• 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)

• 대한치과기공학회지
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• 제13권1호
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• pp.21-26
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• 1991

The mesiodistal crown diameters and crown length of the permanent anterior teeth have been studied and analyzed about the mean size, S.D, S.E etcs from stone models of 100 Korean male and 74 female. From the study, the following conclusions were made : 1. Statistical differences of left and right teeth were not found in the mesio distal crown diameters and crown length of the permanent anterior teeth. 2. The mean values of mesiodistal crown diameters of permanent anterior teeth were slightly larger in male than in females and statistical differences of males and females were found in maxillary right central incisor, mandibular left canine, mandibular right lateral incisor and mandibular right canine. 3. The mean values of crown length of permanent anterior teeth were slightly larger in male than in female and statistical differences of males and females were found in mandibular left canine, mandibular right canine. 4. Mesiodistal crown diameters and crown length of maxillary left lateral incisors and right lateral incisors of female are larger than that of male.

• 대한소아치과학회지
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• 제48권1호
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• pp.115-121
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• 2021

치아 만곡은 치아의 치관부 혹은 치근부에서 발생한 장축의 갑작스러운 굽힘을 의미한다. 이는 주로 선행 유치에 대한 기계적 외상이 원인이 되어 발생한다. 만곡된 치아는 종종 맹출 장애를 동반한다. 치아 만곡은 하악에서 드물게 발생하지만, 함입과 같은 심한 외상성 손상 이후에 충분히 발생할 수 있다. 본 증례는 두 명의 환아에서 확인된 선행 유치의 함입성 외상 이후 발생한 하악 영구 중절치에서의 만곡에 대한 증례를 보고하고 있으며, 두 증례 모두에서 만곡 치아의 자발적 맹출이 관찰되었다. 첫 번째 증례는 치관과 치근의 경계부 주위에서 측방치근만곡을 보였으며, 두 번째 증례는 치관만곡을 보였다. 본 증례를 통해서 유치의 외상 이후 하악 영구 중절치에서 치관부 만곡 혹은 치관과 치근 경계부에서의 측방만곡이 관찰된다면, 만곡치아의 자발적 맹출을 기대해 볼 수 있음을 확인할 수 있었다.

• 대한소아치과학회지
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• 제32권3호
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• pp.550-556
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• 2005

매복치아란 어떤 원인에 의하여 구강점막이나 악골내에서 치아의 맹출이 중지된 상태를 말하며, 악궁내의 어떠한 치아도 매복될 수 있으나 가장 흔하게 이환되는 치아는 상, 하악 제 3대구치, 상악 견치, 상, 하악 제 2소구치, 상악 중절치의 순으로 나타난다. 이 중 상악 영구 전치의 매복률은 0.1-0.5% 정도이며 매복 원인으로는 여러 가지가 있으나 유전치의 외상, 과잉치, 치근단 병소로 인한 매복이 흔하며 조기에 적절히 치료되지 못하면 정중선의 변위, 인접치에 의한 맹출공간 감소, 치조골 높이의 차이 등의 결과를 유발한다. 치료로는 주기적 관찰방법, 매복치의 맹출로가 정상이며 치근이 미완성일 경우 상부 연조직과 경조직을 단순히 제거하여 맹출을 유도하거나 외과적 노출 후 매복치를 교정하는 방법, 치아이식술, 발치 등을 시행할 수 있다. 본 증례들은 상악 중절치의 맹출 지연을 주소로 본원에 내원한 환아들로 상악 중절치의 변위 매복을 외과적 노출과 교정적 견인을 시행하여 양호한 결과를 얻어 보고하는 바이다.

• 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.

• 대한치과기공학회지
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• 제35권4호
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• pp.415-424
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• 2013

Purpose: This study is to present a standard value for clinical crown angulation and inclination required in laboratory process and see if the value can be used for actual laboratory process. Methods: In order to find out a standard value for clinical crown angulation and inclination, this study made a study model of normal occlusion of 21 females in twenties. The clinical crown angulation and inclination of both six-maxillary and six-mandibular anterior teeth are measured by Set-up Model Checker. From the measured value above, the mean and standard deviation of the twelve teeth are obtained, and then the mean of the teeth between right and left side is calculated. Results: Each clinical crown angulation of maxillary central incisor, lateral incisor, and canine is like this; $1.0^{\circ}{\pm}1.3^{\circ}$, $3.0^{\circ}{\pm}1.3^{\circ}$, and $5.0^{\circ}{\pm}1.4^{\circ}$. In case of mandibular, each degree is like this; $0.6^{\circ}{\pm}1.1^{\circ}$, $1.5^{\circ}{\pm}1.1^{\circ}$, and $4.1^{\circ}{\pm}1.1^{\circ}$. Each clinical crown inclination of maxillary central incisor, lateral incisor, and canine is like this; $6.1^{\circ}{\pm}1.8^{\circ}$, $4.5^{\circ}{\pm}1.9^{\circ}$, and $-6.2^{\circ}{\pm}1.4^{\circ}$. In case of mandibular, each degree is like this; $0.3^{\circ}{\pm}1.5^{\circ}$, $0.3^{\circ}{\pm}1.8^{\circ}$, and $-7.5^{\circ}{\pm}1.8^{\circ}$. Conclusion: As the result, the mean value for clinical crown angulation and inclination can be referred to actual laboratory process. However, the mean value is different from those of the precedent study and an unsatisfied one for adopting the standard value.

• 대한소아치과학회지
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• 제25권2호
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• pp.383-399
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• 1998

Tooth development is usually described in four stages such as bud stage, cap stage, bell stage and crown stage. Exact time of appearance of tooth primordia is different among reports, and up to now there is no timetable regarding initial tooth development. To understand the congenital malformations and other disorders of the orofacial region, there is a need to establish a standard timetable on early tooth development. Till now, studies on the tooth development were mainly on later fetuses, and only few reports on early stage. Also, there were no reports on the time when bud stage turns to cap stage, and cap stage to bell stage. In this study, external morphology of face and the early development of the tooth, and transition of bud stage to cap stage, cap stage to bell stage were studied using 27 staged human embryos and 9 serially sectioned human fetuses. The results are as follows: 1. Mandibular region was formed by union of both mandibular arch at stage 15, and maxillary region by union of maxillary arch, medial nasal prominence, and intermaxillary segment at stage 19. 2. Ectodermal thickening which represents the primordia of tooth appeared in mandibular region at stage 13, and maxillary region at stage 15. 3. Bud stage began from mandibular primary central incisor at stage 17, and maxillary primary central incisor at stage 18. And the sequence of appearance was in the mandibular primary lateral incisor at stage 19, maxillary primary lateral incisor at stage 20, mandibular primary canine at stage 22, maxillary primary canine and primary first molar at stage 23, madibular primary first molar and maxillary primary second molar at 9th week, and mandibular primary second molar at 10th week of development. 4. Cap stage began from the primary anterior teeth at 9th week, and primary second molar still had the characteristics of cap stage at 12th week of development. 5. Transition to bell stage started from the primary anterior teeth at 12th week, and primary second molar started at 16th week of development. 6. Trnasition to crown stage started from primary anterior teeth at 16th week, and primary second molar at 26th week of development.

• 대한소아치과학회지
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• 제7권1호
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• pp.85-93
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• 1980

This study was undertaken in order to observe the prevalence of congenital dental anomalies especially that of oligodontia and supernumerary teeth in 1024 children at age from 4 to 14 years, through history taking, oral examinations, roentgenographic observations of subjects, and statistic analysis was made. The following results were obtained: 1. The prevalence of oligodontia in 1024 children was $6.45{\pm}.8$ percent with a total of 122 teeth absent in sixty-six subjects, excluding 3rd molars, and most of children (86.4%) who have congenitally missing teeth showed abscence of one or two teeth individually. 2. The teeth most frequently absent were the mandibular second premolar, maxillary second premolar, maxillary lateral incisor, mandibular central incisor, and mandibular lateral incisor in order. 3. There was no statistically significant difference found in tooth abscence in the following comparisons; .Male vs Female .Bilateral vs Unilateral .Maxilla vs Mandible .Right vs Left 4. The prevalence of supernumerary teeth in 1024 children was $4.79{\pm}.67$ percent with a total of 59 supernumerary teeth in forty-nine subjects, all of children who have supernumerary teeth showed one or two supernumerary teeth individually. 5. Statistically significant difference was found in supernumerary teeth in the comparison of male vs female, and they were more frequent in male.

• 대한치과기공학회지
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• 제29권2호
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• pp.151-161
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• 2007

To obtain the information of dental arch size and the distance from one tooth center to adjacent tooth center of occlusal surface of each tooth which is perforated by Pindex system on working cast for removable die system, 600 dental casts in Busan were examined. The distance of center of occlusal surface of each tooth and dental arch size were digitized. The results were as follows; 1. Mean values of the distance from center of maxillary central incisor to maxillary lateral incisor(tooth number 11$\sim$12, 21$\sim$22) is 5,7 mm, 12$\sim$13(22$\sim$23) is 5.9 mm, 13$\sim$14(23$\sim$24) is 6.9 mm, 14$\sim$15(24$\sim$25) is 7.1 mm, 15$\sim$16(25$\sim$26) is 8.4 mm, 16$\sim$17(26$\sim$27) is 10.2 mm, 11$\sim$21 is 7.30 mm. Mean values of the distance from center of mandibular central incisor to mandibular lateral incisor(tooth number 31$\sim$32, 41$\sim$42) is 4.5 mm, 32$\sim$33(42$\sim$43) is 4.8 mm, 33$\sim$34(43$\sim$44) is 6.3 mm, 34$\sim$35(44$\sim$45) is 7.2 mm, 35$\sim$36(45$\sim$46) is 9.2 mm, 36$\sim$37(46$\sim$47) is 10.7 mm, 31$\sim$41 is 4.7 mm. 2. Mean values of the distance from the center of maxillary right central incisor to the center of maxillary left central incisor(11$\sim$21) is 7.3 mm, 12$\sim$22 is 18.2 mm, 13$\sim$23 is 26.9 mm, 14$\sim$24 is 37.2 mm, 15$\sim$25 is 43.2 mm, 16$\sim$26 is 48.5 mm, 17$\sim$27 is 53.5 mm. Mean values of the distance from the center of mandibular right central incisor to the center of mandibular left central incisor(31$\sim$41) is 4.7 mm, 32$\sim$42 is 13.3 mm, 33$\sim$43 is 21.7 mm, 34$\sim$44 is 31.9 mm, 35$\sim$45 is 38.2 mm, 36$\sim$46 is 44.8 mm, 37$\sim$47 is 50.7 mm. 3. Mean values of the distance from the line of between 11$\sim$21 to 12$\sim$22 is 10.9 mm, 12$\sim$22 to 13$\sim$23 is 8.7 mm, 13$\sim$23 to 14$\sim$24 is 10.3 mm, 14$\sim$24 to 15$\sim$25 is 6.0 mm, 15$\sim$25 to 16$\sim$26 is 5.3 mm, 16$\sim$26 to 17$\sim$27 is 5.0 mm. 31$\sim$41 to 32$\sim$42 is 8.6 mm, 32$\sim$42 to 33$\sim$43 is 8.4 mm, 33$\sim$43 to 34$\sim$44 is 10.2 mm, 34$\sim$44 to 35$\sim$45 is 6.3 mm, 35$\sim$45 to 36$\sim$46 is 6.6 mm, 36$\sim$46 to 37$\sim$47 is 5.9 mm. 4. We checked the bottom side of cast to verify the position of dowel pin. There is no difference upper side and lower side.

• 대한치과의사협회지
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• 제14권10호
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• pp.841-843
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• 1976

The author observed the eruption pattern of mandibular anterior teeth by orthopantonography taken by children who came to pedodontic department, school of dentistry, S.N.U. and then got the following results. 1) In the degree of eruption pattern of anterior teeth, female is slightly faster than male. 2) Eruption pattern of central incisors was similar to lateral incisor, but the degree of lateral incisors movement was more severe. 3) Eruption pattern of canine was out of normal process when the adjacent teeth were abscence and there was not distal movement such as in maxillary canine.