Marginal accuracy of press-ceramic veneers influenced by preparation design and fatigue.

Abstract

PURPOSE: To investigate the influence of preparation design and mouth motion fatigue on the marginal accuracy of press-ceramic veneers bonded to human maxillary central incisors. METHODS: Forty-eight extracted human maxillary central incisors divided in three groups of 16 specimens each, received veneer preparations. In Group WP a window preparation (WP) was performed. Specimens in Group IOP were prepared with an incisal overlap (IOP) of 2 mm without palatal chamfer. For Group CVP, specimens received a complete-veneer preparation (CVP) of 3 mm incisal reduction and 2 mm palatal extension. Veneers were fabricated with IPS Empress and bonded adhesively with dual polymerizing composite Variolink II. The discrepancies of marginal fit were examined on epoxy replicas before and after mouth motion fatigue at x200 magnification. RESULTS: The mean (geometrical) (95% confidence limits) marginal accuracy after cementation was recorded as follows: WP-46 (43-49) microm, IOP-46 (44-49) microm and CVP-54 (51-58) microm. Fatigue led to a significant decrease of marginal accuracy in all groups (P < 0.036) [WP-47 (44-50) microm, IOP-51 (48-53) microm and CVP-63 (59-67) microm]. Group CVP demonstrated significantly higher marginal gap values than groups WP and IOP, before and after fatigue (P < 0.004). No significant differences were found between groups WP and IOP.