The International Journal of Oral & Maxillofacial Implants, 02/2009

Purpose: To understand the contribution of stromal cells, such as granulation tissue fibroblasts, to peri-implantitis with regard to (1) the secretion of constitutive factors promoting migration/survival of infiltrates into osseointegrated sites; and (2) the effect of exogenous infiltrate cytokines on the cells' secretion. Materials and Methods: Fibroblasts were cultured from eight peri-implantitis sites. Multiplexed enzyme-linked immunosorbent assay was used to quantify factors secreted by the cells either unstimulated or stimulated with gamma interferon (IFNg), interleukin 4 (IL4), or tumor necrosis factor alpha (TNFa). Controls consisted of fibroblasts cultured from healthy gingival and chronic periodontitis granulation tissues. Results: Peri-implantitis fibroblasts differed significantly from periodontitis fibro-blasts in their reduced secretion of the collagen inducer transforming growth factor beta-1 (TGFb1) and tissue inhibitor of metalloproteinase-1. The cells exhibited enhanced secretion of angiogenic factor vascular endothelial growth factor (VEGF) and collagenolytic matrix metalloproteinase 1 (MMP1) compared to both healthy and periodontitis fibroblasts. Fibroblasts from both periodontitis and peri-implantitis sites exhibited a pronounced proinflammatory profile compared to normal gingival fibro-blasts with respect to secretion of chemokines IL6, IL8, and monocyte chemoattractant protein 1 (MCP1). Fibroblasts stimulated with TNFa showed increased levels of IL6, IL8, MCP1; neutrophil chemokine growth-related oncogene alpha stimulation with IFNg increased MCP1; and stimulation with IL4 increased VEGF. Conclusion: The results indicate that peri-implantitis fibroblasts represent a distinct stromal population. The cells might participate in the pathogenesis of peri-implantitis by up-regulating both vascularity and matrix breakdown, thus promoting migration/maintenance of infiltrates into the site. Cytokines produced by infiltrates could enhance the inflammatory nature of the cells in a self-feeding loop. Keywords: fibroblast heterogeneity, host response, multiprotein arrays, peri-implantitis

Purpose: The use of nanotechnology to enhance endosseous implant surfaces may improve the clinical control of interfacial osteoblast biology. This study investigated the influence of a nanostructure-coated implant surface on osteoblast differentiation and its effects on bone-to-implant contact (BIC) and removal torque values. Materials and Methods: Titanium disks were machined (M) or machined and subsequently treated by acid etching (Ac) or by dipping in an aluminum oxide solution (Al2O3). Surfaces were characterized by scanning electron microscopy, atomic force microscopy, and x-ray microanalysis. For the in vitro experiment, rat mesenchymal stem cells (rMSCs) were grown in osteogenic supplements on the disk surfaces for 3 days. Real-time polymerase chain reaction (PCR) was used to measure mRNA levels of several gene products (bone sialoprotein, osteocalcin, osteopontin, and RUNX-2). For the in vivo experiment, titanium implants were placed in rat tibiae and harvested after 3 to 21 days for measurement of bone-specific mRNA levels by real-time PCR. Removal torque and BIC were measured 3 to 56 days after placement. Results: Average height deviation (Sa, in nm) values for M, Ac, and Al2O3 implants were 86.5, 388.4, and 61.2, respectively. Nanostructured Al2O3 topographic features applied to machined implants promoted MSC commitment to the osteoblast phenotype. Greater bone-specific gene expression was observed in tissues adjacent to Al2O3 implants, and associated increases in BIC and torque removal were noted. Conclusion: Nanostructured alumina may directly influence cell behavior to enhance osseointegration. Keywords: alumina, implant surface, nanostructured surface, nanotechnology, sol-gel coating, surface treatment

Purpose: To establish a basis for weighing the potential diagnostic and therapeutic benefits of three-dimensional cone-beam (CB) data sets in contrast to digital orthopantomography (OPG) and computerized tomography (CT) in implant dentistry. Materials and Methods: Twenty-seven patients requiring implant surgery received a single presurgical CB scan. A follow-up digital OPG was taken within a maximal postsurgical period of 2 weeks. For comparison purposes, a control group of 29 patients receiving CT as well as CB diagnosis was analyzed. Image quality of the different modalities was ranked retrospectively by five experienced examiners (from excellent to insufficient) for up to 10 defined criteria, including general image quality and several specific structures. The results were analyzed statistically, and interobserver agreement was calculated using intraclass correlation coefficients (ICCs). Results: The median rating for all investigated criteria was good for CB imaging and between good and insufficient for OPG in the dental implant group. Except for general image quality, statistical analysis showed that CB imaging was significantly superior to OPG imaging for all investigated anatomic structures. With a few exceptions, all investigated anatomic structures in CT and CB imaging were rated excellent in the control group. No significant difference between CT and CB imaging was detected in the control group for all investigated criteria. With a few exceptions, ICCs were higher for CB images than for OPG. In the control group, ICCs for CT and CB images were similar, with a few exceptions. Conclusion: The results of the present study confirm superior radiographic visualization for all important high-contrast structures in presurgical implant dentistry assessment for CB imaging in contrast to OPG and a CT-like degree of information for high-contrast structures in CB data sets. Clinically, however, the elevated radiation dosages transmitted by CB imaging must be taken into account. Keywords: computerized tomography, cone-beam imaging, dental implants, digital volume tomography, panoramic tomography, three-dimensional imaging

Purpose: The continual use of selective cyclooxygenase-2 (COX-2) inhibitors may have a negative impact on bone repair around titanium implants. Because modified implant surfaces could be considered an important strategy to increase success rates in some conditions that interfere in bone healing, the aim of this study was to investigate whether an aluminum oxide (Al2O3)-blasted implant surface could reduce the negative action promoted by the continuous administration of selective COX-2 inhibitors on bone healing around implants. Materials and Methods: Thirty Wistar rats received one titanium implant (machined or Al2O3-blasted surface) in each tibia and were randomly assigned to one of the following groups: saline (n = 14) or meloxicam (n = 16); each was administered daily for 60 days. Bone-to-implant contact (BIC), bone area (BA) within the limits of threads, and bone density (BD) in a zone lateral to the implant were examined in undecalcified sections. Results: The Al2O3-blasted surface resulted in significantly increased BIC in both groups, and meloxicam significantly reduced bone healing around implants (P .05). For the machined surface, significant differences were observed for BIC (39.48 ± 10.18; 25.23 ± 9.29), BA (60.62 ± 4.09; 42.94 ± 8.12), and BD (56.31 ± 3.64; 49.30 ± 3.15) in the saline and meloxicam groups, respectively. For the Al2O3-blasted surface, data analysis also demonstrated significant differences for BIC (45.92 ± 11.34; 33.30 ± 7.56), BA (61.04 ± 4.39; 44.89 ± 7.11), and BD (58.77 ± 2.93; 50.04 ± 3.94) for the saline and meloxicam groups, respectively. Conclusions: The Al2O3-blasted surface may increase BIC; however, it does not reverse the negative effects promoted by a selective COX-2 inhibitor on bone healing around implants. Keywords: anti-inflammatory agents, dental implants, osseointegration, selective cyclooxygenase-2 inhibitors, wound healing

Purpose: Computer-aided oral implant surgery offers several advantages over the traditional approach. The purpose of this study was to evaluate the in vivo accuracy of computer-aided, template-guided oral implant surgery by comparing the three-dimensional positions of planned and placed implants. Materials and Methods: Oral implant therapy was performed in two treatment centers on eligible patients using computerized tomography (CT)-based software planning and computer-aided design/computer-assisted manufacture stereolithographic templates. A second CT scan was obtained after surgery. Preoperative and postoperative CT images were compared (planned vs actual implant positions), and the accuracy of this type of image-guided therapy was assessed. Results: Twenty-five adult patients were included in this retrospective study; 17 (11 partially and eight fully edentulous arches) were treated in center 1, and eight (six partially and two fully edentulous arches) in center 2. Of the 104 implants inserted with the computer-aided method, 100 integrated, giving a cumulative survival rate of 96% (mean follow-up, 36 months). There were no major surgical complications. With regard to accuracy, 89 implants were available for comparison; mean lateral deviations at the coronal and apical ends of the implants were 1.4 mm and 1.6 mm, respectively. Mean depth deviation was 1.1 mm and mean angular deviation was 7.9 degrees. There was a statistically significant correlation in the accuracy of any implants placed with the same guide. There was no difference in accuracy data from the two private centers; nor could a learning curve be demonstrated. Conclusions: Based upon this clinical study of 25 patients, the following observations were made: (1) computer-aided oral implant surgery used in two treatment centers provided a high likelihood (96%) of implant survival, and (2) deviations from planned implant positions existed in the coronal and apical portions of the implants as well as with implant angulation. Mean deviations were less than 2 mm in any direction and less than 8 degrees. Keywords: computer-assisted surgery, dental implant, minimally invasive surgery, stereolithography, surgical template

Purpose: Because vertical ridge augmentation with autogenous bone blocks carries with it a risk of graft resorption and donor site morbidity, the aim of the present study was to compare histologically the healing following vertical ridge augmentation using screwable, xenogenous deproteinized blocks or autologous bone blocks in dogs. Materials and Methods: Standardized vertical mandibular defects were surgically created in edentulous ridges of six foxhounds. Two bone blocks (6 3 10 3 15 mm) were inserted on each mandibular side and fixed with both a titanium implant and an osteosynthetic screw. Three different therapies were tested: (1) xenogenous block alone; (2) xenogenous block, covered with a chemically cross-linked collagen membrane; and (3) autologous blocks, harvested during defect preparation. After 3 months of submerged healing, the miniscrews were removed and replaced by dental implants. Following an additional healing period of 3 months, the animals were sacrificed, and dissected blocks were prepared for histomorphometric analysis. Results: During the primary healing period, three of 12 hemimandibles (six blocks) had to be removed because of severe inflammatory reactions (two xenogenous block sites with collagen membrane, one autologous block site). In general, histologic analysis revealed that xenogenous blocks, used alone or combined with a collagen membrane, exhibited osteoconductive properties on a level equivalent to that of autologous blocks, resulting in means of 50% to 60% of ossification of the blocks. Some parts of the xenograft were encased in soft tissue, partly surrounded by multinuclear giant cells. However, all groups showed obvious signs of bone/graft resorption. Conclusions: Within the limits of the present study, it was concluded that the examined screwable xenogenous bone block might be a useful scaffold for ridge augmentation procedures. However, the combination of xenogenous blocks with a cross-linked collagen membrane did not appear to improve outcomes. Keywords: alveolar ridge augmentation, animal study, block augmentation, collagen membrane, guided bone regeneration

Purpose: The passive fit of a superstructure on implant abutments is essential to success. One source of error when using a tapered cone-screw internal connection may be the difference between the tightening torque level applied to the abutments by the laboratory technician compared to that applied by the treating clinician. The purpose of this study was to measure the axial displacement of tapered cone-screw abutments into implants and their replicas as a function of the tightening torque level. Materials and Methods: Twenty tapered cone-screw abutments were selected. Two groups were created: 10 abutments were secured into 10 implants, and 10 abutments were secured into 10 corresponding implant replicas. Each abutment was tightened in increasing increments of 5 Ncm, from 0 Ncm to 45 Ncm, with a torque controller. The length of each sample was measured repeatedly with an Electronic Digital Micrometer. The mean axial displacement for the implant group and the replica group was calculated. The data were analyzed by the Mann-Whitney and Spearman tests. Results: For both groups, there was always an axial displacement of the abutment upon each incremental application of torque. The mean axial displacement values varied between 7 and 12 µm for the implant group and between 6 and 21 µm for the replica group at each 5-Ncm increment. From 0 to 45 Ncm, the total mean axial displacement values were 89 µm for the implant group and 122 µm for the replica group. Conclusion: There was a continuous axial displacement of the abutments into implants and implant replicas when the applied torque was raised from 0 to 45 Ncm. Torque applied above the level recommended by the manufacturer increased the difference in displacement between the two groups. Keywords: cone-screw abutment, dental implants, implant-supported dental prosthesis, internal conical interface

Purpose: The aim of this study was to evaluate, through fluorescence analysis, the effect that different interimplant distances, after prosthetic restoration, will have on bone remodeling in submerged and nonsubmerged implants restored with a "platform switch." Materials and Methods: Fifty-six Ankylos implants were placed 1.5 mm subcrestally in seven dogs. The implants were placed so that two fixed prostheses, with three interimplant contacts separated by 1-mm, 2-mm, and 3-mm distances, could be fabricated for each side of the mandible. The sides and the positions of the groups were selected randomly. To better evaluate bone remodeling, calcein green was injected 3 days before placement of the prostheses at 12 weeks postimplantation. At 3 days before sacrifice (8 weeks postloading), alizarin red was injected. The amounts of remodeled bone within the different interimplant areas were compared statistically before and after loading in submerged and nonsubmerged implants. Results: Statistically significant differences existed in the percentage of remodeled bone seen in the different regions. Mean percentages of remodeled bone in the submerged and nonsubmerged groups, respectively, were as follows: for the 1-mm distance, 23.0% ± 0.05% and 23.1% ± 0.03% preloading and 27.0% ± 0.03% and 25.2% ± 0.04% postloading; for the 2-mm distance, 18.2% ± 0.05% and 18.1% ± 0.04% preloading and 21.3% ± 0.07% and 19.9% ± 0.03% postloading; for the 3-mm distance, 18.3% ± 0.03% and 18.3% ± 0.03% preloading and 18.8% ± 0.04% and 19.8% ± 0.04% postloading; for distal-extension regions, 16.6% ± 0.02% and 17.4% ± 0.04% preloading and 17.0% ± 0.04% and 18.4% ± 0.04% postloading. Conclusions: Based upon this animal study, loading increases bone formation for submerged or nonsubmerged implants, and the interimplant distance of 1 mm appears to result in more pronounced bone remodeling than the 2-mm or 3-mm distances in implants with a "platform switch." Keywords: bone remodeling, dental implants, dogs, fluorescence, microscopy

Purpose: The purpose of this study was to explore the influence of extraction on the stability of implanted titanium microscrews. Materials and Methods: Six male beagle dogs received 96 microscrews between the mesial and distal roots of the second, third, and fourth premolars and the first molar in both maxillae and mandibles. The third and fourth premolars were extracted from each dog. Test implants were placed near the extraction sites, and control implants were placed at a distance from the extraction sites. The bone remodeling process at the interface was studied through bio-mechanical pull-out testing, histomorphologic observation, and histomorphometric asssessment after different amounts of healing time (1, 3, or 8 weeks). Results: Two microscrews were loose in the test group at week 1. Near the extraction regions, both the peak pullout force at extraction (Fmax) and the bone-implant contact (BIC) of the microscrews were lower than that seen in the control group at week 1, but quickly surpassed the control groups at week 3. After 8 weeks of healing time, Fmax and BIC values between test and control groups exhibited no differences. The lowest BIC value was 10.12%, and the corresponding pull-out force was 100.23 N. At week 1, the inflammatory reaction at the bone-implant interface in the test groups was stronger than in the control groups. At week 3, many active osteoblasts gathered along the interface and a bone matrix excreted by osteoblasts around the microscrew were observed in the test group. Conclusions: A BIC of at least 10% provided resistance to orthodontic forces. For microscrews placed near extraction regions, the risk of loosening was highest in the first week following implant placement. The most active bone remodeling at the implant-bone interface occurred 3 weeks after implantation, especially for screws near extraction regions. Keywords: anchorage, extraction, microscrews, osseointegration

Purpose: The aim of this prospective clinical study was to evaluate the survival rates at 12 months of a new implant design placed in the anterior and premolar areas of the maxilla and immediately restored with single crowns. Crestal bone loss was also assessed. Materials and Methods: Patients seeking replacement of at least one failing maxillary tooth were recruited to participate in the study. Exclusion criteria included compromised general health conditions, severe maxillomandibular skeletal discrepancies, severe parafunctional habits, drug or alcohol abuse, poor oral hygiene, and a need for bone augmentation. Implants incorporating the platform-switching concept were placed into fresh extraction sockets in the maxilla, with each patient receiving a provisional restoration immediately after implant placement. After 15 days, definitive restorations were inserted. Mesial and distal bone levels were evaluated with digital radiography on the day after implant placement, 15 days later, and 1, 2, 3, 6, 8, and 12 months later. Primary stability was measured with resonance frequency analysis (RFA). Analysis of variance for repeated measures and a binary logistic regression model were used to assess the data. Results: Sixty-one implants were placed into fresh extraction sites in 25 men and 25 women ranging in age from 29 to 51 years (mean, 39.64 ± 6.06 years). One of the implants failed, and one was lost to follow-up. The mean bone loss measured on the mesial was 0.08 mm (SD 0.53 mm). Mean distal bone loss was 0.09 mm (SD 0.65 mm). Over the course of 12 months, the mean RFA value between baseline and 12 months was 71.1 ± 6.2. Conclusions: The implants remained stable over the course of 12 months and had an overall survival rate of 96.7%. Minimal crestal bone loss was recorded around the surviving implants. Keywords: immediate provisionalization, platform switching, resonance frequency analysis

Purpose: To study the outcome of implant placement in fresh extraction sockets with simultaneous use of particulate bone graft material. Materials and Methods: Patients referred to the maxillofacial surgery clinic for extraction and implant therapy were included in the study. A consecutive series of patients suitable for immediate placement in combination with extraction was subjected to implant surgery. Patients with ongoing inflammatory, exacerbating processes were not included. The space between implants and sockets was filled with autologous bone graft material. A two-stage surgical procedure was planned to optimize marginal bone healing. All patients were to be followed clinically and radiologically for 2 years according to a standard protocol. Results: Forty implants were placed in fresh extraction sockets in 26 patients (nine women and 17 men) with an average age of 60 years (range, 19 to 76 years). The most frequent site for implant placement was the anterior maxilla. Autologous bone graft material was used in all cases to fill the space between the implant and the socket borders. All implants were osseointegrated at the time of abutment connection. No complications were observed. Radiographic examination showed only slight marginal bone reduction of 0.13 mm mesially and 0.19 mm distally. Conclusion: Implants can be placed successfully in fresh extraction sockets using autologous bone graft material to fill the gap between implant and labial bone through a submerged surgical technique. This technique demonstrated acceptable clinical and radiographic outcomes over a 2-year period in 26 patients with 40 implants. Keywords: bone graft material, extraction sockets, immediate placement, implant surgery

Purpose: To compare the torsional strengths and the effects of functional loading on five different implant surface structures. Materials and Methods: This in vivo longitudinal study of 9 months' duration examined osseointegration in 180 stepped cylindric implants placed into the mandibles of 18 healthy sheepdogs. Implants with five different surface structures were placed (n = 36 in each group): (1) smooth surface; (2) deep profile structure (DPS); (3) titanium plasma sprayed (TPS); (4) hydroxyapatite coated; and (5) sol-gel hydroxyapatite coated (SGHA). All implants were investigated under standardized conditions. At uncovering (3 months), half the implants were loaded with prefabricated crowns for 6 months, and the other half remained unloaded. Removal torque values were evaluated at 3, 6, and 9 months after implant placement. The data were analyzed using analysis of variance and Scheffé correction (a .05). Results: All smooth-surface and SGHA implants failed in succession during the fourth and ninth months of the study. After 3 months the removal torque resistance of DPS, TPS, and hydroxyapatite-coated implants was significantly higher (P .001) than that seen in the other two groups. Initially, the removal torque resistance of unloaded hydroxyapatite-coated implants was superior, and the decrease during the observation period was not significant. The increase in removal torque resistance under functional loading was not significant for the DPS implants. A significant increase was found in removal torque resistance for the loaded TPS implants (P .05). The unloaded DPS and TPS implants showed no change in removal torque levels after the closed healing period of 3 months. Conclusions: Successful osseointegration was achieved with DPS, TPS, and hydroxyapatite-coated implants, and smooth-surface and SGHA implants failed. Removal torque resistance was enhanced with controlled functional loading. Keywords: functional loading, implant surfaces, osseointegration, torsional strength

Purpose: The purpose of this study was to evaluate the effectiveness of the platform-switching technique to prevent crestal bone loss following the restoration of dental implants. Materials and Methods: This randomized prospective multicenter trial analyzed 60 partially edentulous adults recruited at 12 professional dental centers. Subjects were randomly selected to receive either platform-enlarged or control cylindric implants in three different surgical procedures: conventional nonsubmerged, submerged, and submerged with a reduced abutment. The primary outcome measure was the change in crestal bone level assessed radiographically 12 and 24 months following placement. Nonparametric analysis of variance for repeated measures (the Friedman test) was used to assess the overall significance over time of the differences among implants in changes in crestal bone levels. Comparisons among and between groups of implants were performed by the nonparametric Friedman and Wilcoxon tests, respectively. In all the analyses an a = .05 was considered significant. Results: A total of 360 implants were placed (60 for each group). Three control implants failed during the 2nd year following placement. All submerged and 92% of nonsubmerged platform-enlarged implants exhibited no bone loss. Control implants with an abutment as large as the implant platform exhibited more bone loss than their platform-enlarged counterparts (P .001) or control implants with a reduced abutment (P .001). Submerged implants with an enlarged platform showed better crestal bone preservation than submerged control implants with a reduced abutment (P = .06). Conclusions: The findings of the current trial indicated that the use of implants with an enlarged platform can result in better preservation of crestal bone as compared with conventional cylindric implants when a reduced abutment is mounted. Keywords: bone loss, crestal bone, dental implants, platform-switching technique

Purpose: To evaluate the agreement of quantitative subjective evaluation of esthetic changes in implant dentistry and differences in perception among patients and practitioners. Materials and Methods: Four standardized clinical preoperative and postoperative pictures placed in random order were shown to 30 patients treated with dental implants, on two separate occasions, to subjectively evaluate the esthetic changes using both a graded scale and a visual analogue scale (VAS). The photographs included the front views of the overall smile and, when available, magnified pictures of the area treated including the two neighboring teeth. The same photographs were shown to 10 independent clinicians, who used the same scoring system. Agreement was assessed by evaluating intraobserver and interobserver agreement with a weighted Kappa statistic. Results: In general, agreement was moderate to substantial among patients but only fair among clinicians, with only one practitioner being consistently reproducible. Patients had better agreement than clinicians, but they only evaluated themselves, whereas the clinicians each had to evaluate 30 patients. The agreement of all patients together compared to each individual clinician was poor. The overall agreement between clinicians was also poor. Conclusions: This study of evaluations of pretreatment and posttreatment photographs by 30 patients and clinicians showed that: (1) patient responses were more in agreement, but patients evaluated only their own results; (2) practitioner responses were less in agreement than patient response, but clinicians evaluated all 30 patients; and (3) agreement between patients and clinicians was poor. Keywords: agreement, dental implants, esthetics, reliability, validation studies, visual analogue scale

Purpose: The present study was a 3-year follow-up evaluation of implant clinical success and radio-graphic bone remodeling in sinus floors elevated with different autogenous bone-grafting procedures and in similar native bone regions. Materials and Methods: This retrospective chart review examined consecutive edentulous patients with severe jaw atrophy treated between 2000 and 2002 via sinus lift, when needed, and implant insertion. Implants in sinus lift areas were divided into four groups by graft source (iliac crest, chin area) and technique (bone block, particulate). Implants positioned in native areas beneath the sinus floor served as controls. The cumulative success rate (CSR) and success rate (SR) were calculated, and linear measurements of bone remodeling around implants were assessed on computerized tomographic scans. Results were statistically compared with the Wilcoxon signed rank test. Results: Twenty-eight patients were treated in the posterior maxilla via insertion of 70 screw-type, root-form, rough implants in 39 sinus-lifted areas. All surgical procedures were uneventful. Twenty-four implants were positioned in native areas beneath the sinus floor. The implant CSR was 95.8% in native areas (one failure/24 implants), 85% in sinuses lifted with particulate chin bone (three failures/20 implants), and 100% in the other three groups (eight in particulate iliac crest, 20 in chin block, and 22 in iliac crest block). Computerized tomographic scans revealed that bone remodeling around apices caused implants to bulge into the sinuses in both particulate bone graft groups. Crestal remodeling around implant necks was similar for all groups. Conclusions: The use of particulate chin bone grafts in sinus lift procedures does not seem to yield optimal outcomes. Milled iliac crest and chin bone tends to remodel around the implant apices, leading to bulging within the sinuses. Grafting sinuses with either chin or iliac crest bone blocks yields the highest implant success rates and stable sinus floors. Keywords: atrophic maxilla, autogenous bone graft, dental implants, osseointegration, sinus lift

Purpose: This prospective clinical study evaluated the performance of 290 tapered, anodic oxidized (TiUnite) titanium implants placed in compromised bone in a consecutive series of 126 patients. Materials and Methods: Inclusion criteria were: (1) a need for dental implants in either a single-tooth or partially edentulous segment, (2) sufficient medical fitness to undergo the procedure, (3) enough bone to enable placement of a 10-mm or longer implant, and (4) compromised bone, as judged by computerized tomography and confirmed by clinical findings, in at least one implant site. Implants were placed and left unloaded for at least 6 months (mean 9.9 ± 3.9 months) before placement of the first provisional prosthesis and followed for at least 3 years after loading. Marginal bone was measured by an independent radiologist. Results: A second-stage uncovering was required for approximately half the implants. Failure of osseointegration was observed for only two implants; all other implants provided the intended prosthetic support during the entire observation period. The overall implant survival rate after 3 years of loading was 99.3%. The average mean changes in the marginal bone level showed stability (-2.70 mm, -2.67 mm, and -2.74 mm at 1, 2, and 3 years postloading, respectively). Conclusions: Using a modified surgical technique that minimized the osteotomy dimensions, tapered implants with an oxidized surface proved to be a predictable support for fixed prostheses in both grafted and ungrafted compromised bone. Marginal bone levels were stable throughout at least 3 years of follow-up. Keywords: bone grafts, bone quality, dental implants, marginal bone, titanium oxide

Purpose: This clinical study using a specific technique was carried out to determine the clinical effectiveness of zygomatic implants under an immediate loading protocol. Materials and Methods: All patients treated between May 2000 and October 2006 who received zygomatic implants were included in this retrospective analysis. All patients were treated using the same surgical and restorative protocol. The following data were recorded: gender, age, type of implant, number of implants placed, dimensions of implants, and implant and prosthesis survival. Results: Fifty-six consecutive patients (29 women, 27 men; mean age of 60.58 years [range, 38.78 to 84.01]) were treated. All were in need of oral reconstruction and had maxillary atrophy that warranted zygomatic implant placement. One hundred ten zygomatic implants were placed in these 56 patients. Four of the 110 zygomatic implants failed, resulting in a cumulative survival rate of 96.37% with follow-up data no less than 9 months and in excess of 5 years. All four failures were turned-surface zygomatic implants. There have been no failures to date with the titanium anodized-surface zygomatic implants. The prosthesis survival rate was 100.0%. Conclusion: In this retrospective analysis of 56 patients receiving 110 zygomatic implants, the survival rate of zygomatic implants was in excess of 96% over a period of 9 months to 5 years. This technique resulted in a stable and predictable prosthetic reconstruction. Keywords: advanced bone atrophy, dental implants, immediate loading, osseointegration, Teeth in a Day, zygoma

Purpose: The aim of this prospective study was to evaluate the suitability of intraoral welding of implant frameworks to allow placement of the definitive restoration on the same day of surgery. Materials and Methods: Forty patients with an edentulous mandible were planned to be treated with a fixed restoration supported by an intraoral welded titanium bar. Definitive abutments were to be connected to the implants and then welded to a titanium bar using an intraoral welding unit. This framework was to be used as support for the definitive restoration, which was to be placed on the same day as the implants. Mean marginal bone loss and radiographically detectable alterations of the welded framework were to be assessed using periapical radiographs immediately after surgery, and at 6-, 12-, and 24-month follow-up examinations. Results: Twenty men and 20 women, with a mean age of 47.8 years (± 13.9), were consecutively treated with 160 immediately loaded implants. All implants osseointegrated. No fractures or radiographically detectable alterations of the welded frameworks were present. All implants were clinically stable at the 24-month follow-up. Mean marginal bone loss (n = 160 at all time points), assessed using 640 periapical radiographs, was 0.59 ± 0.12 mm at 6 months, 0.21 ± 0.051 mm at 12 months, and 0.11 ± 0.036 mm at 24 months. The accumulated mean marginal bone loss was 0.91 ± 0.21 mm. Conclusions: It is possible to successfully rehabilitate the edentulous mandible on the same day as implant placement surgery with a fixed definitive prosthesis supported by an intraorally welded titanium framework. Keywords: dental implants, immediate restoration, implant-supported prosthesis, titanium framework

Purpose: When impacted maxillary canines are not amenable to orthodontic traction or reimplantation, extraction is the only solution available, followed by the option of implant placement. The aim of this study was to present a surgical technique that allows placement of immediate implants following extraction of impacted maxillary canines. Materials and Methods: Included in the study were patients with impacted maxillary canines who refused orthodontic treatment or transplantation and/or in whom the position of the canine teeth did not allow fenestration and orthodontic traction. The canines were removed, with the apical and ridge crest bone preserved to allow immediate implant placement anchored bicortically with good primary stability. The full circumference of the implants had no bone coverage except for the apical and coronal parts and were covered with bone shavings collected by the filter of the surgical aspirator during ostectomy. The definitive restorations were positioned after a healing period of 2 to 3 months. After 12 months, data were recorded relating to the clinical and radio-graphic condition of the implants. Results: Ten impacted maxillary canines were extracted from nine patients (in one patient, both impacted maxillary canines were extracted) with a mean age of 40.3 years (range, 32 to 63 years), and 10 immediate implants were placed. All the implants had primary stability with a mean Osstell value of 61.5 on the day of surgery. At 12 months of follow-up, all the implants were considered to be successful. Digital periapical radiographs demonstrated a mean peri-implant bone loss of 0.49 mm (range, 0.15 to 1.1 mm). Conclusion: The removal of impacted canines followed by immediate implant placement minimizes the number of surgical interventions and the waiting time, although increased surgical skill is needed to place the implants. Keywords: dental implants, Defcon®, maxillary impacted canines

Heterotopic ossification is defined as the formation of bone in sites where it does not normally exist. Myositis ossificans is classified as a type of heterotopic ossification, where bone formation occurs following soft tissue trauma. A case is presented of a 65-year-old female patient, diagnosed with maxillary and mandibular atrophy, in whom myositis ossificans developed secondary to iliac crest bone harvesting for preprosthetic augmentation prior to placement of maxillary and mandibular implants. Approximately 3 months after bone was harvested from the right anterior iliac crest, and despite a routine recovery from the bone grafting procedure, the patient developed persistent pain, described in her own words as "incapacitating," in the right lower quadrant of her abdomen. She was evaluated by a number of different specialists before a diagnosis of myositis ossificans was reached by her orthopedist. Management of the pain proved difficult, but eventually the symptoms improved to the extent that there was minimal disruption to her daily activities. Implant placement and prosthodontic treatment concluded to the patient's satisfaction. It may be advisable to include the possibility of occurrence of heterotopic ossification and resultant pain as a specific preoperative warning when iliac crest bone harvesting is planned to prepare patients for this potentially serious complication and to avoid litigation. Keywords: bone transplantation, dental implants, heterotopic ossification, iliac crest, myositis ossificans, preprosthetic surgery