• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.255-258
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• 2002

Dental chewing masticator, which is an essential device for evaluating the wear of dental resin and the interfacial failure between the filling resin and enamel of tooth used in conservative dentistry, was developed. This dental chewing masticator mimics the chewing motion and loading by adapting DC motor and rotary cam system. Chewing loading of 49N was imposed by computer-displacement control, loadcell, LM guide, and spring system. Extracted tooth was fixed into a holding jig, and this jig was mounted with rubber pad on the $15^{\circ}$inclined surface to consider the lateral movement of periodontal ligament. A water bath was installed for providing the environment of inside mouth and for circulating the $5^{\circ}C-55^{\circ}C$ water to evaluate the effect of hydrothermal cycling on the damage of resin filled teeth during long-term chewing activity.

• Journal of the korean academy of Pediatric Dentistry
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• v.7 no.1
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• pp.75-83
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• 1980

Rickets is not the deposite of minerals in the skeletal tissue and the retardation of skeletal growth in growing in growing animals. This study was undertaken to investigate the histologic effects of experimental rickets on the dental structure of the albino rats, and to show the relationship between the histological effects and the pulpal disease which induced premature loss of the primary teeth. This study was based on material obtained from 40 white rats that were placed on a rachitogenic diet for a period 1 to 56 days after weaning (at 24 days). In addition, a study was made of 25 litter mates, 24 to 80 days, that were fed a normal diet. The following results were obtained: 1. Enamel formation and calcification showed no significant changes and no hypoplasia. 2. Dentin formation and calcification was retarded and disturbed. In the experimental group, predentin/calcified dentin was remarkablly increased. 3. Newly formed dentin showed interglobular texture (less homogenous calcification) and the predentin was significantly wider and thicker, and there was an irregular wave in the basal portion of the rat's incisors. 4. In cementum, Matrix formed at almost a normal rate but calcification was defective. So cementoid tissue was increasesd. 5. The formation of the alveolar bone was at almost a normal rate but calcification was retarded. The trabecular bone was filled with osteoid tissue and thicker than in normal groups.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.6
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• pp.365-369
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• 2016

Objectives: To determine the prevalence and oral characteristics of cancer patients treated with bisphosphonates in the oncology and maxillofacial prosthesis departments of the General Hospital of Mexico between 2011 and 2013. Materials and Methods: This cross-sectional study included patients who received prior treatment with bisphosphonates; an intraoral examination was performed by 2 standardized examiners. Results: The prevalence of bisphosphonate-related necrosis in 75 patients was 2.6%; the most common malignancy was breast cancer (84.0%), followed by prostate cancer (16.0%). Exostosis was present in 9.3% of patients and the mean Decayed, Missing, Filled Teeth index was 4.64; 44.0% of the study group had a Community Periodontal Index value between 2 and 2.9 (mean, 0.60). Conclusion: A detailed intraoral assessment must be performed before initiating treatment with bisphosphonates to identify risk factors for osteonecrosis.

• Journal of Korean society of Dental Hygiene
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• v.13 no.6
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• pp.1063-1070
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• 2013

Objectives : The purpose of the study is to investigate the relationship between appearance perception, appearance satisfaction, and self-esteem in adolescents who demand the orthodontic treatment. Methods : A total sample of 403 high school students filled out the questionnaire and data were analyzed by using SPSS ver 20.0. for n (%), chi-square test, t-test, and a logistic regression. Results : Girl students (68.3%) tended to have a higher demand for orthodontic treatment than male students (31.7%). Higher appearance perception(t=6.967, p<0.001), lower appearance satisfaction(t=-5.477, p<0.001) and lower self-esteem(t=-7.333, p<0.001) were higher in group of demand for orthodontic treatment. The logistic regression analysis revealed that a gender, self-perception of their teeth, appearance perception, and self-esteem were significantly associated with orthodontic treatment demand. Conclusions : The result of this study will provide basic data for the consideration of psychosocial factors in orthodontic treatment in adolescents.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.27.1-27.7
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• 2015

The aim of this study was to evaluate the clinical relevance of autogenous fresh demineralized tooth (Auto-FDT) prepared at chairside immediately after extraction for socket preservation. Teeth were processed to graft materials in block, chip, or powder types immediately after extraction. Extraction sockets were filled with these materials and dental implants were installed immediately or after a delay. A panoramic radiograph and a conebeam CT were taken. In two cases, tissue samples were taken for histologic examination. Vertical and horizontal maintenance of alveolar sockets showed some variance depending on the Auto-FDT and barrier membrane types used. Radiographs showed good bony healing. Histologic sections showed that it guided good new bone formation and resorption pattern of the Auto-FDT. This case series shows that Auto-FDT prepared at chairside could be a good material for the preservation of extraction sockets. This study will suggest the possibility of recycling autogenous tooth after immediate extraction.

• Journal of Periodontal and Implant Science
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• v.35 no.1
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• pp.177-185
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• 2005

The purpose of the study was to investigate the influence of an endodontic infection on presence of furcation involvement in periodontally-involved mandibular molars. All first and second mandibualr molars in 45 patients were selected if at least one was root-filled or had a possible periapical radiolucency. The sample consisted of patients from a referral population at a periodotnal clinic which represented an adult population with a mean age of 47.5 years (range 31 to 63) For mandibular molars with periapical destruction at both roots, frequency of horizontal furcation depth ${\geqq}$ 3 mm was significantly more compared to teeth without periapical destruction. Mean periodontal probing depth was significantly greater at mandibular molars with periapical destruction. It is suggested that a root canal infection in periodontitis-involved molars may potentiate periodontitis progression by spreading of endodontic pathgens through patent accessory canals and dentinal tubules. In conclusion, an endodontic infection in mandibular molars was found to be associated with additional attachment loss in the furcation area, and may thus be considered to be one of several risk factors influencing the prognosis of molars in periodontitis-prone patients.

• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.31-37
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• 1989

The purpose of these study was to compare the sealing ability of a injection-molded thermoplasticized gutta-percha and silver amalgam as retroseal material in vitro. Sixty two upper and lower extracted human teeth with single root were randomly selected and instrumented in a conventional method with H-file. After instrumentation the root canal was obturated with gutta-percha by lateral condensation technique with AH26 and an apicoectomy was performed by beveling the root tip 45 angle. In the experimental group 1 and 2, a class I preparation was made and filled with silver amalgam or gutta-percha and in the experimental group 3 an apicoectomy only was performed. All specimens were immersed in black Indian ink, decalcified and cleared. The depth of dye penetration into the canals were evaluated by califer. The results were as follows ; 1. The experimental group 1 displayed the smallest mean dye penetration as 0.45mm. 2. The experimental group 3 displayed the greatest mean dye penetration as 0.65mm. 3. There was the difference in dye penetration between each group, but the difference was not statistically significant(P>0.05).

• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.151-157
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• 1991

The roles of temporary sealing materials used in endodontics are impotant Especially, its marginal sealing properties affect endodontic success and failure in endodontic treatment The purpose of this in vitro study was to compare and evaluate the marginal sealing properties of various temporary restorative materials used in endodontic access cavity by using electrochemical method. Standard endodontic access cavities were prepared in extracted human molar teeth and filled with Caviton, IRM, zinc oxide - eugenol cement. Each specimen was immersed in 1 % solution of KCl, and applied a potential of 9 V external power supply. Marginal microleakage and water sorption were measured for marginal sealing effect evaluation in comparison with each group. A comparative study of the obtained results have led to the following conclusions. 1. The Caviton group showed lower marginal microleakage value than the zinc oxide - eugenol cement and IRM group the 6 th day after. The IRM group showed lwoer marginal microleakage value than the zinc oxide - eugenol cement group from the 6 th day to the 12 th day. But there was no significant difference between zinc oxide - eugenol cement and IRM group after the 13 th day. 2. As time went by, marginal microleakage value was increased in Caviton, IRM and zine oxide - eugenol cement.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.7 no.2
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• pp.99-102
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• 2011

A-12year-old boy visited the clinic with chief complaint of anterior maxillary trauma. He was diagnosed with first degree mental retardation and cerebral disorders. By clinical and radiographic examination, intrusion of maxillary central incisors were found. The intrusion was not severe, teeth were luxated with a slight force and the prognosis was followed. After the first year, external root resorption was seen radiographically. Due to difficult behavior management, one visit root canal filling with OrthoMTA(BioMTA, Korea) which is known to generate of cementum and periodontal ligament was planned along with general anesthesia. OrthoMTA was filled from the apex to 1-2mm below cervical area and composite resin used for crown restoration. 6 months after, further resorption, discoloration and mobility was not found. This case is currently checked yearly and further research is needed for inflammatory root resorption and ankylosis.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.899-905
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• 1996

For the purpose of evaluation of microleakage of class V resin restoration, 64 extracted bovine teeth were filled with two kinds of light curing composite resins(Z-100, Clearfil) and polymerized with 40 seconds of visible light and with 10 seconds of argon laser. After 1000 thermocycling($5^{\circ}C/55^{\circ}C$), specimens were placed in 1 % methylen blue dye solution for 72 hours in $37^{\circ}C$ water bath. The specimens were sectioned at center of filling body and the degree of dye penetration was observed with a stereomicroscope. The following results were obtained, 1. Differences of the microleakage of resin restorations polymerized with 10 seconds of argon laser and 40 seconds of visible light were statistically insignificant. 2. There was more microleakage in Z-100 than clearfil and there was a statistical significancy (p<0.05).