(A) study of the shear bond strength of metal brackets and ceramic brackets and the condition after debonding

치의학과/박사[한글] 자연치아 및 금주조금관과 도재금관에 metal bracket과ceramic bracket을 각각 부착하여 37℃ 인공 타액에 72시간 보관한 후 만능시험기를 이용하여 전단 결합 강도를 측정 비교하긴 주사전자 현미경과 광학입체 현미경을 이용하여 debonding후 피착면과 bracket base를 관찰하여 다음과 같은 결론을 얻었다. 1. metal bracket과 ceramic bracket을 자연치아에 각각 부착한 군들과 도재금관에 부착한 군들의 전단 결합 강도는 비슷하였고 metal bracket을 금주조금관에 부착한 군에서 가장 낮은 값을 보였다. 2. metal bracket을 자연치아에 부착한 군에서는 대부분 bracket base와 접착제 사이에서 분리가 일어났으며 대부분의 접착제가 치면에 남아 있었다. 3. metal bracket을 금주조금관에 부착한 군에서는 금관표면과 접착제 사이에서 분리가 일어나 모든 접착제가 bracket barre에 남아 있었다. 4 . ceramic bracket을 자연치아나 도재금관에 각각 부착한 판들에서는 자연치아와 도재금관 표면과 접착제 사이에서 분리가 일어나 대부분의 접착제가 bracket base에 남아 있었다. ceramic bracket을 도재금관에 부착한 군들의 전단 결합 강도는 도재금관의 부식시간에 영향을 받지 않았다. [영문] Metal brackets and ceramic brackets were bonded to natural teeth, porcelain crowns and gold crowns. After stored in artificial saliva solution for 72 hours at 37℃, the shear bond strengths were measured by Instron and compared with them, the bonding sites and bracket bases were examined by scanning electron microscope and light optical stereomicroscope. The results were as follows: 1. The shear bond strengths of the group which metal brackets were bonded to natural teeth and the groups which ceramic brackets were bonded to natural teeth and porcelain crowns were comparable to each ether, the shear bond strength of the group which metal brackets were bonded to gold clowns was significantly low. 2. The bond failed predominantly at the bracket base/adhesive interface with the bulk of adhesive remaining on enamel in the group which metal brackets were bonded to natural teeth. 3. The bond failed consistently at the crown/adhesive interface with all of adhesive remaining on the bracket bases in the group which metal brackets were bonded to gold crowns. 4. The bond failed at the enamel or crown/adhesive interface with the bulk of adhesive remaining on the bracket bases in the groups which cramic brackets were bonded to natural teeth and porcelain crowns. 5.The shear bond strengths of the group which ceramic bracket were bonded to porcelain crowns were not affected by etching time.restrictio

(A) study of the crown angulation in normal occlusion

치의학과/석사[한글] 최근에는 Straight-wire appliance의 여러 가지 장점으로 인하여 많은 임상가들이 Straight-wire appliance를 선호하는 경향이 증가 되고있다. 이에 저자는 Straight-wire appliance의 기초자료와 second-order bend의 양을 설정하기 위하여 정상교합자 50명의 석고모형에서 crown angulation을 측정하여 분석한 결과 다음과 같은 결론을 얻었다. 1. 상악 중절치는 4°, 상악 측절치는 7°,상악 중절치와 측절치는 0°의 crown angulation을 가진다. 2. 상악 견치는 8°,하악 견치는 2°,crown angulation을 가진다. 3. 상악 제 1,2소구치와 하악 제2소구치는 4°, 하악 제1소구치는 1°의 crown angulation을 가진다. 4. 상악 제1대구치는 3°,상악 제2단구치는 0°,하악 제1단구치는 5°,하악 제2단구치는 8°의 crown angulation을 가진다. 5. 하악 치아에서는 제1소구치에서 후방 치아로 가면서 점차 crown angulation이 증가되는 경향을 보였다. 6. 상악에서는 한 치아의 crown angulation이 크며 인접치아들의 crown angulation도 큰 수치를 보였다. 7. 하악에서는 측절치의 crown angulation이 크며 견치의 crown angulation도 크고, 제1소구치의 crown angulation이 크며 제2대구치의 crown angulation도 큰 수치를 보였다. [영문] The purpose of this study was to collect the inpormation of the straight-wire appliance and to determine the amount of second-order bends in clinical orthodontics. The author analysed the study model of 50 individuals with normal occlusion and reaults were obtained as follows. 1. The crown angulation was 4 degree in upper cental incisor, 7 degree in upper lateral incisor,and 0 degree in lower central incisor and lateral incisor. 2. The crown angulation was 8 degree in upper cuspid and 2 degree in lower cuspid. 3. The crown angulations were 4 degree in upper first bicuspid, upper second bicuspid and lower second bicuspid and 1 degree in lower first bicuspid. 4. The crown angulation was 3 degree in upper first molar, 0 degree in upper second molar, 5 degree in lower first molar and 8 degree in lower second molar. 5. The crown angulations in lower arch were progressively increased from first premolar to second molar. 6. In upper arch, as the crown angulation of one tooth was increased, those of adjacent teeth were in creased, too. 7. In the case of lower arch, the crown angualtion of cuspid was increased as that of lateral incisor was increased, the crown angulation of second premolar was increased, and similarity the crown angulation of second molar was increased as that of first molar was increased.restrictio