• 대한치과교정학회지
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• 제41권4호
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• pp.255-267
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• 2011

본 연구에서는 cone beam computed tomography (CBCT)를 이용한 삼차원 영상을 기준으로 CBCT-재구성 파노라마영상 형성 시의 신뢰성을 입증하고 CBCT 삼차원 영상과 비교하여 실제 근원심 치축을 가장 잘 나타낼 수 있는 이차원 파노라마영상을 찾고자 하였다. 연구 모형은 두부계측방사선사진의 평균치에 따라 제작되었고 CBCT와 파노라마방사선영상 촬영을 위해 촬영 시마다 연구 모형이 반복적으로 재위치되었다. 파노라마방사선영상은 $-5^{\circ}$, $0^{\circ}$, $+5^{\circ}$로 연구 모형의 교합평면을 변화시키면서 촬영되었다. 이후 CBCT 삼차원 영상과 CBCT-재구성 파노라마영상 및 파노라마방사선영상에서 측정된 계측값을 평가하였다. CBCT 삼차원 영상과 CBCT-재구성 파노라마영상의 전치 및 견치부에서 통계학적으로 유의성 있는 차이를 나타내지 않았으나 대부분의 소구치부에서는 통계학적으로 유의성 있는 차이를 나타내었다. 그리고 CBCT-재구성 파노라마영상과 파노라마방사선영상은 대부분의 치아에서 통계학적으로 유의성 있는 차이를 나타내었다. CBCT-재구성 파노라마영상이 근원심 치축 평가 시 임상적으로 사용 가능함을 보여주었다.

• 대한치과교정학회지
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• 제50권4호
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• pp.229-237
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• 2020

Objective: To evaluate the construction reproducibility of a composite tooth model (CTM) composed of an intraoral-scanned crown and a cone-beam computed tomography (CBCT)-scanned root. Methods: The study assessed 240 teeth (30 central incisors, 30 canines, 30 second premolars, and 30 first molars in the maxillary and mandibular arches) from 15 young adult patients whose pre-treatment intraoral scan and CBCT were available. Examiner-Reference (3 years' experience in CTM construction) and Examiners-A and Examiner-B (no experience) constructed the individual CTMs independently by performing the following steps: image acquisition and processing into a three-dimensional model, integration of intraoral-scanned crowns and CBCT-scanned teeth, and replacement of the CBCT-scanned crown with the intraoral-scanned crown. The tooth axis angle in terms of mesiodistal angulation and buccolingual inclination of the CTMs constructed by the three examiners were measured. To assess the construction reproducibility of CTMs, intraclass correlation coefficient (ICC) assessments were performed. Results: The ICC values of mesiodistal angulation and buccolingual inclination among the 3 examiners showed excellent agreement (0.950-0.992 and 0.965-0.993; 0.976-0.994 and 0.973-0.995 in the maxillary and mandibular arches, respectively). Conclusions: The CTM showed excellent construction reproducibility in mesiodistal angulation and buccolingual inclination regardless of the construction skill and experience levels of the examiners.

• 대한소아치과학회지
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• 제3권1호
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• pp.19-31
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• 1976

To study the eruption pattern of the mandibular first permanent molar, the author took 263 cases of Oblique Cephalogram from age 3 to 6 years old children and observed the vertical and mesiodistal directional change and tooth axis change. The following results were obtained.; 1. The eruption pattern of the mandibular first permanenl molar was changed at about 60~66 months or calcification stage IX. 2. At the early stage, the path of eruption of the mandibular first permanent molar directed upward and forward and after calcification stage IX it changed to the direction of upward. 3. The height of the alveolar bone of the upper part of the mandibular first permanent molar was almost equal to that of the interseptal bone of the first and second deciduous molar, but the height showed gradual descent afterwards. 4. At the early stage, the distance from the distal end of the mandibular second deciduous molar to the anterior portion of the ascending ramus was 1.2~1.4 times larger than the mesio-distal diameter of the mandibular first permanent molar, but at the later stage it was enlarged 1.7~1.9 times larger than the mesiodistal diameter of the mandibular first permanent molar.

• 대한소아치과학회지
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• 제6권1호
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• pp.53-63
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• 1979

To Study the eruption pattern of the mandibular second permanent molar, the author took 425 cases of Oblique Cephalogram from 6 to 13 years old children and observed the vertical and mesiodistal directional change and tooth axis change. The following results were obtained. : 1. The eruption pattern of the mandibular second permanent molar was changed at about 10.0~10.1 ages or calcification stage IX. 2. At the early stage, the path of eruption of the mandibular second parmanent molar directed upward and forward and after calcification stage IX it changed to the direction of upward. 3. At the early stage, the distance from the distal end of the mandibular first permanent molar to the anterior portion of the ascending ramus was 0.9~1.0 times larger than the mesio-distal diameter of the mandibular second molar, but at the later stage it was increased 1.4 times larger than the mesio-distal diameter of the mandibular second permanent molar.

• 대한소아치과학회지
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• 제43권2호
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• pp.176-186
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• 2016

본 연구는 전치부 지르코니아 전장관을 위한 적정 치아 삭제량을 조사하기 위해 3차원 스캐너를 이용, 지르코니아와 다른 유치 전장관들의 크기와 형태를 분석하였다. 상악 좌측 유중절치, 유측절치 지르코니아 전장관과 금속관의 내/외면, 레진관의 외면을 스캔하여, 근원심경이 유사한 세 종류의 전장관을 한 군으로 만들어 분석하였다. 외면에서 모든 중절치, 1번 측절치 지르코니아 전장관이 같은 군의 전장관 중 가장 큰 순설경을 나타냈다. 내면에서 지르코니아 전장관은 금속관에 비해 근원심경 0.7-1.0 mm, 치관길이는 1 mm 가량 작았으며, 순설경은 중절치에서는 더 컸으나 측절치에서는 더 작았다. 비교결과, 지르코니아 전장관은 절단면 2.5-3.0mm, 근원심 1.5-2 mm, 순면 0.5-1 mm, 설면결절을 장축에 평행하게 삭제 후 측절치에서만 0.5 mm 설면삭제를 시행하는 것을 제안할 수 있다.

• Restorative Dentistry and Endodontics
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• 제16권1호
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• pp.74-86
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• 1991

The purpose of this study was to evaluate the resulting root canal angulation and shape change after using various enlarging instruments. The mesial canals (120) of extracted human mandibular 1st and 2nd molars were randomly divided into 6 groups; Control, K-type me, Heliapical me, Canal Master me, sonic and ultrasonic instrumentation group. Vertical angulation of each canal was determined by a straight line through the long axis of canal and another straight line through the apical foramen to intersect at the point where the canal began to leave the long axis of the tooth. By recording and comparing the measured angles of the each set of pre-and postinstrumentation. Then, the roots were sectioned horizontally in the apical, middle, coronal thirds and the canal shapes examined, as was the mesiodistal canal diameter as it relates to the external root surface. The results were as follows: 1. Instrumentation using K-type me group resulted in the highest mean change in angulation ($9.900^{\circ}$) (p < 0.005), while Sonic Air MM 3000 group resulted in the least degree of straightening canals ($8.250^{\circ}$) (p < 0.005). 2. Canal Master file group resulted in the best canal shape at the three levels (P < 0.005). 3. Measured minimal mesial root width produced Heliapical me group at the apical 1/3 level, Sonic Air MM 3000 group at the middle 1/3 level, Heliapical me group at the coronal 1/3 level (P < 0.005). 4. Measured minimal distal root width produced Sonic Air MM 3000 group at the apical 1/3 level (P < 0.05), Heliapical me group at the middle 1/3 level (P < 0.005), Canal Master me group at the coronal 1/3 level (P < 0.005). 5. HeIiapical me group produced more increased canal diameter than any other groups (P < 0.005).

• Restorative Dentistry and Endodontics
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• 제26권1호
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• pp.32-40
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• 2001

The aim of this study was to evaluate the effect of various polymerization techniques on the microleakage of compomer restorations. Fifty extracted human premolars and molar were used and randomly divided into 5 groups. After cavity preparation, compomer (F2000$^{\circledR}$) was filled according to the manufacturer's directions. All groups, except group 5, were filled using an incremental technique. Group 1 was polymerized for 40 seconds at a continuous 485mW/$\textrm{cm}^2$ with a VIP$^{\circledR}$(Bisco, USA) light cure unit. Group 2 was polymerized for 20 seconds at 345mW/$\textrm{cm}^2$ and then for 20 seconds at 645mW/$\textrm{cm}^2$ with the VIP equation omitted light cure unit. Group 3 was polymerized at 400mW/$\textrm{cm}^2$, gradually increased to 50mW/$\textrm{cm}^2$ 10 seconds until 550mW/$\textrm{cm}^2$ was reached; total 40 seconds with a Spectrum 800$^{\circledR}$ (Dentsply Caulk, USA) light cure unit. Group 4 was polymerized for 3 seconds using an incremental technique with a Flipo$^{\circledR}$ (LOKKi, France) light cure unit. Group 5 was polymerized for 3 seconds using a bulk fill technique with the Flipo$^{\circledR}$ light cure unit. The specimens were embedded with acrylic resin, and were sectioned with diamond saws in a mesiodistal direction along the longitudinal axis of the tooth so as to pass through the center of the restoration, and three surfaces (occlusal, pulpal, and gingival) were examined with SEM. The results were as follows ; 1. Group 5 showed a significantly larger gaps compared to other groups on the gingival, occlusal, and pulpal walls. 2. All groups except group 5 had no statistically significant gap on the gingival, occlusal, and pulpal walls. 3. There was no significant correlation between the amount of enamel on the gingival and occlusal walls and polymerization shrinkage.