• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.261-270
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• 2004

The purpose of this experiment was to examine the histological changes and the pattern of expression of type I, II collagen in the elongated area by distraction osteogenesis in the rabbit mandible. Sixteen rabbits weighing 2.5kg-3kg were used for this experiment. Experimental group was distracted at the rate of 0.7mm, twice/day for 7days, and control group was only osteotomized. After 5 days latency, osteotomic site is distracted for 7days. Consolidation period is 28days. The animal was sacrificed at the 3rd, 7th, 14th, 28th day after the operation. The distracted bone was examined by histological analysis and RT-PCR analysis. The results were summarized as follows: 1. Experimental group was observed that the gaps between the distracted bone edges were occupied by new bone. 2. Expression of Type I collagen were detected throughout the experiment in both groups and Expression of Type I collagen were markedly increased during distraction and consolidation period in experimental group than control group. 3. Expression of Type II collagen were detected throughout the experiment in both groups and expression of Type II collagen were maintained at high level during distraction and consolidation period in experimental group than control group. From these results, in contrast to type II collagen, type I collagen seemed to be more expressed by mechanical stimuli during distraction and consolidation period. The predominent mechanism of new bone formation in the distraction gap was intramembranous bone formation, but some of the regenerated bone was formed by endochondral ossification.

• BMB Reports
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• v.48 no.11
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• pp.636-641
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• 2015

There are controversial findings regarding the roles of nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway on bone metabolism under oxidative stress. We investigated how Nrf2/HO-1 pathway affects osteoblast differentiation of MC3T3-E1 cells in response to hydrogen peroxide (H₂O₂), N-acetyl cysteine (NAC), or both. Exposing the cells to H₂O₂ decreased the alkaline phosphatase activity, calcium accumulation, and expression of osteoblast markers, such as osteocalcin and runt-related transcription factor-2. In contrast, H₂O₂ treatment increased the expression of Nrf2 and HO-1 in the cells. Treatment with hemin, a chemical HO-1 inducer, mimicked the inhibitory effect of H₂O₂ on osteoblast differentiation by increasing the HO-1 expression and decreasing the osteogenic marker genes. Pretreatment with NAC restored all changes induced by H₂O₂ to near normal levels in the cells. Collectively, our findings suggest that H₂O₂-mediated activation of Nrf2/HO-1 pathway negatively regulates the osteoblast differentiation, which is inhibited by NAC.

• International Journal of Oral Biology
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• v.34 no.3
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• pp.157-164
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• 2009

We recently described a novel animal model of trigeminal neuropathic pain following compression of the trigeminal ganglion (Ahn et al., 2009). In our present study, we adapted this model using male Sprague-Dawley rats weighing between 250-260 g and then analyzed the behavioral responses of these animals following modified chronic compression of the trigeminal ganglion. Under anesthesia, the rats were mounted onto a stereotaxic frame and a 4% agar solution ($10{\mu}L$) was injected in each case on the dorsal surface of the trigeminal ganglion to achieve compression without causing injury. In the control group, the rats received a sham operation without agar injection. Air-puff, acetone, and heat tests were performed at 3 days before and at 3, 7, 10, 14, 17, 21, 24, 30, 40, 55, and 70 days after surgery. Compression of the trigeminal ganglion produced nociceptive behavior in the trigeminal territory. Mechanical allodynia was established within 3 days and recovered to preoperative levels at approximately 60 days following compression. Mechanical hyperalgesia was also observed at 7 days after compression and persisted until the postoperative day 40. Cold hypersensitivity was established within 3 days after compression and lasted beyond postoperative day 55. In contrast, compression of the trigeminal ganglion did not produce any significant thermal hypersensitivity when compared with the sham operated group. These findings suggest that compression of the trigeminal ganglion without any injury produces prolonged nociceptive behavior and that our rat model is a useful system for further analysis of trigeminal neuralgia.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.2
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• pp.71-77
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• 2012

Objectives: This study sought to investigate the positioning of the posterior superior alveolar artery in relation to the performance of the maxillary sinus bone graft procedure in a Korean population. Materials and Methods: We identified the position of the posterior superior alveolar artery relative to 93 maxillary sinuses in 58 patients and determined the distance from the inferior border of the artery in the premolar and molar areas to the alveolar ridge and sinus floor. Results: The mean distance from the alveolar ridge to the posterior superior alveolar artery in the dentate group ($20.62{\pm}3.05mm$ in the premolar region, $17.50{\pm}2.84mm$ in the molar region) was greater than as compared to the edentulous group ($18.83{\pm}2.79mm$ in the premolar region, $15.50{\pm}1.64mm$ in the molar region), and this difference was statistically significant (P<0.05). In contrast, there was no statistically significant difference (P>0.05) between the mean distance from the sinus floor to the posterior superior alveolar artery in the dentate group ($8.21{\pm}2.79mm$ in the premolar region, $7.52{\pm}2.07mm$ in the molar region) or in the edentulous group ($7.75{\pm}3.31mm$ in the premolar region, $7.97{\pm}2.31mm$ in the molar region). Conclusion: Prior to surgery, it is important to evaluate the position of the posterior superior maxillary artery by using computed tomography scans. The premolar area is safer than the molar area for performing the maxillary sinus bone graft without bleeding.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.2
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• pp.81-93
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• 2007

Purpose: Adenoid cystic carcinoma (ACC) is a relatively rare tumor that arises in glandular tissues of the head and neck region and sometimes has a protracted clinical course with perineural invasion and delayed onset of distant lung metastasis. Treatment failure of salivary ACC is most often associated with perineural and hematogenous tumor spread. However, very little has been known about the cellular and molecular mechanisms of perineural invasion and hematogenous distant metastasis of parotid ACC. This study was designed to develop an orthotopic tumor model of parotid adenoid cystic carcinoma in athymic nude mice. Experimental Design: A melanoma cell line was injected into the parotid gland of athymic mice to determine whether such implantation was technically feasible. A parotid ACC cell line was then injected into the parotid gland or the subcutaneous tissue of athymic mice at various concentrations of tumor cells, and the mice were thereafter followed for development of tumor nodule. The tumors were examined histopathologically for perineural invasion or regional or distant lung metastasis. We used an oral squmous cell carcinoma cell line as control. Results: Implantation of tumor(melanoma) cell suspension into the parotid gland of nude mice was technically feasible and resulted in the formation of parotid tumors. A parotid ACC cell line, ACC3 showed no significantly higher tumorigenicity, but showed significantly higher lung metastatic potential in the parotid gland than in the subcutis. In contrast, mucosal squmous cell carcinoma cell line doesn’t show significantly higher lung metastatic potential in the parotid gland than in the subcutis. The ACC tumor established in the parotid gland seemed to demonstrate perineural invasion of facial nerve, needs further study. Conclusion: An orthotopic tumor model of salivary ACC in athymic nude mice was successfully developed that closely recapitulates the clinical situations of human salivary ACC. This model should facilitate the understanding of the cellular and molecular mechanisms of tumorigenisis and metastasis of salivary ACC and aid in the development of targeted molecular therapies of salivary ACC.

• Korean Journal of Clinical Pharmacy
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• v.23 no.3
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• pp.206-212
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• 2013

Purpose: The aim of this study was to investigate the effect of nimodipine on the pharmacokinetics of warfarin after oral and intravenous administration of warfarin in rats. Methods: Warfarin was administered orally (0.2 mg/kg) or intravenously (0.05 mg/kg) without or with oral administration of nimodipine (0.5 or 2 mg/kg) in rats. The effect of nimodipine on the P-glycoprotein as well as cytochrome P450 (CYP) 3A4 activity was also evaluated. Results: Nimodipine inhibited CYP3A4 enzyme activity with 50% inhibition concentration ($IC_{50}$) of $10.2{\mu}M$. Compared to those animals in the oral control group (warfarin without nimodipine), the area under the plasma concentration-time curve (AUC) of warfarin was significantly greater (0.5 mg/kg, P<0.05; 2 mg/kg, P<0.01) by 31.3-57.6%, and the peak plasma concentration ($C_{max}$) was significantly higher (2 mg/kg, P<0.05) by 29.4% after oral administration of warfarin with nimodipine, respectively. Consequently, the relative bioavailability of warfarin increased by 1.31- to 1.58-fold and the absolute bioavailability of warfarin with nimodipine was significantly greater by 64.1-76.9% compared to that in the control group (48.7%). In contrast, nimodipine had no effect on any pharmacokinetic parameters of warfarin given intravenously. Conclusion: Therefore, the enhanced oral bioavailability of warfarin may be due to inhibition of CYP 3A4-mediated metabolism rather than P-glycoprotein-mediated efflux by nimodipine.

• Journal of Periodontal and Implant Science
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• v.50 no.6
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• pp.418-434
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• 2020

Purpose: The purpose of the present study was to evaluate the effect of silica-calcium phosphate composite (SCPC) granules on bone regeneration in extraction sockets. Methods: Ten patients were selected for a split-model study. In each patient, bone healing in SCPC-grafted and control ungrafted sockets was analyzed through clinical, radiographic, histomorphometric, and immunohistochemical assessments 6 months postoperatively. Results: A radiographic assessment using cone-beam computed tomography showed minimal ridge dimension changes in SCPC-grafted sockets, with 0.39 mm and 1.79 mm decreases in height and width, respectively. Core bone biopsy samples were obtained 6 months post-extraction during implant placement and analyzed. The average percent areas occupied by mature bone, woven bone, and remnant particles in the SCPC-grafted sockets were 41.3%±12%, 20.1%±9.5%, and 5.3%±4.4%, respectively. The percent areas of mature bone and woven bone formed in the control ungrafted sockets at the same time point were 31%±14% and 24.1%±9.4%, respectively. Histochemical and immunohistochemical analyses showed dense mineralized bundles of type I collagen with high osteopontin expression intensity in the grafted sockets. The newly formed bone was well vascularized, with numerous active osteoblasts, Haversian systems, and osteocytes indicating maturation. In contrast, the new bone in the control ungrafted sockets was immature, rich in type III collagen, and had a low osteocyte density. Conclusions: The resorption of SCPC granules in 6 months was coordinated with better new bone formation than was observed in untreated sockets. SCPC is a resorbable bone graft material that enhances bone formation and maturation through its stimulatory effect on bone cell function.

• The Journal of Advanced Prosthodontics
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• v.13 no.2
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• pp.107-116
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• 2021

PURPOSE. Several studies focused on the accuracy of intra-oral scanners in implant dentistry, but the data of inter-implant distances were not widely mentioned. Therefore, this study aimed to evaluate the effect of distance between two implants on the surface distortion of scanned models generated by intra-oral scanners. MATERIALS AND METHODS. Three models with the distances between two fixed scan bodies of 7, 14, and 21 mm were fabricated and scanned with a highly precise D900L dental laboratory scanner as reference models. Fifteen scans were performed with TRIOS3 and CEREC Omnicam intra-oral scanners. Trueness, precision, and angle deviation of the test models were analyzed (α=.05). RESULTS. There was a significant difference among inter-implant distances in both intraoral scanners (P<.001). The error of trueness and precision increased with the increasing inter-implant length, while the angle deviation did not show the same trend. A significant difference in the angle deviation was found among the inter-implant distance. The greatest angle deviation was reported in the 14-mm group of both scanners (P<.05). In contrast, the lowest angle deviation in the 21-mm group of the TR scanner and the 7-mm of the CR scanner was reported (P<.001). CONCLUSION. The inter-implant distance affected the accuracy of intra-oral scanner. The error of trueness and precision increased along with the increasing distance between two implants. However, the distortions were not clinically significant. Regarding angle deviation, the clinically significant angle deviation may be possible when using intra-oral scanners in the partially edentulous arch.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.5
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• pp.278-286
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• 2023

Objectives: This review assessed the performance of implant-supported fixed hybrid prostheses in 21 patients who received a total of 137 implants between 2003 and 2010. The implants were evaluated for marginal bone resorption, complications, success rate, and survival rate based on their vertical angularity, type of bone graft, and measured implant stability. Materials and Methods: One-way ANOVA and chi-square tests were used to analyze the relationships among long-term evaluation factors and these variables. The mean initial bone resorption in the implant group with a vertical angle of more than 20° was 0.33 mm and mean final bone resorption was 0.76 mm. In contrast, the mean initial bone resorption in the implant group with a vertical angle of less than 10° was 1.19 mm and mean final bone resorption was 2.17 mm. Results: The results showed that mean bone resorption decreased with an increase in the vertical placement angle of the implants used in fixed hybrid prostheses, as well as in the group without additional bone grafts and those with high implant stability. The success rate of implants placed after bone grafting was found to be higher than those placed simultaneously. Conclusion: These results suggest that implant-supported fixed hybrid prostheses may be an effective treatment option for edentulous patients, and intentionally placing implants with high angularity may improve outcomes.

• Journal of dental hygiene science
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• v.17 no.6
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• pp.508-515
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• 2017

This study was conducted to investigate the optimal management interval in 33 healthy adults by observing changes in oral health on the basis of the plaque control index and gingival index. When plaque control score was compared according to the period, it was found that oral hygiene management was the best in the fourth visit (p<0.05). Improved oral hygiene status was observed during the 3- and 6-month follow-up (p<0.05). Regarding gingival index, the fourth visit showed the healthiest gingival status (p<0.05). At the 3-month follow-up, the gingival index worsened, but a healthy gingival status was attained by 6-month follow-up (p<0.05). The plaque control score according to interest in dental health showed that the 'interested' group had good oral hygiene management (p<0.05). As a motivation for oral hygiene status and gingival health, examination with a 'phase contrast microscope' in the first visit and calculation of the 'evaluation index' in the follow-up visit tended to improve the patients' ability for oral hygiene management (p>0.05). The questionnaire survey showed, that the optimal management interval was 1, 3, and 6 months. As a result, with the effective management interval for the preventive management program focused on professional mechanical tooth cleaning, which was administered weekly, the maximum ability for oral hygiene management was attained at the fourth visit. The effective management period was 1 month. The use of a phase contrast microscope and the calculation of the evaluation index for oral hygiene management could influence the motivation to improve oral hygiene management.