Purpose The aim of this study was to evaluate the preclinical results of 2 types of commercially available deproteinized bovine bone mineral (DBBM) when applied to alveolar bone defects in dogs. Methods This study was conducted using 6 beagles. Alveolar defects in the mandible were formed and filled with 2 DBBMs produced by a similar procedure. Defects were randomly assigned to be filled using DBBM 1 or 2. All defects were covered with a collagen membrane and had a healing period of 12 weeks. After the dogs were sacrificed, histological, histomorphometric, and linear/volumetric analyses were performed. Results Both DBBM groups showed similar histological findings, demonstrating that bone remodeling had occurred and new bone had formed. The residual bone particles were surrounded by newly formed vital bone. In the histomorphometric analysis, the ratio of the area of vital bone and residual bone substitute in DBBM 2 (38.18% and 3.47%, respectively) was higher than that of DBBM 1 (33.74% and 3.41%, respectively), although the difference was not statistically significant. There were also no statistically significant differences between both groups in linear and volumetric analyses using micro-computed tomography scans and digitized images of dental casts. Conclusions In the present study, DBBM 1and 2, which were produced by similar processes, showed similar results in histological, histomorphometric, and volumetric analyses. Further studies are needed to identify more specific differences between the 2 DBBMs.

Background and Purpose The purpose of this study was to assess the occurrence and prognosis of dental implant proximity or direct contact with the adjacent tooth and to evaluate the symptoms and complications in both the implant and the adjacent tooth. We then elaborate on treatment modalities and discuss the prevention of this phenomenon. Materials and Methods This retrospective study was conducted based on the dental clinical and radiographic records of 43 patients with implant‐tooth proximity of <1.0 mm or direct implant‐tooth contact. Multivariate Bayesian logistic regression was performed to examine the influence of individual variables on correcting major clinical variables. Results In the multivariate regression analysis, the rate of occurrence of tooth symptom decreased by about 95% with every increase of 1.0 mm distance between implant and tooth (odds ratio [OR] = 0.1, 95% confidence interval [CI]: 0.004–0.680, p = 0.024). In the case of implant‐tooth root proximity in the anterior area, the OR of peri‐implantitis occurrence was 30.4‐fold greater than in posterior sites (OR = 30.4, 95% CI: 1.189–785.914, p = 0.040). Conclusion Implant‐tooth root proximity or direct implant‐tooth contact is an iatrogenic factor that causes various complications, including devitalization of the adjacent tooth and peri‐implantitis. Proactive prevention with surgical stents and intra‐operative periapical radiographs is needed. If proximity or contact is found during surgery, repositioning of the fixture to the correct location is recommended in order to maintain peri‐implant health and prevent complications.

Purpose Hyaluronic acid (HA) affects angiogenesis and promotes the migration and differentiation of mesenchymal cells, thereby activating the osteogenic ability of osteoblasts. Although studies on the action of HA during bone regeneration are being actively conducted, the optimal dose of HA required for bone regeneration remains unclear. Therefore, the purpose of this study was to elucidate the most effective HA dose for bone formation using a rat critical-size defect model. Methods Thirty rats were randomly divided into 5 groups, with 6 rats in each group. An absorbable collagen sponge soaked with HA or saline was used to fill an 8-mm defect, which was then covered with a collagen membrane. Different treatments were performed for each group as follows: (1) saline control, (2) 1 mg/mL HA, (3) 25 mg/mL HA, (4) 50 mg/mL HA, or (5) 75 mg/mL HA. After a healing period of 4 weeks, micro-computed tomography and histological analysis were performed. The obtained values were analyzed using analysis of variance and the Tukey test ( P <0.05). Results At week 4, the 75 mg/mL HA group had the highest bone volume/total volume ratio, new bone, and bone fill among the 5 groups, and these values were significantly different from those observed in the control group ( P <0.01) and 1 mg/mL HA group ( P <0.001). More active bone formation was observed in the higher-dose HA groups (25 mg/mL, 50 mg/mL, and 75 mg/mL HA), which included a large amount of woven bone. Conclusions The 75 mg/mL HA group showed better bone formation than the other groups (1, 25, and 50 mg/mL HA and control).

Purpose The aim of this study was to retrospectively evaluate the survival and failure rates of RESTORE ® implants over a follow-up period of 10–15 years at a university dental hospital and to investigate the factors affecting the survival rate of these dental implants. Methods A total of 247 RESTORE ® dental implants with a resorbable blast media (RBM) surface inserted in 86 patients between March 2006 and April 2011 at the Department of Periodontology of Seoul National University Dental Hospital were included. Patients with follow-up periods of less than 10 years were excluded, and data analysis was conducted based on dental records and radiographs. Results Over a 10- to 15-year period, the cumulative survival rate of the implants was 92.5%. Seventeen implants (6.88%) were explanted due to implant fracture (n=10, 4.05%), peri-implantitis (n=6, 2.43%), and screw fracture (n=1, 0.4%). The results of univariate regression analysis using a Cox proportional hazards model demonstrated that implants placed in male patients (hazard ratio [HR], 4.542; 95% confidence interval [CI], 1.305–15.807; P =0.017) and implants that supported removable prostheses (HR, 15.498; 95% CI, 3.105–77.357; P =0.001) showed statistically significant associations with implant failure. Conclusions Within the limitations of this retrospective study, the RESTORE ® dental implant with an RBM surface has a favorable survival rate with stable clinical outcomes.

Purpose This study aimed to evaluate the long-term cumulative survival rate (CSR) of dental implants with micro-threads in the neck over a 10-year follow-up period and to examine the factors influencing the survival rate of dental implants. Methods This retrospective study was based on radiographic and dental records. In total, 151 patients received 490 Oneplant ® dental implants with an implant neck micro-thread design during 2006–2010 in the Department of Periodontology of Seoul National University Dental Hospital. Implant survival was evaluated using Kaplan–Meier analysis. Cox proportional hazard regression analysis was used to identify the factors influencing implant failure. Results Ten out of 490 implants (2.04%) failed due to fixture fracture. The CSR of the implants was 97.9%, and no significant difference was observed in the CSR between external- and internal-implant types (98.2% and 97.6%, respectively, P =0.670). In Cox regression analysis, 2-stage surgery significantly increased the risk of implant failure (hazard ratio: 4.769, P =0.039). There were no significant differences in influencing factors, including sex, age, implant diameter, length, fixture type, location, surgical procedure, bone grafting, and restoration type. Conclusions Within the limitations of this retrospective study, the micro-thread design of the implant neck was found to be favorable for implant survival, with stable clinical outcomes.