• The Journal of Advanced Prosthodontics
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• 제12권6호
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• pp.338-343
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• 2020

PURPOSE. The present study aimed to investigate the relationships between the crown form of the upper central incisor and their labial inclination, overbite, and overjet. MATERIALS AND METHODS. Maxillary and mandibular casts of 169 healthy dentitions were subjected to 3D dental scanning, and analyzed using CAD software. The crown forms were divided into tapered, square, and ovoid based on the mesiodistal dimensions at 20% of the crown height to that at 40%. The degree of labial inclination of the upper central incisor was defined as the angle between the occlusal plane and the line connecting the incisal edge and tooth cervix. The incisal edges of the right upper and lower central incisor that in contact with lines parallel to the occlusal plane were used to determine the overbite and overjet. One-way ANOVA was performed to compare the labial inclination, overbite, and overjet among the crown forms. RESULTS. The crown forms were classified into three types; crown forms with a 20%/40% dimension ratio of 1.00±0.01 were defined as square, >1.01 as tapered, and <0.99 as ovoid. The labial inclination degree was the greatest in tapered and the least in square. Both overbite and overjet in tapered and ovoid were higher than those in square. CONCLUSION. Upper central incisor crown forms were related to their labial inclination, overbite, and overjet. It was suggested that the labial inclination, overbite, and overjet should be taken into consideration for the prosthetic treatment or restoring the front teeth crowns.

• 대한소아치과학회지
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• 제45권3호
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• pp.334-343
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• 2018

이번 연구에서는 상악 중절치의 편측성 맹출 장애의 원인을 조사하고 매복된 치아들의 매복깊이, 매복각도, 치근발육 상태를 치과용 Cone-beam CT로 분석하여 치료방향을 예측하는데 도움이 되고자 하였다. 총 134명의 환자 중 상악 중절치의 편측성 맹출 장애로 진단된 평균연령은 7.9세였으며, 남자가 여자보다 2.1배 더 높은 빈도를 나타냈다. 맹출 장애의 주원인은 물리적 장애물로 과잉치와 치아종이 대부분을 차지하였다. 편측성 맹출 장애를 보였던 치아 중 물리적 장애물을 제거한 후, 78증례는 자발적으로 맹출하였으며 56증례는 비자발적으로 맹출하였다. 또한 편측성 매복 상악 중절치의 자발적 혹은 비자발적 맹출은 매복깊이, 매복각도, 치근발육 정도와 연관성이 있었다. 정상적으로 맹출한 치아의 매복 각도는 $50^{\circ}-90^{\circ}$ 사이였으며, 매복 상악 중절치의 자발적 맹출 빈도도 이 범위에서 가장 높았다. 또한 자발적 맹출에 걸린 시간은 매복각도와 치근 발육보다 매복깊이와 높은 상관관계를 보였다. 비자발적 맹출을 보였던 치아들 중 대부분은 교정적 견인에 의해 구강내로 맹출 되었고, 그 기간은 약 12개월 정도 걸렸으며, 교정적 견인기간은 매복깊이, 매복각도, 치근발육 정도와 통계적인 유의성을 나타내지 않았다. 이번 연구의 결과들은 편측성 상악 중절치 맹출 장애의 원인과 치료에 대한 정보를 제공할 수 있었으며, 치료 결과를 제공함으로써 향후 치료계획을 세우는데 도움이 될 수 있으리라 생각된다.

• 대한치과교정학회지
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• 제37권2호
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• pp.159-163
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• 2007

심한 치근 만곡을 동반한 매복은 흔하지 않으며, 특히 상악 전치의 경우에 그러하다. 이는 외과적 노출과 교정적 견인이 임상적으로 매우 어려우며, 치근유착, 치근의 외흡수, 교정적 견인 후 치근 노출 등의 위험이 있을 수 있기 때문이다. 비록 성공적으로 치료된 증례라 하더라도 치은의 심미를 향상시키기 위하여 치주수술이 필요한 경우가 많다. 본 증례보고는 발육중인 만곡된 치근을 가진 역위 매복된 상악 중절치의 closed eruption technique를 이용한 교정 치험예를 소개하였다.

• 대한치과교정학회지
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• 제26권6호
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• pp.657-666
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• 1996

Orthopantomogram is commonly used to evaluate root parallelism. "Good parallelism" between roots is widely accepted as one of the guidelines of a successful orthodontic treatment. In case there was a large angle between crown axis and root axis, and if we valued only the position of crown in establishing occlusal relationship without considering of the situation of root, the problem of root arrangement between adjacent teeth would be occurred. The estimate of root parallelism in mesiodistal direction before and after orthodontic treatment must be emphasized. The intent of this study was to determine the clinical importance and correlation of the angle between crown axis and root axis. Orthopantomograms of 105 orthodontic patients being treated in Yonsei university were used in this study. Twenty-eight teeth in both maxilla and mandible were selected and analyzed quantitively to evaluate the angle between crown axis and root axis, and obtain the correlationship among the individual teeth. The results are as follows: 1. Among the teeth presenting normal distribution, the maxillary right canine showed the largest mean value( $5.73{\pm}4.42^{\circ}$), which was composed of the crown-root angles, and the mandibular left lateral incisor showed the smallest mean value( $0.60{\pm}3.76^{\circ}$). 2. The crown-root angles of the maxillary incisors and the first molars, and the mandibular central incisors and the first molars didn't show normal distribution and the ranges of these angles were dispersed. 3. Significant differences were present between the crown axis and the root axis except for lower first premolars. (p<0.05) 4. No significant difference was present for the crown-root angle between right and left side, (p<0.05) 5. No significant difference was present for the crown-root angle between male and female except for lower left first premolar. (p<0.05) 6. In the upper right quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor, lateral incisor and canine. In the upper left quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor. In the lower right quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor, first molar and second molar. In the lower left quadrant, significant correlations were present between crown-root angles of the central incisor and lateral incisor, lateral incisor and canine, first molar and second molar. (p<0.05)

• 대한소아치과학회지
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• 제26권1호
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• pp.1-13
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• 1999

To study the caries patterns in primary dentition, 719 preschool children, 4-6 years old, were examined for their caries activity(salivary reductase activity) and caries experience of individual teeth. Teeth groups were made by cluster analysis using dft indexes of individual teeth as criteria. The six major teeth groups in the order of dft index from high to low were (1) lower primary molars, (2) upper primary molars, (3) upper central incisor, (4) upper lateral incisor, (5) canines, and (6) lower incisors. There were significant differences in dft index between teeth groups except upper lateral incisor and canines. Upper and lower primary molars showed the highest correlation in dft index, and the next couples were upper central incisors and upper lateral incisors, upper lateral incisor and canines, upper central incisor and canines, upper lateral incisor and upper primary molars, and canines and upper primary molars in descending order. Upper first primary molar showed the greatest differences in dft index between caries activity levels.

• 대한치과교정학회지
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• 제4권1호
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• pp.57-61
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• 1974

The patient, a girl of 19 years in good health, had a class I malocclusion. The maxillary left centra1 incisors and both lateral incisors had already erupted. But the space for the right central incisor was partially closed by the mesial drifting of the neighboring teeth. The caused a shift in the midline and a cross-bite relation on the incisors. X-ray examination revealed the presence of the right central incisor in the alveolar bone and odontoma just above the crown of the right central incisor. After enough space for the impacted incisor was created in the dental arch with a open-coil spring the rectangular incision was made. Removing the odontoma uncovered the flat surface of the labial aspect of the incisor. During the tooth had erupted of its own accord, any unnecessary force had been imposed on the tooth. When it was decided that the tooth should be brought out by the mechanical device, the gold cast onlay with hook was used and run a light elastic between this hook and the main arch wire. Finally the tooth was brought down to the arch level. The result was excellent. Fortunately the esthetic problem and any detrimental effects on the psychological make-up could be avoided.

• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.178-181
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• 2013

Traumatic injuries to an immature permanent tooth may result in cessation of dentin deposition and root maturation. Endodontic treatment is often complicated in premature tooth with an uncertain prognosis. This article describes successful treatment of two traumatized maxillary central incisors with complicated crown fracture three months after trauma. The radiographic examination showed immature roots in maxillary central incisors of a 9-year-old boy with a radiolucent lesion adjacent to the right central incisor. Apexogenesis was performed for the left central incisor and revascularization treatment was considered for the right one. In 18-month clinical and radiographic follow-up both teeth were asymptomatic, roots continued to develop, and periapical radiolucency of the right central incisor healed. Considering the root development of these contralateral teeth it can be concluded that revascularization is an appropriate treatment method in immature necrotic teeth.

• Journal of Oral Medicine and Pain
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• 제6권1호
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• pp.101-110
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• 1981

For the purpose of an estimation of age based on the changes in the human dental cavity caused by increase in age, 1,208 extracted teeth in the parts from central incisors and lateral incisors and lateral incisors to second premolars of upper and lower, right and left side were evaluated and analized all of surface index of pulp cavity. The results are as follows : 1. The surface index of pulp caxities of upper and lower, central and lateral incisors, and tend to decrease regularly as the age increase. So above teeth are more applicable to age estimation than canine and premolars. 2 For the purpose of age estimation by surface index of pulp cavity of central and lateral incisor, linear equations are as follows. Upper central incisor: X=(16.301-Y)/0.12 Upper lateral incisor: X=(16.620-Y)/0.11 Lower central incisor: X=(20.963-Y)/0.16 X=Age Y=Surface index of pulp cavity Correlation coefficient between chronologic age and estimated age is 0.699 3.The least error(3.3 yrs of age)reveals in 41-45 age group, which shows the highest possibility of estimation of age. The highest error(4.1 yrs of age)reveals in 61-65 age group and 56-60 age group.

• 대한치과교정학회지
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• 제15권1호
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• pp.75-84
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• 1985

By observing the correlationships between the characteristics of the facial pattern and the methods of establishing the position of the lower central incisor to the five reference lines on the lateral roentgenocephalograms, the author tried to find the most useful method of them, the criteria of which were the independence of a variation according to facial patterns, the close relationships with soft tissue and lip balance, and the simple and consistent usefulness in clinical practice. The subject consisted of forty normal occlusions, forty class II div I malocclusions, forty class III malocclusions, ten treated claas II div 1 cases and ten treated class III cases, all were in 14-17 yrs of age. The findings of this study are as follows: 1. The position of the lower central incisor to EP, OP, MP and NB showed variations according to ANB, FMA, facial convexity and Holdaway angle. 2. The position of the lower central incise. to AP line (A-Pog) was not co..elated with ANB, FMA, facial convexity and Holdaway angle, so it can be used consistently, regardlesss of the facial pattern. 9. The lineal position of the incisal edge of the lower central incisor to AP line has a profound influence on harmonious soft tissue and lip balance.

• Journal of Oral Medicine and Pain
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• 제4권1호
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• pp.22-30
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• 1979

In order to evaluate the normal eruption time of Korean permanent teeth, the uthor had examined the eruption phases of permanent central incisors in 714 malw and 581 female children aged from 4.5 to 9-year old and analysed. The eruption was divided into 3 phases; the tip of crown can be seen, the half of the crown can be easily seen, and full length of the crown can be seen. The obtained results were as follows : 1. It seemed that percentage of the erupting and erupted permanent central incisor in female by age was higher than that of male. 2. In general, percentage of the erupting and erupted lower central incisor by age was higher than that of upper first molar.