RESUMO
Objective: To study the effect of the sharp marginal ridge of the abutment on the casting of the fit metal full crown in dental preparation.Methods: We established the models of the designed crown-based-teeth(American Dental Association style,No2 trail) with a sharp or smooth marginal ridge,and cast a metal crown for each model.We injected silicone into the crown and immediately fixed it onto each model.Then we took out the solidified silicone and measured its thickness between the crown and the occlusal face of each model.The thinner the thickness,the better the fitness.Results: The average silicone thickness was 250 ?m in the smooth marginal ridge group and 1 660 ?m in the sharp marginal ridge group,with significant difference in between(P