The International Journal of Oral & Maxillofacial Implants, 04/2015

Purpose: A biochemical approach to implant surfaces can improve bone growth, resulting in desirable boneimplant interfaces. This study was conducted to identify the effect on osseointegration of direct coating of titanium (Ti) implants with poly(D,L-lactide-co-glycolide)(PLGA)/recombinant human bone morphogenetic 2 (rhBMP-2) submicron particles by electrospray. Materials and Methods: Anodized Ti implants were used as a control group, and implants coated with 80 μL of PLGA/rhBMP-2 (50 μg/mL rhBMP-2 per implant) submicron particles by electrospray were used as the experimental group in an in vivo rabbit tibia model. After 3 or 7 weeks of healing, specimens were obtained and prepared for histologic and histomorphometric analyses. Results: The implant surface coated with submicron PLGA/rhBMP-2 showed new bone growth in the apical direction earlier than control implants. In the experimental group at 3 weeks, the bone-to-implant contact ratio and bone area of the three best consecutive threads were significantly higher than those in the control group. However, there was no significant difference between groups at 7 weeks. Conclusion: Within the limitations of this study, the PLGA/rhBMP-2-coated implants facilitated osseointegration between bone and the Ti surface during the early healing phase. Keywords: anodized implant, electrospray, implant coatings, osseointegration, polylactic polyglycolic acid, recombinant human bone morphogenetic protein 2, submicron particle

Purpose: To determine the accuracy of applied torque of different implant controller and handpiece combinations by using an electronic torque gauge. Materials and Methods: Four combinations of the following devices were tested: Surgic XT controller (NSK), XIP10 controller (Saeshin), X-SG20L handpiece (NSK), CRB26LX handpiece (Saeshin). For five torque settings, 30 measurements were recorded at 30 revolutions per minute by using an electronic torque gauge fixed to jigs, and means were calculated. Results: Applied torques were generally higher than the set torque of 10 and 20 Ncm and lower than the set values of 40 and 50 Ncm. The average torque deviations differed significantly among the combinations (P .05). At 10 and 20 Ncm, the Surgic XT/X-SG20L combination yielded the closest value to the intended torque, followed by the XIP10/X-SG20L combination. At 30 Ncm, the XIP10/X-SG20L combination showed the nearest value. At 40 Ncm, the Surgic XT/X-SG20L, XIP10/CRB26LX, and XIP10/X-SG20L combinations showed deviations within 10%. At 50 Ncm, all the combinations showed lower applied torque than the set value. Large standard deviations were observed in the Surgic XT/CRB26LX (13.288) and Surgic XT/X-SG20L (7.858) combinations. Conclusion: Different combinations of implant controllers and handpieces do not generate significant variations in applied torque. The actual torque varies according to the torque setting. It is necessary to calibrate devices before use to reduce potentially problematic torque. Keywords: deviation, handpiece, implant controller, torque

Purpose: To evaluate correlations between marginal bone resorption and high insertion torque value (> 50 Ncm) of dental implants and to assess the significance of immediate and early/conventional loading of implants under a certain range torque value. Materials and Methods: Specific inclusion and exclusion criteria were used to retrieve eligible articles from Ovid, PubMed, and EBSCO up to December 2013. Screening of eligible studies, quality assessment, and data extraction were conducted in duplicate. The results were expressed as random/fixed-effects models using weighted mean differences for continuous outcomes with 95% confidence intervals. Results: Initially, 154 articles were selected (11 from Ovid, 112 from PubMed, and 31 from EBSCO). After exclusion of duplicate articles and articles that did not meet the inclusion criteria, six clinical studies were selected. Assessment of P values revealed that correlations between marginal bone resorption and high insertion torque were not statistically significant and that there was no difference between immediately versus early/conventionally loaded implants under a certain range of torque. Conclusion: None of the meta-analyses revealed any statistically significant differences between high insertion torque and conventional insertion torque in terms of effects on marginal bone resorption. Keywords: dental implant, dental implant loading, insertion torque, meta-analysis

Purpose: This study evaluated the clinical and histomorphometric results of titanium (Ti) and custom-made zirconia (Zr) implants placed into fresh extraction sockets in beagles that did not receive oral hygiene attention or a softened diet during postoperative healing. Materials and Methods: The roughness of the Ti and Zr implant surfaces was assessed by confocal microscopy. In eight beagle dogs, four implants each (two Ti and two Zr) were placed in the distal sockets of the third and fourth premolars with the implant shoulder at the bone crest and subjected to submerged healing. Standardized radiographs were taken after placement and 5 months after placement (at sacrifice). Histologic and histomorphometric measurements were performed on nondecalcified histologic sections. The main outcome measures included implant survival, bone-implant contact (BIC), and bone loss on the buccal and lingual plates. Results: Topographic analysis showed significant differences between the Zr and Ti surfaces. Roughness was higher for Ti than for Zr implants, kurtosis was close to 3 for Ti, and skewness was negative for Zr. After 5 months, the mean BIC was similar for the Zr (57.0% ± 15.2%) and Ti (56.5% ± 14.4%) implants, and the most severe bone loss site was observed on the buccal wall. The risk of failure was significantly higher for the Zr (43.8%) than for the Ti (12.5%) implants. Conclusion: The implant failure rate for the Zr implants was 3.5 times higher than that of the Ti implants. This may be partially explained by the less favorable topography of the Zr implants, which had, on average, significantly lower roughness (Ra = 0.85 ± 0.04 μm), negative skewness of the surface profile (-1.56 ± 0.27), and higher kurtosis (7.88 ± 1.99). Keywords: histomorphometry, immediate implant, osseointegration, titanium, zirconia

Purpose: Clinicians need to know whether there are any differences among the many abutment options available for restoring a particular implant. This study aims to compare nine abutments for one implant system for positional changes between hand tightening and torqueing. Materials and Methods: Nine Tapered Screw-Vent (TSV) implants were placed into a resin block. Five specimens of nine different abutments (n = 45) were tried in one of the nine implants. Initially, the abutments were torqued to 20 Ncm to represent hand tightening. Abutments were tightened to 30 Ncm using a torque driver as recommended by the manufacturer for final seating. Images were recorded in 12-second intervals for approximately 10 minutes after the torque was applied. The spatial relationship of the abutments to the resin block was determined using three-dimensional digital image correlation. Commercial image correlation software was used to analyze the displacements. Mean displacements for the nine different abutments were calculated in all three dimensions and for overall displacement in space. A t test with a step-down Bonferroni correction was used for a pairwise comparison of each abutment's mean displacements to the other abutments to determine statistical differences (α = .05). Results: The Atlantis titanium, Inclusive titanium, and Legacy zirconia abutments showed mean displacements that were statistically significantly higher than other abutments in the horizontal direction. The overall three-dimensional displacement of the Atlantis titanium abutment after an applied 30-Ncm torque was significantly higher than that of six of the other eight abutments (P .0144). Conclusion: Within the limitations of this in vitro study, the Zimmer PSA demonstrated less displacement between hand tightening and torqueing than the Atlantis titanium or Inclusive titanium abutments when used to restore a TSV implant. Keywords: abutment, cement-retained, displacement, implant, torque

Purpose: Because the microtopography of titanium implants influences the biomaterial-tissue interaction, surface microtexturing treatments are frequently used for dental implants. However, surface treatment alone may not determine the final microtopography of a dental implant, which can also be influenced by the implant macrogeometry. This work analyzed the effects on surface roughness parameters of the same treatment applied by the same manufacturer to implants with differing macro-designs. Materials and Methods: Three groups of titanium implants with different macro-designs were investigated using laser interferometry and scanning electron microscopy. Relevant surface roughness parameters were calculated for different regions of each implant. Two flat disks (treated and untreated) were also investigated for comparison. Results: The tops of the threads and the nonthreaded regions of all implants had very similar roughness parameters, independent of the geometry of the implant, which were also very similar to those of flat disks treated with the same process. In contrast, the flanks and valleys of the threads presented larger irregularities (Sa) with higher slopes (Sdq) and larger developed surface areas (Sdr) on all implants, particularly for implants with threads with smaller heights. The flanks and valleys displayed stronger textures (Str), particularly on the implants with threads with larger internal angles. Conclusion: Parameters associated with the height of the irregularities (Sa), the slope of the asperities (Sdq), the presence of a surface texture (Str), and the developed surface area of the irregularities (Sdr) were significantly affected by the macrogeometry of the implants. Flat disks subjected to the same surface treatment as dental implants reproduced only the surface topography of the flat regions of the implants. Keywords: dental implants, implant design, osseointegration, surface texturing, surface topography, titanium

Purpose: To investigate the effect of core dental implant materials supporting single crowns on the probability of survival and failure modes. Materials and Methods: Thirty-six standard external-hex titanium implants (4.0 mm in diameter) were selected to restore single crowns and divided into two groups according to core material: commercially pure grade 2 titanium (G2) and grade 5 titanium-aluminum-vanadium alloy (Ti-6Al- 4V) (G5). Abutments were screwed to the implants, and standardized maxillary central incisor metal crowns were cemented and subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and reliability for missions of 100,000 cycles at 150 N and 200 N (with 90% two-sided confidence intervals [CIs]) were calculated. Polarized light and scanning electron microscopes were used to determine the failure modes. Results: Use-level probability Weibull calculations showed beta values of 0.59 (CI, 0.31 to 1.11) and 1.22 (CI 0.81 to 1.84) for G2 and G5, respectively, and significantly higher characteristic strength and Weibull modulus for G5. The calculated reliability (90% CIs) for a mission of 100,000 cycles at 150 N showed that cumulative damage would lead to survival of 45% of implant-supported crowns of G2 and 98% of G5. At 200 N the probability of survival decreased to 0.03% for G2 and 21% for G5. Abutment screw fracture was the failure mode for all groups. Conclusion: Reliability, characteristic strength, and Weibull modulus were significantly higher for Ti-6Al-4V dental implants than for commercially pure (grade 2) titanium implants. Failure modes were similar for both groups. Keywords: biomechanics, dental implants, failure testing, fatigue testing, reliability, Weibull curves

Purpose: To evaluate the effect of diamondlike carbon (DLC) coating on abutments and/or abutment screws on the reliability, characteristic strength, and Weibull modulus of implant-supported single crowns. Materials and Methods: Seventy-two external hexagon implants (Emfills Implant 4 mm diameter, 10 mm length, Emfills) were divided into four groups (n = 18 each), according to the presence or not of a DLC coating in the abutment and/or abutment screw, as follows: abutment without coating, screw without coating (AwcSwc); abutment without coating with coated screw (AwcSC); abutment coated with noncoated screw (ACSwc), and coated abutment with coated screw (ACSC). Abutments and screws were evaluated with scanning electron microscopy. The specimens were subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and reliability for a mission of 100,000 cycles at 150 N (90% two-sided confidence intervals) were calculated. Polarized light and scanning electron microscopes were used for fractographic analysis. Results: For a mission of 100,000 cycles at 150 N, reliability was 0.45 (0.20 to 0.67), 0.12 (0.00 to 0.47), 0.56 (0.17 to 0.82), and 0.44 (0.07 to 0.77) for AwcSwc, AwcSC, ACSwc, and ACSC, respectively. The probability Weibull calculation showed a Weibull modulus (m) of m = 5.50, m = 11.64, m = 16.96, and m = 15.08 and the characteristic strengths (η, which indicates the load at which 63.2% of the specimens of each group fail) of η = 202.67 N, η = 206.64 N, η = 192.54 N, and η = 203.59 N for AwcSwc, AwcSC, ACSwc, and ACSC, respectively. Abutment screw fracture was the chief failure outcome in all groups. Conclusion: Characteristic strength values were not different among groups; neither was reliability. However, an increase in Weibull modulus (indicating low variability of the results) was observed with DLC coating of abutment or screw or both. Keywords: abutment screw, dental implants, carbon, reliability, step-stress accelerated life testing, Weibull

Purpose: To compare the choice and placement of virtual dental implants in the posterior edentulous bounded regions using the full cross-sectional and transaxial capabilities of cone beam computed tomography (CBCT) vs reformatted panoramic images and three-dimensional (3D) virtual models. Materials and Methods: Fifty-two cases with posterior bounded edentulous regions (61 dental implant sites) were identified from a retrospective audit of 4,014 radiographic volumes. Two image sets were created from selected CBCT data: (1) a combination of reformatted panoramic imaging and a 3D model (PIref/3D), and (2) the full 3D power in CBCT image volume analyses (XS). One virtual implant was placed by consensus of three prosthodontists in each image set: PIref/3D and XS. The choice of implant length and the perceived need for ridge augmentation were recorded for implant placement in both test situations. All the virtual implant placements from both PIref/3D and XS image sets were inspected retrospectively using virtual 3D models, and the number of exposed threads on both the buccal and lingual/palatal aspects of the virtual dental implant was evaluated. The chi-square and paired t tests were used with the level of significance set at α = .05. Results: Shorter implants were chosen more often using XS than PIref/3D (P = .001). Fewer threads were exposed when placed with XS than with PIref/3D (P = .001). The use of XS reduced the perceived need for ridge augmentation compared with PIref/3D (P = .001). Conclusion: The use of the full 3D power of CBCT (including cross-sectional images in all three orthagonal planes and transaxially) provides supplemental information that significantly changes the choice of virtual implant length and vertical position of the implant, and reduces the frequency of perceived need for ridge augmentation before implant placement. Keywords: computed tomography, dental implants, digital image processing, reformatted panoramic imaging, virtual study model, virtual surgical planning, x-ray cone beam

Purpose: To establish a method for measuring the heat generated when preparing an osteotomy site, and to assess for correlations of rotational speed, proceeding speed, loading value of the drill (contact pressure), motion pattern, and bone density with temperature increases. Materials and Methods: A thermocouple was placed in the internal irrigation hole of a 2.0-mm-diameter twist drill used for measuring osteotomy site temperature. In the artificial blocks, two different densities were used to drill under varying conditions including drill proceeding, rotating speed, and motion pattern. The drilling procedure was repeated five times for each combination, and the data collected were statistically analyzed using multiple regression analysis. Results: Strong positive correlations were found among bone density, drill motion pattern, and maximum temperature, and a positive correlation was found in proceeding speed (P .001). Rotation speed and maximum temperature were not correlated (P .001). Conversely, loading values of the drill increased with the lower rotation speed and higher proceeding speed, which were effective in controlling the temperature rise. Conclusion: When preparing a simulated bone for an osteotomy with a thermocouple inserted into a twist drill with internal irrigation, the drilling motion pattern, bone density, drill speed, and proceeding rate affected bone temperature, in descending order. It was also observed that bone temperature correlated positively with speed and negatively with proceeding speed, independent of density. This indicates that lower drill speed and higher proceeding speed without excessive loading values minimize the bone temperature heat. Keywords: heat generated, methods for measuring, socket preparation

Purpose: Mechanical imbalance caused by mechanical overload or poor bone quality around a dental implant can result in osseointegration failure. To avoid that, it is important to identify an appropriate safety stress margin (critical stress level). For this study, a novel device was developed to generate a quantitative amount of static compressive stress under an aseptic closed condition. The aim was to clarify the amount of critical stress produced on the cortical bone when static compression is applied to the osseointegrated bone-implant interface. Materials and Methods: Small parts for bone sustaining, load generation, and load transmittance were developed to generate quantitative static compressive stress at the bone-implant interface and implanted inside the tibial cortical bone in adult beagle dogs. Each tibia in two dogs received bone-sustaining parts, then after 2 months, the load-transmitting parts were placed into the bone-sustaining parts. After another 2 months, various magnitudes of static compressive stress (0-180 MPa) were generated by tightening the load-generating part to the osseointegrated bone-implant interface. After 7 days, the animals were euthanized, and dissected blocks were prepared for histomorphometric analyses. Results: There were no obvious signs of bone resorption or loss of osseointegration in any of the dogs. The change in shape of osteon was not influenced by the amount of static compressive stress. However, periosteal reactions were observed under the cortical bone on the opposite side. Conclusion: These results indicate that osseointegrated bone-implant interfaces show minimal response based on the magnitude of static compressive stress, even when such stress is greater than 120 MPa. Keywords: bone-implant interface, critical stress, osteon, quantitative analysis, static compressive stress, structural optimization

Purpose: To compare implants in healthy conditions and implants with peri-implantitis with regard to their clinical parameters and the microbiologic composition at the peri-implant sulcus, inside the implant connection, and the gingival sulcus of neighboring teeth. Materials and Methods: A cross-sectional study was performed including consecutive patients with implants in healthy conditions and with peri-implantitis. Clinical parameters for which patients were screened included bleeding on probing, pocket depth, and plaque index at six sites. Samples for microbiologic analysis were obtained from three locations: the peri-implant sulcus, inside the implant connection, and the gingival sulcus of neighboring teeth. Quantitative real-time polymerase chain reaction (PCR) was carried out for total counts of 10 microorganisms: Aggregatibacter actinomycetemcomitans, Porphyromona gingivalis, Tanerella forsythia, Tanerella denticola, Prevotela intermedia, Peptostreptococcus micros, Fusobacterium nucleatum, Campylobacter rectus, Eikenella corrodens, and Candida albicans. The response variables were the percentage of positive sites and total bacterial counts. Results: One hundred twenty-two implants in 57 patients were analyzed in the healthy group and 113 implants in 53 patients in the peri-implantitis group. Differences between the groups were statistically significant for bruxism, probing pocket depth, bleeding on probing, and radiographic bone level. Orange complex species (P intermedia, P micros, F nucleatum) were the most prevalent in the three types of sites for both groups, and prevalence values were higher in the peri-implantitis group. Differences in prevalence between groups were more marked inside the connection than in the peri-implant sulcus. Absolute loads of most microbes and total bacterial counts were higher for the peri-implantitis group in the three locations. Again, differences were bigger inside the connection than at the peri-implant sulcus. Significant interactions were found for prevalence and absolute microbial loads between groups and locations, and for the interaction of group × location. Conclusion: Clinical and microbiologic differences were observed between healthy subjects and those with peri-implantitis. Microbiologic differences between groups were more marked inside the connection than in the peri-implant sulcus. The potential role of the implant connection as a microbial reservoir for peri-implant diseases and in the outcome of their treatment should be confirmed with further studies. Keywords: contamination of the implant connection, microbiologic contamination, peri-implantitis, periopathogen bacteria, RT-PCR

Purpose: Safe loading of dental implants requires an optimal osseointegration. This osseointegration process during healing could be analyzed by resonance frequency analysis (RFA). The purpose of the study was to evaluate RFA changes during healing in splinted, early-loaded, thermal acid-etched, hydrophilic implants over time. Materials and Methods: Patients received a minimum of two implants: an implant with the prosthetic abutment connection at the crestal bone level (bone level) and one with the prosthetic abutment connection at a 2.5-mm supracrestal site (tissue level). Implant stability was measured at weeks 0, 2, 3, and 12 using the Osstell device. Results: Seventy-six implants were placed in 32 patients. By week 2, early-loaded tissue-level implants showed a significant drop in mean ± standard deviation (SD) implant stability quotient (ISQ) values of 2.2 ± 3.6 (P .001). Changes in ISQ values were significant between weeks 3 and 12 and also between weeks 0 and 12, with mean differences of 4.2 (P .001) and 2.8 (P .001), respectively. Early-loaded bonelevel implants show a significant change in ISQ of 2.3 ± 3.7 at week 2 (P .01) and -1.3 ± 4.7 at week 12 when compared to an ISQ value of 2.9 ± 4.9 at week 3 (P .01). Bone-level implants achieved higher ISQ values compared with tissue-level implants at weeks 0, 2, 3, and 12, with mean differences being 3.8 ± 5.5 (P .01), 3.8 ± 6.1 (P .01), 3.7 ± 6.7 (P .01), and 2.3 ± 5.8 (P .05), respectively. Conclusion: This study found a significant dip in ISQ values, with the lowest point seen at week 2. ISQ values remained higher in bone-level implants throughout the process of healing and osseointegration. Keywords: abutment connection, dental implant, osseointegration

Purpose: To assess and compare the outcomes and economic complication burden of three-unit toothsupported fixed dental prostheses (TFDPs) and implant-supported single crowns (ISCs) provided to a sequential cohort in a specialist prosthodontic practice over a 15-year period. Materials and Methods: Sequential patients requiring replacement of a single missing tooth between 1996 and 2010 with a metal-ceramic three-unit TFDP (n = 145 patients, n = 174 prostheses) or ISC (n = 174 patients, n = 220 prostheses) were included. Prostheses subjectively judged at insertion to have an unfavorable 10-year prognosis (17 TFDPs, 0 ISCs) were removed from statistical analyses. The estimated cumulative survival (ECS) was calculated with the life table actuarial method and standard errors calculated with the Greenwood formula. Differences in outcomes between all prostheses and those replacing only anterior or only posterior teeth were assessed with the log rank test. Complication incidence, severity, and economic burden, measured in time/cost accounting units (TAUs), were tallied and compared descriptively. Results: The 15-year ECS did not differ for 112 TFDPs (92.75% ± 3.28%) and 81 ISCs (95.95% ± 2.92%) replacing posterior teeth. However, the 15-year ECS was significantly greater for 139 ISCs (93.33% ± 6.44%) than for 45 TFDPs (82.82% ± 6.50%) replacing anterior teeth. The economic burden of nonterminal complications for both prostheses was low (mean = 0.3 and 0.2 TAUs per prosthesis for TFDPs and ISCs, respectively). This equated to 3 TAUs/100 years in clinical service and 4 TAUs/100 years in clinical service for the TFDPs and ISCs, respectively. Conclusion: The survival of three-unit TFDPs and ISCs over 15 years was not statistically different when replacing posterior teeth, but ISCs survived significantly better when replacing anterior teeth. The complication rates of the TFDPs and ISCs were similar, but the economic burden for the TFDPs was greater. Keywords: cost analysis, fixed dental prostheses, implant-supported single crowns, prospective study, survival analysis

Purpose: To determine whether performing an inferior meatal antrostomy as a prophylactic intraoperative maneuver in patients who underwent zygomatic implant surgery significantly reduces the incidence of postoperative sinusitis. Materials and Methods: A double-blind randomized controlled trial was implemented. The study included 44 patients seen at the Oral and Maxillofacial Surgery Department at Universidad El Bosque in Bogota, Colombia, who required zygomatic implant surgery. Patients were randomly allocated to either group 1 (without inferior meatal antrostomy) or group 2 (with inferior meatal antrostomy). Patients were evaluated clinically and radiographically 15 days and 3 months after surgery, and classified depending on whether they did or did not develop sinusitis. Results were analyzed using descriptive and bivariate statistics. The control group event rate, experimental group event rate, relative risk, relative risk reduction, absolute risk reduction, and number needed to treat values were calculated for further analysis. Results: Three patients allocated to group 1 showed clinical and radiographic signs of sinusitis after zygomatic implant surgery, for an overall rate of sinusitis of 13.6%. No patient in group 2 developed clinical or radiographic signs of sinusitis. Conclusion: The results of this study suggest that performing an inferior meatal antrostomy as a prophylactic intraoperative maneuver in patients who require zygomatic implant surgery is an effective method to prevent postoperative sinusitis. Keywords: inferior meatal antrostomy, sinusitis, zygomatic implants

Purpose: Treatment of titanium with UV light immediately before use, or photofunctionalization, is gaining traction as a simple method to improve the biologic capability and clinical performance of dental implants. The objective of this study was to examine the effect of photofunctionalization on the biologic capability and mechanical anchorage of orthodontic miniscrews. Materials and Methods: Untreated and photofunctionalized Ti-6Al-4V orthodontic miniscrews were placed into rat femurs. Photofunctionalization was performed by treating miniscrews with UV light for 12 minutes using a photo device immediately before placement. After 3 weeks of healing, miniscrews were pushed laterally to measure the resistance against the tipping force. The miniscrews were also evaluated for morphology and chemistry of tissue formed around them using scanning electron microscopy and energy dispersive spectroscopy. Rat bone marrow-derived osteoblasts were cultured on Ti-6Al-4V disks with and without photofunctionalization. The number of osteoblasts attached to the disks and the behaviors, alkaline phosphatase activity, and mineralization capability of osteoblasts were evaluated. Results: Photofunctionalization converted both disk and screw surfaces from hydrophobic to superhydrophilic. In vivo biomechanical testing showed that the displacement of untreated screws was 1.5 to 1.7 times greater than that of photofunctionalized screws when subjected to lateral tipping force. Robust bone formation was observed around photofunctionalized miniscrews with strong elemental peaks of calcium and phosphorus, whereas the tissue around untreated miniscrews appeared thin and showed no clear peak of calcium. The attachment, initial spreading, adhesion, and expression of functional phenotypes of osteoblasts were significantly increased on photofunctionalized Ti-6Al-4V disks. Conclusion: These in vivo and in vitro results comprehensively and consistently demonstrate that photofunctionalization increases the bioactivity of Ti-6Al-4V and improves the anchoring capability of orthodontic miniscrews. Keywords: biologic aging, bone-implant integration, hydrophilicity, Ti alloy, osseointegration

Purpose: To evaluate the efficacy, associated morbidity, and results of a three-dimensional reconstruction technique for repairing severe defects of the maxilla using a calvarial autogenous bone graft and a soft tissue double-layered surgical approach in preparation for placing dental implants. Materials and Methods: Bone defects of the maxilla consecutively reconstructed with calvarial autologous graft in the authors' institution were retrospectively evaluated. Patients with combined maxilla alveolar ridge defects with a width less than 4 mm and a height less than 7 mm (to the level of the maxillary sinus or the nostril), with at least three teeth involved, were included in the study. Calvarial bone blocks were sagittally sectioned in fine layers and fixed three-dimensionally in a boxlike structure with particulate bone inside. The purpose was to obtain an adequate amount of vertical and horizontal alveolar bone to enable restoration with dental implants at least 3.4 mm in diameter and 11 mm in length. Results: Eleven reconstructive procedures were performed in 10 patients. Bone graft integration was successful in all of them. No major complications were observed in the donor cranial site. A mean bone gain of 5.04 mm (range, 3.4 to 7.8 mm) in height was obtained (standard deviation [SD], 1.69). The implant surgery was performed between the 15th and 19th weeks. A total of 28 implants were placed, and the mean follow-up time was 45 months (range, 23 to 65 months; SD, 12). The mean graft vertical resorption was 0.78 mm (range, 0.50-1.50 mm; SD, 0.00) 41 months after implant fixation. Conclusion: Three-dimensional reconstruction technique using calvarial bone grafts to restore severe segmental or crestal bone defects in the maxilla is an effective and predictable procedure that can increase the horizontal and vertical bone volume in preparation for the successful placement of dental implants. Keywords: atrophic maxilla, calvarial bone graft, dental implants, onlay bone grafting, preprosthetic surgery, 3D reconstruction

Purpose: To evaluate the ideal implant insertion time in human bone biopsies after sinus elevation with a composite graft consisting of an equal amount of biomaterial and autologous bone, by comparing the bone regeneration obtained 4 to 5 months after surgery with that obtained after 6 to 8 months, and using the adjacent native bone as reference. Materials and Methods: Twenty-six biopsy specimens of 11 patients were analyzed. Two groups were created depending on the time of implant insertion: group t1 at 4 to 5 months (n = 13) and group t2 at 6 to 8 months (n = 13). The same volume of grafted bone and native bone were analyzed for each biopsy with microcomputed tomography (microCT) and gene expression analysis. Results: Statistically significant differences were found in bone mineral density (BMD), bone volume fraction, and trabecular separation (TbSp) between native and grafted bone in both groups, with higher grafted bone values, except for the variable TbSp, which was lower in the grafted bone. This decrease in TbSp in the grafted bone in both groups can be explained by the significant increase in trabecular thickness in group t2 and the trabecular number in group t1, compared with native bone. No significant differences were found between the two groups in the morphometric parameters and BMD of the grafted bone. Also, no significant changes in the messenger RNA (mRNA) levels of bone formation, bone resorption, and inflammatory markers were found between both groups, with the exception that alkaline phosphatase mRNA levels were significantly lower in group t1 relative to native bone. Conclusion: This composite graft showed no differences in threedimensional microstructure, BMD, or at the molecular level between 4 to 5 months and 6 to 8 months of healing time. Thus, this time can be shortened to 4 months with the security of a grafted area of mature bone. Keywords: clinical study, composite graft, dental implant, gene expression, microcomputed tomography (microCT), sinus lift (SL)

Purpose: To prospectively evaluate peri-implant bone and soft tissue dimension changes around adjacent implants placed at different horizontal interimplant distances. Materials and Methods: Thirty partially edentulous patients, who underwent rehabilitation with two adjacent implant-supported crowns as part of their treatment plan, were assigned to three groups based on their prosthetic needs. Patients in group A (10 patients, 20 implants) were to have two implants placed at a 2-mm interimplant distance, patients in group B (10 patients, 20 implants) were to have two implants placed at a 3-mm interimplant distance, and patients in group C (10 patients, 20 implants) were to have two implants placed at an interimplant distance of > 4 mm according to their prosthetic needs. All patients received single-crown restorations after 3 months. Clinical examinations were performed at the time of crown placement (T3), and 6 months (T6), 12 months (T12), and 24 months (T24) after implant placement. Peri-implant bone levels were assessed radiographically at the time of implant placement (T0), and at T3, T12, and T24. Results: One patient from group C did not return for follow-up examinations after implant placement. The mean (± standard deviation) horizontal interimplant distance was 1.97 ± 0.44 mm for implants in group A, 3.12 ± 0.15 mm for implants in group B, and 5.3 ± 0.64 mm for implants in group C. For group A, the mean marginal bone loss was 0.29 ± 0.51 mm at the T0-T3 interval, 0.31 ± 0.36 mm at the T0-T12 interval, and 0.27 ± 0.33 mm at the T0-T24 interval. For group B, the mean marginal bone loss was 0.16 ± 0.29 mm at the T0-T3 interval, 0.20 ± 0.28 mm at the T0-T12 interval, and 0.23 ± 0.28 mm at the T0-T24 interval. For group C, the mean marginal bone loss was 0.51 ± 0.84 mm at the T0-T3 interval, 0.45 ± 0.72 mm at the T0-T12 interval, and 0.44 ± 0.74 mm at the T0-T24 interval. For group A, the mean midproximal bone loss was 0.33 ± 0.50 mm at the T0-T3 interval, 0.45 ± 0.35 mm at the T0-T12 interval, and 0.40 ± 0.32 mm at the T0-T24 interval. For group B, the mean midproximal loss was 0.31 ± 0.37 mm at the T0-T3 interval, 0.32 ± 0.39 mm at the T0-T12 interval, and 0.33 ± 0.42 mm at the T0-T24 interval. For group C, the mean midproximal bone loss was 0.40 ± 0.44 mm at the T0-T3 interval and 0.41 ± 0.50 mm at both the T0-T12 and T0-T24 intervals. There were no statistically significant differences in marginal and midproximal bone crest loss between the different groups at any time point. Conclusion: The study failed to support the hypothesis that horizontal interimplant distance has an effect on peri-implant bone and soft tissue dimension changes for implants with internal conical implant-abutment interface connection and platform-switching characteristics. Keywords: bone loss, clinical, dental implants, prospective, radiology

Purpose: To clinically and histologically evaluate the soft tissue thickening seen on acellular human dermis grafting at implant placement, taking into consideration the biotype. Materials and Methods: Mucosal thickness was measured before and 4 months after implant placement, when the thickness of the epithelium and corium and the inflammation were histologically evaluated with a skin biopsy. Results were analyzed using the Mann-Whitney U test and linear regression analysis. Results: In a total of 47 implant sites (22 uncovered and 25 covered by the allograft matrix), the grafted sites showed a significantly greater increase in thickness compared with the control sites. Histology was unable to show differences between groups. Nevertheless, using an individual variation index involving the histologic and initial clinical thickness, the increase in thickness of grafted sites was statistically significant (P = .017) compared with the decrease in control sites. Furthermore, the greatest thickness increase was recorded in sites with thin biotype, whereas a decrement was found in control sites. The inflammation index was similar in both groups. Conclusion: This study demonstrated the effectiveness of evaluating the increase in mucosal thickness with acellular human dermis grafting, particularly in subjects with thin biotype. Keywords: acellular human dermis, dental implant, histometry, soft tissue augmentation

Purpose: The purpose of this retrospective clinical study was to evaluate the clinical outcomes of fixed implant-supported dental prostheses (FISDPs) and removable ISDPs (RISDPs) retained by telescopic attachments, the factors influencing survival, and the type and number of maintenance treatments required during the observation period. Materials and Methods: This retrospective clinical study is based on patients who were provided with ISDPs between 2004 and 2010. Patient sex, type of prosthesis, location, opposing dentition, and the effect of continuous follow-up on the probability of a favorable outcome, as well as the number of maintenance treatments, were analyzed. A statistical analysis was performed using the Kaplan- Meier method. Results: A sample of 233 patients with 157 FISDPs and 76 RISDPs supported by a total of 567 implants was randomized and included in the analysis. The mean observation period was 15.9 ± 15.4 months (maximum, 66.0 months). During the observation period, 3.9% of prostheses (7/157 FISDPs and 2/76 RISDPs) ceased to function and 2.3% of implants (13 implants) were lost. The mean survival time was 59.7 ± 2.3 months, with a survival probability of 90.2% after 3 years. Prostheses in the mandible showed significantly higher survival rates than those in the maxilla. Maintenance treatments had to be performed at an earlier stage for patients with RISDPs than for patients with FISDPs. In patients with a conventional removable prosthesis in the opposing arch, the time until maintenance was needed was significantly shorter. Conclusion: Within the limitations of a retrospective study, it can be concluded that the FISDPs and RISDPs show equally good survival rates after 3 years in function. RISDPs showed a greater and earlier need for maintenance treatments during the first years in function. Keywords: dental implants, dental prosthesis, dental prosthesis failure, implant-supported dental prosthesis, survival analysis

Purpose: This retrospective study evaluated and compared the 2-year outcomes for sinus floor elevation performed via either an osteotome-mediated sinus floor elevation (OSFE) technique or a reamer-mediated sinus floor elevation (RSFE) technique. Implant survival, as well as surgical and postoperative complications, were used as measures of comparison. Materials and Methods: Patients were analyzed according to defined inclusion criteria. Orthopantography was used to assess preoperative; immediate postoperative; and 6-, 12-, and 24-month postoperative bone level changes. Implant survival and the incidence of complications, including sinus membrane perforation, were evaluated using appropriate statistical tests. Results: From 2008 to 2010, 126 implants were placed simultaneously with sinus floor elevation in 85 patients (n = 43 women and 42 men; mean age ± standard deviation [SD] = 58.1 ± 10.2 years). The OSFE procedure (control) was used to place 65 implants in 45 patients, and the RSFE procedure (experimental) was used to place 61 implants in 40 patients. The mean maxillary residual bone height was 7.1 ± 1.6 mm. Endosinus bone gains were 5.7 ± 1.5 mm and 5.6 ± 2.3 mm for the experimental and control groups (P = .164), respectively, and the 2-year survival rates were 98.4% and 98.5%, respectively. Although no significant differences were observed between the two groups, three (6.7%) membrane perforations occurred in the OSFE group, and none occurred in the RSFE group. Other postoperative complications, including nasal bleeding, postoperative headache, and dizziness, were documented in 7 (15.6%) of 45 OSFE cases and 3 (7.5%) of 40 RSFE cases. Conclusion: The results presented herein indicate that comparable survival rates were achieved for implants placed in conjunction with a reamer- vs osteotome-mediated technique. Therefore, RSFE is a reliable and predictable procedure for implant placement in the posterior maxilla, with a low incidence of complications. Keywords: bone graft, dental implant, maxillary sinus, osteotome, reamer, sinus floor elevation

Purpose: The aim of this retrospective study was to investigate the possible association between peri-implant marginal bone loss and the apicocoronal (vertical) positioning of dental implants placed adjacent to a tooth. Materials and Methods: Dental records at the University of Michigan, School of Dentistry, were screened. To be included in the study, the patient had to have at least one implant in the premolar or molar region, unilaterally or bilaterally, in either arch, with an immediately mesial adjacent tooth. The implant had to have been functionally loaded for at least 3 years after crown insertion, and clear, nondistorted periapical films had to be available. Several landmarks were identified: the cementoenamel junction (CEJ) and crestal bone (CB) of the tooth adjacent to the implant, the implant platform (PL), and the first radiographic implant-bone contact (BL). The following parameters were measured: CEJ-PL, CEJ-CB, CB-PL, horizontal distance between the adjacent tooth and PL (HD), and vertical distance between BL and the first implant thread at the mesial (BL-m) and distal (BL-d) implant surfaces. Results: A total of 139 patients with a mean age of 62.1 ± 9.3 years were included. The mean follow-up period was 4.42 ± 2.5 years. When the implant was placed more than 3 mm apical to the CEJ of the adjacent tooth, significantly greater peri-implant bone loss occurred at the mesial (difference of means = 0.57 mm) and distal (difference of means = 0.83 mm) implant surfaces. Conclusion: In this study population, implants placed in the posterior area with a vertical distance greater than 3 mm from the CEJ of the adjacent tooth displayed more peri-implant bone loss. Further investigation is required to determine whether this increased peri-implant bone loss predisposes a site to peri-implantitis. Keywords: alveolar bone loss, dental implants, peri-implantitis, retrospective study

Purpose: To evaluate the performance of dental implant-supported telescopic crown (TC)-retained overdentures to restore the oral function of patients who have insufficient jawbone volume resulting from tumor resection or trauma. Materials and Methods: From January 2004 to December 2008, implant-supported TC-retained overdentures were used to restore the oral function of patients with severe bony defects resulting from tumor resection or trauma. Clinical data, including implant success and survival rates, biologic and mechanical complications, prosthodontic maintenance efforts, and patient satisfaction, were analyzed annually after delivery of the final prostheses. Results: Twenty-four patients were treated, and a total of 88 implants were inserted to support TC-retained overdentures. The mean modified plaque index of implants remained low (20%), and the majority of implants (>76.3%) in the study showed the absence of bleeding on probing at follow-up visits. Peri-implant marginal bone loss (MBL) ranged from 0.8 to 1.2 mm. There was no statistically significant difference in the MBL between maxillary and mandibular implants (P = .43). The implant success rate was 100% after 5 years, and the prosthodontic maintenance and complication rate was 0.22 times per year. More than 90% of patients were satisfied with the restoration of their oral function using TCs. Conclusion: Based on our study of 24 patients treated with TC-retained overdentures, it appears that this treatment may be a viable option for patients with insufficient jawbone volume. Keywords: implant-supported overdentures, telescopic crown, trauma, tumor resections

Purpose: Implant placement entails disruption of the epithelial continuity, which can lead to various complications. Therefore, the area of mucosal penetration is of particular interest clinically. The goal of the present study was to compare gene expression in peri-implant soft tissue (PIST) with that in oral mucosal tissue (OMT) using microarray analysis, and to investigate which genes were specifically expressed in PIST. Materials and Methods: The bilateral upper first molars were extracted from 4-week-old rats and titanium alloy implants placed only in the left-side extraction sockets. Four weeks after surgery, samples were harvested from the left-side PIST and right-side OMT and total RNA samples isolated. Microarray analysis was used to compare gene expression in PIST and OMT, which was then confirmed using quantitative realtime polymerase chain reaction. Immunohistochemical staining was also performed to confirm protein level expression. Results: The number of genes expressed with more than a twofold change in PIST compared with OMT was 1,102, of which 750 genes were upregulated and 352 genes were downregulated. The messenger RNA (mRNA) expression of three selected genes-CEACAM1, IFITM1, and MUC4-were more significantly expressed in PIST than in OMT(P .01). Immunohistochemical localization of CEACAM1, IFITM1, and MUC4 was observed in PIST, but no immunoreaction was recognized in OMT. Conclusion: The result of microarray analysis showed that, because of implant placement, 750 genes were upregulated in PIST compared with OMT. CEACAM1, IFITM1, and MUC4 were specifically upregulated in PIST. Keywords: dental implant, microarray analysis, oral mucosal tissue, peri-implant soft tissue

Purpose: Autologous bone is used for augmentation in the course of oral implant placement. Bone grafts release paracrine signals that can modulate mesenchymal cell differentiation in vitro. The detailed genetic response of the bone-derived fibroblasts to these paracrine signals has remained elusive. Paracrine signals accumulate in bone-conditioned medium (BCM) prepared from porcine cortical bone chips. Materials and Methods: In this study, bone-derived fibroblasts were exposed to BCM followed by a whole genome expression profiling and downstream quantitative reverse transciptase polymerase chain reaction of the most strongly regulated genes. Results: The data show that ADM, IL11, IL33, NOX4, PRG4, and PTX3 were differentially expressed in response to BCM in bone-derived fibroblasts. The transforming growth factor beta (TGF-β) receptor 1 antagonist SB431542 blocked the effect of BCM on the expression of the gene panel, except for IL33. Conclusion: These in vitro results extend existing evidence that cortical bone chips release paracrine signals that provoke a robust genetic response in mesenchymal cells that is not exclusively mediated via the TGF-β receptor. The present data provide further insights into the process of graft consolidation. Keywords: ADM, bone-conditioned medium, bone supernatant, IL11, IL33, NOX4, PRG4, PTX3, SB431542