Abstract
A significant correlation has been found between static creep of amalgam and clinical marginal fracture characteristics.To reveal mechanical details, stress, time and temperature dependencies of creep rate of amalgam have been studied.However, the relationship between static creep properties and creep behavior of the amalgam in the cavity under occlusal force has only been done from groundless discussion.The creep of amalgam in Class I cavity was then simulated by an axisymmetric elastic creep finite element method.In this procedure, the stress and time dependence of creep strain was assumed as follows:εc=kσmtn Here, exponents m and n of stress and time dependencies were postulated as 2.0 and 1.0, respectively.The creep values of 0.1, 1.0 and 8.0%(tested by American Dental Association Specification no.1)were selected for the creep calculation of amalgam.Occlusal force was assumed as 40 N on the caps of enamel and vertical direction to the axis of the tooth.Simulated results show that the creep strain of amalgam in the cavity did not increase linearly with time because the amalgam deforms to become stress-free and creep rate is a function of the stress.It was concluded that elastic deformation of the crown which has no restorative material is an important factor to determine the creep strain and the gap between the cavity wall and restorative material.
