Marginal fit and microleakage of indirect inlay systems

Three different indirect adhesive inlay systems were investigated for marginal fit and microleakage. MOD cavities were prepared in 67 extracted sound premolar teeth initially with parallel cavity walls. Thirty-four of the premolars had the cavity walls modified to a 10 degrees and 33 to a 15 degrees occlusal divergence. EOS, Isosit and Hi-Ceram porcelain inlays did not fit cavities prepared with parallel walls. All inlays in the Isosit and porcelain groups were able to be seated without modifications in cavities prepared with either a 10 degrees or 15 degrees occlusal divergence. Inlays made by the EOS system required considerable modification of the fitting surface in order for them to fit. Results showed the EOS system to have the largest marginal gaps before cementation (P < 0.001). There was no significant difference in leakage between the three inlay systems after cementation (P < 0.05). The cementum margins leaked more than margins finished on enamel for all inlay systems (P < 0.05). It is concluded from this study that inlay cavities for Isosit and porcelain require at least a 10 degrees occlusal divergence of cavity walls to permit the fitting of inlays without unacceptable modification. The EOS inlays required considerable trimming even when a 15 degrees occlusal divergence of the cavity walls was used.