The International Journal of Oral & Maxillofacial Implants, 01/2014

Purpose: To examine the osseointegration of various implant surfaces after bacterial contamination and cleaning. Materials and Methods: Four types of implant surface were manufactured: machined (M); plasmaspray hydroxyapaptite (HA); sandblasted, large-grit, acid-etched (SA); and titanium anodic oxide (TAO) were manufactured. The surface characteristics of these implants were determined using a scanning electron microscope, an energy dispersive spectrometer, and a contact profilometer. Each surface was subdivided into control and test groups. Test implants were co-incubated with Prevotella intermedia for 2 weeks, then cleaned with cotton pellets, soaked in saline, and irrigated. Control implants underwent the same cleaning procedure, but without bacterial contamination. Four control or test implants with different surface types were randomly inserted into the tibia of 10 New Zealand white rabbits. After 6 weeks of healing, 5 rabbits were sacrificed for histomorphometry, and the rest for removal torque assay. Results: Bacterial contamination adversely influenced every implant surface in terms of bone-to-implant contact (BIC) ratio and required removal torque. The negative results reached significant levels for rougher surfaces (HA and SA). For both contaminated and uncontaminated samples, HA and SA implants required significantly higher removal torque than that required for M implants. Conclusion: Bacterial contamination jeopardized osseointegration on every tested implant surface. A more negative effect on BIC was found for implants with rougher surfaces. However, contaminated rough-surfaced implants showed more removal torque resistance than contaminated smooth implants. Keywords: histometry, osseointegration, peri-implantitis, Prevotella intermedia, rabbit, removal torque assay

Purpose: To evaluate the neurocompatibility of different types of dental implant surface treatments using the P19 neural cell line. Materials and Methods: P19 cells were plated and supplemented with retinoic acid to grow as aggregates for 4 days. Twenty dental implants were selected from four different implant systems with five different surface treatments. The implants were divided into four groups (n = 5), placed inside medical rings, and fixed by injection of warm gutta-percha using a thermoplastic injection technique. Implant molds were placed inside graded culture dishes, and culture medium containing P19 neural cells were plated on the dishes for 4 days. After 24 hours, the surfaces of the implant molds were covered with self-curing resin to make a replica of each mold surface. Replicas were assessed under a scanning electron microscope, and the number of cells and the total cells covering the areas were evaluated. Data were analyzed by a post hoc Tukey test. Results: There were significant differences in P19 cell counts between all modified and electropolished surfaces. The highest P19 cell counts were shown on OsseoSpeed and Laser-Lok surfaces. The lowest counts were shown on the Nanotite surface at the collar. OsseoSpeed and Laser-Lok surfaces showed higher counts at the collar than on the body; the opposite was seen for SLActive and Nanotite surfaces. Cell-covered areas on Laser-Lok surfaces showed significantly higher values than the resorbable blasted media (RBM)-treated surfaces, while it was not significantly different from the OsseoSpeed surface of collar regions. SLActive collar regions showed larger cell-covered areas than the SLActive body surfaces, but this was not significant. Conclusion: All test surface treatments in this study showed better neurocompatibility than control group surfaces. The Laser-Lok, RBM, and OsseoSpeed surfaces were superior to the Nanotite and SLActive surfaces in terms of neurocompatibility. Keywords: dental implants, neurocompatibility, P19 cell line, titanium

Purpose: This study evaluated and compared bone heating, drill deformation, and drill roughness after several implant osteotomies in the guided surgery technique and the classic drilling procedure. Materials and Methods: The tibias of 20 rabbits were used. The animals were divided into a guided surgery group (GG) and a control group (CG); subgroups were then designated (G0, G1, G2, G3, and G4, corresponding to drills used 0, 10, 20, 30 and 40 times, respectively). Each animal received 10 sequential osteotomies (5 in each tibia) with each technique. Thermal changes were quantified, drill roughness was measured, and the drills were subjected to scanning electron microscopy. Results: Bone temperature generated by drilling was significantly higher in the GG than in the CG. Drill deformation in the GG and CG increased with drill use, and in the CG a significant difference between G0 and groups G3 and G4 was observed. In the GG, a significant difference between G0 and all other groups was found. For GG versus CG, a significant difference was found in the 40th osteotomy. Drill roughness in both groups was progressive in accordance with increased use, but there was no statistically significant difference between subgroups or between GG and CG overall. Conclusion: During preparation of implant osteotomies, the guided surgery technique generated a higher bone temperature and deformed drills more than the classic drilling procedure. The increase in tissue temperature was directly proportional to the number of times drills were used, but neither technique generated critical necrosisinducing temperatures. Drill deformation was directly proportional to the number of times the drills were used. The roughness of the drills was directly proportional to the number of reuses in both groups but tended to be higher in the GG group. Keywords: bone overheating, dental implants, osteotomy

Purpose: The aim of this study was to investigate the effects of abutment screw length on screw loosening after thermocycling. Materials and Methods: Twenty-one grade 5 titanium (Ti) abutments were connected to grade 4 Ti implants with grade 5 Ti abutment screws. These implant/abutment screw/abutment assemblies were divided into seven groups according to the length of the abutment screw; each group included three assemblies. The screws were tightened to 30 Ncm and subjected to 2,000 thermocycles in water baths at 4°C and 60°C, with 60 seconds of immersion at each temperature. Removal torque values (RTVs) were measured before and after thermocycling, and differences in RTVs according to abutment screw length pre- and postthermocycling were analyzed statistically. Results: Mean RTVs before and after thermocycling were as follows: 23.0 ± 4.4 Ncm and 25.5 ± 0.9 Ncm for 1.4-mm-long abutment screws, 26.7 ± 2.5 and 24.5 ± 2.6 Ncm for 1.8-mm screws, 26.0 ± 1.3 and 25.0 ± 1.8 for 2.2-mm screws, 25.0 ± 2.0 and 25.3 ± 0.8 for 2.6-mm screws, 22.5 ± 4.4 and 22.5 ± 0.5 for 3.0-mm screws, 26.5 ± 2.3 and 25.2 ± 1.3 for 3.4-mm screws, and 25.5 ± 4.8 and 23.2 ± 0.8 for 3.8-mm screws, respectively. As the screw length increased, no statistically significant differences were found in the mean RTVs among the groups before or after thermocycling. Additionally, none of the groups showed significant changes in RTVs after cyclic thermal stress. Conclusion: Abutment screw length had no significant effect on screw loosening under thermal stress. From the results of this study, daily temperature changes in the oral cavity may have no negative influence on the integrity of an implant-abutment joint when a minimum of three and a half threads of an abutment screw are engaged. Keywords: abutment, fracture, implant, removal torque value, screw length, thermocycling

Purpose: To examine the biologic response to titanium implant surfaces treated with a neodymium:yttriumaluminum- garnet laser. Materials and Methods: Sixty mini-implants made of grade 2 titanium were placed in the femora of 30 Wistar rats. Thirty implants had a machined surface and the other 30 had surfaces that were roughened by laser treatment. The animals were subdivided into three groups according to bone repair periods of 15, 30, and 60 days. The samples were observed under light and electron scanning microscopes and analyzed with the Student t test. Results: Formation of new bone trabeculae toward the surface was apparent for the laser-treated implants at 15 days. Thin layers of bone matrix in intimate contact with the surface in the area of the central screw threads were observed, indicating high biocompatibility. Similar results were seen with machined implants after 30 days. A significant difference in bone formation was observed between the implant types at 15 days. Conclusion: Bone-to-implant contact was better on the surfaces subjected to laser treatment than on the machined titanium implants. The development of new laser treatments, which promote alterations in the surface energy as well as in the macro- and microstructures of titanium, may lead to improved bone-to-implant contact and thus better outcomes. Keywords: animal study, biocompatibility, laser treatment, machined titanium implants, surface properties

Purpose: The aim of this study was to assess and compare the visibility, diameter, and course of the mandibular incisive canal (MIC) using cone beam computed tomography (CBCT) and panoramic radiography. Materials and Methods: CBCT images and panoramic radiographs from 243 patients were used in this study. Standard exposure and patient positioning protocols were used for all the patients. Both types of images were assessed by two dentomaxillofacial radiologists. The diameter and the endpoint level of the MIC were measured using the CBCT images. Statistical analysis was performed using t tests in statistical software. Results: Of the 486 hemimandibles examined, the MIC was visible in 249 (51.2%) radiographs and 459 (94.4%) CBCT images. The mean diameters of the MICs were 1.91 ± 0.45 mm on the right side and 1.94 ± 0.41 mm on the left side. The MICs on both the right and left sides of the mandible showed statistically significant differences in diameter in male versus female patients. The visibility of the MIC on the panoramic radiographs according to the increase in the diameter was not statistically significant for both sides. Twenty MICs reached to the midline of the mandible, and the majority of the MICs (n = 114) terminated between the canine and the first premolar. Conclusion: The visibility of the MIC in CBCT is much better than that observed in conventional panoramic radiography. Even some large MICs could not be observed in panoramic radiographs. Detection of the MIC using CBCT may be crucial for surgical procedures involving the interforaminal region. Keywords: cone beam computed tomography, mandibular incisive canal, panoramic radiography, safety zone

Purpose: The objective of this systematic review and meta-analysis was to assess and compare the marginal bone loss around implants supporting single fixed prostheses and multiple-unit screw-retained prostheses. Materials and Methods: The literature was searched manually and electronically to identify studies in which the marginal peri-implant bone loss around single-implant prostheses and screw-retained multiple-implant prostheses was evaluated radiographically. Two reviewers independently selected the literature and extracted the data. The random-effects method was used to obtain estimates of marginal peri-implant bone loss (means and 95% confidence intervals [CIs]). Results: Of the 2,107 studies identified by a preliminary search, 17 fulfilled the inclusion criteria; 7 were related to single-implant prostheses and 10 to multiple-implant screwretained fixed prostheses. The mean marginal peri-implant bone loss was 0.9 mm (95% CI, 0.49 to 1.32 mm) for multiple-implant screw-retained prostheses and 0.58 mm (95% CI, 0.37 to 0.80 mm) for single-implant prostheses. Conclusion: This indirect comparison provided no evidence to support the assertion that there are differences in marginal peri-implant bone loss between single implant prostheses and multiple screw-retained prostheses. Keywords: meta-analysis, multiple implant-supported prosthesis, peri-implant bone loss, single implant-supported prosthesis, systematic review

Purpose: The purpose of this study was to determine whether abutment screw tightening and untightening influenced loss of preload in three different implant/abutment interfaces, or on the implant body. Materials and Methods: Five custom-fabricated machined titanium implants were used, each with its respective abutment, with different connection types, retention screws, and torque values (external hexagon with titanium screw/32 Ncm, external hexagon with coated screw/32 Ncm, internal hexagon/20 Ncm and internal conical/20 and 32 Ncm). Each implant tested had two strain gauges attached and was submitted to five tightening/untightening sequences. Results: External hexagons resulted in the lowest preload values generated in the implant cervical third (mean of 27.75 N), while the internal hexagon had the highest values (mean of 219.61 N). Conclusions: There was no immediate significant loss of preload after screw tightening. Tightening/untightening sequences, regardless of the implant/abutment interface design or type of screw used in the study, did not result in any significant loss of initial preload. Conical implant connections demonstrated greater structural reinforcement within the internal connections. Keywords: dental abutments, dental implants, dental implant-abutment design, preload

Purpose: The surface integrity associated with implant placement was examined to determine whether the topography of common implant surface modifications is retained after implant insertion. Materials and Methods: Turned (TU), acid-etched (AE), and anodized (AN) experimental implants prepared inhouse were inserted into polyurethane foam blocks using a standard drilling protocol at maximum torque of 37 Ncm. Qualitative analysis of the surfaces of preinserted and postinserted implants was done by scanning electron microscopy (SEM), and quantitative analysis of the implant threads was performed by interferometry. Among the roughness parameters calculated were average height deviation (Sa), peak height above core roughness (Spk), and maximum peak height (Sp). Results: SEM showed that TU implants exhibited similar morphology before and after implant insertion. The AE implants showed reduced peak height associated with flattened areas after insertion. AN implants demonstrated the most extensive damage associated with insertion; the entire porous oxide layer had been removed at the apical region and on the crests of the threads. Surface roughness evaluation was corroborated with the SEM findings. Roughness parameters were similar for TU implants, and reduced Sp and Spk values were observed for the AE implants after insertion. AN implants were more complex to measure quantitatively because of variations in the extent of damage to the oxide layer during insertion. In some cases, the AN layer had been completely removed, exposing the underlying material and clearly decreasing the roughness, and in other cases it remained intact and rough. Polyurethane foam blocks in contact with AN implants demonstrated loose titanium particles of different sizes. Conclusion: This preliminary study demonstrated surface damage after insertion of experimental anodized implants into polyurethane blocks associated with loose titanium particles at the interface. Future in vivo studies should investigate the relevance of such loose particles on the peri-implant bone response. Keywords: dental implants, osteolysis, surface characterization, surface roughness

Purpose: The aim of this study was to test whether damping factor is an adequate parameter for monitoring the status of the trabecular bone-implant interface. Materials and Methods: Implants were placed in epoxy resin with elastic moduli of 2,900, 210, and 1.4 MPa to simulate cortical bone, cancellous bone, and connective tissue, respectively. Resonance frequency and damping factor (DF) values of the tested implants were measured using vibration analysis. An impulse force was used to induce vibration within implants. The DF values of the tested implants were calculated from the obtained frequency spectrum using a half-power method. The resulting data were analyzed to test the statistical effects of the cortical height and trabecular status on the DF values of the sample implants. Results: When the simulated tissue at the implant-bone interface changed from connective tissue to bone, the detected DF value decreased markedly. In addition, the mean DF value of the tested implants increased significantly (P .05) from 0.043 ± 0.008 when the elastic modulus of the surrounding resins was 2,900 MPa to 0.114 ± 0.018 when the modulus was 1.4 MPa. Furthermore, when the tested implants were firmly fixed with 2 mm of simulated cortical bone, the alternation of healing tissue at the trabecular bone area could be detected by the DF method. Conclusion: DF is a sensitive measure for monitoring the status of oral implant osseointegration when implant boundary conditions are good at the cortical level but still weak at the trabecular bone area. Keywords: damping factor, ISQ, implant, osseointegration, vibration analysis

Purpose: To evaluate the effect of the presence of a prefabricated cobalt-chromium (CoCr) margin in a universal castable long abutment (UCLA) on the sealing capability and fit of the implant-abutment interface. Materials and Methods: One-hundred twenty external hexagon implants (SIN) were divided into two groups (n = 60 each) to receive UCLA abutments from six manufacturers (n = 10 each) either with or without a CoCr margin (n = 60 each). Abutments were cast and 12 groups were formed: M (Microplant), I (Impladen), S (SIN), Sv (Signo Vinces), T (TitaniumFix), and B (Bionnovation). Sealing was determined by placing 0.7 μL of 0.1% toluidine blue in the implant wells before abutment torquing. Implant-abutment samples were placed into 2.0-mL vials containing 0.7 mL of distilled water to maintain the implant-abutment interface, and aliquots of 100 μL of water were retrieved at 1, 3, 6, 24, 48, 72, 96, and 144 hour incubation times for measurement of absorbance in a spectrophotometer, and returned for repeated measurements. Two-way ANOVA (P .05) and Tukey's test were used. Scanning electron microscopy (SEM) was used for observation of the implant-abutment fit. Results: Groups M, Sv, and T without the CoCr margin resulted in complete release of toluidine blue at 1 hour, whereas I, S, and B did so at 3, 24, and 96 hours, respectively. Complete leakage in abutments with the prefabricated margin occurred at 6 hours for S; 24 hours for Sv, T, and B; and 72 hours for M and I. Implant-abutment gaps were observed in all groups. A poorer fit was depicted for groups M and T without the CoCr margin. Conclusion: Complete leakage was observed for all UCLA abutments regardless of the presence of the CoCr margin. Implant-abutment gaps were observed in all groups. Keywords: dental implant, gap, implant-abutment connection, in vitro, microleakage, spectrophotometry

Purpose: Bacterial penetration and colonization of the microgap at the implant-abutment interface have been reported in several studies. The aim of this study was to evaluate the effectiveness of placing a silicone membrane between the abutment and the implant platform in an attempt to seal the interface. Materials and Methods: A total of 15 external-hex implants were placed in 10 patients with clinically healthy peri-implant tissues, and all of the patients had ceramic prosthetic crowns. Samples were collected from the microgaps before, 30 days after, and 90 days after insertion of a silicone membrane. Bacterial DNA was extracted and submitted in triplicate to polymerase chain reaction using primers specific for four peri-implant pathogens: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia. Results: In the initial samples, a positivity of 52% was found, which was different from that found in samples collected after 30 days (32%) and 90 days (27%) after insertion of the membrane. Conclusion: It was evident that the silicone membrane reduced, but did not prevent, penetration of these species into external-hex implants. Keywords: bacterial infiltration, dental implants, microbiology

Purpose: To evaluate gingival margin changes in the esthetic zone after immediate implant placement and provisionalization over 5 years with a custom anatomic provisional abutment. Materials and Methods: Single maxillary incisor immediate implant placement and provisionalization procedures, completed and followed between February 2006 and August 2006, were analyzed retrospectively. During clinical recalls at 3 months, 1 year, and 5 years, changes in gingival margins were recorded with clinical photographs and recorded in millimeters. Results: Forty-seven patients each received a single implant (19 central incisors, 28 lateral incisors) and were followed for 5 years. Implants and restorations had a 100% survival rate during the study. The mean gingival margin changes (recession) were 0.17 mm at the time of definitive restoration, 0.27 mm at 3 months, 0.30 mm at 1 year, and 0.30 mm at 5 years. After 5 years, 24 of the 47 implant crowns had no significant gingival recession. All central incisor sites received 4.3-mm-diameter implants and had a mean change in tooth length of 0.03 mm at 5 years. Lateral incisor sites (n = 28) received either a 3.5-mm-diameter implant (n = 20) or a 4.3-mm-diameter implant (n = 8). Lateral sites with the 3.5-mm implant had a mean change in gingival margin height of 0.08 mm of tooth length at 5 years; lateral sites with a 4.3-mm platform displayed a mean change of 0.82 mm of tooth length. Conclusion: This study suggests that implant diameter, gingival biotype, surgical technique, and/or the reason for tooth loss can influence the amount of gingival recession occurring over 5 years. Most recession occurred within the first 3 months, between implant placement/provisionalization and definitive restoration. The use of a customized anatomic provisional abutment can reduce the amount and frequency of recession. Keywords: dental implants, esthetics, gingival biotype, gingival recession, immediate implant placement, immediate loading, immediate provisionalization

Purpose: Inadequate bone width in atrophic edentulous jaws is a challenge for successful oral rehabilitation with endosseous dental implants. The aim of this clinical study was to evaluate the effectiveness of a new method for ridge expansion with sagittal splitting using a new surgical device (Crest-Control Bone Splitting System, Meisinger) and to determine whether it is necessary to fill the expansion area with bone substitute to maintain the expanded bone volume. Materials and Methods: During a 3-year period, a prospective study was performed in 32 patients (59% women, 41% men). All participants needed implants in the horizontally atrophied edentulous mandible and were treated in a private practice and a hospital. The only inclusion criteria were a mandibular ridge width between 3 and 4 mm and ridge height of at least 11 mm. Expansion with horizontal splitting of the ridge was performed simultaneously with implant placement. In 17 of the 32 arches, selected alternately, the expanded ridges were filled with a biphasic calcium phosphate (hydroxyapatite 60% and beta-tricalcium phosphate 40%) synthetic bone substitute (SBS 60/40). The other 15 expanded arches were left unfilled. All areas were covered with a resorbable collagen membrane (Bio-Gide, Geistlich). Results were analyzed with the Mann-Whitney and Kruskal-Wallis tests (α = .05). Results: There was a significant difference (α = .02) between the patients who received SBS 60/40 (17 cases) and those who did not (15 cases). The ridges that received SBS 60/40 after expansion showed no bone resorption. Conclusion: Horizontal expansion of the ridge is easily reproducible. In this study, in very narrow ridges, a lack of bone substitute resulted in significant resorption of 3- to 4-mm-wide crests (5%), even after expansion. A bone substitute should be placed to maintain the alveolar bone walls after expansion. Keywords: bone expansion, bone grafting, narrow ridge, synthetic bone

Purpose: The purpose of this study was to compare the clinical efficacy of an anorganic bovine bone graft particulate to that of a calcium phosphosilicate putty alloplast for socket preservation. Materials and Methods: Thirty teeth were extracted from 24 patients. The sockets were debrided and received anorganic bovine bone mineral (BOV, n = 12), calcium phosphosilicate putty (PUT, n = 12), or no graft (CTRL, n = 6). The sockets were assessed clinically and radiographically 5 months later. Eight sockets in the BOV group and nine in the PUT group received implants 5 to 6 months postgrafting. The maximum implant insertion torque (MIT) was measured as an index of primary implant stability. The data were analyzed with the Mann-Whitney test. Results: Both test groups had statistically significantly less reduction in mean ridge width (BOV: 1.39 ± 0.57 mm; PUT: 1.26 ± 0.41 mm) in comparison to the control group (2.53 ± 0.59 mm). No statistically significant difference was identified between the test groups. MIT for PUT was ≤ 35 N/cm2 (MIT grade 4) for seven of the nine implants. MIT values in the BOV group ranged from grade 1 (10 to 19 N/cm2) to grade 4, which was statistically significantly lower than for the PUT group. The overall implant success rate was 94.1% (16 of 17 implants were successful). No implants were lost in the PUT group; one implant failed in the BOV group. Conclusion: Both tested bone substitutes can be recommended for preservation of alveolar ridge width following extraction. PUT might be more suitable for achieving primary stability for implants placed at 5 to 6 months postextraction. Keywords: socket preservation, bone graft, dental putty, tooth extraction, primary implant stability, insertion torque

Purpose: The long-term success of machined-surface implants is well documented, whereas the reliability of the moderately rough oxidized implant surface has not been definitively assessed in the long term. The aim of this retrospective study was to assess the long-term clinical and radiologic outcomes of moderately rough oxidized implants supporting fixed prostheses. Materials and Methods: Seventy-three consecutive patients needing an implant-supported restoration received 1 to 11 implants each (n = 167). All implants (82 cylindric and 85 tapered-body implants) had a self-tapping design and a moderately rough oxidized surface and were immediately loaded (n = 48) or loaded after a delay (n = 113). Patients were followed for up to 10 years. Outcomes were implant and prosthetic survival rates, peri-implant bone level changes, bleeding on probing, and plaque and gingival indices. Results: One patient (one implant) dropped out. Seventy-two patients (166 implants) were followed for at least 8 years (mean, 8.82 years; range, 8.0 to 10.4 years. No implants or prostheses were lost, resulting in a cumulative implant and prosthetic survival rate of 100% after up to 10 years in function. At the final follow-up, the accumulated mean marginal bone loss values were -1.72 ± 1.53 mm (n = 27) and -1.27 ± 1.67 mm (n = 44) for cylindric and tapered implants, respectively, with no statistically significant difference. Bleeding on probing was 12.1%. The cumulative plaque score was 19.7%; 83.8% of patients showed normal gingiva, 10.1% displayed mild inflammation, and 6.1% showed moderate inflammation. Conclusion: This retrospective study of 73 patients treated with either cylindric or tapered-body moderately rough oxidized implants and followed for up to 10 years demonstrated good treatment outcomes with regard to implant survival, marginal bone changes, and soft tissue conditions. Keywords: dental implants, immediate loading, long-term study, oxidization, postextraction sites, surface properties

Purpose: Dental implants are used to stabilize, support, and retain prostheses in the mandible following fibula free flap reconstruction. A previous longitudinal prospective study showed that an implant-supported prosthesis (IP) provided additional improvement in masticatory performance compared to a conventional prosthesis (CP). Therefore, in this paper, the impact of implant retention and support of mandibular prostheses on neuromuscular function is reported via a within-subject analysis. Materials and Methods: Forty-six participants were enrolled in the study. Prosthetic treatment with a CP was completed in 33 subjects following oromandibular resection and fibula free flap reconstruction. Twenty-five subjects completed evaluation of the CP after an adaptation period. Standardized masticatory tests with peanuts were given to subjects on the defect and nondefect chewing sides. Electromyography (EMG) of masseter muscles and jaw movement was performed and recorded simultaneously in 19 of these subjects. IP treatment was then completed in 16 of these subjects, and 15 of them participated in the IP evaluation after an adaptation period. Of these 15 subjects, 13 completed EMG and jaw movement recordings for both CP and IP. Results: EMG activity of the defect-side masseter muscle increased significantly from CP to IP conditions when chewing on either side, but no significant change was found for nondefect-side muscle activity. Jaw movement parameters showed no significant changes from CP to IP. Conclusion: In patients restored with mandibular fibula free flap reconstruction, implant support for mandibular prostheses has the benefit of permitting greater muscle effort on the defect side, irrespective of the side on which the bolus is being chewed. The impact of an IP on jaw movements is limited. Keywords: dental implant, electromyography, fibula transplantation, jaw movement, mandibular prostheses, oral neoplasms/rehabilitation/surgery

Purpose: The aim of this cone beam computed tomography (CBCT) study was to investigate the incidence of fenestration and associated risk factors with virtual placement of an implant in the maxillary incisor region. Materials and Methods: Edentulous ridges missing a maxillary central or lateral incisor and amenable for single implant placement were included. Root-form implants (4 × 12 mm and 3.5 × 12 mm for the central and lateral incisors, respectively) were placed virtually in the edentulous space following the axis of the ipsilateral crown. Buccolingually, the implants were placed in the ideal prosthetic cingulum position. The angles of the ridge (RA) and implants (IA) in relation to the hard palate and the incidence of fenestration were recorded. Results: A total of 48 CBCT scans were analyzed. The mean RA and IA were 124.32 degrees and 110.91 degrees, respectively. Nine cases resulted in fenestration, equivalent to 18.75% of the total cases. The discrepancy between the RA and IA was statistically significantly larger in the fenestration sites (19.93 degrees) than in the nonfenestration sites (13.05 degrees). The concavity depth of the alveolar ridge was statistically significantly higher in the fenestration sites (4.79 mm) than in the nonfenestration sites (3.40 mm). Conclusion: Within the limitations of this study, it can be concluded that the occurrence of fenestration is common (approximately 20%) if an implant is placed in the cingulum position with the axis following that of its restoration. Keywords: computed tomography, computer-guided surgery, cone beam virtual implant placement, dental implants, fenestration, maxilla

Purpose: The purpose of this study was to evaluate the three-dimensional radiographic changes of 100% anorganic bovine bone xenograft volume in a grafted maxillary sinus, based on a computerized analysis of cone-beam computed tomography (CBCT) scan. Materials and Methods: A maxillary sinus augmentation procedure done with a lateral approach using 100% anorganic bovine bone was performed in 20 patients. A CBCT scan of the grafted area was taken immediately after the procedure (T1) and 8 to 9 months later (T2). CBCT scan data were analyzed with image processing software to evaluate differences in the volume of grafted material between T1 and T2. Residual ridge height and width were also measured at T1. Results: The mean residual bone height and width at the implant sites was 4.40 ± 0.87 mm and 7.9 ± 2.22 mm, respectively. The mean graft volume was 1,432 ± 539 mm3 and 1,287 ± 498 mm3 at T1 and T2, respectively. A significant difference in graft volume was found between T1 and T2 data by paired t test (P = .01). The mean ratio between the volume at T2 and the volume at T1 was 0.90 ± 0.12, meaning a graft volume contraction of 10%. Conclusion: Within the limits of the present investigation, good stability of anorganic bovine bone graft volume up to 8 months after the grafting procedure was demonstrated. Three-dimensional computed tomographic volumetric assessment seems to be a promising approach to quantify long-term changes in the regenerated area. Keywords: bone graft, maxillary sinus, three-dimensional radiographic changes

Purpose: This prospective case series evaluated the use of a new titanium-reinforced nonresorbable membrane (high-density polytetrafluoroethylene), in combination with a mixture of anorganic bovine bone-derived mineral (ABBM) and autogenous particulated bone, for vertical augmentation of deficient alveolar ridges. Materials and Methods: A mixture of ABBM and autogenous particulated bone was used for vertical ridge augmentation and covered with a new titanium-reinforced nonresorbable membrane. Ridge measurements were obtained before and after the procedure, complications were recorded, and biopsy specimens were taken for histologic examination. Results: Twenty vertical ridge augmentation procedures were carried out in 19 patients. All treated defect sites exhibited excellent bone formation, with an average bone gain of 5.45 mm (standard deviation 1.93 mm). The healing period was uneventful, and no complications were observed. Eight specimens were examined histologically; on average, autogenous or regenerated bone represented 36.6% of the specimens, ABBM 16.6%, and marrow space 46.8%. No inflammatory responses or foreignbody reactions were noted in the specimens. Conclusion: The treatment of vertically deficient alveolar ridges with guided bone regeneration using a mixture of autogenous bone and ABBM and a new titanium-reinforced nonresorbable membrane can be considered successful. Keywords: anorganic bovine bone-derived mineral, case series, guided bone regeneration, nonresorbable membrane, vertical augmentation

Purpose: This study compared the effect of magnesium-incorporated hydroxyapatite (MgHA) coating with that of HA coating on implant fixation in ovariectomized (OVX) rats. Materials and Methods: Coatings of HA and MgHA (10 mol% Ca2+ replaced by Mg2+) were prepared on the surface of titanium substrates using the sol-gel dip-coating method, and powders of HA and MgHA were produced by the same method. The two kinds of materials were then characterized by scanning electron microscopy and x-ray diffraction. Twelve weeks after bilateral ovariectomy, 18 OVX rats received implants in the distal femora; half of the implants were HA-coated and the other half were MgHA-coated. After 12 weeks of healing, rats were selected randomly for histomorphometry, microcomputed tomography evaluation, and biomechanical testing. Results: Surface characterization analysis demonstrated that the addition of Mg did not dramatically change the surface topography or apatite patterns of the coating. Histomorphometry revealed higher bone-to-implant contact and bone area ratio for MgHA-coated implants than for HA-coated implants. Microcomputed tomographic evaluation revealed improved trabecular parameters and increased osseointegration for MgHA-coated implants. Biomechanical testing revealed that the MgHA coating increased the maximum push-out force and interfacial shear strength compared to the HA coating. Conclusion: Mg incorporated into an HA coating on titanium implants could improve the biologic fixation of implants in osteoporotic bone. Keywords: dental implants, hydroxyapatite, magnesium, osseointegration, osteoporosis

Purpose: This study tested the null hypothesis that phosphate-treated titanium implants would perform no differently on mineral apposition rates (MARs), new bone-to-implant contact (new BIC), and total bone-to-implant contact (total BIC) compared to standard titanium implants. Materials and Methods: Forty 3.3 × 8.0-mm titanium implants, either phosphate-treated or untreated, were placed in the mandibles of five foxhounds following 6 weeks of postextraction healing. The untreated implants (control) had sandblasted, acid-etched (SLA) surfaces, while the treated implants were electrolytically phosphorylated at 50 volts (T50) or 100 volts (T100). Confocal and histologic analyses were performed on all the implants after 4 weeks of healing. Results: The MARs could not be analyzed due to a lack of delineation between the three bone markers. New BIC results for control implants ranged from 6.0% to 56.0% with a mean of 23.92% and standard deviation (SD) of 13.29%; T50 implants ranged from 8.0% to 43.0% with a mean of 22.29% and SD of 10.26%; and T100 implants ranged from 0.0% to 47.0% with a mean of 17.43% and SD of 11.40%. Total BIC results for control implants ranged from 8.0% to 68.0% BIC with a mean of 41.4% and SD of 19.3%; T50 implants ranged from 21.0% to 65.0% with a mean of 43.7% and SD of 15.2%; and T100 implants ranged from 5.0% to 68.0% with a mean of 38.0% and SD of 19.5%. Conclusion: Within the limitations of this pilot study, no significant differences in new BIC or total BIC were found between the three implant groups (C, T50, and T100). Given the very large sample size required to show clinically significant differences, phosphated surfaces do not appear to provide additional advantages to SLA surfaces. Keywords: acid-etched, BIC, phosphate, titanium

Purpose: This study established local delivery with a calcium phosphate (CaP) coating and investigated effects of delivery on implant osseointegration by in vitro and in vivo experiments. Material and Methods: Simvastatin was prepared onto titanium surfaces with varying concentration (10-7, 10-6, 10-5, and 10-4 mol/L). Surface characteristics were performed by field-emission scanning electron microscope (FSEM), x-ray diffractometer (XRD), and fourier transform infrared spectroscopy (FTIR). Alkaline phosphatase activity (ALP) and osteocalcin release were used to measure osteoblastic activities. Ovariectomized rats randomly received control and test implants in both tibiae. After 4 and 12 weeks of implantation, the tibiae were retrieved and prepared for histomorphometric evaluation. Results: FSEM observation showed that the size of flakes decreased with an increase of simvastatin concentrations. XRD and FTIR examinations demonstrated that all coatings were composed of octacalcium phosphate (OCP). Simvastatin-loaded titanium surface had an increased effect on ALP activities at different concentrations on day 4 and day 7, and only the 10-6 mol/L group showed significant differences on day 14 (P .05). The 10-6 mol/L group showed significant expression of osteocalcin (P .05). Test implants (10-6 mol/L) showed a significantly greater bone area and boneimplant contact compared to control implants during the observation periods (P .05). Conclusions: It was concluded that the local delivery of simvastatin was established onto implant surfaces using the biomimetic CaP coating and could improve osteoblast function and implant osseointegration in ovariectomized rats. Keywords: calcium phosphate coating, implant, osteoblast, osseointegration, simvastatin

Purpose: To evaluate the effects of caffeine and/or estrogen deficiency on trabecular bone area (TBA) and bone healing in rats. Materials and Methods: Rats were divided into groups (n = 15/group) as follows: control, caffeine, ovariectomy (OVX), and caffeine/OVX. Critical-sized defects were created in the tibiae (57 days after beginning caffeine administration and 43 days after OVX). The intact femurs were evaluated for TBA and the number of positive cells for tartrate-resistant acid phosphatase (TRAP), receptor activator of nuclear factor-κB ligand (RANKL), and osteoprotegerin (OPG). In the defects, bone healing, the number of TRAP+ and RANKL/OPG+ cells, and gene expression of bone morphogenetic protein (BMP)-2, BMP-7, osteopontin, and CBP/p300-interacting-transactivator-with-ED-rich-tail-2 (CITED-2) were evaluated. Results: Bone healing was poorer in defects of the caffeine group than in those of the control group. The femurs of the OVX and OVX/caffeine groups presented lower TBAs and higher RANKL/OPG+ cell ratios. The number of TRAP+ cells was higher in femurs of the caffeine group and in defects of the OVX group. The caffeine/ OVX group presented the highest RANKL/OPG+ cell ratio in femurs and defects. The OVX group presented the highest expression of BMP-2, BMP-7, and CITED-2. Conclusion: Caffeine affected bone healing, while estrogen deficiency mainly affected TBA, but no significant deleterious synergic effects of both conditions were observed. Keywords: bone density, bone morphogenetic protein, caffeine, osteoprotegerin, receptor activator of nuclear factor kappa-B ligand (RANKL)

Purpose: The purpose of this study was to analyze the functional stresses around implants and supporting tissues placed in different combinations in the grafted and nongrafted atrophic posterior maxilla and to consider the acceptability of various fixed partial denture treatment options. Materials and Methods: A computer model of the atrophic posterior maxilla was created from the computed tomography images of an actual patient. Three different treatment scenarios were modeled with partial denture restorations, grafted and nongrafted maxillary sinuses, and various implant inclinations. Oblique forces were applied to simulate chewing movements. Stress analyses were performed with a three-dimensional finite element analysis computer program, and the von Mises and minimum principal stresses on the implants and supporting tissues were compared. Results: In all models, minimum principal (compressive) stress peak points were the highest within the crestal cortical bone (49.761 MPa), lower within sinus cortical (14.144 MPa) and trabecular bone (4.347 MPa), and lowest within grafted bone (0.049 MPa). The second molar implant in the third model (5 × 11-mm implant, inclined 45 degrees) showed the highest von Mises stresses (499.50 MPa), and the second molar implant in the first model (6 × 5-mm implant) showed the lowest (219.63 MPa) von Mises stresses. Conclusions: The stress absorption capacity of graft material is not sufficient and is much lower than that of other supporting tissues. For a fixed partial prosthesis, the use of short, wide implants with sinus floor bicortical fixation was found to be the most feasible approach for the atrophied posterior maxilla. Keywords: dental implants, finite element analysis, fixed partial prosthesis, maxillary sinus augmentation, short implants

Attached gingiva is a crucial aspect of healthy peri-implant tissue. Severely atrophied jaws have minimal quantities of attached gingiva. Any surgical procedure bears the potential risk of further loss of attached gingiva. The split-thickness flap described here provides excellent access. Using a biopsy punch, the periosteum is easily cut in semicircular fashion on the labial surface of the bone so that it remains pedicled on the lingual or palatal ridge. The split-thickness flap permits fixation of the gingival flap to the periosteum. The periosteal flap is closed with sutures to achieve soft tissue closure over the implants even in case of simultaneous vestibuloplasty. Keywords: split thickness flap, periosteal flap

Purpose: This study compared the 1-year success rates of immediately loaded dental implants to delayed loaded implants, regardless of the surgical technique (flapless or conventional full-thickness flap) and regardless of extraction time. It also examined whether the surgical technique had an influence on the success rate of the immediately loaded implants. Materials and Methods: A total of 344 dental implants, some with a new expanded winged-thread design, were placed in 155 patients; 53% of the implants were immediately loaded. Of the immediately loaded implants, 68.9% were placed with a flapless surgical technique and 88% were placed in extraction sites. Pocket depth, mobility, bleeding on probing, presence of erythema, pain, or radiolucency around the implants, as well as clinical findings, were recorded. Implants were followed from placement through definitive restoration. Descriptive, univariate, and multivariate analyses using clustered marginal approach of the Cox proportional hazards model were applied. Results: Of the 344 implants in the study, 10 (2.9%) failures were recorded, 7 of which were immediately loaded; however, there was no significant difference in failure rates between the immediate and delayed loading groups. Seven of the implants that failed were placed with a flapless (extraction site) technique; however, there was no significant difference in the failure rates between the flapless versus full-thickness flap technique in immediately loaded implants. Conclusions: The clinical success of immediately loaded implants after 1 year showed no difference from the success rate of delayed loaded implants. The implantation procedure (flapless versus conventional flap) or extraction time also had no influence on the success rate of the immediately loaded implants. Keywords: dental implants, flapless implant placement, immediate loading, implant failure, implant success, open flap

Purpose: A retrospective study was performed to evaluate the feasibility of simultaneous use of immediately loaded zygomatic and mandibular implants for full maxillomandibular restoration. Materials and Methods: A total of 40 zygomatic and 112 conventional implants were placed in 19 edentulous and partially edentulous patients and restored with full-arch acrylic resin prostheses within 3 hours of surgery. Implant insertion torque values were between 35 and 45 Ncm. Results: During the 1-year follow-up period, none of the 19 patients experienced implant or prosthesis failures. The patients did not experience any sinus infections or any other surgical complications from the performed procedures. Conclusion: Zygomatic and conventional implants can be simultaneously placed in the maxilla and mandible and successfully loaded with an acrylic resin prosthesis using the All-on-Four concept. Keywords: dental implants, immediate loading, insertion torque, zygomatic implants

Purpose: To report on the use of angled implants placed into the vomer/nasal crest to support a complete-arch maxillary prosthesis. Materials and Methods: Consecutive patients were treated with the All-on-Four concept to restore the maxillary dentition. When bone volume in the subnasal region was inadequate, angled implants were placed into the vomer/nasal crest area to support the restoration. All implants were loaded immediately. Results: One hundred consecutive maxillary All-on-Four patients were treated over a period of 2 years. Four hundred six implants were placed; 12 were inserted into the vomer/nasal crest area. One year later, at definitive restoration, the 12 vomer implants were found to be osseointegrated without bone loss or instability. Conclusions: Midline maxillary bone volume at the nasal crest appeared to be a viable alternative to the lateral nasal rim when subnasal bone was deficient. Vomer implants allowed for immediate function or were sometimes used as a rescue implant when an anterior implant failed. Keywords: All-on-Four protocol, M point, nasal crest, vomer implant, vomer/nasal crest bone mass, V point

The randomized prospective double-blinded clinical trial (RCT) is accepted as Level I evidence and is highly regarded. However, RCTs that gained FDA approval of drugs such as Vioxx, Fen- Phen, and oral and intravenous bisphosphonates have proven to generate misleading results and have not adequately identified serious adverse reactions. The development, research, and clinical marketing of the oral and intravenous bisphosphonates can serve as a representative example for the deteriorated value of many of today's RCTs. The expected high value of RCTs is jeopardized by: (1) sponsorship that incorporates bias; (2) randomization that can select out an expected improved result or eliminate higher-risk individuals; (3) experimental design that can avoid recognition of serious adverse reactions; (4) blinding that can easily become unblinded by the color, shape, odor, or administration requirements of a drug; (5) definitions that can define an observation as something other than what it actually represents, or fail to define it as an adverse reaction; (6) labeling of retrospective data as a prospective trial by using adjudicators prospectively to look at retrospective data; (7) change of the length of study to avoid the longerterm adverse reaction from accumulation of drug or treatment effects; (8) ghost writing, as when drug company physicians or a hired corporation either edit or write the entire protocol and/or manuscript for publication. Such corruption of the well-intended properly conducted RCT should be viewed with a sense of outrage by practitioners and requires a restructuring of the levels of evidence accepted today. Keywords: intravenous bisphosphonates, oral bisphosphonates, randomized clinical trials

Just a decade ago, the outlook appeared limitless for the use of bisphosphonates for the treatment of a large number of metabolic bone diseases ranging from osteoporosis to cancerrelated bone alterations to oral bone loss. Soon thereafter, however, osteonecrosis of the jaw (ONJ) emerged as a rare but significant condition associated with bisphosphonate treatment. Although many questions remain concerning ONJ, some significant knowledge has been gained over the past decade. Ideas have emerged regarding how to stage and treat the condition, and a number of preclinical models have been developed that will soon begin to speed progress toward understanding the pathophysiology of this condition. Researchers have also discovered that ONJ is not specific to bisphosphonates, as other potent antiremodeling agents have now been associated with the condition. While antiremodeling agents remain essential tools in medicine, ONJ has somewhat slowed the momentum for this drug class, especially as it relates to new and emerging applications. Until more effective prevention or treatment regimens for ONJ are developed, this side effect of remodeling suppression will continue-for better or worse-to have a significant impact on the field. One potential treatment option may be in the form of osteoanabolics. Exciting new data have emerged demonstrating the efficacy of teriparatide (parathyroid hormone) in reversing oral cavity bone loss and even as a potential therapy for ONJ. Keywords: anabolic agents, antiremodeling agents, bisphosphonates, bone remodeling, osteonecrosis of the jaw

Purpose: It was hypothesized that mesenchymal stem cell (MSC)-derived growth factor applied by iontophoretic transdermal delivery might improve ultraviolet beam (UVB)-induced photoaged skin. This experimental study was performed to confirm this hypothesis. Materials and Methods: Photoaged skin was induced in nude rat after an 8-week regimen of UVB irradiation, and an MSC-conditioned medium (MSC-CM) was conducted by an iontophoretic transdermal transport system. The effect of iontophoresis with MSC-CM was evaluated by replica method and measurement of the hyaluronic acid level in the dermis after treatment. Results: MSC-CM conducted by iontophoresis significantly reduced all parameters for wrinkles and increased hyaluronic acid in the dermis. Conclusion: MSC-CM application by iontophoresis can be considered as a supplemental treatment to the methods for skin rejuvenation. Keywords: growth factor, iontophoresis, skin rejuvenation, stem cell

Purpose: This study sought to confirm, through histologic evaluation, the vitality and viability of the island osteoperiosteal flap (i-flap) in a rabbit tibia model. Materials and Methods: In four rabbits, an osteotomy was performed on the tibial aspect of the right leg. A bone flap was raised, but the periosteal attachment was kept intact. The free-floating i-flap was separated from the rest of the bone by a silicone sheet. The rabbits were to be sacrificed after 1, 2, 4, and 8 weeks and histologic samples examined. Results: All surgeries were accomplished successfully; however, three animals showed fractured tibiae within a few days after surgery and were sacrificed immediately after the fractures were discovered. The fourth rabbit was sacrificed at 4 weeks. Histologic specimens showed vital new bone in the i-flap area and signs of remodeling in the transition zone and the original basal bone. Conclusion: The i-flap remained vital. This suggests potential for use in bone augmentation strategies, particularly for the alveolar split procedure. Keywords: alveolar split osteotomy, bone augmentation, island osteoperiosteal flap, rabbit model, tibia

Purpose: Modern bone tissue engineering associated with mesenchymal stem cells (MSCs) provides promising treatment alternatives for the loss of bone, one of the foremost challenges in oral and craniofacial surgery today. The effect of gabapentin-lactam (GBP-L) and its analogs on osteogenic differentiated MSCs has not yet been deciphered. Consequently, this study investigates the effect of novel trans-8- tertbutylgabapentin-lactam (trans-8-TB-GBP-L) hydroxamic acid derivatives on metabolism, proliferation, and physiologic mineralization characteristics of ovine osteoblast cells. Materials and Methods: Osteoblasts were extracted and prepared from sheep femoral heads and cultured in medium enriched with hydroxamic acid derivatives of trans-8-TB-GBP-L. The cell proliferation rate, cell metabolism, cell viability, and basic osteoblastic function were assessed. Results: After 3 and 5 days of incubation, no significant increase in DNA content was detected in any of 12 test groups versus the control group. However, after 8 days of incubation, a significant increase of DNA contents in the test groups containing nanomolar concentrations of trans-8-TB-GBP-L hydroxamic acid derivatives was found. No significant aberration in metabolic activity was detected when any of the test substances were applied. ALP displayed similar activity rates among the test groups and the control at all time points. Calcification of osteoblastic cells occurred solely when nanomolar concentrations were used. Conclusion: Trans- 8-TB-GBP-L hydroxamic acid derivatives do not interfere with physiologic function and phenotype of ovine osteoblasts. However, when applied at nanomolar concentrations, the assessed GBP-L derivatives significantly increased the cell proliferation rate after 8 days of incubation, indicating a doseresponse curve with the maximum peak at nanomolar concentration and a retarded drug response between 5 and 8 days. Keywords: gabapentin-lactam analogs, osteoblast proliferation, tissue engineering, trans-8-tertbutylgabapentin-lactam hydroxamic acid derivatives

This report presents seven patients who were treated with combined alveolar split/sinus grafting technique and dental implants and followed for 1 to 3 years. The grafting material included bone morphogenetic protein-2 in an absorbable collagen sponge plus allograft. The procedure was successful in all patients, who received implants either simultaneously with grafting or 4 to 6 months after grafting. Keywords: allografts, alveolar split osteotomy, bone morphogenetic protein, book flap, dental implants, i-flap, interpositional bone grafting, sinus elevation

In the face of growing demands and challenges in implant therapy, implant surfaces with improved biologic capabilities are required. This review paper summarizes the findings of recent in vitro and in vivo studies related to ultraviolet (UV) photofunctionalization of titanium. UV photofunctionalization is defined as an overall phenomenon of modification of titanium surfaces occuring after UV treatment, including the alteration of physicochemical properties and the enhancement of biologic capabilities. Bone morphogenesis around UV-treated titanium implants is distinctly improved compared with that seen around untreated control implants, leading to rapid and complete establishment of osseointegration with nearly 100% bone-toimplant contact in an animal model, as opposed to less than 55% for untreated implants. A series of in vitro studies demonstrated considerable enhancement of attachment, retention, and subsequent functional cascades of osteogenic cells derived from animals and humans after UV treatment. UV treatment converts titanium surfaces from hydrophobic to superhydrophilic and removes unavoidably contaminated hydrocarbons. UV-treated titanium surfaces also manifest a unique electrostatic status and act as direct cell attractants without the aid of ionic and organic bridges, which imparts a novel physicochemical functionality to titanium, which has long been understood as a bioinert material. UV treatment is simple and low in cost, and it has been proven effective for all types of titanium surfaces tested. These data suggest that UV photofunctionalization can be a novel, effective measure to improve implant therapy in the dental and orthopedic fields. Future research will focus on validating these findings in clinical studies. Keywords: bioactivity, biologic aging, bone-titanium integration, hydrocarbon, osseointegration, superhydrophilic, ultraviolet treatment

The engineering, design, manufacture, and rationale for use of printed titanium shells for alveolar bone reconstruction using BMP-2/ACS/allograft are described. This is proposed as a possible improvement to the current hand-configured mesh graft technique in common use today. Keywords: alveolar bone graft, graft containment, titanium mesh, titanium shell

Purpose: Successful repair and regeneration in bone tissue engineering vastly depends on proper interaction between the tissue-engineered construct and the recipient's immune system. In clinical application, adverse responses to bioartificial implants may result in chronic inflammation and loss of the implant. It is known that prolonged inflammation linked to NF-κB inflammatory pathways inhibits bone-forming activity of osteoblast cells. Contributing to orchestrate inflammatory processes, the ligand-activated transcription factor peroxisome proliferator-activated receptor alpha (PPARα) holds inhibitory effects on NF-κB and CEBβ activity. Sp1, a widely expressed transcription factor, has been linked to PPAR pathways, cellular homeostasis, and responsiveness to environmental perturbation. Formerly not being characterized, the role of PPARα in inflammatory-mediated bone loss requires further investigation. The aim of the present study was to identify regulatory transcription factor binding sites (TFBS) on the PPAR alpha promoter and to assess the role of Sp1 and associated proteins in its regulation. Materials and Methods: In a first set of experiments, polymerase chain reaction assessed the presence of PPARα gene expression in isolated murine bone tissue. Deletion mutagenesis was performed on the human PPARα (hPPARα) promoter gene, and the deletion constructs were transiently transfected to murine osteoblasts to identify important TFBS. PPARα promoter-driven reporter gene expression was monitored in response to overexpression and repression of Sp1 to analyze functional transcription factor recruitment to the PPARα promoter. Results: This study could demonstrate that the full-length hPPARα promoter contains inhibiting promoter regions and that hPPARα basal expression can be significantly increased by deletion mutagensis. Sp1 TFBS proved functional in the regulation of PPARα promoter activity, and the first five Sp1 motifs on the PPARα promoter were sufficient to significantly increase PPARα expression. Additional transient co-transfection experiments could not detect any direct effect of NF-κB/IκB downstream pathway on the regulation of PPARα promoter activity. Taken together, we could demonstrate that Sp1 plays a key role in transcriptional regulation of PPARα promoter activity and gene expression. Conclusion: This study provides further insight on Sp1-dependent PPARα regulatory mechanisms and suggests that Sp1-regulated PPARα expression plays a key role in inflammatory mediated bone loss. Keywords: bone tissue engineering, inflammation, NF-κB, PPARα, osteoblast, Sp1

Purpose: The objective of this study was to establish a method for accurate cell counting from matrix-rich cell sheets in the clinical setting. Materials and Methods: Human periodontal ligament (HPDL) cells were obtained from healthy donors to prepare PDL cell sheets. To obtain single cell suspensions, the cell sheets were treated with three different enzymatic formulations: collagenase alone, trypsin-ethylenediaminetetraacetic acid (EDTA) alone, and a combination of collagenase and trypsin-EDTA. After cell dispersion, cell numbers and cell survival rates were measured. To evaluate damage to the cell surfaces from the enzymes, the dispersed cells were analyzed by a flow cytometer with an anti-alkaline phosphatase antibody. Results: Treatment with collagenase alone or trypsin-EDTA alone dispersed few cells from HPDL cell sheets. In contrast, combined treatment with collagenase and trypsin-EDTA successfully produced a large amount of single cells from cell sheets. Flow cytometry analysis showed that single cells obtained by combined use of collagenase and trypsin-EDTA preserved alkaline phosphatase epitopes on the cell surfaces. Conclusions: Cell sheets rich with extracellular matrix were dispersed via combined treatment with collagenase and trypsin-EDTA without destroying the expression of cell surface markers. The results suggest that this method would be useful for determining the accurate cell number of cell sheets for cell therapies and should also be applicable for other kinds of matrixrich cell sheets. Keywords: cell sheet, collagenase, extracellular matrix, human periodontal ligament cells, trypsin-ethylenediaminetetraacetic acid

Purpose: To determine whether a collagen scaffold could provide an environment for mesenchymal stem cell (MSC)-related bone repair of critical-size bone defects in rat calvaria. Materials and Methods: Craniotomy defects were created in 28 adult Sprague-Dawley rats. Two additional rats were used as MSC donors by means of femoral bone marrow lavage and culture. The rats were randomly divided into four groups: (1) empty/no graft; (2) collagen scaffold (matrix) + saline; (3) matrix + MSCs; (4) matrix + bone morphogenetic protein. The animals were euthanized 28 days after surgery. Microcomputed tomographic reconstructions were obtained to measure bone fill. The specimens were processed for histologic examination, and the total defect and bone fill areas were measured. Results: Mean bone fill (± standard deviation) of 9.25% ± 10.82%, 19.07% ± 17.38%, 44.21% ± 3.93%, and 66.06% ± 15.08%, respectively, was observed for the four groups; the differences were statistically significant. Bone repair was statistically significant for groups 3 and 4. No significant difference was seen for bone repair between groups 1 and 2 or between groups 3 and 4. Bone formation differed significantly across the four groups. Statistically significant changes in radiodensity were observed between groups 1 and 3, groups 1 and 4, and groups 2 and 4. Significant differences were not observed between groups 1 and 2, groups 2 and 3, or groups 3 and 4. Conclusion: After grafting of adult MSCs adherent within a collagen matrix, repair of bone was significant. Expanded three-dimensional collagen represents a radiolucent, resorbable, biocompatible scaffold that is capable of supporting MSC repair of bone. Keywords: adult mesenchymal stem cell, bone repair, collagen matrix, osteogenesis, rat calvaria model, tissue engineering

Paranasal bone affects the decision-making process for placement of implants for immediate function in the highly resorbed maxilla. The most important bone for apical fixation of implants in this setting is the lateral nasal bone mass. Maximum available bone mass found at the pyriform above the nasal fossa, designated M point, can most often engage two implants placed at 30-degree angles. The second most important area of paranasal bone mass is the subnasal bone of the premaxilla, which is required to engage an angled implant at the alveolar crest. However, only 4 to 5 mm in height is needed when implants are angled posterior to engage M point. The third most important paranasal bone site for implant fixation is the midline nasal crest extending upward to the vomer. This site, which is usually type 1/2 bone, can engage implants apically and provide enough fixation for immediate function even if implants are short. These anatomical bone sites enable placement of implants to obtain a 12- to 15-mm anterior-posterior spread, which is favorable for immediate function. Keywords: anterior-posterior spread, immediate function, M-4, M point, pyriform rim, V point, vomer/nasal crest, zygomatic implants

Purpose: To present a retrospective report of eight significant alveolar defects in which the alveolus was regenerated with recombinant human bone morphogenetic protein 2 (rhBMP-2) combined with anorganic bovine bone and contoured using titanium mesh to facilitate implantsupported restorations. Materials and Methods: A total of seven patients underwent extractions and debridement of the compromised alveolar sites with simultaneous grafting using a mixture of rhBMP-2 and anorganic bovine bone. The three-dimensional contour of the compromised alveolus was reestablished using titanium mesh with rigid screw fixation. Implants were placed a minimum of 6 months after healing and subsequently were restored. Results: The treated defects were successfully regenerated and did not require any additional surgery prior to implant placement or prosthetic restoration. A total of 14 implants were placed and restored with fixed single or multiple restorations. Thirteen of the 23 treated sites were in the anterior esthetic zone. Conclusion: Vertical and horizontal alveolar bone defects can be predictably regenerated by grafting with a combination of rhBMP-2 and anorganic bovine bone contained by titanium mesh to successfully accommodate implant placement. Keywords: bone grafting, bone regeneration, rhBMP-2, titanium mesh