(A) study on the effects of cavity forms on fracture of amalgam restoration in deciduous molars

치의학과/석사[한글] 아말감 수복물의 파절의 주요원인은 대부분 잘못된 와동형성과 수복재료의 부적절한 조작에 기인된다. 와동형성시 치질삭제량과 수복물간의 상호관계에서 적절한 와동형성 방법이 점진적으로 변형 되어왔다. 와동형성이 아말감 파절에 어떠한 영향을 주는가를 연구하기 위하여 치아우식증이 없는 상 ·하악 유구치 80개로 와동의 협부를 교합면 치아 교두간 넓이의 1/3 과 1/4로 하고, Internal line angle을 예각과 둥글게 형성하여, Instron universal testing machine(Mo del 1123)으로 그 파절 하중을 측정 비교한 결과, 아래와 같은 결론을 얻었다. 1) 협부 넓이가 치아 교두간 넓이의 1/3군이 1/4군보다 파절하중에 잘 견디었으며 특히 상·하악 제 2유구치에서 뚜렷하였다. 2) Internal line angle을 둥글게 형성한 군이 예각으로 형성한 군보다 파절하중에 잘 견디어 냈다. 이상의 결과에 따르면 협부 넓이가 치아 교두간 1/3이고 internal line angle이 둥근 군이 파절하중에 가장 잘 견디어냈으며 협부 넓이가 치아 교두간 1/4 이고 internal line angle이 둥근 군도 교합력의 범주 내에서는 파절에 대해 견디어 낼 수 있으므로 실제 임 상에서 받아들여질 수 있다. A STUDY ON THE EFFECTS OF CAVITY FORMS ON FRACTURE OF AMALGAM RESTORATION IN DECIDUOUSMOLARS Dae Song Ha, D.D.S. Department of Dental Science, Graduate School, Yonsei University (Directed by Associate Professor Chong Kwan Kim, D.D.S., M.S.D., Ph.D.) In this experiments, the fracture loads were measured and analysed by using of Instron universal testing machine (Model 1132). With 80 upper and lower deciduous mortars that were free of dental caries. Isthmus of teeth were prepared to ⅓ and ¼ of intercuspal width, and internal line angles with round and sharp shape , and then amalgam restoration were performed. The results of this study were as follows ; 1. Resistance to fracture loads were greater with isthmus of ⅓ intercuspal width than of ¼ intercuspal width, especially, staistically significant difference on upper and lower second deciduous molars. 2. Resistance to fracture loads were feater with rounded internal line angle than sharp interval line angle. The above results were as follows, the fracture load? had Venter resistance on isthmus of ⅓ intercuspal width, and rounded internal line antre, but normal physiological occlusal forces could permit isthmus of ¼ intercuspal width and rounded internal line angle. [영문] In this experiments, the fracture loads were measured and analysed by using of Instron universal testing machine (Model 1132). With 80 upper and lower deciduous mortars that were free of dental caries. Isthmus of teeth were prepared to ⅓ and ¼ of intercuspal width, and internal line angles with round and sharp shape , and then amalgam restoration were performed. The results of this study were as follows ; 1. Resistance to fracture loads were greater with isthmus of ⅓ intercuspal width than of ¼ intercuspal width, especially, staistically significant difference on upper and lower second deciduous molars. 2. Resistance to fracture loads were feater with rounded internal line angle than sharp interval line angle. The above results were as follows, the fracture load? had Venter resistance on isthmus of ⅓ intercuspal width, and rounded internal line antre, but normal physiological occlusal forces could permit isthmus of ¼ intercuspal width and rounded internal line angle.restrictio