• 구강회복응용과학지
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• 제20권1호
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• pp.19-29
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• 2004

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal reduction(2.0mm, 2.5mm, 3.0mm) and axial inclination ($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the lower canine. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 3.0mm depth and $12^{\circ}$ inclination was the highest(1377N). Crowns of 2.0mm depth and $4^{\circ}$ inclination had the lowest strength (731 N). 2. There were no significant differences of the fracture strength by axial inclination in same incisal reduction group. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal reduction.

• 구강회복응용과학지
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• 제16권3호
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• pp.237-245
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• 2000

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal depth(2.0mm, 2.5mm, 3.0mm) and axial inclination($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the upper central incisor. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results were : 1. The fracture strength of the ceramic crown with 2.5mm depth and $8^{\circ}$ inclination was the highest(965N). Crowns of 2.0mm depth and $4^{\circ}$ inclination had the lowest strength(713N). There were no significant differences of the fracture strength by axial inclination in same incisal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal depth. There had correlation between fracture strength and fractured surface area.

• 대한치과교정학회지
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• 제35권5호
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• pp.331-340
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• 2005

치관경사도 연구는 부정교합 진단과 치료 계획 수립 및 더욱 편리한 교정 장치 개발과 관련한 기초 자료로써 중요시되어 왔다 이에 본 연구는 307명(남자 187명, 여자 120명)의 대표본 성인 정상교합자를 연구대상으로 삼아 자료의 신뢰성 검증이 병행된 치관경사도를 보고함으로써 치과교정학 임상에 도움이 되는 기초자료를 도출해 보고자 시행되었다. 치관경사도 측정을 위하여 정상교합자 표본의 모형 상에서 개개 치아의 근원심 각도 및 협설측 각도를 측정하였으며, 측정 전후 측정자간 및 측정자 내의 신뢰성 검증을 시행하였고. 남녀간의 성차와 기존 연구자료와의 차이를 검증하였다. 연구 결과 본 연구가 대표본을 대상으로 하여 높은 신뢰성 지표를 보였음에도 불구하고 정상교합자의 치관경사도는 변동이 심한 것이 관찰되었고 이에 따라 기존 연구들에 대비하여 임상적으로 유의한 자료상의 차별성은 고찰할 수 없었으며 변동의 양상 또한 선학들이 보고한 자료와 유사하였다 결론적으로 치관경사도 측정시 드러난 정상변동을 해석하여 개별 적합성이 최대로 증진된 효율적인 치과교정장치를 개발하기 위해 좀 더 발전된 수학적·통계학적 모형 구성이 필요할 것으로 생각되었다

• 구강회복응용과학지
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• 제20권2호
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• pp.135-141
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• 2004

Statement of problem: Arrangement and angulation of clinical crown is very important for esthetic restoration in the upper anterior dentition. However, there was no clinical criteria to mesial angulation of the crown for Korean. Purpose: This study was undertaken to estimate the mesial angulation of the crown of the anterior teeth and the Oh's E-triangle made of the inter-pupillary line and the mesial inclination lines of the canines. Material and Method: 270 portraits of Korean were used for this study. The mesial angulation of the upper anterior teeth and the relationship of the inter-pupillary line and the mesial inclination lines of the canines were measured with the tools of PhotoShop software on the scanned images. Results: The angulation between the clinical crowns having a same name in the upper anterior dentition were $3.6^{\circ}$ between the central incisors, $8.6^{\circ}$ between the lateral incisors, and $13.6^{\circ}$ between the canines. There was no significance according to occupation and gender( P > 0.05). The ratio of height to base line of Oh's E-triangle was 4.47. 81.6% of the subjects showed the mesial inclination line of the canine passed by mesial border area of pupil. Conclusion: These data for Korean would be useful clinically to give the esthetic arrangement and to make the contour of upper anterior teeth.

• 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.

• 대한치과교정학회지
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• 제29권6호
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• pp.637-648
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• 1999

교정 치료 후 이상적인 교합과 양호한 심미적 결과를 얻기 위해서 일반적으로 교정 장치 제거하기 4개월에서 7개월 전에 detailing을 시행한다. 이와 같은 과정을 finishing이라고 하며, 이 과정은 최종적인 양호한 결과를 얻는데 있어서 필수적이다. 일부 교정의는 finishing을 위한 특별한 이론적 근거 및 기준 없이 이 과정을 교정 치료의 마지막 단계에서 시행하면 되는 것으로 여기고 있다. 그러나, 최종적인 양호한 교정 치료 결과를 얻기 위해서는finishing 과정이 총 치료 계획의 부분으로 치료의 초기 단계에서부터 고려되어야만 하며, 교정 장치 제거를 위한 이론적 근거 및 기준에 근거한 finishing을 위한 checklist가 필요하다. 이 checklist는 크게 네 부류로 분류할 수 있다. 즉, 교합 요인, 심미적 요인, 치주적 요인과 습관적 요인으로 분류할 수 있다. 교합 요인에서 점검해야할 요소로는 alignment, marginal ridge discrepancy, interproximal contact, anterior inclination, posterior inclination, overjet, overbite, arch form과 functional occlusion 등이 있다. 심미적 요인에는 gingival form, crown form, crown width과 crown length 등이 있다. 치주적 요인에는 root angulation, bone level 등이 있다. 습관적 요인에는 mouth breathing, tongue position at rest, tongue thrust habit, lip biting, nail biting과 finger sucking 등이 있다.

• 구강회복응용과학지
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• 제19권3호
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• pp.219-237
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• 2003

he purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown, and 0.5mm width chamfer finish lines on the maxillary first premolar. 30 sound maxillary first premolars were selected and then storaged in 5% NaOCl and saline. 15 teeth were performed preparation for each group(1.0mm rounded shoulder, 0.5mm chamfer). After 30 stone dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the natural teeth. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co., Germany)was used to measure the fracture strength, with stress loading on the occlusal surface between buccal and lingual cusp. And also, three-dimensional finite element model was used to measure the stress distribution with two types of the finish lines(1.0mm rounded shoulder, 0.5mm chamfer) and two loading conditions(both buccal and lingual cusp inclination, lingual cusp inclination only). The result of the this study were as follows. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(842N) showed higher value than that of the chamfer(590N) (p<0.05). In the three dimensional finite element analysis of all ceramic crown, metal die and natural teeth model did not show any differences in stress distribution between finish lines. Generally, when force was loaded on the occlusal inclination of buccal and lingual cusp, the stress was concentrated on the loading point and the central groove of occlusal surface. When force was loaded only on the occlusal inclination of lingual cusp, the stress was concentrated on the lingual finish line and loading point.

• 구강회복응용과학지
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• 제19권3호
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• pp.207-217
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• 2003

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the lower central ncisor. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results of this study were as follows : The fracture strength of the ceramic crown with 2.0mm depth and $12^{\circ}$ inclination was the highest (648 N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength (482 N). There were no significant differences of the fracture strength by axial inclination in same incisal depth group. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal depth. There had correlation between fracture strength and fractured surface area.

• 대한치과교정학회지
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• 제54권3호
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• pp.142-152
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• 2024

Objective: This retrospective cohort study aimed to assess and compare the accuracy of 3 different Invisalign^® treatment regimens in terms of variations of aligner change frequency and type of aligner material in achieving maxillary dental buccal expansion. Methods: Altogether, 120 adult patients whose treatment involved maxillary dental expansion with Invisalign^® were included. The patients were divided into 3 groups, with each group comprising 40 patients as follows: SmartTrack^® 1-week changes (ST1), SmartTrack^® 2-week changes (ST2), and EX30^® 2-week changes (EX2). The groups were assessed by comparing actual changes achieved with those prescribed by ClinCheck^®. The rates of clinically significant inaccuracies (CSI) observed for buccal expansion (≥ 0.5 mm) and buccolingual inclination (≥ 2°) during expansion were then determined. Results: In terms of expansion, the ST1 group demonstrated the highest CSI rate at all tooth levels, whereas the ST2 group had the lowest rate of CSI and the lowest mean inaccuracy for each tooth level. In terms of buccolingual inclination, the ST1 group had the highest CSI rate across all tooth levels, whereas the EX2 group had the lowest CSI rate at all tooth levels except for the canine level where the ST2 group had the lowest CSI rate. A tendency toward overexpression of buccal crown inclination, and underexpression of buccal expansion was observed at all tooth levels. Conclusions: Two-week aligner change regimens offer improved accuracy compared with 1-week aligner changes. SmartTrack^® 2-week changes were the most accurate for buccal expansion, whereas EX30^® 2-week changes were the most accurate for buccolingual inclination.

• 대한치과교정학회지
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• 제32권6호
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• pp.401-411
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• 2002

정교한 교합을 달성하기 위해서는 브라켓을 정확하게 위치시키는 것이 필수적이다. 그러나, 많은 원인에 의해 브라켓의 위치가 변할 수 있다. 본 연구는 브라켓의 수직적 위치에 변화가 있을 때 이것이 치관경사도에 미치는 영향을 연구하고자 함이다. 연구대상으로는 서울대학교 치과대학 교정학교실의 정상교합자 표본 중 상태가 양호한 10명(남자 6명, 여자 4명, 평균 연령 22.3세)을 대상으로 하였으며 , 이들의 치아모형을 laser scanner를 이용, 3차원적으로 스캔을 시행하였고, 컴퓨터 프로그램 상에서 스캔된 치아모형에 대한 계측을 실시하였다. 각 모형에 대하여 Bracket plane을 설정하였고, 각 치아에서 Bracket plane에 수직이며 치아의 장축을 지나는 Tooth plane을 순협면에서 결정한 뒤 Bracket plane상에서의 치관경사도를 계측하였다. 이로부터 Bracket plane을 상하로 0.5mm, 1.0mm, 1.5mm 변위시켰을 때의 치관경사도를 계측하였다. 각 계측 항목에 대해 일원분산분석 (oneway ANOVA)과 Duncan's multiple comparison test를 시행하였다. 이상의 연구로부터 다음과 같은 결과를 얻었다. 1. 상악중절치, 측절치, 견치, 대구치와 하악소구치, 대구치에 있어서 브라켓의 수직적 위치가 변화함에 따라 치관경사도가 통계적으로 유의성 있게 차이 있는 것으로 나타났다(p<0.05). 2. 상악전치와 대구치, 하악소구치와 대구치에서는 기준평면으로부터 수직적으로 같은 양만큼 변위되었다 할지라도 보다 교합면쪽에 위치하는지, 보다 치은쪽에 위치하는지에 따라 치관경사도의 변화량이 다르게 나타났다. 3. 브라켓의 수직적 위치변화가 있을 경우 상악전치부와 대구치, 하악구치부, 이 중 특히 하악구치부의 치관경사도는 임상적으로 영향을 받게 되므로 브라켓을 위치시킬 때 주의를 요해야 할 것으로 생각된다.