Survival of three types of veneer restorations in a clinical trial: a 2.5-year interim evaluation

Abstract Objectives : In this clinical trial, 180 veneer restorations (VRs) were evaluated. The purpose of the study was to collect survival data and to find possible relations between survival and (1) `type of VR', (2) `preparation design', (3) `operator' and (4) the patient-related variables `tooth-type' and `vitality of the tooth'. Methods : The restorations were provided by seven dentists in 112 patients on central and lateral maxillary incisors. Experimental variables were: `type of VR' (either direct resin composite (DC), indirect resin composite (IC) or porcelain (P)), `preparation design' (with and without incisal overlap) and `operator'. Failures were recorded at two levels: absolute failure (need for new restoration) and relative failure (need for repair). Survival was defined at three levels: (1) s!urvival of original restoration (S r , endpoints: `absolute' failures), (2) functional survival (S f , endpoints: `relative' failures) and (3) overall survival (S o , endpoints: both `absolute-' and `relative failures'). Results : The variable `type of VR' showed significant influence on S f and S o but not on S r . S f and S o rates of P, IC and DC were, respectively: S f -P, 94%; S o -P, 94%; S f -IC, 94%; S o -IC, 90%; S f -DC, 80%; S o -DC, 74%. VRs on vital teeth showed a significantly better survival than VRs on non-vital teeth at all survival levels. Conclusions : Preparation of the incisal edge for incisal coverage is considered to be unnecessary to assure or improve the strength of VRs. c non-vital teeth showed higher risk to fail than veneers placed on vital teeth. Porcelain veneers showed the best overall survival.