• 대한치과보철학회지
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• 제29권1호
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• pp.233-248
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• 1991

The purpose of this study was to qunatatively analyze the stress patterns induced in the abutment, superstructure, supporting bone and to determine the deflection of abutment and superstructure by appling occlusal force to natural teeth supported fixed prostheses and implant-supported fixed prostheses. The analysis has been conducted by using the two dimensional finite element method. The implant and natural tooth-supported bridge has a first molar pontic supported by mandibular second bicuspid and implant posterior retainer, which were rigidly(Model A) or flexible(Model B). The natural teeth-supported bridge has a first molar pontic supported by mandibular second bicuspid and second molar, which were rigidly splinted together(Model C). 63.5kg(Load P1) of localized load on central fossa of first molar pontic and 24kg(Load P2) of distributed load on each occlusal surface were applied respectively. 1. The coronal portion of premolar pontic and posterior abutment in fixed partial denture deflected inferiorly in order of Model B, Model C and Model A under Load P1 and Load P2. 2. Mesial displacement of the coronal portion of premolar showed in Model A, Model B and Model C under Load P1, but mesial displacement of that in Model B and distal displacement of that in Model A and Model C showed under Load P2. 3. Mesial displacement of the coronal portion of the pontic and distal displacement of the coronal portion of posterior abutment showed in Model A, Model B and Model C under Load P1 and Load P2. Displacement in the case of Model B was greater than that of Model A and Model C. 4. In the case Model A under Load P1 and Load P2, high stress apically was concentrated in the mesiocervical portion of the posterior abutment than in the disto-cervical portion of the premolar. 5. In the case of Model B under Load P1 and Load P2 high stress was concentrated in the case of the premolar than in that of posterior abutment and high stress especially was concentrated in the connected portion of pontic and posterior abutment. 6. In the case of Model C under Load P1 and Load P2, high stress was concentrated in the distal area of the cornal portion of premolar and the mesial area of the coronal portion of posterior abutment, and stress pattern was anteroposterially symmetric around the pontic. 7. Load P1 and Load P2 compared, stress magnitude was different but stress pattern was similar in Model A, Model B and Model C. 8. Under Load P1 and P2, stress magnitude in the mesial distal portion and the portion of root apex of the posterior abutment was in order of Model B, Model A and Model C.

• 대한치과교정학회지
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• 제23권1호
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• pp.123-136
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• 1993

The purpose of this report is to present the successful improvement of occlusal relationship and facial esthetics in class II division 1 malocclusion with severe labioversion of upper anterior teeth and severe overjet, and in class II malocclusion with infraversion of bilateral maxillary canines by MEAW mechanics, which enables us to get effective distal on mass movement of maxillary dentition, with upper second molar extraction. After treatment, there were natural contact points at canine and premolar regions, normal occlusal relation-ship and treatment results, satisfied the gnathologic concept, in this 2 cases. Compared with the routine treatment with premolar extraction, the treatment time and patients' discomfort were reduced. And the MEAW mechanics, which enables us to get effective distal on mass movement of maxillary dentition, resulted in reduction of the treatment time and getting the good treatment results. Consequently, the majot concerns in orthodontic treatment are appropriate diagnosis and treatment plan, so, the application of second molar extraction with appropriate case analysis and diagnosis is very helpful to orthodontic treatment.

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.41-45
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• 1981

A 19-year-old Korean woman presented with left mandibular dental pain and swelling. Periapical radiolucencies were associated with the mandibular left first molar, second molar and the mandibular right second molar. The mandibular right second molar root developed incompletely and has the open apex. Clinical examination revealed worn accessory occlusal cusps of premolars. A diagnosis of dens evaginatus with associated periapical lesion secondary to pulpal necrosis was made. The root canal of the lower right second premolar was sealed with Calcium hydroxide paste for apexification. About two months later Calcium hydroxide paste was removed and the canal was resealed with new Calcium hydroxide paste. After four months the canal was sealed permanently with guttapercha and zinc oxide-eugenol sealer. The root canals of the lower left premolars were irrigated every week with 3.5% NaOCl solution for and half month. And the canals were sealed with gutta-percha and ZOE sealer. Preventive endodontic treatment for the lower right first premolar was undertaken.

• 대한치과의사협회지
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• 제22권2호통권177호
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• pp.129-140
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• 1984

• 대한치과보철학회지
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• 제32권3호
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• pp.431-443
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• 1994

As the dental arch is the curve connecting the cusp tip of tooth, the dental arch form, composing of the occlusion, is one the important factors of occlusal reconstruction. Many studies about the horizontal dental arch form have been reported, but until now, it is unclear to infer the position of the teeth in dental arch form, to evaluate the effect of the horizontal dental arch form on chewing movement. The purpose of this study is to make objective criteria to infer the position of the teeth in dental arch. In this study, 100 subjects with individdual normal occlusion were evaluated. By multiple regression analysis on the basis of the relation of the canine and the first molar, the positions of teeth in dental arch were inferred. According to buccolingual relationship of maxillary to mandibular posterior teeth, the dental arch forms were classified into five groups, i, e. the normal group, the group which the maxillary second molar positions buccal side, the group which the maxillary premolars position buccal side, the group which the maxillary premolar position lingual side. From the results, objective criterial to infer the positons of the first premolar, the second premolar, the second molar in dental arch were made.

• 대한치과교정학회지
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• 제49권6호
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• pp.349-359
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• 2019

Objective: The aim of this study was to analyze three-dimensional (3D) changes in maxillary dentition in Class II malocclusion treatment using arch wire with continuous tip-back bends or compensating curve, together with intermaxillary elastics by superimposing 3D virtual models. Methods: The subjects were 20 patients (2 men and 18 women; mean age 20 years 7 months ${\pm}$ 3 years 9 months) with Class II malocclusion treated using $0.016{\times}0.022-inch$ multiloop edgewise arch wire with continuous tip-back bends or titanium molybdenum alloy ideal arch wire with compensating curve, together with intermaxillary elastics. Linear and angular measurements were performed to investigate maxillary teeth displacement by superimposing pre- and post-treatment 3D virtual models using Rapidform 2006 and analyzing the results using paired t-tests. Results: There were posterior displacement of maxillary teeth (p < 0.01) with distal crown tipping of canine, second premolar and first molar (p < 0.05), expansion of maxillary arch (p < 0.05) with buccoversion of second premolar and first molar (p < 0.01), and distal-in rotation of first molar (p < 0.01). Reduced angular difference between anterior and posterior occlusal planes (p < 0.001), with extrusion of anterior teeth (p < 0.05) and intrusion of second premolar and first molar (p < 0.001) was observed. Conclusions: Class II treatment using an arch wire with continuous tip-back bends or a compensating curve, together with intermaxillary elastics, could retract and expand maxillary dentition, and reduce occlusal curvature. These results will help clinicians in understanding the mechanism of this Class II treatment.

• 대한소아치과학회지
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• 제29권4호
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• pp.607-617
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• 2002

연령과 치아 발육상태 단계와의 상관관계, 치아의 발육에 따른 치아의 이동상태를 평가하기 위하여 최근 5년 이내에 경북대학교 병원에 내원한 아동(남아 446명, 여아 326명)의 파노라마 방사선사진을 대상으로 하여, Moorrees의 기준에 의하여 하악 영구치아의 발육단계를 평가한 후, 발육단계와 연령, 치조골내 치아의 위치를 평가하여 다음과 같은 결론을 얻었다. 치아의 발육시기는 치관이 완료될 때까지 남, 여의 차이가 없었으나, 치근형성이 되면서 부터는 남아보다 여아에서 더 빨리 발육되는 경향을 나타내었다. 치관형성의 완료시점의 평균연령은 남아 여아 각각에서 중절치 3.71, 4.05세, 측절치 4.44, 4.60세, 견치 5.35, 5.11세, 제1소구치 6.62, 6.36세, 제2소구치 7.36, 7.17세, 제1대구치 3.51, 3.69세, 제2대구치 7.90, 7.64세 이었고, 치근단이 폐쇄되기 전단계인 $A_{1/2}$는 중절치 8.70, 8.18세, 측절치 9.55, 8.99세, 견치 12.48, 11.60세, 제1소구치 12.30, 12.01세, 제2소구치 12.19, 12.26세, 제1대구치 912, 8.87세, 제2대구치 12.59, 12.45세 이었다. 치조골내의 교두점 위치는 치관형성 완료시까지는 거의 변화가 없었으나, 치근이 형성됨에 따라 빠르게 교합평면을 향해 이동하였고, 치근형성 완료단계(Rc)에서 다시 움직임 없이 정체되었다. 치근단의 위치는 치관형성 시작부터 치근 1/4 형성 시까지 일정한 위치에 유지되었으나, 그 후에 급격하게 교합면 쪽으로 이동하였고, 치근 3/4 형성시점부터 비교적 일정한 위치에 유지되었다. 치아의 석회화가 시작되는 초기의 치배 위치는 견치가 가장 하방에 위치하였으며, 그 다음이 제2소구치, 제1소구치, 측절치 제2대구치, 제1대구치 순이었고, 중절치가 가장 상방에 위치하였다.

• 대한치과보철학회지
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• 제34권2호
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• pp.277-289
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• 1996

The purpose of this study was to compare the amount of the vertical pin opening of dentures processed by the conventional compression method & the injection-processing method. The articulating ribbon and T-Scan system were used to determine the changes in tooth contacts and the correlation between the changes in tooth contacts and the amount of the vertical pin opening after processing was analyzed statistically. The obtained results were as follows. 1. The amounts of the vertical pin opening were 0.75mm, 0.31mm for conventional compression method and injection-pressing method, respectively. The difference between the two methods was highly significant on the basis of t test statistics(p<0.05). 2. The total number of contact points recorded by articulating ribbon after processing was decreased to 48%, 72%, of that before processing for conventional compression method and injection-pressing method, by T-Scan system, 39%, 53%, respectively. 3. The mean values for the number of contacts points per tooth recorded by articulating ribbon after processing were 1.6 for the second molar, 2.2 for the first moalr, 0.4 for the second premolar, 0.6 for the first premolar in conventional compression method, and 2, 3.2, 1.2, 0.8 in injection-pressing method. 4. The correlation between the reduction of contact points and the amount of the pin opening after processing was not significant. 5. The mean values for the number of contact points per tooth recorded by T-Scan system after processing were 1.25, 1.4, 0.7, and 0.55 at the second molar, the first molar, the second premolar, and the first premolar in conventional compression method, and 1.45, 2.1, 1.0, 0.75 in injection method, respectively. 6. The correlation between the number of contact points by using articulating ribbon and T-Scan system after processing was not significant in both methods.

• 대한치과교정학회지
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• 제45권4호
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• pp.180-189
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• 2015

Objective: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. Methods: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. Results: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. Conclusions: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

• 치과방사선
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• 제3권1호
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• pp.7-18
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• 1973

The authors have taken the x-ray films of carpal bone and orthopantomographs in Korean children to research the degree of ossification of carpal bone, that of calcification of tooth in jaw bone, the eruption rate of tooth, and the completion rate of apical foramen, and have compared the bone age and tooth age. We have gained a series of intersting conclusions to dare to report. 1. The ossification of carpal bone and the growth of tooth had processed proportionally to each other. 2. Both the bone age and tooth age were earlier in the female than in the male. 3. The completion of tooth crown formation and that of tooth root formation had processed proportionally to each other, and the general tendency of process was the earliest in the mandibular first molar and the latest in the second molar. 4. The eruption of tooth was the earliest in the mandibular first molar. The other teeth had erupted in the following orders: the central incisor, the lateral incisor, the first premolar, the second premolar, the canine and the second molar.