https://oak.chosun.ac.kr/handle/2020.oak/18960 2026-04-09T19:06:23Z 2026-04-09T19:06:23Z Sun-mi Yang Hyun-ju Chung https://oak.chosun.ac.kr/handle/2020.oak/19103 2024-04-30T02:16:44Z 2018-12-31T15:00:00Z

Title: Three-dimentional finite element analysis of a mandibular premolar with reduced periodontal support under a non-axial load Author(s): Sun-mi Yang; Hyun-ju Chung Abstract: This study analyzed stress profiles of a mandibular premolar and its supporting periodontium under non-axial occlusal load as a function of the level of periodontal bone support using finite element analysis (FEA) and compared biomechanical behaviors to the profile under axial loading. A composite three-dimensional FEA model of a lower second premolar and its supporting tissue was developed using scanned image and computed tomography (CT) data. Material properties for enamel, dentin, periodontal ligament (PDL), and alveolar bone were used in this analysis. Four levels of periodontal support were simulated by varying the bone level, and a 90 N load was applied axially on the buccal cusp or 45° non-axially on inner inclines to simulate vertical or lateral forces. Finally, the von Mises stress (VMS) was calculated using FEA software. The non-axial load resulted in a peak VMS at the cervical enamel region, regardless of the bone level, and in extensive concentration of the peak VMS at the root dentin, PDL, and bone crest opposite to the loading direction, which increased with decreased periodontal bone support. The stress concentration along the root and PDL to the non-axial load shifted apically with periodontal bone support decrease. In the PDL and alveolar bone, the increase in peak VMS was significant with less than half of the bone height. Non-axial occlusal loads present asymmetric stress distribution in root dentin and PDL at the crest level, depending on the loading direction, with a significant increase in severe bone reduction (≥50%). The periodontal bone support decrease shifts the peak stress apically away and can result in apical extension of the root defect.

2018-12-31T15:00:00Z Won-pyo Lee Do-young Park Ki-won Lee Keon-il Yang Byung-ock Kim Sang-joun Yu https://oak.chosun.ac.kr/handle/2020.oak/19096 2024-04-30T02:16:43Z 2018-12-31T15:00:00Z

Title: Guided bone regeneration in peri-implant defects using a 1:1 mixture of cancellous and cortical freeze-dried bone allograft: A randomized controlled trial Author(s): Won-pyo Lee; Do-young Park; Ki-won Lee; Keon-il Yang; Byung-ock Kim; Sang-joun Yu Abstract: The results of guided bone regeneration (GBR) in peri-implant defects using anorganic bovine bone (ABB) were compared with those using a 1:1 mixture of cancellous and cortical freeze-dried bone allograft (FDBA). In total, 37 participants (10 males and 27 females) and 63 sites were evaluated. Full mucoperiosteal flap was reflected followed by implant insertion. The length and width of the defect were measured using a periodontal probe. Furthermore, the most buccal (Dis) and lingual (Dd) points of the exposed implant surface at the implant shoulder level were determined. The participants were randomly divided into two groups based on the graft material used: ABB only (control group) and 1:1 mixture of cancellous and cortical FDBA allograft (experimental group). Each transplanted site was covered by the collagen barrier membrane. After 5-6 months of surgery, re-entry was performed, and any residual defect length and width were measured. Moreover, the amount of regenerated bone was measured by calculating the distance from the Dis and Dd points to the regenerated bone in the buccolingual direction. Between-group comparisons were performed using the t-test. No differences in defect length, exposed implant surface, and horizontal bone gain were observed between ABB and allograft. Similarly, no significant differences in these measures and the defect width were observed between the two materials in both the maxilla and mandible. The 1:1 mixture of cancellous and cortical FDBA allograft combined with resorbable barrier membrane could be an effective alternative for ABB for the treatment of peri-implant defects when using GBR.

2018-12-31T15:00:00Z Do-kyeong Kim Jae-won Kwak Ryeong-mi Jo Da-som Jung Da-young Youn Na-yeon Oh Ji-hye Jang https://oak.chosun.ac.kr/handle/2020.oak/19101 2024-04-30T02:16:43Z 2018-12-31T15:00:00Z

Title: Effects of dental acid etchants in oral epithelial cells Author(s): Do-kyeong Kim; Jae-won Kwak; Ryeong-mi Jo; Da-som Jung; Da-young Youn; Na-yeon Oh; Ji-hye Jang Abstract: Phosphoric acid (P.A.; 37%) can induce necrosis on the oral mucosa and cause the ulceration of periodontal tissue. However, most studies reported are clinical case studies, with few basic science studies on oral epithelial cells. Our study aimed to investigate the effects of dental acid etchants on oral epithelial cells. After treatment with dental acid etchants for the indicated periods (0 second, 10 seconds, 30 seconds, 1 minute, and 5 minutes), cell damage, including vacuoles, pyknosis, and karyolysis, was observed by hematoxylin-eosin staining. The percentage of cell damage significantly increased after 10 seconds of etchant application. Furthermore, as the etchantapplied time increased from 10 seconds, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay results showed that cell viability was significantly reduced. Dental acid etchants were diluted with distilled water at ratios of 1:2 (18.5% P.A.) to 1:10 (3.7% P.A.). After the application of 1:5 (7.4% P.A.) diluted etchants, cells were enlarged, with some cells showing nuclear injury, including pyknosis. When treated with 1:2 (18.5% P.A.) diluted etchants, karyorrhexis and vacuoles were observed. The percentage of damaged cells significantly increased after the application of 1:2 (18.5% P.A.) diluted etchants. Moreover, cell viability significantly decreased in cells treated with 1:5 (7.4% P.A.) and 1:2 (18.5% P.A.) diluted etchants. This study examined the effects of dental acid etchants on oral epithelial cells as a basic experimental study in vitro and demonstrated the risks of dental acid etchants. Therefore, dentists and dental hygienists should pay strict attention to the handling of acid etchants during restoration and orthodontic treatments.

2018-12-31T15:00:00Z Gwi-hyeon Min Kyoung-hoon Lee Se-jin Sung Won-pyo Lee Sang-joun Yu Byung-ock Kim https://oak.chosun.ac.kr/handle/2020.oak/19097 2024-04-30T02:16:43Z 2018-12-31T15:00:00Z

Title: Bone and tissue reaction of porous nickel-titanium alloy implant for dental implants in rabbits Author(s): Gwi-hyeon Min; Kyoung-hoon Lee; Se-jin Sung; Won-pyo Lee; Sang-joun Yu; Byung-ock Kim Abstract: Porous nickel-titanium (Ni-Ti) alloy implants have been previously introduced, and many studies have been performed. Porous Ni-Ti alloys have excellent properties for use in the dental field. Thus, the use of a porous Ni-Ti coating to combine the advantages of Ni-Ti with titanium implants should be considered. The aim of this study was to investigate the tissue response to porous Ni-Ti alloy in vivo. Three 8-mm diameter calvaria bone defects were established in New Zealand rabbits. In the control group, only a collagen membrane was applied to the defect. In experimental group I, the alloy disk was applied to the defect with a bone graft and resorbable membrane. In experimental group II, the alloy disk was placed in the defect covered by a resorbable membrane. After 4 and 8 weeks of healing, the experimental animals were euthanized for specimen preparation. Histomorphometric analysis was performed to quantify new bone formation and connective tissue. The data were analyzed by Kruskal-Wallis and Mann-Whitney U-tests. At 4 and 8 weeks, new bone formation was seen in all groups. The new bone formation was insufficient in the groups with the titanium implants. There was minor inflammation in the experimental groups compared with the control group. In this study, new bone formation and tissue reactions were seen around the porous Ni-Ti alloy. Minor inflammation and insufficient new bone formation were noted in the experimental groups. This meant that the porous Ni-Ti alloy affected the adjacent tissue.

2018-12-31T15:00:00Z