• 대한치과보철학회지
• /
• 제34권3호
• /
• pp.457-463
• /
• 1996

An esthetically pleasing result in denture service is dependent upon several consideration. Esthetic considerations for the edentulous patient include tooth size, shape, arrangement, positioning, gingival contour, age, sex, personality differences, and ethnic type. Especially, the form of anterior artificial teeth is an important factor on the esthetics. The selection of artificaial teeth requires understanding and knowledge on physical and biologic factors and has to meet the indivisul esthetics and functional needs of each patient. However, the selection of artificial teeth is based on the large degree of subjective judgement of the dentist, Therefore, this is one of the most unscientific processes. Many attempts have been made to find a guideline for the selection of artificial teeth. Temperamental theory by White and Hall utillized with the physical characteristics such as body size, body form, color of eyes and hair, and disposition. SPA theory by Frush and Fisher utilized with the basis of sex, personalities, and age of the indivisual. There has not been provided for a guideline and study on the selection of artificial teeth for Koreans yet. This study was aimed to evaluate the William's typal matching theory in Koreans. 1. The facial forms of korean adult were ovoid(46.3%), square(36.7%) and tapered(17.0%) form. 2. The anatomic forms of natural maxillary incisors were ovoid(45.3%), tapered(31.3%), square(23.3%) form. 3. The forms of face and natural maxillary incisors were ovoid(21.9%), squared(11%), tapered(6.3%). 4. The natural maxillary incisors were similar in form to the facial form only in 39%. There was no correlation between the form of the face and the form of natural maxillary central inisors in Koreans. 5. Artificaial teeth which was selected according to the typal matching theory did not represent the form of the natural teeth in 61 per cents of the fatal, but it felt that they harmonized with the form of the patient's face and produced good results.

• 구강회복응용과학지
• /
• 제35권4호
• /
• pp.253-259
• /
• 2019

본 증례 보고는 하악 전치에 발생한 치은 퇴축을 laterally closed tunnel technique을 이용하여 처치하였다. 환자는 모두 과거 교정 치료 시 하악 전치의 경사도를 변화시켰으며 치주 적으로 얇은 생체형을 가지고 있었다. 터널링법으로 수여 부를 형성하고 구개 측에서 채득한 결합조직이식편을 터널내에 위치시킨 후 판막의 변연을 치근 중앙부를 향해 측방으로 이동시켜 봉합하여 이식편을 피개 하였다. 얇은 치주 생체형에도 불구하고 치근 피개를 성공적으로 얻을 수 있었으며 각화 치은의 획득과 주변 조직과의 색, 형태 조화로 심미성을 달성할 수 있었다.

• 한국산업융합학회 논문집
• /
• 제23권4_2호
• /
• pp.701-708
• /
• 2020

In this paper, we analyzed the optical properties of the LED module for dental care, which has the effect of promoting cell regeneration and scar treatment. The LED module is a U-shaped module suitable for the shape of teeth. It is manufactured with an LED module (632 nm) and an LED module (632 nm + 870 nm), analyzes the results of optical properties, sets the irradiation distance, irradiation time, and is effective in healing skin wounds. Evaluation was conducted. It was tested in 6 test groups according to the light irradiation conditions, and light was irradiated to the scar site every other day for 7 days, 1 day and 3 days. As a result, it was confirmed that the effect of scar treatment was the highest when the combined wavelength of 632 nm + 870 nm was irradiated in pulse mode than when the single wavelength was irradiated and the composite wavelength was continuously irradiated. In group C group irradiated with PW Mode: pulse mode (period 36 ms, pulse width 35 ms) using a composite wavelength with LED module (632 nm + 870 nm) than group A without light irradiation, the length of scar reduction was 19 %, the area of the scar was further reduced by 10%, and it was confirmed that it is effective in treating scars in the wound area.

• Restorative Dentistry and Endodontics
• /
• 제25권2호
• /
• pp.289-298
• /
• 2000

Carbamide peroxide is usually used for vital teeth bleaching at home. Complications such as tooth hypersensitivity and/or gingival irritation are frequently reported. Therefore, this study was performed to evaluate any possible histological changes in pulp and periodontal tissue by carbamide peroxide bleaching gel in rats. 10% and 15% carbamide peroxide containing nightguard for upper molar were worn for 4 hours a day. The rats were sacrificed after 1 day, 2 days, 3 days, 4 days and 6 days application of carbamide peroxide respectively. The results were as follows : Mild infiltration of inflammatory changes below the junctional epithelium and hyperplasia of epithelium were observed in both 10% and 15% carbamide peroxide treated groups. In all experimental groups, odontoblasts were changed from columnar to cuboidal shape and/or obliterated and the focal loss of predentin was observed in pulp horn. With increasing time of application, these changes were more remarkable, but limited in pulp horn. Inflammatory reactions, vacuolar changes and hyaline degenerations of the pup tissue were also observed in some cases. These results suggested that carbamide peroxide gel used in home bleaching could cause reversible pulpal irritation.

• 대한치과보철학회지
• /
• 제59권4호
• /
• pp.469-477
• /
• 2021

상악 전치부 임플란트의 성공적인 수복을 위해서는 pink esthetics와 white esthetics가 모두 충족되어야 한다. Pink esthetics 부분의 경우 적절한 임시보철물의 역할이 중요하고, white esthetics 부분의 경우에는 최종 보철물의 색상과 형태가 중요하다. 다층 지르코니아는 기존의 단일구조 지르코니아에 비해 절단 부위의 투명도가 높기 때문에 추가적인 도재 축성 없이 자연스러운 보철물 제작이 가능하다. 따라서 본 증례에서는 상악 전치를 상실한 환자에서 적절한 임시보철물을 통해 기능과 심미성을 충분히 회복한 후 다층 지르코니아를 통해 white esthetics를 달성하였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제47권5호
• /
• pp.360-364
• /
• 2021

Objectives: The purpose of this study was to evaluate the clinical and radiographic characteristics of idiopathic bone cavity (IBC) to determine the effect of surgical intervention on the process of healing. Materials and Methods: All cases diagnosed with IBC during the period of 2011 to 2020 at our Department of Oral and Maxillofacial Surgery were searched. Ninety cases were retrieved. The features evaluated were sex, age, contour of the lesion, number of teeth involved, site, history of trauma, and postoperative healing pattern. The significance of differences was assessed by Mann-Whitney U test and chi-square test. Results: The female:male ratio showed no predilection toward either sex (0.9:0.8). The mean age of the collected sample was 22.05±14.38 years, and the age ranged from 10 to 58 years. All cases presented in the mandible and showed well-circumscribed radiolucency. Margins were either scalloped or round in shape, and the size varied from one tooth to six teeth involvement. Seventy cases involved three or fewer roots. Three cases showed bilateral lesion. Four cases had a history of trauma at the area of the lesion. Fifty-one cases were followed for six months after surgery, and all showed increased bone density at the lesion. Conclusion: There is no definitive radiological or clinical feature of IBC. Considering the diversity of clinical and radiological features, such a diagnosis relies primarily on surgical findings of an empty bone cavity with no epithelial lining. Our data suggest that surgical intervention be the first choice of treatment as opposed to observation.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제42권
• /
• pp.30.1-30.7
• /
• 2020

Background: Dental studies of precocious puberty have focused on examination of jaw and dentition growth. The aim of the study was to analyze the relationship between precocious puberty and maxillary dental developmental abnormalities (DDAs). Methods: This retrospective study was conducted on the Korean patients in whom dental panoramic and hand-wrist radiographs had been taken before they were 15 years of age. The maxillary DDAs were assessed as mesiodens, congenital missing teeth, peg-shape lateral incisors, or impacted teeth. The chronological ages of the control group members were within the normal range of the hand-wrist bone age. Others with a peak luteinizing hormone of ≥ 5 and < 5 IU/L were allocated to central precocious puberty (CPP) and peripheral precocious puberty (PPP), respectively. Results: Of the enrolled 270 patients, 195, 52, and 23 were allocated to the control, CPP, and PPP groups, respectively. The maxillary DDAs were significantly more prevalent in the CPP group than in the other groups. Among those with maxillary DDA, the mesiodens predominated. Age- and sex-adjusted multivariate analysis revealed maxillary DDA (odds ratio, 3.36; 95% CI, 1.60-7.05) and especially mesiodens (odds ratio, 5.52; CI, 2.29-13.28) to be significantly associated with CPP. Conclusions: Maxillary DDAs were significantly more prevalent in the CPP group than in the PPP or control groups. Among the many types of maxillary DDAs, mesiodens was significantly associated with CPP and may be considered a predictor of the development of CPP.

• 한국가스학회지
• /
• 제26권2호
• /
• pp.9-13
• /
• 2022

벨트나 체인을 이용한 감속기는 간단한 장치이긴 하지만 공간을 많이 차지하여 공간상의 제약이 있기 때문에 전동휠체어 구동부에는 부적합하다. 하지만 유성기어형태의 감속기는 동일 축에서 감속이 이루어지기 때문에 부피를 작게 할 수 있어 공간의 제약이 벨트나 체인형태의 감속기보다 덜하다. 따라서 본 연구에서는 수·전동전환이 가능한 휠체어의 구동부에 대한 연구를 통하여 유성기어형태를 이용한 감속기로 큰 추진력을 얻을 수 있는 구동부를 개발하였다. 그에 따라 감속기에 적용되는 유성기어의 치형을 Kisssoft 프로그램을 이용하여 설계를 진행하였다. 또한 기존 휠체어 바퀴에 적용 가능하도록 구동부의 설계를 진행하였고, 구동부의 수·전동 전환원리 및 작동원리에 대한 메커니즘의 최적화를 진행하였다. 연구내용을 토대로 하나의 선기어와 2개의 유성기어, 하나의 링기어를 갖는 유성기어 형태의 휠체어 감속기 구동부의 최종 설계 및 제작을 진행하였다.

• Journal of Korean Dental Science
• /
• 제16권1호
• /
• pp.23-34
• /
• 2023

Purpose: This study aims to investigate the force delivery profile of thermoformed aligners (TFA) compared with direct-printed aligners (DPA) and to explore the effect of different activation amounts on forces and moments of respective groups. A secondary objective is to observe the amount of stress relaxation that occurs over the 7~14 days when aligners are maintained in a simulated intraoral environment. Materials and Methods: An in vitro setup was created to quantify forces and moments. It consisted of a three dimensional-printed base plate and segmented maxillary teeth, placed in a semi-enclosed chamber to maintain a temperature of 37℃. Ninety clear aligners were divided into nine groups of ten aligners each based on material types (Zendura, ATMOS, TC-85) and activation amounts. Aligners were created with 0.00, 0.25- and 0.50-mm activations for lingual bodily movement of the upper left central incisor and kept on models in the "stressed" position in a 37℃ water bath. Three force components acting on the upper left lateral incisor, upper left central incisor, and upper right central incisor were measured for each time point, beginning from the initial baseline measurement, 8 hours, 16 hours, 24 hours, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, and lastly, 14 days. Result: TC-85 aligners in every activation group showed less force on teeth than Zendura and ATMOS. Significant force levels from 0.0 mm activation were present and stayed consistent over the course of 14 days. Comparisons made for baseline measurements to 7-days and 14-days showed statistically significant change from the baseline force level. Conclusion: TC-85 aligners demonstrated lower, more consistent forces with fewer side effects. Aligners can generate forces even when no activation is programmed. No major decreases in force levels over time were observed; the intra-oral clinical simulated environment and length of observation time could contribute to this.

• Tribology and Lubricants
• /
• 제40권1호
• /
• pp.8-16
• /
• 2024

This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.