284 한국생산제조시스템학회지 Vol.20 No.3 2011. 6. pp. 284~291 Korean Society of Manufacturing Technology Engineers * 아주대학교 대학원 기계공학과 (dmishra@ajou.ac.kr) 주소: 443-749 경기도 수원시 영통구 원천동 산5 + 아주대학교 기계공학부 (ryseung@ajou.ac.kr) ++ 아주대학교 기계공학부 A Study on the Fracture Behavior of Tooth Interfacial Layer, DEJ (Dental Enamel Junction) Dhaneshwar Mishra*, Seung-Hyun Yoo + , Ung-Rak Jeong ++ (논문접수일 2011. 05. 09, 심사완료일 2011. 05. 20) 치아 계면 층 DEJ(Dental Enamel Junction)의 파괴 거동에 관한 수치해석적 연구 다네사와 미시라*, 유승현 + , 정웅락 ++ Abstract Numerical experiments on biological interfacial layer, DEJ by finite element software ABAQUS have been conducted to study its fracture behavior including crack bridging / arresting characteristics in the model. Crack growth simulation has been carried out by numerical tool, XFEM, devoted to study cracks and discontinuities. The fracture toughness of DEJ has been estimated before and after crack bridging. The implications of bridging in numerical study of fracture behavior of DEJ-like biological interface have been discussed. It has been observed that the results provided by the numerical studies without proper accommodation of bridging phenomenon can mislead. This study can be helpful for understanding the DEJ-like biological interface in terms of its fracture toughness, an important material characteristics. This property of the material is an important measure that has to be taken care during design and manufacturing processes. Key Words : Dental Enamel Junction(치아계면층), Graded fracture toughness(계층적 파괴인성), Crack healing/bridging(균열 치유/ 브리징), Graded microstructure(계층적 미소 구조), Bridging elements(브리징 요소) 1. Introduction Human-tooth system is one of the most important organs for the mastication process. It consists of a hard and brittle enamel cover and porous dentin. They are separated by very thin interfacial layer, called the Dentin Enamel Junction (DEJ) or crown dentin. DEJ has unique biomechanical properties. It provides crack-arrest barrier for flaws that form in the brittle enamel (1~5) . Enamel envelopes the softer dentine, which is a biological composite that is tougher than enamel and similar in terms of the nano-structure to bone. The DEJ has a hierarchical microstructure with a 3-D scalloped appearance along the interface. It has a different microstructure at the boundaries with enamel and dentin; therefore, DEJ has been represented by a functionally graded structure (1,2,6,7) , as shown in Fig. 1. In these works, the authors have discussed profiles of the mechanical properties such as elastic modulus and hardness across the