[Marginal accuracy of pressed ceramic full veneers with different preparation techniques before and after simulated...

This in-vitro study investigated the marginal accuracy of press-ceramic full veneers with different preparation designs. Measurements of the marginal gap were performed after adhesive cementation as well as after mouth motion fatigue of the veneers. 64 extracted human maxillary central incisors were divided into four groups of 16 specimens each and prepared as follows: Group SZ = enamel (S) restricted 0.5 mm deep preparation with a high palatal shoulder (contact point on tooth structure [Z]), Group SK = enamel (S) restricted 0.5 mm deep preparation with a low palatal shoulder (contact point on ceramic [K]), Group DZ = dentine (D) included 1 mm deep preparation with a high palatal shoulder (contact point on tooth structure), Group DK = dentine included 1 mm deep preparation with a low palatal shoulder (contact point on ceramic). IPS e.max Press ceramic was used to fabricate the full veneers. Restorations were adhesively luted with a dual-polymerizing resin-cementVariolinkII* (*Ivoclar-Vivadent AG). Specimens underwent fatigue in a masticatory simulator (1.2 million cycles; 49 N), including thermal cycling (5500; 5 degrees C/55 degrees C). Computer-aided measurements of the marginal accuracy using stereo-light-microscopy (200x) resulted in mean values of 56 pm to 64 pm after adhesive luting. Masticatory simulation did not cause significant changes of mean marginal accuracies. In comparison, neither the adhesive cementation of the veneers to mainly enamel or dentin nor the position of load application did demonstrate a significant influence on the marginal fit in the given investigation period. Based on the used measurement methods, mouth motion fatigue of the restorations did not demonstrate a significant change of marginal fit.