a comparative study of marginal adaptation between monolithic and layered zirconia crowns: a literature review

Introduction: marginal adaptation highly affects the long-term success of crowns. this study intends to investigate the marginal adaptation of monolithic zirconia and veneered zirconia crowns. methods: based on our searches in pubmed and google scholar from 2011 to 2020, 22 articles were obtained, and after studying their full-texts. five articles that were most related to our subject were selected.  results: in almost all articles, the greatest mean marginal gap value was recorded for monolithic zirconia, whereas layered zirconia crowns demonstrated the lowest mean marginal gap values.  conclusion:  based on finding of the current study, monolithic zirconia restorations had a superior marginal adaptation than layered zirconia restorations. however, clinically both restorations have an acceptable marginal fit