The International Journal of Oral & Maxillofacial Implants, 01/2011

Purpose: Titanium dioxide (TiO2), a photocatalyst, is known to decompose various organic compounds under ultraviolet (UV) illumination by generating various radicals, which is useful for killing bacteria. The purpose of the present study was to evaluate the photocatalytic bactericidal effects of variously treated titanium surfaces on Streptococcus sanguinis SL1. Materials and Methods: Specimens were fabricated from grade 4 commercially pure titanium, 10 mm in diameter and 2 mm in thickness. Three different surfaces were prepared: anodized (AO) at 270 V, heat-treated (HT), and machined (MA). Surface analysis was performed using confocal laser scanning microscope, scanning electron microscopy, and thin-film x-ray diffractometry. The antibacterial activities were assessed by comparing adhesion and survival rates of S sanguinis on various surfaces under UV illumination. Results: The AO surface was rougher than the HT and MA surfaces. The AO surface showed TiO2 peaks of anatase structure, while the HT surface showed TiO2 peaks of rutile structure in x-ray diffractometry. HT and AO surfaces showed significantly decreased bacterial adhesion under UV illumination (AO and HT > control, AO > MA). In addition, bacterial adhesion decreased more significantly with extended UV illumination time. With respect to survival rates of bacteria, AO and HT showed a significant reduction over time compared to MA. The photocatalytic bactericidal effect was maximal on the AO titanium, followed by HT and MA. Conclusions: The photo-induced bactericidal efficacy of TiO2 films is dependent on their surface characteristics. Keywords: anatase, photocatalytic bactericidal effect, rutile, titanium dioxide, ultraviolet illumination

Purpose: This study compared the removal torque values (RTVs) of different abutments (straight, angled, and gold premachined UCLA-type) in external- and internal-hex implants after dynamic cyclic loading with the clinical situation of the anterior maxilla simulated. Materials and Methods: An ideal cast of a maxilla with a missing right central incisor was fabricated in dental stone, and an implant analog was embedded in this model at a 15-degree angle labial to the long axis of the left central incisor. Thirty external-hex and 30 internal-hex implants were used. A total of 10 straight abutments, 10 angled abutments, and 10 gold premachined UCLA-type abutments of each system and 60 abutment screws were tested. Initial RTVs were measured after each assembly was tightened to 30 Ncm. Straight abutments and angled abutments were prepared and gold-premachined UCLA-type abutments were waxed and cast with low-fusing gold alloy for the central incisor. RTVs were then measured again. After each assembly was tightened, a metal crown was temporarily cemented. After cyclic loading of 20 to 200 N was applied 1 million times, RTVs were measured for a third time. Statistical analysis (α = .05) was performed to evaluate the results. Results: The angled abutment group showed significantly higher RTVs than the straight abutment and gold premachined UCLA-type abutment groups in external-hex implants. However, no significant difference in RTVs was found among abutments in internal-hex implants. The time of analysis of RTV was found to significantly influence mean RTVs. Mean RTVs of external- and internal-hex implants showed significant differences. Conclusions: Within the limitations of this study, there were significant differences in RTVs among different abutment groups in external-hex implants. There were no significant differences in RTVs among different abutment groups in internal-hex implants. Keywords: abutment angulation, anterior maxilla, dental implant, dynamic cyclic loading, prosthetic screw, screw loosening

Purpose: Gaps between an abutment and a dental implant are unavoidable, and microleakage may occur, leading to problems such as malodor and peri-implantitis. The aim of the present in vitro study was to investigate leakage of Staphylococcus aureus through the implant/abutment interface by the method of bacterial culture, and to compare the leakage rates of two different types of implant-abutment connections. Materials and Methods: Twenty Morse taper implants with abutments were divided into two groups: group A, which were evaluated for microleakage into the inner part of the implants, and group B, which were evaluated for microleakage from the inner part of the implants. Twenty internal-hexagon implants with abutments were also divided into two groups: group C, which were evaluated for microleakage into the inner part of the implants, and group D, which were evaluated for microleakage from the inner part of the implants. For the evaluation of leakage from the implants, the assemblies had the inner parts inoculated with S aureus, and each assembly was incubated in sterile brain heart infusion broth for 1 week. For assessment of leakage into the implants, each assembly was submerged in 4 mL S aureus culture in tubes and incubated for 2 weeks. The microleakage of the two implant connections was compared. Results: Microbial leakage occurred in all groups, and there was no statistically significant difference between groups A and C or between groups B and D. Conclusions: In vitro, S aureus leakage through the implant/abutment interface occurred with both Morse taper and internal-hexagon implants. Keywords: bacterial leakage, culture media, dental implants, implant-supported dental prosthesis, Staphylococcus aureus

Purpose: This study evaluated the bone mineral apposition rate (MAR) at the bone-implant interface region of alumina-blasted/acid-etched (AB/AE), plasma-sprayed hydroxyapatite (PSHA), and nanometric-scale bioceramic-coated surfaces at early implantation times in a dog tibia model. Materials and Methods: Implants (n = 12 per group) with three different surfaces-AB/AE, PSHA, and a bioceramic coating in the 300- to 500-nm thickness range-were placed bilaterally along the proximal tibiae of six male beagles. Implants remained for 3 and 5 weeks in vivo. Ten and 2 days prior to euthanization, calcein green and oxytetracycline were administered for bone labeling. Following euthanization, the limbs were retrieved by sharp dissection and the implants and bone were processed nondecalcified into ~30-µm-thick sections along the implant long axis. MAR was measured by the distance between bone labels over time at the interface region (to 0.5 mm from the implant surface) and at regions > 3 mm from the implant surface (remote site). A generalized linear mixed-effects analysis of variance model was conducted with significance levels set at .05. Results: Irrespective of implant surface, the MAR at the interface region was significantly higher than the MAR at the remote site. Significant MAR differences in the interface region were observed between the different surfaces (PSHA > AB/AE > nano). Conclusions: Bone kinetics during early healing stages were influenced by implant surface modifications. Keywords: endosseous implant, in vivo, mineral apposition rate, surface properties

Purpose: The aim of this study was to compare the relative accuracy of the ridge-mapping method against that of standard computed tomography (CT). Materials and Methods: Consecutive partially edentulous subjects requiring dental implants were recruited for this prospective study. Vacuum-formed radiographic templates with reference points were used for the ridge-mapping procedure and CT scanning. Ridge-mapping measurements were translated onto study models, which were subjected to CT scanning with the templates in place. CT images of the study models obtained from the ridge-mapping method were compared with CT images of the subjects. The data were analyzed with the Wilcoxon signed-rank test. Differences were considered significant if P .05. Results: Fourteen subjects were recruited and a total of 21 implant sites were evaluated. The ridge dimensions measured by the bone-mapping method and CT scanning were significantly different (P .05). The mean difference ranged from 0.3 to 0.5 mm, and large variations were found in the sulcus region. Conclusion: Measurements of the alveolar bone dimension using the ridge-mapping method are different from CT scanning, with a mean difference of about 0.4 mm. Keywords: computed tomography, dental implant, measurement, ridge mapping

Purpose: To evaluate the biomechanical fixation, bone-to-implant contact (BIC), and bone morphology of screw-type root-form implants with healing chambers with as-machined or dual acid-etched (DAE) surfaces in a canine model. Materials and Methods: The animal model included the placement of machined (n = 24) and DAE (n = 24) implants along the proximal tibiae of six mongrel dogs, which remained in place for 2 or 4 weeks. Following euthanasia, half of the specimens were subjected to biomechanical testing (torque to interface failure) and the other half were processed for histomorphologic and histomorphometric (%BIC) assessments. Statistical analyses were performed by one-way analysis of variance at the 95% confidence level and the Tukey post hoc test for multiple comparisons. Results: At 4 weeks, the DAE surface presented significantly higher mean values for torque to interface failure overall. A significant increase in %BIC values occurred for both groups over time. For both groups, bone formation through the classic appositional healing pathway was observed in regions where intimate contact between the implant and the osteotomy walls occurred immediately after implantation. Where contact-free spaces existed after implantation (healing chambers), an intramembranous-like healing mode with newly formed woven bone prevailed. Conclusions: In the present short-term evaluation, no differences were observed in BIC between groups; however, an increase in biomechanical fixation was seen from 2 to 4 weeks with the DAE surface. Keywords: animal study, bone-to-implant contact, dental implants, implant design, surface properties, torque

Purpose: To determine whether sinus membrane elevation alone can lead to new bone formation on the maxillary sinus floor. Materials and Methods: Among patients who were to receive implant treatment, those who had 4 to 5 mm of bone height in the maxillary sinus floor (as measured radiographically) were selected as candidates for sinus membrane elevation. The lateral sinus wall was exposed through a buccal mucoperiosteal incision. The sinus membrane was elevated through a bone window, and the space underneath the membrane was filled with absorbable collagen sponge (Collaplug). In the presence of blood in the space, the collagen sponge was left to soak up the blood; in the deficiency of blood, the sponge was saturated with venous blood drawn from the brachial vein. The mucoperiosteal flap was repositioned and closed with interrupted silk sutures. The sinus was left to heal for 6 months. Core specimens of the maxillary sinus floor were obtained using a trephine bur at 6 months after sinus elevation in patients treated between January 2006 and June 2009. The trephined sites were used for implant placement. The biopsy specimens were analyzed histologically to identify the presence and amount of new bone tissue. Results: Thirteen specimens from eight patients were included in the study. Microscopically, 11 specimens exhibited no recognizable new bone tissue. Two specimens exhibited a small amount of woven bone on the surface of the sinus floor. Conclusion: Within the limits of this study of eight patients, little to no new bone formation was observed on the maxillary sinus floor at 6 months following sinus membrane elevation and support with blood-soaked collagen sponges. Keywords: bone formation, bone graft, lateral window, maxillary sinus, membrane elevation, sinus floor augmentation

Purpose: The directional dependence of accuracy with cone beam computed tomography (CBCT) has not been investigated thoroughly. The purpose of the present study was to clarify the effects of measurement direction and of phantom locations in the fields of view (FOVs) on the accuracy of linear measurement and on the limits of measuring thin objects with CBCT. Materials and Methods: An aluminum phantom was scanned by CBCT. The thickness in both the longitudinal and horizontal directions (LD and HD) was measured at both the center and periphery in the three FOVs. The length was determined by a 50% relative threshold method to eliminate observer-dependent measurement errors. The measurement limits of a thin object were assessed in thin parts of the phantom (thickness, 0.3 to 1.0 mm). Results: The measurement accuracy in the LD was excellent (within 1 pixel), while that in the HD was fair (0 to 2.35 pixels difference); a slight overestimation was found near the center of the phantom (1.06 to 2.35 pixels difference) in comparison to that of the edges (within 1 pixel difference). The overestimation was more marked at the longitudinal periphery than at the center of each FOV. A thickness of at least three to four pixels was necessary to keep errors within the one-pixel range along both directions. Conclusions: The accuracy of linear measurement with CBCT is excellent, especially when measuring in the LD. Distances are slightly overestimated in the HD near the center of the phantom. Close attention is therefore necessary when planning the placement of implants adjacent to horizontal vital structures. Second, a thickness of at least 3 to 4 pixels was necessary to maintain high accuracy for linear measurement. This must be taken into consideration when measuring a minute structure, such as thin cortical bone. Keywords: cone angle, cone beam computed tomography, dental implants, directional dependence, measurement accuracy, thresholds

Purpose: The purpose of this study was to compare zirconium oxide and titanium alloys with respect to their tendency to adhesion and colonization of two periodontal pathogens on both hard surfaces and on soft tissues in vivo. Materials and Methods: The present study was designed as a prospective stratified randomized controlled clinical trial. Patients were scheduled to receive two implants with different types of abutments in the posterior mandible. Three months after implant placement, titanium and zirconium abutments were connected. Five weeks after abutment connections, the abutments were removed, probing depth measurements were recorded, and gingival biopsy samples were obtained. Abutments and biopsy specimens were analyzed by reverse-transcriptase polymerase chain reaction to compare the DNA copy numbers of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and total bacteria. The surface free energy of the abutments was calculated by sesile water drop before replacement. Results: No statistically significant differences were found between probing depths or DNA copy numbers of A actinomycetemcomitans, P gingivalis, and total bacteria both for both titanium alloys and zirconium oxide surfaces and the biops specimens obtained from their buccal gingival. With respect to the surface free energy of zirconium and titanium abutments, zirconium abutments showed lower surface free energy than titanium abutments. Conclusion: The results of this study showed that zirconium oxide surfaces have comparable properties to titanium alloy surfaces in their tendency to adhesion and colonization of two periodontal pathogens on both hard surfaces and in soft tissues. Keywords: dental implants, real-time polymerase chain reaction, titanium alloys, zirconium oxide

Purpose: Insertion torque and resonance frequency analysis are currently used to assess the initial biomechanical competence of an implant. It would be advantageous to have this information during treatment planning. Therefore, the aim of this study was to assess the correlation between a descriptor of bone architecture, namely the fractal analysis of plain radiographs, and implant insertion torque and resonance frequency. Materials and Methods: Sixteen femoral condyles from adult rabbits were subjected to conventional radiography and then received an implant each. The final insertion torque and resonance frequency were recorded for each implant. The fractal dimension of the bone area corresponding to the osteotomy was calculated using a box-counting algorithm. The Spearman test was used to evaluate the correlation between the variables examined. Results: A linear correlation was observed between fractal dimensions and insertion torque values (rs = 0.704; P = .007). No correlation resulted between fractal dimension and resonance frequency. In addition, a receiver operating characteristic analysis defined a fractal dimension breakpoint of 1.83 to detect soft bone quality, as defined by insertion torque values, with a sensitivity of 80%. Conclusions: Given its correlation with insertion torque, the box-counting fractal dimension could be useful to evaluate bone quality at implant sites preoperatively and noninvasively. Further studies are needed to confirm the same accuracy for human bone. Keywords: bone quality, dental implants, fractal dimension, insertion torque, resonance frequency

Purpose: The aim of this study was to investigate the bone response to rough titanium implants treated with hydrofluoric acid/nitric acid (HF/HNO3) solution. Materials and Methods: Implants were treated with HF/HNO3 solution (test implants) or without HF/HNO3 solution (control implants). Forty-five test and 45 control implants were inserted into both tibias of 15 rabbits. After 2, 4, and 8 weeks in situ, tibias were retrieved and prepared for removal torque testing and histomorphometric evaluation. The removed implants were prepared and observed with an electron microscope. Results: Mechanical tests showed that mean removal torque values for the test implants were higher than those of the control implants after 8 weeks (33.1 Ncm versus 25.7 Ncm, P = .012). Histomorphometric analysis showed that the bone area in the threads of the cortical bone region was significantly higher for test implants (81.99% and 86.38%) than for control implants (75.33% and 81.62%) after 4 and 8 weeks of healing, respectively. The implant-bone contact rate in the cortical region was higher for test implants than for control implants after 8 weeks in situ (79.56% versus 68.45%, P = .003). Conclusions: The treatment with HF/HNO3 solution promotes bone formation and osseointegration after 4 and 8 weeks of bone healing in the rabbit tibia model. Keywords: dental implant, fluoride, nanotopography, rabbit, titanium

Purpose: Long-term success of dental implants has been demonstrated when placed simultaneously with or after a sinus augmentation procedure. However, optimal bone formation can be from 6 to 9 months or longer with grafting materials other than autogenous bone. For this reason, there is interest in any surgical technique that does not require autogenous bone harvesting, yet results in sufficient bone formation within a relatively short time frame. Materials and Methods: This study evaluated and compared bone formation following sinus-augmentation procedures using either an allograft cellular bone matrix (ACBM), containing native mesenchymal stem cells and osteoprogenitors, or conventional allograft (CA). Results: Histomorphometric analysis of the ACBM grafts revealed average vital bone content of 32.5% ± 6.8% to residual graft content of 4.9% ± 2.4% for the 21 sinuses in the study, at an average healing period of 3.7 ± 0.6 months. Results for the CA, in the same time frame, were average vital bone content of 18.3% ± 10.6% to residual graft content of 25.8% ± 13.4%. A comparison of ACBM and CA grafts, for both vital and residual bone contents, showed P values of .003 and .002, respectively, indicating a statistically significant difference between the groups. Conclusion: The high percentage of vital bone content, after a relatively short healing phase, may encourage a more rapid initiation of implant placement or restoration when a cellular grafting approach is considered. Keywords: bone regeneration, osteoblasts, ridge augmentation, stem cells, tissue engineering

Purpose: To compare the load-bearing capacity of custom-made zirconia abutments with that of prefabricated commercially available zirconia abutments. Materials and Methods: Zirconia (ICE Zircon) blocks were manually copy-milled to abutments using prefabricated commercially available abutments as models, divided into four groups (n = 10/group), and sintered at 1,500°C. Prefabricated commercially available abutments were used as controls (groups 1 and 4, n = 10/group). The abutments in the study groups were: (1) Astra ZirDesign (AstraTech); (2) copy-milled Zirkonzahn-Astra; (3) copy-milled Zirkonzahn-Astra, short; (4) Xive Cercon (Dentsply/Friadent); (5) copy-milled Zirkonzahn-Xive; and (6) copy-milled Zirkonzahn-Xive, modified. Seven abutments per group were screwed onto implant replicas (size 3.5/4.0 mm for AstraTech, 3.8 mm for Dentsply Friadent) with acrylic resin sample base; the implants were loaded dry with a universal testing machine at room temperature and a 45-degree loading angle. Statistical analyses were made using one-way analysis of variance. The three remaining abutments per group were screwed onto implant replicas, and the distance between the replica and the abutment was measured with a scanning electron microscope. Results: Significant differences were seen among the groups in terms of load-bearing capacity; copy-milled Zirkonzahn-Xive modified abutments (group 6) were statistically significantly stronger (1,099 N) than the other abutments (P .05). The Xive models resulted in catastrophic failure, whereas the Astra-design revealed visual bending before failure. Conclusions: Custom-made zirconia abutments have comparable failure loads to those seen for prefabricated commercially available zirconia abutments. Keywords: custom-made abutment, dental abutment, load-bearing capacity, marginal fit, zirconia

Purpose: This study sought to evaluate treatment outcomes of implant-prosthetic rehabilitation with implants in the edentulous maxilla or mandible that were immediately loaded by fixed prostheses. Special consideration was given to the time of implantation (immediate, delayed, or late implant placement). Materials and Methods: Twenty-five patients who received 283 immediately loaded screw-type implants were included in this retrospective study. Data captured included patient file information, panoramic and periapical radiographs obtained during treatment, and clinical parameters examined during the recall period. Clinical and radiographic status of peri-implant soft and hard tissue was evaluated, as well as the function of prostheses and subjective assessment by the patients of the treatment. Survival/success rates were analyzed with respect to the time of implantation. Results: Following a maximum observation period of 120 months (median 29 months) postimplantation and subsequent immediate functional loading, implant survival was 99.6% (one implant failed after 20 months). The success rates were 98.2% for implants and 88% for patients; five implants in three patients did not meet success criteria. Neither the implant site nor the time of implantation were associated with unsuccessful outcomes. Implant-related evaluations revealed a significant association between implant success and implant length of 10 mm or less (P .018). Conclusion: Within the limits of this study, immediate loading of rough-surfaced, screw-type implants supporting fixed dentures for the treatment of edentulous maxilla or mandible appears to be a reliable treatment option with a high probability of success. The time of implantation did not influence implant survival or success rates. Keywords: delayed implantation, dental implants, edentulism, fixed prostheses, immediate loading, immediate implant placement, implant-prosthetic rehabilitation, late implantation

Purpose: The purpose of this study was to analyze retrospectively the survival rate of implants used in pairs to support a single molar crown over a long-term follow-up period and to compare the efficacy of this technique to other existing methods of treatment. Materials and Methods: The charts and radiographs of 105 patients who each received two implants to support a screw-retained single molar were examined according to the following criteria: age, gender, location of implant, time of loading (delayed versus immediate), opposing dentition, and the existence of adjacent implants. Results: Patients with follow-up between 3 and 12 years were selected to illustrate the long-term outcomes of the two-implant replacement procedure. Two hundred fifty implants were placed in 125 molar sites in 105 patients. Five of the 250 implants failed, resulting in a cumulative survival rate of 98.0%. Seven of 125 restorations experienced porcelain fracture (5.6%), seven prosthetic screws loosened (5.6%), and one abutment screw loosened ( 1.0%). Discussion: The placement of two implants to support a screw-retained single molar successfully reduces rotational forces that create stress on the implant. A single regular-diameter or even a wide-diameter implant is susceptible to these forces, which may lead to fatigue over the long term. Conclusions: Two implants for the replacement of a single molar represent an effective method that provides a high survival rate over a long-term follow-up period. This approach produced a cumulative survival rate higher than that usually seen in studies of single implants used for molar replacement. The two implant-supported molar crown showed fewer complications than single implant-supported molar crowns. Keywords: dental implants, molar replacement, osseointegration, teeth in a day, two-implant molar

Purpose: The purpose of this study was to retrospectively analyze a cohort of patients who had implants placed in the posterior maxilla and assess and identify the predictors of implant failure. Materials and Methods: With institutional review board approval, dental records from a population of patients who had maxillary posterior implants placed were used to create a database. Independent variables were divided into continuous (age of the patient at stage-one implant surgery [S1], time between extraction and S1, time between extraction and sinus augmentation, time between sinus augmentation and S1, time between S1 and stage-two implant surgery [S2], and the time between S2 and restoration of the implant) and categorical (gender, American Society of Anesthesiologists [ASA] status, current smoking status, implant position, implant proximity, residual crestal bone height, implant length and diameter, and sinus augmentation technique and materials). The dependent variable was implant failure, which was defined as complete removal of the implant. Simple logistic regression was used to assess the influence of each of the predictors on implant failure (P .05). Results: The final database included 504 maxillary posterior implants with an overall survival rate of 93.2% over a mean follow-up period of 35.7 months. For the continuous variables, the age of the patient at S1 was statistically associated with implant failure (P = .028), as was the time between extraction and S1 (P = .014). For the categorical variables, ASA status (P .001), implant proximity (P = .043), residual crestal bone height (P .001), implant diameter (P = .050), sinus augmentation technique (P = .002), and sinus graft materials (P .001) were statistically associated with implant failure. Conclusion: Within the limitations of this retrospective study, the results suggest that there are risk factors associated with maxillary posterior implant failure. Implants placed in areas with inadequate residual crestal bone height that required sinus augmentation were statistically associated with implant failure. Keywords: dental implants, implant failure, posterior maxilla, predictors, retrospective cohort study, risk factors

Purpose: The aim of this retrospective analysis was to report on the clinical outcome of immediate provisionalization using one-piece narrow-diameter implants. Materials and Methods: The dental records of patients who received narrow implants were reviewed. Narrow-diameter (3.0-mm) one-piece implants were used to support restorations of missing maxillary lateral incisors and mandibular incisors. All implants were placed in a one-stage procedure according to the protocol recommended by the manufacturer, with immediate placement of provisional restorations. Following an average healing period of 3 months in the mandible and 5 months in the maxilla, the definitive prostheses were fabricated. The survival rate of the implants was analyzed, and radiographic evaluation was performed. Results: Thirty-six patients (20 men and 16 women), aged from 42 to 72 years (average age of 53 years), were treated with 62 one-piece narrow implants. A success rate of 100% was observed over a period up to 33 months (mean, 23 ± 4.3 months). Among these, 8 implants were placed in maxillary lateral incisor positions and 54 implants were placed in mandibular incisor areas. Forty-four implants supported fixed partial prostheses, and 18 implants supported single crowns. The majority of the implants were 15 mm in length. Mean marginal bone loss at the 12-month follow-up visit was 0.53 ± 0.37 mm (range, 0 to 1.4 mm). Conclusions: The results obtained in this retrospective analysis suggest that the one-piece narrow-diameter implant can predictably restore missing maxillary lateral incisors and mandibular incisor with narrow interdental spaces and labiolingual widths. Keywords: dental implants, fixed prostheses, immediate provisionalization, mini-implant, one-piece implant, retrospective analysis

Purpose: The purpose of the present study was to compare the clinical and radiographic outcomes of single implants immediately placed and restored with two different implant-abutment connections. Materials and Methods: Forty subjects requiring single maxillary premolar replacement were consecutively included in this study and prospectively followed for 12 months. One implant was placed at the time of tooth extraction and immediately restored in each patient. Subjects were randomly selected to receive either prosthetic abutments with a Morse taper connection and a platform switch (test group) or conventional abutments with an internal connection and a matching diameter (control group). A provisional screw-retained crown was positioned and adjusted for nonfunctional loading within 24 hours. Four months later, the definitive crowns were delivered. Periodontal parameters and clinical and radiographic measurements of soft and hard tissue levels were recorded at the moment of prosthesis placement and at 4 and 12 months afterward. Means of the two groups were compared using paired and independent-sample t tests (P = .05). Results: Of the 40 patients recruited, 38 (24 women and 14 men) completed the study. No implants were lost in the control group, whereas one implant failed in the test group. At the 12-month examination, no statistically significant differences were seen between the two groups for periodontal parameters, marginal soft tissue level change, or papilla height (P > .05), but greater marginal bone loss was observed at the control sites (0.51 ± 0.24 mm) compared to the test sites (0.2 ± 0.17 mm) (P = .0004). Conclusion: Although the control group demonstrated a slight increase in marginal bone loss compared to the test group, the peri-implant soft tissues were very stable with both types of implant-abutment connection after 12 months of loading. Keywords: immediate implants, marginal bone loss, Morse taper connection, platform switching, single-tooth implant restoration

Purpose: This is a follow-up of an earlier 1-year prospective study on implant success rates and the peri-implant response after immediate placement and provisionalization of single implants in the esthetic zone. The effects of gingival biotype on the peri-implant tissues were also evaluated. Materials and Methods: Thirty-five patients were evaluated clinically and radiographically at presurgical examination (T0), immediately after immediate implant placement and provisionalization (T1), 1 year after implant surgery (T2), and the latest follow-up appointment (T3). Data were analyzed using t tests and repeated-measures analysis of variance at the significance level of α = .05. Results: After a mean follow-up time of 4 years (range, 2 to 8.2 years), all implants remained in function. At T3, the mean mesial and distal marginal bone level changes were significantly greater than those observed at T2. At T3, the mean mesial and distal papilla level changes were significantly smaller than those observed at T2, whereas the mean facial gingival level change was significantly greater than that observed at T2. Sites with a thick gingival biotype exhibited significantly smaller changes in facial gingival levels than sites with a thin gingival biotype at both T2 and T3. Conclusions: Favorable implant success rates and peri-implant tissue responses can be achieved with this procedure. While the results suggest the possibility of spontaneous papilla regeneration over time following this procedure, continuing recession of the facial gingival tissue was also observed. The effect of gingival biotype on peri-implant tissue response seemed to be limited only to facial gingival recession and did not influence interproximal papilla or proximal marginal bone levels. Keywords: dental implants, esthetics, gingival biotype, gingival recession, immediate implant placement, immediate loading, immediate provisionalization, papilla, single tooth replacement

Purpose: The purpose of this study was to evaluate clinical outcomes, posttreatment care, and patient satisfaction with overdenture treatment in the severely resorbed mandible. Materials and Methods: Two implants were inserted in the intraforaminal region of 36 edentulous patients. Seventy-two implants were placed: 24 ITI (Institut Straumann), 24 SwissPlus (Zimmer Dental), and 24 Astra (Astra Tech). Implants were not loaded until osseointegration was complete. Following osseointegration and insertion of the prosthesis, the implants were evaluated by clinical and radiographic parameters. Clinical parameters, including Plaque Index, Sulcus Bleeding Index, peri-implant probing depth (PD), and marginal bone loss (MBL), were recorded, and any biologic and mechanical complications at baseline and recall evaluations were noted. Patient satisfaction with mastication, phonetics, retention, oral hygiene, and esthetics was also evaluated by means of a questionnaire. The results were analyzed statistically. Results: The cumulative implant survival rate after 5 years of loading was 100%. There were significant differences in mean PD values between the three implant groups at baseline and recall evaluations. Mean PD values for the Astra group were significantly higher than those for the ITI and SwissPlus groups. Although the mean MBL was within clinically acceptable levels for all groups, there were significant differences among the three groups for MBL scores between baseline and 5 years. The mean MBL for the ITI group was significantly lower than the MBL values seen for the Astra and SwissPlus groups. Over the 60-month evaluation period, the most common prosthetic complications were mandibular denture fracture and dislodgement of the female attachment. Conclusions: Mandibular implant overdenture treatment is a successful treatment modality for the severely resorbed mandible. Keywords: clinical evaluation, dental implants, overdenture

Purpose: Treatment of the posterior atrophic mandible has long been a challenge in implant dentistry and maxillofacial surgery. The objective of this study was to reevaluate the safety and efficacy of the sandwich osteotomy and bone grafting in patients with moderate to severe posterior mandibular atrophy. Materials and Methods: This retrospective study included patients with an edentulous posterior mandible in which there was not enough bone above the dental nerve to insert implants at least 10 mm in length; patients with adequate bone volume but with an excessive interocclusal distance at the posterior occlusal region were also included. Twenty-three patients with 30 sites of moderate to severe posterior atrophy were treated using a sandwich osteotomy above the mental nerve and an interpositioned block of autologous or allogeneic bone. Success criteria were based on the possibility of implant insertion after bone grafting. Results: The average gain in height was 5.3 mm (range, 2 to 10 mm). Partial loss of alveolar height was observed in only one patient from the allogeneic graft group. Patients were followed for 12 to 93 months after bone grafting. No signs of infection were observed. Minor dehiscence of the surgical wound occurred in four segments, but healing ultimately occurred in every patient. Sixty-five implants were placed, and none were lost during follow-up. Insertion of implants of 10 mm or more in length was successfully achieved in 90.8% of the sites, and partial success (ie, bone segments suitable for insertion of shorter implants) was seen in the remaining sites. Conclusions: Moderate to severe posterior mandibular atrophy can be successfully treated by interpositional sandwich osteotomy and bone grafting, allowing for the subsequent placement of implants and fixed prostheses in all segments. Keywords: atrophic mandible, dental implants, inlay bone grafting, sandwich osteotomy

Focal osteoporotic bone marrow defects usually appear as asymptomatic radioluencies in the edentulous posterior mandible of middle-aged women. The exact causative factor in the majority of focal osteoporotic bone marrow defects is still unknown. Because of their radiological similarity with many intraosseous lesions, accurate diagnosis is possible only with histopathological examination. A focal osteoporotic bone marrow defect that occurred 2 years postoperatively apical to an implant is presented with clinical, radiographic, and histopathologic features. According to the literature scan, this is the first case report of this phenomenon caused by a dental implant. Keywords: bone marrow, defect, dental implant, hematopoietic, hemoglobin h

Postoperative parotid swelling (PPS) of unknown etiology following abdominal surgery has been well documented. This report reviews the occurrence of PPS after implant surgery in five patients. The patients had no previous experience of parotid swelling, sialadenitis, or sialoangiitis. The incidence of PPS at the author's clinic was 1.7%. Although a causal relationship is suspected between the implant surgical procedure and PPS in these patients, no exact relationships were found. Keywords: complication, implant surgery, parotid swelling, parotitis, salivary gland

Treatment of peri-implant osseous defects represents a significant challenge for clinicians, and the need to evolve within predictable surgical procedures is important. This case report describes the surgical treatment and grafting with porous titanium granules (PTG) of one patient with a peri-implant osseous defect. The suggested thrombogenic properties of titanium are intriguing from the perspective of osseous reconstructive surgery. In an ongoing randomized clinical trial using PTG for treatment of peri-implant osseous defects, one patient with one test implant was excluded and scheduled for implant removal. The surgical therapy included open flap debridement with surface decontamination with 24% EDTA gel, grafting with PTG, and resubmersion of the implant. After 12 months of healing, the implant with surrounding tissues was excised en bloc and micro CT and histological analyses were performed. Analyses showed PTG in close contact with new bone and with bone growing both into the porosities of the graft material and onto the adjacent implant surface. Element analysis demonstrated calcium and phosphorus in the new tissue embedding the PTG and the implant. Keywords: human histology, peri-implantitis, porous titanium granules, re-osseointegration