removed and the implant-abutment connection disinfected routinely, along with implant surface decontamination. Keywords: implant connection, microbiologic analysis, opportunistic pathogens, peri-implant disease, peri-implantitis

Purpose: To evaluate the capability of carbon dioxide (CO2) laser in reducing Escherichia coli on sandblasted acidetched (SAE) titanium dental implants. Materials and Methods: SAE dental implants were contaminated with E coli, incubated in a sterile bacterial culture medium for 24 hours, and then exposed to CO2 laser (10,600-nm wavelength) in superpulsed waves (SPW) at 1.5, 1.7, and 2 W at 100-Hz frequency and continuous wave (CW) at 1.5, 2, and 2.5 W. The presence of bacteria trapped in the implant surfaces after contamination and decontamination was verified using spectrophotometry. Scanning electron microscopy (SEM) was used to evaluate the topography of laser irradiation. After implant surface contamination was verified, implants were exposed to CO2 laser irradiation, and bacterial growth was measured with spectrophotometry. Results: The control implants showed the highest bacterial growth (100% growth). Implants exposed to laser showed progressive increase in the percentage of decontamination (DC%) corresponding to the higher wattage in the SPW and CW groups. The DC% were 20.4%, 49.6%, and 51.7% in the SPW group at 100 Hz, at 1.5, 1.7, and 2 W of power, respectively. In the CW group, the DC% were 34.3%, 69.9%, and 85.5% at 1.7, 2, and 2.5 W, respectively. Kruskal-Wallis statistical analysis showed a significant difference between the groups (P .05). In the pulsed mode (100-Hz) group, statistical analysis showed that the DC% of 1.5 W was significantly lower than the 2 W power. In the CW group, statistical analysis showed that the DC% at 1.7 W was significantly lower (P .05) than with the other treatments. SEM assessment showed craterlike wear damages and accretions to the implant surfaces that increased progressively as the laser wattage increased. Conclusion: CO2 laser irradiation failed to completely decontaminate the implant surfaces. SEM analysis demonstrated damage to the top of the dental implant threads at all settings studied. Thus, CO2 laser irradiation may not be the optimal method to decontaminate implants. Keywords: CO2 laser, decontamination, sandblasted acid-etched implants, scanning electron microscopy

Purpose: Many techniques have been proposed to overcome the limitations displayed by maxillary atrophy. The aim of this systematic review was to assess the predictability, dimensional changes, and associated factors to successfully perform the alveolar ridge split (ARS) technique of augmentation. Materials and Methods: An electronic and manual literature searches was conducted by two independent reviewers in several databases, including Medline, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register, for articles written in English up to February 2014. A manual search was also performed to ensure a thorough screening process. Based on the PICO (problem, intervention, comparison, outcome) model, the chief question of this study was: Can patients with horizontal ridge deficiency be successfully treated with the ARS technique and implant therapy? Results: Overall, 17 articles met the inclusion criteria, and a subsequent meta-analysis was performed. A Cohen kappa interagreement rate of 0.82 was reached. The implant survival rate of the included studies was 97.0% (range, 94.4% to 100%) with the full-thickness flap (FTF) approach and 95.7% (range, 86.6% to 100%) with the partial-thickness flap (PTF) approach. The weighted mean (WM) of horizontal bone width gain was calculated for included studies using FTF for the ARS technique. Four studies that had data were included in the meta-analysis. The WM ± standard deviation of bone width gain was 3.19 ± 1.19 mm (range, 2.00 to 4.03 mm). For studies using PTF for ARS, only one study provided mean and standard deviation of horizontal bone width gain (4.13 ± 3.13 mm); hence, meta-analysis could not be performed. Buccal wall fracture represented the most frequent postoperative complication, followed by postoperative ridge resorption. Conclusion: In selected scenarios, the ARS technique might represent a predictable approach as demonstrated by a high implant survival rate, adequate horizontal bone gain, and minimal intra- and postoperative complications. Further research is needed to determine the influence of the grafting materials inserted and flap tissue biotype, as well as the anatomical characteristics on final bone augmentation outcomes. Keywords: alveolar ridge augmentation, bone regeneration, dental implants, osteotomy, systematic review, treatment outcome

Purpose: Sinus floor elevation via the lateral window approach represents a reliable technique for augmenting bone volume in the atrophic posterior maxilla. However, controversy remains regarding the effect of placement of a barrier membrane over the lateral window. This histomorphometric meta-analysis sought to clarify the effect of barrier membranes in lateral window sinus augmentation. Materials and Methods: An electronic search of three databases and a hand search in implant-related journals for studies published through January 2013 in the English language was conducted. Randomized controlled trials, prospective human clinical studies, retrospective investigations, and case series reporting histomorphometric results after sinus elevation using the lateral window approach with at least six patients and a minimum followup period of 6 months were included. Results: The initial search yielded 1,040 articles, of which 94 were further evaluated for eligibility. Finally, 37 studies were chosen and separated into membrane (group 1) and no-membrane (group 2) groups. Similar vital bone formation was found in both groups: 32.36% for group 1 and 33.07% for group 2. Conclusion: Based upon this meta-analysis, the presence of a barrier membrane over the window does not influence the amount of vital bone formation after sinus augmentation. Additionally, the type of grafting material used and healing time did not influence the histomorphometric outcome. Keywords: dental implants, dental prosthesis, endosseous implants, implant-supported prosthesis, sinus floor augmentation

Purpose: The aim of this short communication was to analyze time-dependent changes of the supraimplant mucosa architecture in the esthetic zone. Materials and Methods: Five patients underwent single-tooth replacement with implant crowns in the anterior maxilla. The supraimplant soft tissue was conditioned with fixed provisional crowns. Quadrantlike digital impressions were taken with an intraoral optical scanning device at three time points: t0, immediately after removal of the provisional (baseline); t1, after 5 minutes; and t2, after 10 minutes. To analyze time-dependent mucosal changes, the corresponding digital files were superimposed for each patient, and baseline (t0) scans were compared with t1 and t2 scans, respectively. Wilcoxon rank sum tests were used for statistical calculations with a strict level of significance at P .01. Results: Mean values for supraimplant soft tissue changes were statistically significantly different after 5 minutes (5.5%; standard deviation ± 0.3%) in comparison to the results after 10 minutes (21.7%; standard deviation ± 1.8%). The direction of mucosa shrinkage showed a trend toward palatal sites. Conclusion: Based on the findings of this analysis, changes in supraimplant mucosa architecture seem to be affected only slightly during the first 5 minutes after removal of soft tissue support. Keywords: dental implant, intraoral optical scanning, soft tissue, supraimplant mucosa, superimposition

Purpose: The implant-abutment interface may affect peri-implant mucosal architecture, and influence health and esthetics. The goal of this 1-year follow-up report of a 5-year clinical investigation was to examine the periimplant mucosal tissue responses to different implant-abutment interface designs. Materials and Methods: Subjects requiring an anterior maxillary implant were recruited. Tooth extractions, with or without preservation or ridge augmentation procedures, were performed as required. After 5 months of healing, one of three different implant-abutment combinations (conical interface [CI] n = 48); flat-to-flat interface [FI] n = 49); or platform switch interface [PS] n = 44) was placed and provisionalized. Twelve weeks later, permanent crowns were placed and data gathered throughout the first year. Peri-implant mucosal architecture and bone levels were evaluated clinically, photographically, and radiographically. Results: At 1 year, seven FI and six PS implants failed and two FI and two PS implant participants were lost to follow-up, resulting in survival rates of 100% (CI), 85.7% (FI), and 86.4% (PS) (90.8% overall). Marginal bone level changes were -0.22 mm (CI, P .05), -1.2 mm (FI, P .05), and -1.32 mm (PS, P .05) after 1 year. Marginal bone level stability (≤ 0.5-mm bone loss or gain) was recorded for 87% (CI), 8% (FI), and 27% (PS) of implants. Measurement of midbuccal mucosal zenith and papilla positions revealed no change in the mucosal positions and 0.2 to 0.3 mm of gain in papilla dimensions in all groups. Conclusion: Significant differences in marginal bone loss were observed among the three implant-abutment interfaces. At 1 year follow-up, changes in the buccal mucosal zenith position or papilla dimensions were not discernable. A continued longitudinal evaluation of peri-implant bone and mucosal changes around these different interfaces is ongoing. Keywords: immediate provisionalization, esthetics, marginal bone levels, peri-implant mucosa

Purpose: The aim of this clinical investigation was to evaluate the clinical and radiologic outcomes of a singlestep surgical procedure that includes functional endoscopic sinus surgery (FESS) and maxillary sinus elevation by the lateral window approach in patients with reversible contraindications to sinus elevation. Materials and Methods: Thirty-eight patients with insufficient bone height in the posterior maxilla caused by pneumatization of the sinus and with reversible ear-nose-throat (ENT) contraindications to sinus elevation were recruited for this investigation between January 2010 and January 2012. All patients were treated in a single session under general anesthesia for a total of 69 consecutive sinus augmentations. FESS was performed by an ENT specialist, and an oral surgeon carried out sinus elevation through the lateral window approach. Particulate xenograft was used beneath the sinus membrane. Intraoperative and postoperative complications (eg, membrane tears, rhinosinusitis, graft infection or loss) were reported. Nasal endoscopies were performed at 7, 14, and 30 days and 3 months after treatment. After a healing period of 6 months, 137 implants were inserted. Computed tomography scans were performed after 6 months and 1 year. Results: Intraoperative membrane perforation occurred in only one case. No implant failures were recorded during the follow-up period. Radiologic and clinical findings showed the resolution of ENT disease and good bone graft integration after 1 year. A relapse of mucosal thickening observed in some patients did not influence the graft healing. Conclusion: Preliminary rhinosinusal evaluation by an ENT specialist and computed tomography of the ostiomeatal complex are necessary in patients needing maxillary sinus elevation. A single-step approach to FESS and sinus elevation is a predictable technique to manage patients with ENT reversible contraindications to sinus elevation. Keywords: bone graft, chronic hyperplastic sinusitis, dental implants, functional endoscopic sinus surgery, maxillary sinus elevation, sinus membrane

Purpose: The purpose of this 6-month randomized, controlled, blinded, clinical trial was to evaluate and compare the efficacy of amnion membrane (AM) with deproteinized bovine bone mineral (BBM) and a collagen membrane (CM) with BBM in guided tissue regeneration (GTR) for the treatment of intrabony periodontal defects. Materials and Methods: Ten chronic periodontitis patients with bilateral intrabony defects with radiographic evidence of intrabony component ≥ 4 mm and probing pocket depths (PPDs) ≥ 6 mm were randomly divided into two groups. The test group was treated with AM+BBM, and the control group was managed with CM+BBM. Periodontal clinical parameters were recorded at baseline and at 6 months after treatment. Results: PPD, clinical attachment level (CAL), and probing bone (PB) showed significant improvements after 6 months in both the test and control groups. Gingival recession showed a significant increase in the control group but not in the test group. The changes in mean PPD, PB, and CAL preoperatively and postoperatively between the groups were not significant. There was no significant relationship between the depth of the baseline bony defect and CAL gain. Conclusion: Both AM and CM in conjunction with BBM provided improvement of clinical periodontal parameters. AM did not induce significant gingival recession and is suggested as a new barrier membrane in GTR treatment. Keywords: amnion membrane, bovine bone mineral, collagen membrane, guided tissue regeneration, intrabony defect

Purpose: To evaluate preliminary data on clinical outcomes associated with timing of placement of single implant-supported provisional crowns and implants in augmented bone. Materials and Methods: Twenty patients underwent sinus elevation bone grafting followed by a 6-month healing period before implant placement and immediate placement of a provisional crown (group [G] 1); 20 patients received sinus elevation bone grafting at the time of implant placement and immediate placement of a provisional crown (G2); 20 patients required no bone augmentation before implant placement and immediate placement of a provisional crown (G3); and 20 patients received sinus elevation bone grafting followed by a 6-month healing period before implant placement followed by a 6-month healing period before restoration (G4). The height of the crestal bone was measured and recorded to determine mean bone changes, and success rates were determined. Results: Mean bone level comparisons were made between G2 and G3, G2 and G4, and G3 and G4. No statistically significant differences were found between the groups (P .05). G1 was discontinued based on the initial results: two implants did not meet the 35-Ncm insertion test, and one implant failed within 1 month after implant placement. The 1-year implant survival rates were 86% (n = 12/14), 95% (n = 19/20), and 100% (n = 16/16) for G2, G3, and G4, respectively. Differences in survival rates between the groups were not statistically significant (P .05). Conclusion: Implant survival is affected by the timing of sinus augmentation and implant placement in relation to the timing of crown placement. Implants that were restored immediately regardless of the timing of bone augmentation showed greater failure rates than implants in augmented bone with delayed restoration protocols or those that were restored immediately in sites without bone augmentation. Neither the timing of loading nor timing of implant placement in relation to bone augmentation surgery affected mean bone loss. Keywords: bone augmentation, bone loss, clinical outcomes, immediate implant placement, immediate provisionalization

Purpose: This study aimed to investigate and compare the residual ridge resorption (RRR) induced by an implant-retained overdenture (IRO) and associative biomechanics and by a conventional complete denture (CD) without implants. Materials and Methods: Cone beam computed tomography was used to quantify RRR in a three-dimensional (3D) manner before and after 1 year of treatment with either IROs or CDs. Twenty patients were treated with IROs, and nine patients were treated with CDs in the mandible. Their maximum bite forces were recorded. The same sets of high-resolution scan images were used to create patient-specific 3D finite element analysis models. The hydrostatic stresses, contact surface deformation, and strain energy absorption in soft tissue mucosa were correlated with the changes in RRR for patients with and without implants. Results: With the IROs, contact surface deformation on the mucosa was two times greater than with CDs (0.32 ± 0.23 mm vs 0.16 ± 0.06 mm) and was in agreement with the amount of RRR measured, which was also two times higher for the IRO than the CD (-3.8% ± 4.5% vs -1.9% ± 0.4%). Taking into account the differences in bite forces with and without implants, which again were twice as high with IROs, the hydrostatic stress within the mucosa was found to correlate well to the RRR map measured over the 1-year interval of treatment. Conclusion: IROs resulted in at least twice the RRR as CDs. This could be caused by the higher hydrostatic stress and less effective energy absorption capabilities of the mucosa underneath the IRO. While implants associated with the IRO provide stronger bite force, they could potentially concentrate hydrostatic stress and cause greater RRR compared to a conventional CD. Keywords: bite force, blood flow, bone remodeling, cone beam computed tomography, denture, finite element analysis, hydrostatic pressure, mandible, mucous membrane, permeability

Purpose: Primary implant stability is critical to achieving implant success, especially in a situation with immediate implant placement and provisionalization (IIPP) when bone quality and quantity are compromised. The purpose of this study was to examine the effects of implant morphology (tapered vs cylindric) and the final drill-implant diameter discrepancy (FD-IDD) of six implant systems on the incidence of rotational instability during IIPP in the esthetic zone. Materials and Methods: One hundred seventy-one implants in 112 patients were evaluated. Implants that exhibited inadequate resistance to the torque generated by the surgeon's hand during implant placement were classified as rotationally unstable. Results: The overall incidence of rotational instability for the tapered implants (1.1%) was significantly lower than that exhibited by the cylindric (nontapered) implants (20.5%). Among the cylindric implants, those with 0.5 mm FD-IDD experienced a significantly higher incidence of rotational instability (36.6%) than groups with ≥ 0.5 mm FD-IDD. The incidence of rotational instability of cylindric implants with ≥ 0.5 mm FD-IDD was significantly greater than that of the tapered implants with a comparable FD-IDD. Conclusion: Within the confines of this study, the use of a tapered implant with an FD-IDD of ≥ 0.5 mm minimized the incidence of rotational implant instability for the IIPP procedure. Keywords: dental implants, immediate implants, immediate provisionalization, implant morphology, implant shape, implant stability

Purpose: To evaluate radiographic and clinical outcomes of immediate occlusally loaded one-piece zirconia implants after 5 years of follow-up. Materials and Methods: This longitudinal clinical investigation included patients older than 18 years, in need of implant-supported single-unit dental rehabilitations. One-piece zirconia implants were placed in healed and postextraction sites and immediately restored with provisional crowns in light occlusal contact. Definitive zirconia-ceramic restorations were delivered 3 to 4 months after surgery. Primary estimated outcomes were implant survival and success. Periapical radiographs were taken at implant insertion (T0), after 1 year (T1), and after 5 years (T2) to assess marginal bone loss (MBL). Probing depth (PD), modified Bleeding Index (mBI), modified Plaque Index (mPI), and gingival recession (REC) were also measured repeatedly for implants and reference teeth. Changes in parameters over time were assessed using the Wilcoxon signed rank test. In addition, multilevel mixed effects linear and logistic regression models were fitted to take into account within-subject correlations and baseline values. Results: Thirty-two implants were inserted in postextraction and healed sites (n = 16 of each) in 17 patients. One immediate implant was lost after 3 months, and one patient with one implant dropped out after T1. Therefore, the cumulative survival rates were 96.9% at T1 and 96.8% at T2 (4.3 to 6 years). No significant differences were observed in mean MBL between immediate and delayed implants at either T1 or T2. Moreover, different baseline parameters (sex, arch, implant location, smoking habits, grafting) did not show any influence on MBL at either time. In general, for all clinical parameters (PD, mBI, mPI, REC), implants seemed to perform similar to if not better than natural teeth. Conclusion: Radiographic and clinical evaluations after 5 years showed satisfactory amounts of MBL and acceptable soft tissue health. Keywords: immediate loading, marginal bone loss, occlusal loading, one-piece implant, zirconia

Purpose: The aim of this study was to retrospectively evaluate the factors affecting facial peri-implant mucosa topography of posterior single implant-supported restorations. Materials and Methods: The cohort comprised 25 patients with a single implant-supported restoration with platform switching and Morse taper- connection implants. Patients were divided into three groups based on facial soft tissue topography. Patients of group A (n = 8), group B (n = 9), and group C (n = 8) had a facial peri-implant tissue margin at the level of, coronal to, and apical to the zenith of the facial gingival margins of the adjacent teeth, respectively. Variables possibly associated with the facial peri-implant tissue margin level were obtained from clinical measurements, periapical radiographs, and cone beam computed tomograms. Results: Implants in group C were placed in a more subcrestal position than implants of group B (1.50 ± 0.53 mm vs 0.44 ± 0.88 mm). Implants in group C had their platform in a more apical position in relation to the bone level of the adjacent teeth than implants of group B (3.45 ± 1.32 mm vs 1.53 ± 1.17 mm). The horizontal distance between adjacent teeth was greater for group C than for group A and group B (13.53 ± 2.37 mm vs 10.65 ± 2.09 mm and 9.82 ± 1.77 mm, respectively). Conclusion: In this study, facial peri-implant mucosa margins for implants in the posterior region with platform switching and a Morse taper connection were significantly affected by the distances from the implant platform to the buccal aspect of the ridge at the time of implant placement and from the implant platform to the bone level of the adjacent teeth and by the horizontal spaces between the adjacent teeth. Keywords: bone loss, clinical study, dental implants, radiology, retrospective study, subcrestal

Purpose: The aim of this prospective study was to evaluate the outcome of bone block harvesting from the external oblique ridge with the MicroSaw, assess the volume of the harvested block, and identify possible morbidity and complications related to the procedure. Materials and Methods: Bone blocks were harvested from the external oblique line of the mandible according to the MicroSaw protocol. The bone blocks were split into two thinner blocks with a diamond disk according to the split bone block (SBB) technique for biologic grafting procedures. Results: In all, 3,874 bone blocks were harvested from the external oblique line of the mandible in 3,328 patients. Four hundred nineteen patients (12.59%) underwent bilateral bone block harvesting, and 127 patients (3.82%) had more than one block harvested from the same area during the study period. In 431 cases (11.12%), only one block was required, so the second was repositioned to reconstruct its donor site. The average harvesting time was 6.5 ± 2.5 minutes, and a mean volume of 1.9 ± 0.9 cm3 was obtained (maximum 4.4 cm3). In 168 (4.33%) cases, the alveolar nerve was exposed, leading to sensory problems lasting up to 6 months. In 20 cases (0.5%), minor nerve injury resulted in hypesthesia or paresthesia that lasted for up to 1 year in most patients. No major nerve lesions with permanent anesthesia were observed. Sixty-one (1.58%) donor sites showed primary healing complications, most in smokers (80.4%). Reentry of 16 reimplanted harvested areas was performed between 6 and 40 months later, showing a well-regenerated and healed external oblique ridge. Conclusion: This study demonstrated that relatively large volumes of bone block graft can be retrieved in the mandible with a low complication rate. Reimplantation of half of the bone block offers the possibility for complete regeneration of the donor site. Keywords: autogenous bone block, diamond disk, external oblique line, mandibular bone graft, mandibular bone harvesting, MicroSaw, split bone block

Purpose: The objective of this study was to evaluate the efficacy of guided bone regeneration (GBR) employing recombinant human platelet-derived growth factor-BB (rhPDGF-BB) incorporated into a beta-tricalcium phosphate (β-TCP)/hydroxyapatite (HA) carrier as a graft material and to compare it to autogenous bone block grafting. Materials and Methods: Adult patients with a site that required bone grafting to increase the thickness of the alveolar bone ridge were treated. After mucoperiosteal flap elevation, experimental bone defects were treated by GBR with rhPDGF incorporated into β-TCP/HA, and control defects were treated with autogenous bone. Primary tension-free wound closure was obtained for all treated sites. Results: Thirty patients were treated. No significant differences were observed between the groups for any of the parameters evaluated, including the amount of bone regeneration and a need for additional grafting. Conclusion: A composite bone ceramic graft that incorporated rhPDGF appears to be a suitable substitute for autogenous bone block grafting when employed in conjunction with GBR in humans. Keywords: bone grafting, dental implants, growth factors, guided bone regeneration, platelet-derived growth factor

Purpose: Bone formation and healing are diminished in experimental type 1 diabetes. The present study investigated whether controlled local release of recombinant human bone morphogenetic protein 2 (rhBMP-2) stimulates bone defect healing in diabetes as a consequence of its anabolic effects on bone. Materials and Methods: Bilateral experimental circular bone defects were created in the temporal bones of 64 BALB/ cByJ mice. Defects were treated with acellular collagen sponge plus 0.4 or 1.8 μg of rhBMP-2 per defect, and untreated defects served as controls. The healing of the defects over a 14-day period in diabetic and nondiabetic mice was analyzed histomorphometrically. Results: Diabetes inhibited bone formation in both untreated and BMP-treated bone defects. Controlled local release of rhBMP-2 significantly stimulated bone formation in diabetic animals, bringing it nearly to normal levels, and enhanced bone regeneration in normal animals. Conclusion: Recombinant human BMP-2 may be beneficial in treating deficient intramembranous bone formation in diabetes. Keywords: bone regeneration, diabetes, recombinant human bone morphogenetic protein-2

Purpose: The purpose of this study was to evaluate the stress distribution during application of occlusal loads to maxillary anterior single external- and internal-connection implant-supported restorations with different amounts of bone loss and with the use of different metal alloys for restorations and fixation screws. Materials and Methods: Models of external- and internal-connection implants, corresponding abutments/crowns, and fixation screws were developed. These models were then imported into finite element analysis software to study the impact of forces on different implant connections and materials. Each prosthesis was subjected to a 200-N compressive shear force applied at 130 degrees relative to the long axis of the implant. The materials were considered linear, isotropic, and homogenous. The parameters changed for each connection type included: bone resorption in relation to the prosthetic platform (no, 2 mm, or 4 mm of resorption); alloys of the restorations (nonprecious vs precious); and alloys of the abutment screws (titanium vs gold). Von Mises stresses were used to display the stress in five models: implant, restoration, screw, cancellous bone, and cortical bone. Results: Statistically significant differences in the stresses of all involved structures occurred when the bone level decreased by 2 mm and by 4 mm. The connection type contributed to statistically significant differences in the stresses in both the restoration and the screw. The alloy type resulted in statistically significant differences in the implant, the superstructure, and the cortical bone stresses. Conclusion: As bone resorbed, the stresses generated within the internal-connection implant were greater than those generated in the external-connection implant. The same findings applied for the restoration and for cancellous and cortical bone. The stresses generated in the fixation screw were greater in the external-connection implant than in the internal-connection implant for all bone resorption scenarios. Keywords: bone resorption, dental alloy, dental implants, finite element analysis, implant connection

The authors present a case study in which a virtual model was created from a patient's cone beam computed tomographic scans that simulated a dentoalveolar defect associated with periapical pathosis. With the information provided by the virtual model, the tooth was extracted, and both defect and alveolus were virtually grafted. The virtual amount calculated was similar to the amount used in the actual site. Keywords: cone beam computed tomography, grafting material, virtual grafting, virtual models