An analysis of effects on composite resin cavity margin design

Objectives:To evaluate the distribution of stress on cavity margins of different angles with composite resin filling. Methods:The distribution of stress on different angle cavity margins on the occlusive surface of molar was analyzed with the method of three dimensional finite element.The cavity was filled with composite resin under vertical force and lateral force. Results:In the 5 different angles of 90°,75°,60°, 45°and arc.The vertical force and lateral force are 18.757Mpa and 22.309Mpa respectively when the angle is 90°; When the angles are 75°and60,°they are 10.580Mpa ,14.265Mpa and 25Mpa,13.230Mpa respectively.The vertical force and lateral force produced by the surface of composite resin while being stressed were up to 18.757Mpa and 22.309Mpa.The forces of the second layer were significantly reduced to 2.586Mpa and 6.8Mpa. Conclusions:When filling the molars with resin in clinical practice,the angles of cavity margins should be prepared to be slopes of 60° to 75°.