Shrinkage of Composite Resin during Hardening　Part II Influence of the Length of Specimen on Linear Shrinkage

Abstract

The influence of the specimen length and the filler shape in composite resin and their affect on linear shrinkage was investigated.The amount of linear shrinkage that occurred during the hardening process linearly increased by increasing the length of the specimen.The percent of linear shrinkage was very large when the length of the specimen was less than 5mm.However, the shrinkage became constant with values of approximately 0.8% to 1.2%, when the length of the specimen was more than 5mm.Because the shrinkage in both the width and depth directions was restricted by the block, in the case of a short specimen, the composite resin adhered to the aluminum block.However, when the length was more than 5mm, the shrinkage occurred equally in all directions.This was because the restriction on the shrinkage decreased.Further more, these findings were in agreement with those obtained from the finite element analysis.