Resonance Frequency Analysis of Tapered Implants Placed at Maxillary Posterior Sites After Lateral Sinus Augmentation: A 1.5-year Follow-Up Prospective Study.

OBJECTIVES: To use resonance frequency analysis to evaluate tapered implants placed at maxillary posterior sites after lateral sinus augmentation. MATERIALS AND METHODS: Patients who had missing teeth in the maxillary posterior area and required lateral sinus augmentation before implant placement were enrolled in this study. After a 6-month healing period, a tapered implant (Osstem TSIV) was placed. Implant success rate, survival rate, and marginal bone loss of the implants were measured. For resonance frequency analysis, implant stability quotient (ISQ) values were measured at each visit during a 1.5-year follow-up period. RESULTS: Twenty-four patients completed the study procedure. The residual bone height was 2.57 ± 1.10 mm (mean ± SD). Healing of the grafted area was uneventful in all cases, and 55 tapered implants were installed. The implant success rate was 95.56%, and the survival rate was 100% throughout the observation period. The marginal bone loss was limited to 0.22 ± 0.44 mm. ISQ increased gradually from 68.40 ± 11.14 to 82.24 ± 4.75 during the 1.5-year follow-up period. CONCLUSION: The tapered implants showed good initial and final stability after placement in the soft bone of the maxillary posterior area after lateral sinus augmentation.

Chemokine in inflamed periodontal tissues activates healthy periodontal-ligament stem cell migration.

AIM: The present study aimed to characterize the expression pattern of chemokines obtained from inflamed periodontal defects and to determine the characteristics of human periodontal-ligament stem cells (hPDLSCs) migrated by each specific chemokine. MATERIALS AND METHODS: Both inflamed and healthy periodontal tissues were obtained from periodontitis patients (n = 11), and the chemokine expression levels were analyzed. The periodontal-tissue-specific chemokines were applied to healthy hPDLSCs from extracted teeth (n = 3), with FGF-2 acting as a positive control. Cells were separated by selected chemokines using transwell method into migrated/unmigrated hPDLSCs. The characteristics of the hPDLSC subpopulation recruited by each chemokine were assessed, and gene expression pattern was analyzed by microarray. RESULTS: Chemokines were categorized into three groups by specific patterns of "appearing," "increasing," and "decreasing/disappearing" from healthy to inflamed tissues. A representative chemokine from each group enhanced the capacities for colony formation and osteogenic/adipogenic differentiation while maintaining the surface markers of hPDLSCs. RANTES/CCL5 significantly increased the cellular migration of hPDLSCs, via enhancement of signaling pathways, regulation of the actin skeleton, and focal adhesion. CONCLUSION: The present study found a specific chemokine profile induced by inflammation in periodontal tissues, with RANTES/CCL5 appearing to play a role in the migration of hPDLSCs into inflammatory periodontal lesions.

Long-term outcomes of dental implants placed in elderly patients: a retrospective clinical and radiographic analysis.

OBJECTIVES: The aim of this retrospective study was to determine the clinical and the radiographic outcomes of dental implants placed in elderly people older than 65 years. MATERIALS AND METHODS: In total, 902 implants in 346 patients (age: 65-89 years) were followed up for 2-17 years following the implant surgery. The survival rate of these implants was recorded and analyzed. Changes in marginal bone levels were also analyzed in serial radiographs, and Cox regression analysis for implant loss was performed. RESULTS: The survival rates were 95.39% and 99.98% in the implant- and patient-based analyses, respectively (involving a total of 29 implant failures), and the marginal bone loss at the implants was 0.17 ± 0.71 mm (mean ± SD). The number of failures was greatest in patients aged 65-69 years. The Cox regression with shared frailty analysis showed that implant loss was significantly greater in those aged 65-69 years than in those aged 70-74 years (P < 0.05), and it varied between specific implant systems. CONCLUSIONS: Within the limitations of this retrospective study, it was concluded that implant therapy can be successfully provided to elderly patients and that age alone does not seem to affect the implant survival rate.

In Vivo Evaluation of Commercially Available Gel-Type Polyethylene Glycol Membrane for Carrier of Recombinant Human Bone Morphogenetic Protein-2.

PURPOSE: This study evaluated a commercially available, 3-dimensional gel-type polyethylene glycol (PEG) membrane as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) using a rat calvarial defect model. Another gel-type carrier, fibrin-fibronectin system (FFS), was used as a positive control. MATERIALS AND METHODS: Critical-size defects were made in the rat calvarium, which were allocated to 1 of 10 groups comprising 2 healing periods and biomaterial conditions: 1) sham control, 2) FFS only, 3) FFS plus BMP-2, 4) PEG only, and 5) PEG plus BMP-2. Radiographic and histologic analyses were performed at 2 and 8 weeks after surgery. RESULTS: After 2 weeks, some parts of the FFS were biodegraded and extensive cellular infiltration was observed at sites that received FFS or FFS plus BMP-2. The PEG membrane retained its augmented volume without cellular infiltration at sites that received PEG or PEG plus BMP-2. After 8 weeks, the FFS was completely degraded and replaced by new bone and connective tissues. In contrast, the volume of residual PEG was similar to that at 2 weeks, with slight cellular infiltration. In particular, there was progressive bone regeneration around micro-cracks and resorbed outer surface in the PEG + BMP-2 group. Although the PEG + BMP-2 group showed increased area and percentage of new bone, there was no statistical relevance after 2 and 8 weeks in histomorphometric analyses. However, the appearance of the healing differed (with new bone formation along micro-cracks in the PEG + BMP-2 group), and further studies with longer healing periods are needed to draw conclusions about clinical applications. CONCLUSION: Evidence of mechanical stability and new bone formation along micro-cracks when using PEG plus BMP-2 might support the PEG membrane as a candidate carrier material for rhBMP-2.

Ridge regeneration of damaged extraction sockets using rhBMP-2: an experimental study in canine.

OBJECTIVES: This study evaluated the dimensional ridge alteration in a buccal-bone-deficient extraction socket, and ridge regeneration following socket grafting accompanied by recombinant human bone morphogenetic protein 2 (rhBMP-2) or a collagen membrane covering. MATERIAL AND METHODS: In five beagle dogs, entire buccal bone of the extracted sockets of premolars was surgically removed and immediately grafted using one of the following graft protocols: (1) sham surgery without any grafting, and grafting with (2) deproteinized bovine bone mineral (DBBM), (3) DBBM/rhBMP-2 and (4) DBBM covered with a collagen membrane (DBBM/Membrane). Quantitative/qualitative analyses were performed radiographically/histologically after 8 weeks. RESULTS: Buccal-deficient extraction sockets healed with significant reduction in buccolingual dimension along the entire length of the socket, but all grafting techniques reduced the dimensional changes compared to the non-grafted control sites. Histologically, sites received DBBM only exhibited minimal regeneration, whereas sites grafted with DBBM/rhBMP-2 or DBBM/Membrane exhibited greater new bone formation extending the entire augmented area. CONCLUSIONS: Buccal-bone-deficiency may lead to significant volume reduction after tooth extraction along the entire length of the socket, and socket grafting accompanied by rhBMP-2 or covered with a membrane can be candidate therapies for preservation of the buccolingual dimension and successful ridge regeneration.

Prospective randomized, controlled trial of sinus grafting using Escherichia-coli-produced rhBMP-2 with a biphasic calcium phosphate carrier compared to deproteinized bovine bone.

AIM: This study compared the effects of Escherichia-coli-produced recombinant human bone morphogenetic protein 2 (ErhBMP-2) with a biphasic calcium phosphate (BCP) carrier to those of deproteinized bovine bone in human maxillary sinus floor augmentation. MATERIAL AND METHODS: Screening for this clinical trial selected 56 sites that provided informed consent to participate, of which 46 were ultimately enrolled and 41 were finally included in the study. The sites were divided into two groups using a random-number table, and the material was applied. A trephine biopsy was performed after 24 weeks, and implants wider than the biopsy site were inserted. Computed tomography and plain panoramic images were obtained immediately and then again at 24 weeks after the surgery. Radiographic images were reconstructed to allow measurement of the linear and volumetric changes. The biopsy samples were processed for histologic and histometric analyzes. RESULTS: All sites healed uneventfully with no complications. Radiographic analysis revealed a tendency for the volume to increase, but the difference was not statistically significant in either group. Comparison of volumetric changes between the two groups also revealed no significant difference. Moreover, none of the histometric parameters differed significantly between the groups, although different healing patterns were observed on histologic analysis. CONCLUSIONS AND CLINICAL IMPLICATIONS: It can be concluded that sinus augmentation with ErhBMP-2 carrying BCP carrier did not enhance bone regeneration compared to the conventional treatment using deproteinized bovine bone at 24 weeks after the surgery.

Sinus augmentation using BMP-2 in a bovine hydroxyapatite/collagen carrier in dogs.

AIM: The objective of this study was to determine the efficacy of bone morphogenetic protein 2 (BMP-2) in a bovine hydroxyapatite/collagen (BHC) carrier to augment bone formation in a canine nasal sinus model. METHODS: Eight mongrel dogs, approximately 12 months old and 30 kg in weight were used. Following preparation of bilateral sinus access windows, BHC alone (control) or loaded with E. coli-derived BMP-2 at 0.1 mg/ml was implanted in four animals, and BHC loaded with E. coli-derived BMP-2 at 0.5 and 1.5 mg/ml was implanted in four animals. The animals were euthanized at 20 weeks when block sections were obtained for micro-computed tomography and histometric analyses. RESULTS: Total augmented volumes did not differ significantly between groups. Histometric analysis showed significantly enhanced bone formation for the BMP-2 groups compared with control. CONCLUSION: BMP-2 in a BHC carrier, even at the low 0.1-mg/ml concentration, induces osteogenic activity, enhancing local bone formation in a canine sinus model.

Ridge preservation using demineralized bone matrix gel with recombinant human bone morphogenetic protein-2 after tooth extraction: a randomized controlled clinical trial.

PURPOSE: The aim of the present randomized controlled trial was to determine the safety and efficacy of injectable demineralized bone matrix (DBM) gel combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) on alveolar ridge preservation after tooth extraction. MATERIALS AND METHODS: A total of 69 patients were randomly assigned to either a test group (n = 35) or a control group (n = 34). In the test group, DBM, together with rhBMP-2 (0.05 mg/mL; rhBMP-2/DBM) was transplanted into the extraction sockets. The control group received DBM alone. The safety of rhBMP-2/DBM was evaluated by oral examination, serum chemistry, and hematologic examination. The radiographic changes in alveolar bone height and width were measured using computed tomography scans performed immediately after transplant and again 3 months thereafter. RESULTS: Healing was uneventful in all subjects, with no anticipated adverse events and no clinically significant changes in the serum chemistry and hematologic findings. No meaningful immune response was found among the study groups. No significant difference was found in the radiographic changes of alveolar bone height and width (P > .05). CONCLUSIONS: This new injectable biomaterial can be used easily and safely in clinical applications.

Acquisition of human alveolar bone-derived stromal cells using minimally irrigated implant osteotomy: in vitro and in vivo evaluations.

OBJECTIVES: Implant osteotomy yields a substantial amount of bone in the form of bone chips entrapped within drill flutes, and can provide a promising cell source for tissue engineering. The aims of this study were to isolate human alveolar bone-derived stromal cells (hABCs) obtained during implant osteotomy, and to evaluate osteogenic differentiation capacity of hABCs. MATERIAL AND METHODS: Bone chips were obtained by minimally irrigated implant drilling technique from 10 human donors. Isolated cells were studied with respect to their colony-forming efficiency, surface marker expression by immunofluorescence staining, fluorescence-activated cell sorting analysis and self-renewal potency. To verify the differentiation activity, in vitro osteogenic and adipogenic gene expressions were evaluated by reverse transcription-polymerase chain reaction, and in vitro formation of mineralized nodule and adipocytes was also evaluated. In vivo bone-forming activity was assessed by ectopic transplantation in immunocompromised mice (n = 5). RESULTS: Human alveolar bone-derived stromal cells population with characteristics of mesenchymal stem cells was present in the isolated cells. Upon hABC transplantation, significant ectopic bone formation was induced with the characteristics of fully matured bone tissue. CONCLUSION: The data support the feasibility of using hABCs as a source of stem cells for dentoalveolar bone tissue reconstruction. The cell source has an advantage that the hABCs can be easily acquired during implant surgery.

The clinical effect of locally delivered minocycline in association with flap surgery for the treatment of chronic severe periodontitis: a split-mouth design.

OBJECTIVE: The purpose of this study was to determine the effectiveness of adjunctive application of locally delivered minocycline ointment associated with flap surgery for the treatment of patients with chronic severe periodontitis. MATERIAL AND METHODS: Twenty patients with chronic severe periodontitis were treated in a split-mouth study to either adjunctive application of locally delivered minocycline ointment in association with flap surgery (FM) or flap surgery only (FO); additional minocycline application was performed at 3 months post operation. Clinical evaluation of the plaque index, probing depth (PD), bleeding on probing (BOP), gingival recession, and clinical attachment level (CAL) was conducted at baseline and at 3 and 6 months after treatment. RESULTS: Clinical evaluations revealed that although both sites exhibited clinical improvement, there was a statistically significant reduction in PD (3.34 ± 0.03 mm) and BOP (78.01 ± 11.42%), and a significant gain of CAL (1.88 ± 0.21 mm) at the FM site compared with the FO site (reduction of PD and BOP: 2.62 ± 0.06 mm, 50.33 ± 15.01%, and gain of CAL: 1.55 ± 0.13 mm) at 6 months post operation (p < 0.05). CONCLUSION: Adjunctive application of locally delivered minocycline may be beneficial to the surgical treatment protocol of chronic severe periodontitis.

The influence of perforating the autogenous block bone and the recipient bed in dogs. Part II: histologic analysis.

OBJECTIVES: This study histologically evaluated the influence of cortical perforation of grafted autogenous block bone (ABB) and/or the recipient bed at different healing periods in dogs. MATERIAL AND METHODS: Four ABBs harvested from the posterior mandible were bilaterally fixed onto the maxillary premolar region in five mongrel dogs. The experiments involved four groups according to the perforation site: the ABB and/or the recipient bed. The animals were killed at 1, 4, and 10 days (early healing periods) and 4 and 8 weeks (late healing periods) postoperatively. Specimens were prepared for histological evaluation. RESULTS: In the perforated ABB groups, blood clots had reached the inner surface of the ABB through a surgically prepared pathway, indicating that revascularization had taken place earlier than in the solid ABB groups. Finger-like bony projections into the graft were observed at the interfaces between the ABB and the recipient bed at the fourth week in all four groups. The remodeling process was observed over the entire ABB in the perforated ABB groups, whereas in the solid ABB groups it occurred only at the interface, and the ABB maintained its original lamella structure with more osteoclastic activity. Interestingly, in the perforated ABB groups, additional new bone with a smooth margin was formed above the block bone's original border. CONCLUSION: It was conjectured that intentional cortical perforation of the recipient bed and the ABB might enhance the initial angiogenesis and the integration of the graft.

Flap extension attained by vertical and periosteal-releasing incisions: a prospective cohort study.

OBJECTIVES: To evaluate the effect of vertical and periosteal-releasing incisions (PRI) on the extension of the buccal flap in a trapezoidal flap design. MATERIAL AND METHODS: Thirty patients scheduled for implant surgery accompanied by bone augmentation were recruited. The amount of flap extension pulled with a minimal tension of 5 g using a dynamometer was measured before and after the first and the second vertical incisions (VI) and PRI. The results were compared based on gender, surgical site and operator's experience. RESULTS: The first VI extended flap length by 1.1 ± 0.6 mm, 113.4% more compared with the original flap length. The second VI increased flap length by 1.9 ± 1 mm (124.2%), and the PRI significantly extended flap length by 5.5 ± 1.5 mm (171.3%) (P<0.001). The length of the first and the second VI and the amount of flap extension by each incision were compared, and there were no statistically significant differences between gender, surgical site (maxilla vs. mandible) and operator's experience (faculty vs. residents). CONCLUSION: Vertical and PRI in a trapezoidal flap design can be successfully utilized to attain tension-free primary closure during implant or periodontal surgeries. However, the PRI appears to be the only determinant key factor that can significantly extend the length of the flaps, while host- and operator-related factors might not have any significant effect on such flap extension.

Prevalence and anatomic topography of mandibular tori: computed tomographic analysis.

PURPOSE: Mandibular tori are located above the mylohyoid ridge. These features are relatively common in most populations, but their prevalence varies with race. The purpose of this study was to identify the prevalence and features of mandibular tori in a Korean population using computed tomographic (CT) images. MATERIALS AND METHODS: The CT images of 726 patients were analyzed in this study. The presence or absence of a mandibular torus was identified on the CT images of each patient's quadrants and categorized according to gender and age. The most common location was also evaluated according to the corresponding teeth. The cortical thickness of each torus was evaluated using a 3-dimensional reconstruction software program. RESULTS: The prevalence of mandibular tori in the entire sample was 24.1%, and most cases were bilateral. Mandibular tori were observed more frequently in young adults, with the prevalence being inversely related to age. The most frequently observed location was the premolar region, and the mean cortical thickness was 6.9 mm. CONCLUSIONS: Mandibular tori seem to change with aging. The prevalence in the present sample composed of Koreans was 24.1%, and younger patients may be more likely to develop a mandibular torus. Most tori presented a medium size bilaterally in the lingual aspect of the premolar region, and all were composed of cortical bone.

Isolation and characterization of human periodontal ligament (PDL) stem cells (PDLSCs) from the inflamed PDL tissue: in vitro and in vivo evaluations.

OBJECTIVES: Mesenchymal stem cells (MSC) could be isolated from healthy periodontal ligaments (PDL). The aims of this study were to isolate and characterize human PDL stem cells (hPDLSCs) from inflamed PDL tissue, and to evaluate their regenerative potential. MATERIALS AND METHODS: Inflamed hPDLSCs (ihPDLSCs) were isolated from the inflamed PDL tissue obtained from intra-bony defects during flap surgery, and characterized by immunohistochemical staining, colony-forming unit assay, fluorescence-activated cell sorting, and mRNA expression in comparison with healthy hPDLSCs obtained from extracted teeth for orthodontic purpose. The proliferative potential and migratory potential was evaluated, and compared with healthy hPDLSCs. Regenerative potential was assessed by an in vivo ectopic transplantation model. RESULTS: ihPDLSCs were successfully isolated and characterized as MSCs. Both ihPDLSCs and hPDLSCs were successfully differentiated under osteogenic/cementogenic and adipogenic microenvironment. The proliferative potential did not differ between healthy hPDLSCs and ihPDLSCs, while the migratory capacity was significantly increased in ihPDLSCs (p<0.05). Both groups exhibited new cementum-like tissue and related PDL fibre regeneration in an in vivo transplantation model. CONCLUSION: ihPDLSCs could be successfully isolated from inflamed PDL tissue, and they retained the regenerative potential for cementum and related PDL tissues.

Mechanism of alveolar bone loss in a collagen-induced arthritis model in mice.

OBJECTIVE: the aim of this study was to understand the cellular/molecular mechanisms of periodontal breakdown in a collagen-induced arthritis (CIA) model in mice to enhance the understanding of rheumatoid arthritis (RA)-associated alveolar bone loss in humans. MATERIALS AND METHODS: all analyses were performed on paired samples from CIA and control group mice. Mandibles were retrieved for micro-computed tomography (micro-CT), histomorphometric analysis, and isolation of alveolar bone cells (ABCs). In vitro osteoclastogenic/osteogenic/adipogenic potentials of ABCs were evaluated and the mRNA expression of downstream effector genes was assessed. Bone formation of ABCs was assessed using an ectopic transplantation model. RESULTS: histomorphometric and micro-CT data showed that alveolar bone loss was significantly increased in the CIA group (p<0.05). Osteoclastogenesis was significantly increased in the CIA group in vivo (p<0.05), with upregulated mRNA expressions of osteoclastogenesis-associated genes. Osteoblasts appeared to undergo increased apoptosis, and the bone-forming activity of ABCs concomitantly decreased with in vitro osteogenic differentiation and in vivo ectopic transplantation (p<0.05). Also, adipogenesis-associated mRNA expression was highly expressed in the CIA group, resulting in significantly enhanced adipocyte differentiation in vitro (p<0.05). CONCLUSIONS: these data demonstrate that increased osteoclastic activity, decreased bone-forming activity and enhanced adipogenesis promote alveolar bone loss in a CIA model in mice, and they suggest that these mechanisms could account for the same outcome in human RA.

Periodontal wound healing/regeneration following implantation of recombinant human growth/differentiation factor-5 (rhGDF-5) in an absorbable collagen sponge carrier into one-wall intrabony defects in dogs: a dose-range study.

AIM: Recombinant human growth/differentiation factor-5 (rhGDF-5) is being evaluated as a candidate therapy in support of periodontal regeneration. The objective of this study was to evaluate cementum and alveolar bone formation, and aberrant healing events following surgical implantation of rhGDF-5 in an absorbable collagen sponge (ACS) carrier using an established periodontal defect model. MATERIALS AND METHODS: Bilateral 4 x 5 mm (width x depth), one-wall, critical-size, intrabony periodontal defects were surgically created at the mandibular second and fourth pre-molar teeth in 15 Beagle dogs. Five animals received 1 microg/defect and five animals 20 microg/defect rhGDF-5 in unilateral defect sites. Contralateral sites received treatments reported elsewhere. Five animals received rhGDF-5/ACS with 0 (buffer control) and 100 microg/defect rhGDF-5 in contralateral defect sites. The animals were euthanized at 8 weeks post-surgery for histologic and histometric evaluation. RESULTS: Surgical implantation of rhGDF-5 stimulated significant periodontal regeneration. Cementum formation was significantly enhanced in sites implanted with rhGDF-5 (1 and 100 microg) compared with control (p<0.05). Similarly, bone formation height was significantly greater in sites receiving rhGDF-5 (1 and 100 microg) compared with control (p<0.05). There were no significant or remarkable differences in bone and cementum formation within the selected dose interval (1, 20 and 100 microg rhGDF-5). None of the control or the rhGDF-5 sites exhibited root resorption, ankylosis, or other aberrant tissue reactions. CONCLUSION: Surgical implantation of rhGDF-5/ACS may be used safely to support periodontal wound healing/regeneration in intrabony periodontal defects without complications.

Histologic and clinical evaluation for maxillary sinus augmentation using macroporous biphasic calcium phosphate in human.

OBJECTIVES: This study evaluated both the clinical and histological aspects of bone formation in maxillary sinus augmentation using MBCP as the bone-grafting material. MATERIAL AND METHODS: MBCP was used as a primary bone substitute for maxillary sinus augmentation. Fifty-two patients were selected after a medical and dental examination, and were divided into the following three groups: those augmented with MBCP only; MBCP combined with irradiated cancellous bone; and MBCP combined with intraoral autogenous bone. After a healing period (average 6.78 months after surgery), bone cores were harvested for a histological evaluation and the implant fixtures were installed. These bone cores were evaluated via light microscope and implants were followed up for at least six months after loading. RESULTS: Four to ten months after surgery, new vital bone surrounding the MBCP particles was observed in 18 bone biopsies. Two out of the 130 implants installed were explanted due to a failure of osseointegration before the prosthetic procedure. All the remaining implants were functioning for 6 to 27 months (average 12.96 months). The cumulative survival rate of the implants was 98.46%. CONCLUSION: These results show that MBCP can be used as a grafting material for sinus floor augmentation, whether combined with other bone graft materials or not, and lead to a predictable prognosis for dental implants in the posterior maxillary area where there is insufficient vertical height for fixture installation.

Effects of different depths of gap on healing of surgically created coronal defects around implants in dogs: a pilot study.

BACKGROUND: This study investigated the bone growth pattern in surgically created coronal defects with various depths around implants in dogs. METHODS: Four mongrel dogs were used. All mandibular premolars were extracted under general anesthesia and left to heal for 2 months. After ostectomy, bony defects were prepared in test sites, using a stepped drill with a diameter of 6.3 mm and two depths: 2.5 mm (test sites 1 [T1]) and 5.0 mm (test sites 2 [T2]). In the control sites, the implants were placed after ostectomy without any coronal defects. T1, T2, and control sites were prepared in the right and left sides of the mandible. Six implants, 3.3 mm in diameter and 10 mm in length, were placed in each dog; the implants were submerged completely. Two dogs were sacrificed 8 weeks after surgery, and the other two dogs were sacrificed 12 weeks after surgery. The stability of all implants was measured with a resonance frequency analyzer after placement and after sacrifice. All sites were block-dissected for ground sectioning and histologic examination. RESULTS: After 12 weeks of healing, only T2 were not filled fully with bone. At week 8, the mean bone-to-implant contact (BIC) was 47.7% for control, 43.6% for T1, and 22.2% for T2. At week 12, the control BIC was 56.7% and the 2.5-mm defect had a greater BIC (58.8%). However, in the 5-mm defect, the BIC was 35.1%. At insertion, stability was reduced at sites with a greater defect depth. Similar stability was noted in all specimens after 8 and 12 weeks of healing. CONCLUSION: Bone healing between an implant and marginal bone was compromised at sites with a deeper defect when the width of the bone defect was 1.5 mm.

Thickness of posterior palatal masticatory mucosa: the use of computerized tomography.

BACKGROUND: Periodontal plastic surgery is used to fulfill the esthetic and functional demands of patients. The palatal masticatory mucosa is the main donor site for connective tissue, and the thickness of the graft tissue obtained is an important factor for the success of this technique. The aim of this study was to measure the thickness of masticatory mucosa in the posterior palatal area using computerized tomography (CT). METHODS: The thickness measurements were performed on the images of 100 adult subjects who underwent CT on the maxilla for implant surgery. Twenty-four standard measurement points were defined in the hard palate according to the gingival margin and the middle palatal suture. The radiographic measurements were used after calibration. The data were analyzed to determine the differences in the mucosal thickness according to gender, age, tooth position, and depth of the palatal vault. RESULTS: The overall mean thickness of the palatal masticatory mucosa was 3.83 +/- 0.58 mm (range: 2.29 to 6.25 mm). Females had significantly thinner mean masticatory mucosa (3.66 +/- 0.52 mm) than males (3.95 +/- 0.60 mm) (P <0.0001). The thickness of the palatal masticatory mucosa increased with age. The mean thickness according to tooth site was 3.46 mm (maxillary canine), 3.66 mm (first premolar), 3.81 mm (second premolar), 3.13 mm (first molar), 3.31 mm (the base of the interproximal papilla of the first and second molars), and 3.39 mm (second molar). There was an overall increase in the thickness of the palatal masticatory mucosa as the distance from the gingival margin to the middle palatine suture increased, with the exception of the Ca-d (a point at 12 mm from the gingival margin of the canine) region. There was no significant difference in the thickness of the palatal masticatory mucosa between the groups with high or low palatal vaults. CONCLUSIONS: The palatal masticatory mucosa thickness increased from the canine to premolar region but decreased at the first molar region and increased again in the second molar region, with the thinnest area at the first molar region and the thickest at the second premolar region. The canine to premolar region seems to be the most appropriate donor site that contains a uniformly thick mucosa. CT can be considered an alternative method for the measurement of palatal soft tissue thickness.

Evaluation of mandibular posterior single implants with two different surfaces: a 5-year comparative study.

BACKGROUND: Anatomic and biomechanical limitations can jeopardize successful single implantation in the mandibular posterior area. To overcome the limitations, the design and the surface of the fixtures were modified. This study evaluated the cumulative survival rate (CSR) of mandibular molars replaced with a sand-blasted, large-grit, acid-etched (SLA) single implant or an anodized (ANO) single implant and examined associated factors, such as the surface treatment, position, and length and diameter of the implants. METHODS: One hundred ninety-three single implants restored with an SLA implant and 112 single implants restored with an ANO implant in the mandibular molar area were selected from subjects who had visited the Department of Periodontology, Dental Hospital of Yonsei University, from March 2001 through June 2006. In the SLA group, 123 and 70 implants were placed in the first and second molar area, respectively. In the ANO group, 55 and 57 implants were placed in the first and second molar area, respectively. The 1- to 6-year CSR of the SLA and ANO groups was calculated using the life-table analysis. In addition, associated factors, such as the surface treatment, position, and length and diameter of the implants, were compared and analyzed using the chi(2) test (P <0.05). RESULTS: Two of 193 implants in the SLA group failed, giving a CSR of 98.96%; four of 112 ANO implants failed, giving a CSR of 96.43%. There were no significant differences with regard to the surface treatment, position, and length and diameter of the implants. CONCLUSIONS: Despite the anatomic and biomechanical limitation in the mandibular posterior area, mandibular posterior single implants showed a high CSR during the observation period. Mandibular posterior single implants can be an effective and reliable treatment modality that is not affected by the surface treatment, position, or length and diameter of the implant.