The Survival Of All Ceramic Crowns With A Zirconia Core (Lava™)

Background: Few studies have assessed the survival of restorations and particularly zirconia based crowns in the restoration of the severely worn dentition. This study aimed to determine survival and factors associated with failure in anterior teeth worn through to dentine restored with Lava™ crowns. Methods: A convenience sample of 30 participants (27 male, 3 female) had 161 Lava™ crowns placed by one specialist clinician in a hospital setting. Follow-up was over a median 72 month period. Results: Of the 161 Lava™ crowns only 25 failed (15.5%) in 15 individuals up to 84 months for the longest case. Major failures were total debond (N=7) or minor delamination chips within the veneer ceramic layer (N=18). The mean time to first failure was 25.23 months. The Kaplan Meier survival plot estimated the Mean Survival Time for the crowns to be 74 months (95%CI 70.4, 77.3). Failures by subject were not associated with an increase in Occlusal Vertical Dimension using a Dahl approach but were associated with an edge-to-edge incisal relation (p<0.05), attrition (p<0.05) and bruxism (p<0.005). Conclusion: The Kaplan Meier survival plot estimated the Mean Survival Time for the crowns to be 74 months. The high loads in bruxism result in increased risk of fracture or debond. Clinical relevance: A protective bi-laminar splint is thus advisable. Nonetheless, application of zirconia based crowns in a difficult clinical situation such as bruxism can be a successful treatment modality.