5-year follow-up of a prospective clinical study on various types of core restorations

Purpose: This study tested whether: (1) the survival rate of cast post-and-core restorations is better than the survival of direct post-and-core restorations and post-free all-composite cores; and (2) the survival of these buildup restorations is influenced by the remaining dentin height after preparation. Materials and Methods: In a clinical trial, 18 operators made 319 core restorations in 249 patients. The restorations involved were: (1) cast post-and-core restorations; (2) direct post and composite core restorations; and (3) post-free all-composite cores. All restorations were made under single porcelain-fused-to-metal crowns. Treatments were allocated after dentin height assessment using balanced drawing. Failures were registered during a 5-year period. Results: Fifteen restorations failed during the follow-up period. Five failures occurred during the first month; they were considered to be independent from clinical aging and excluded from further survival assessments. The overall survival was 96% +/- 2%. No difference was found between the survivals of the different types of restorations. The factor "remaining dentin height" appeared to have a significant effect on the survival of post-and-core restorations (98% +/- 2% survival for "substantial dentin height" vs 93% +/- 3% for "minimal dentin height"). Conclusion: The type of post and core was not relevant with respect to survival. The amount of remaining dentin height after preparation influenced the longevity of a post-and-core restoration.