A systematic review of the survival and complication rates of zirconia‐ceramic and metal‐ceramic single crowns

Objectives: The aim of the present systematic review was to analyze the survival and com­plication rates of zirconia ­based and metal ­ceramic implant ­supported single crowns (SCs).Materials and Methods: An electronic MEDLINE search complemented by manual searching was conducted to identify randomized controlled clinical trials, prospectivecohort and retrospective case series on implant ­supported SCs with a mean follow ­up time of at least 3years. Patients had to have been clinically examined at the follow ­up visit. Assessment of the identified studies and data extraction was performedindependently by two reviewers. Failure and complication rates were analyzed using robust Poisson’s regression models to obtain summary estimates of 5­year proportions.Results: The search provided 5,263 titles and 455 abstracts, full ­text analysis was performed for 240 articles, resulting in 35 included studies on implant­supported crowns. Meta ­analysis revealed an estimated 5­year survival rate of 98.3% (95% CI: 96.8–99.1) for metal ­ceramic implant supported SCs (n = 4,363) compared to 97.6% (95% CI: 94.3–99.0) for zirconia implant supported SCs (n = 912). About 86.7% (95% CI: 80.7–91.0) of the metal ­ceramic SCs (n = 1,300) experienced no biological/technical complications over the entire observation period. The corresponding rate for zirconia SCs (n = 76) was 83.8% (95% CI: 61.6–93.8). The biologic outcomes of the two types of crowns were similar; yet, zirconia SCs exhibited less aesthetic complications than metal ­ceramics. The 5­year incidence of chipping of the veneering ceramic was similar between the material groups (2.9% metal ­ceramic, 2.8% zirconia­ceramic). Significantly (p = 0.001), more zirconia­ceramic implant SCs failed due to material fractures (2.1% vs. 0.2% metal ­ceramic implant SCs). No studies on newer types of monolithic zirconia SCs fulfilled the simple inclusion criteria of 3 years follow ­up time and clinical examination of the present systematic review.Conclusion: Zirconia­ceramic implant­supported SCs are a valid treatment alternative to metal ­ceramic SCs, with similar incidence of biological complications and less aesthetic problems. The amount of ceramic chipping was similar between the material groups; yet, significantly more zirconia crowns failed due to material fractures.