title: [Three dimensional finite element analysis of effects on composite resin for filling in various cavity margin design].
abstract: OBJECTIVE
  To evaluate the stress distribution of different angles of cavity margins with composite resin filling.
  
  
  METHODS
  The stress distributions of different angles of cavity margins of class I cavity of molars were analyzed by the method of three dimensional finite element. The cavity was filled with composite resin and the stress vertical force and lateral force was calculated.
  
  
  RESULTS
  In the 5 designed different cavity margin angles, the vertical forces and lateral forces were 18.757 MPa and 22.309 MPa respectively when the angle is 90 degrees; when the angles were 75 degrees and 60 degrees, they were 10.580 MPa, 14.265 MPa and 9.025 MPa, 13.230 MPa respectively. The vertical forces and lateral forces produced by the surface of composite resin while being stressed were up to 18.757 MPa and 22.309 MPa. The forces of the second layer evidently reduced to 2.586 MPa and 6.8 MPa.
  
  
  CONCLUSIONS
  When fill the molars with resin in clinic, the angles of cavity margins should be prepared with the slopes of 60 degrees to 75 degrees.
authors.affiliation: School of Stomatology, Shanghai Second Medical University, Shanghai 200011.
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: L
authors.initials: L
authors.lastname: Tao
authors.forename: H
authors.initials: H
authors.lastname: Xiong
mesh_terms: D003188:Composite Resins; D003786:Dental Pulp Cavity / Q000503:physiopathology*; D003799:Dental Stress Analysis / Q000379:methods*; D012387:Root Canal Filling Materials; D013314:Stress, Mechanical
chemical_list: D003188:Composite Resins; D012387:Root Canal Filling Materials