Total Occlusal Convergence and Margin Design in Relation to Survival of Glass-Ceramic Crowns: A Review

Abstract

This review aims to report on preparation geometry parameters and their relation to crown failures in complete glass-ceramic clinical studies. A review of the literature was conducted in MEDLINE/PubMed with an additional manual search. The articles were screened through an inclusion and exclusion criteria and information regarding the Total Occlusal Convergence (TOC) angle and margin design was extracted along with its survivability. Nineteen articles were found, three were retrospective studies and 16 were prospective. Three articles specified TOC and 16 articles specified their margin design. Eighty failures were reported but lack of information between core and margin design and failures meant the relationship was inconclusive. There were a limited number of long-term clinical studies assessing glass-ceramic complete crowns. These studies provided insufficient information regarding the TOC angles of the prepared crowns and its potential effect on the survivability of glass-ceramic crowns. Further studies need to be conducted to determine how the TOC and margin design can affect the survival rates of glass-ceramic complete crowns.