Adaptation of composites to the dentin cavity wall

The cavity adaptation of marketed composite resins was evaluated by measuring the contraction gap width in a cylindrical dentin cavity. Cavity walls were cleaned with neutralized 0.5 M EDTA and treated with an aqueous solution of 35% HEMA and a dentin bonding agent. The inorganic filler content was measured by weighing specimens before and after burning. When the composite which contained an inorganic component of less than 75 wt% was employed, a relatively low contraction value of less than 0.09% was obtained. On the other hand, for the composite with an inorganic component of more than 75 wt%, the gap values varied from 0.01 to 0.43%. However, using regression analysis, no statistically significant correlation was observed between the wall-to-wall polymerization contraction and the inorganic filler content.