• 대한소아치과학회지
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• 제30권2호
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• pp.210-216
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• 2003

이중치는 쌍생치와 융합을 포함한다. 선천적인 결손치는 치아가 하나이상 없는 상태를 의미한다. 이 연구의 목적은 익산시 유치원 어린이에서의 이중치와 선천적 결손치의 유병율을 조사하는 것이다. 조사 인원은 569명의 남아와 462명의 여아로 1,031명의 어린이를 대상으로 하였으며 연령은 17개월에서 84개월의 연령이내였다. 이중치는 다양한 진단학적 치료적 문제를 가진다. 쌍생치는 하나의 치배가 두개의 치관을 형성하는 것으로 정의되며 임상적으로 동일한 두 개의 치관이 나뉘어져 거울상(mirror image)으로 보이게 된다. 융합치는 두 개의 치배가 합쳐져서 형성된 것으로 물리적인 힘이나 압력이 두 개의 정상적으로 분리된 치배를 접촉시켜 발생하는 것으로 알려져 있다. 융합은 두개의 정상치아 사이에서 나타나거나 혹은 정상치아와 과잉치 사이에서 나타나는데 후자의 경우 쌍생치와 구별하기 힘들다. 1,031명중 23명(11명의 남아, 12명의 여아)이 이중치를 보이고 17명(8명 남아, 9명 여아)은 선천적 결손치를 보였다. 이중치의 유병율은 2.2%였다. 선천적 결손치의 유병율은 1.6%였다. 피검자중 1명은 이중치와 결손치를 가지고 있었다. 유치열기의 이중치와 선천적 결손치에서 모두 남녀간에 통계학적으로 유의한 차이가 없었다(p>0.05).

• Journal of Biosystems Engineering
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• 제13권4호
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• pp.9-19
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• 1988

The threshing of head-feed combine may be accomplished mainly by the action of impact between threshing teeth and rice. In this study, it was attempted to assess threshing performance characteristics of head-feed threshing teeth. And the characteristics of threshing teeth will be applied to the method which could analyze the time and order of impact between teeth and the rice, which was used as a basis for predicting the threshing performance and determining the optimum design parameters. The results of the study are summarized as follows: 1. About 50% of threshed material were threshed by the beginning 7 impacts on the rice bundle. Threshing torque decreased until 25 impacts and did not change thereafter. 2. There was significant difference in the threshability according to the shape of threshing teeth. The triangular-shaped tooth was the most efficient in threshability ratio and the semicircle-shaped tooth was the lowest. There was no significant difference in specific energy requirement for the varied teeth design. Torn-head ratio being generated by the semicircle-shaped and the triangular-shaped teeth in series was less than that by a single tooth with the triangular-shaped and the double setting of the triangular-shaped. Chaff generation ratio by the triangular-shaped and the semicircle-shaped teeth was less than the others tried. 3. The triangular-shaped teeth in series, which was newly designed for this study, showed an intermediate characteristics between the double setting of the triangular-shaped and the semicircle- shaped teeth. Threshability ratio of the triangular-shaped teeth in series was higher than that of the semicircle and lower than the double setting of the triangular-shaped tooth. Torn-head generation ratio for it was about same as that of the semicircle. Chaff being generated by the triangular-shaped teeth in series was about same as the double setting of the triangular-shaped teeth. 4. About 40% of threshed grains which passed through concave were concentrated under the threshing tooth and the rest of grains displayed a skew distribution toward the inlet of threshing chamber.

• The Journal of Advanced Prosthodontics
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• 제11권3호
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• pp.187-192
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• 2019

PURPOSE. The purpose of this in vitro study was to investigate the fracture loads and modes of failure for the full range of natural teeth under simulated occlusal loading. MATERIALS AND METHODS. One hundred and forty natural teeth were taken from mandibles and maxillas of patients. There were 14 groups of teeth with 10 teeth in each group (5 males and 5 females). Each specimen was embedded in resin and mounted on a positioning jig, with the long axis of the tooth at an inclined angle of 30 degrees. A universal testing machine was used to measure the compression load at which fracture of the tooth specimen occurred; loads were applied on the incisal edge and/or functional cusp. RESULTS. The mean fracture load for the mandibular first premolar was the highest (2002 N) of all the types of teeth, while the mean fracture load for the maxillary first premolar was the lowest (525 N). Mean fracture loads for the mandibular and maxillary incisors, and the first and second maxillary premolars, had significantly lower values compared to the other types of teeth. The mean fracture load for the teeth from males was significantly greater than that for the teeth from females. There was an inverse relationship between age and mean fracture load, in which older teeth had lower fracture loads compared to younger teeth. CONCLUSION. The mean fracture loads for natural teeth were significantly different, with dependence on tooth position and the sex and age of the individual.

• 대한소아치과학회지
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• 제10권1호
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• pp.123-129
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• 1983

This study was designed to find out the prevalence d the fused teeth in the primary dentition and their successors. The clinical and panoramic radiographic examination was undertaken of 5226 children (male 2812, female 2414) attended department of Pedodontics, College of Dentistry, Yon Sei University, Seoul, Korea. The results were as follows; 1. The prevalence of the fused teeth in the primary dentition was 1.03 percent and female (1.2%) affected more frequently than male (0.89%). 2. Compare with the maxilla and mandible, the prevalence of the fused teeth were higher in the mandible than in the maxilla. 3. The fusion of the primary teeth were occured between central with lateral incisor in the maxilla, and central with lateral and lateral with canine in the mandible. 4. There were 33 cases (61%) of succeding teeth missing among 54 case of the rused teeth.

• 치과방사선
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• 제7권1호
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• pp.5-8
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• 1977

The author has observed 906 full mouth roentgenograms in Korean young man who had the impacted and supernumerary teeth. Impacted and supernumerary teeth were analysed upon several items, such as incidences and positions in the dental arch. The result were as follows; 1. The incidences of impacted teeth were 59.05% and the ratio of upper jaw to lower one was 1:3. 2. The frequency of the supernumerary teeth were 5.52% and the ratio of maxilla to mandible was 49:1. 3. No significant differences between right and left side in both jaws, but incidence rate of the supernumerary teeth was 74% in the maxillary central incisor area. 4. The positions of impacted and supernumerary teeth were vertical and inverted shapes in maxilla, whereas horizontal and mesio-angular forms in mandible.

• 대한치과보철학회지
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• 제42권4호
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• pp.443-457
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• 2004

Purpose: The purpose of this study was to analyze and estimate whether each company may produce the color of artificial teeth as it stands, in the standard of vita classical shade guide using ShadeScan$^{TM}$ System. Material and methods: we chose the products of 6 companies -EFUCERA, IVOCLAR, ENDURA, TRUBYTE, DURADENT, and DURACROSS- estimated the shade value of each fixed point(cervical, body, and incisal area) of artificial tooth, and verified the equality among the samples from the same company. Results: First, the variation appeared significant at cervical and incisal area. It means that there were significant differences between cervical and incisal area although the most similar artificial teeth to the patients’natural teeth were provided. Second, the results in the body area showed that the variation between artificial and natural teeth was finite(p<0.05) in that area. Conclusion: it shows that the reproduction of colors of artificial teeth might be successful regarding the body is the most important part for a determination of the color of artificial teeth. However, more complements are necessary for the better reproduction of the color of artificial teeth between cervical and incisal area.

• 대한소아치과학회지
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• 제37권2호
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• pp.260-266
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• 2010

유치에 가해진 외력은 하방으로 전달되어, 계승 영구치의 손상이라는 합병증이 야기시킬 수 있기 때문에 유치에 손상이 가해진 경우의 치료계획은 영구치의 안전성에 초점을 두어야만 한다. 유치의 외상에 의한 계승 영구치 발육 장애의 정도는, 외상 당시 소아의 연령 및 치아의 발육 상태, 손상의 종류와 정도 및 외상 후부터 치료 전까지의 경과 시간 등에 따라서 달라지며, 그 정도는 미약한 석회화 부전에서 성장 정지에 이르기까지 다양하게 나타난다. 본 증례는 33개월, 만 5세, 26개월의 소아에서 각각 유치의 함입, 완전탈구, 아탈구 등의 외상성 손상이 발생한 후, 후속영구치의 발육 장애가 관찰된 경우로 비슷한 연령대임에도 불구하고, 아탈구와 같은 경미한 외상이 발생한 경우에는 법랑질저형성증과 같은 경미한 수준의 발육 장애가 나타났지만, 합입이 일어난 경우는 치근의 만곡이 관찰되었다. 또한 영구치의 교환 시기에 가까운 나이인 5세경이라 하더라도 완전탈구가 일어난 경우에는 치근의 형성부전 등 보다 심각한 합병증이 관찰되어, 유치의 손상양상과 외상을 당한 시기의 환아의 나이에 따라 계승 영구치에 미치는 영향이 달라진다는 사실을 확인 할 수있었다. 따라서 유치의 변위를 초래하는 모든 종류의 외상이 발생한 경우, 술자는 외상의 유형 및 영구치의 발육상태를 고려하여 적절한 치료 계획을 세워나가는 것이 중요하리라 사료된다.

• 대한치과의사협회지
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• 제27권6호통권241호
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• pp.509-514
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• 1989

국소의치나 총의치에 사용하는 인공치는 대부분 도재치(porcelain teeth)와 레진치(resin teeth, plastic teeth)이다. 도재치나 레진치 모두 자연치아와 유사한 색조를 갖고 있어 자연감을 나타내기 때문이다. 인공치의 대표적인 도재치와 레진치에 대하여 이공학적 측면, 임상측면, 기공측면에서 재료학적 고찰을 한다.

• Journal of Oral Medicine and Pain
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• 제6권1호
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• pp.5-8
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• 1981

The author had sellected stone models of upper premolar teeth from 20 age to 60 ages in male, and studied the attrition pattern of upper premolar teeth having attention to teeth cups on the stone model. All of the attrition patterns were divided (into) 14 forms. The results were as follows : 1. Attrition patterns of upper premolar teeth were divided into 14 forms. 2. Being compared with age group, early attrition pattern (M) showed decreasing tendency and late attrition pattern (A) showed incresing tendency by aging.

• 대한치과의사협회지
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• 제52권5호
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• pp.273-280
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• 2014

Transplantation of one's own teeth from one site to another is called dental autotransplantation. The role of autotransplantation of teeth in several clinical situations, the clinical techniques involved and factors influencing success of the transplant are discussed. Autotransplantation of impacted or retained teeth is an appropriate treatment, if orthodontic traction has failed, especially in growing patients.