Abstract
Design
A randomised controlled trial (RCT) was conducted in a dental school.
Intervention
A total of 224 patients were randomised into two treatment groups, with 123 patients having teeth restored with KaVo Everest high-performance ceramic (HPC) crowns, fabricated by a computer-aided manufacturing procedure (KaVo Dental GmbH, Biberach an der Riss, Germany) and 101 patients receiving gold crowns. All crowns were conventionally cemented with glass–ionomer cement.
Outcome measure
Crowns were assessed for loss of vitality, surface roughness, fractures, marginal integrity, secondary caries at the crown margin, margin discolouration, marginal gap and crown loss at set time intervals of 6 and 12 months. The cumulative incidence of clinical complications was used as the criterion for failure. Time-to-event (failure) analysis was used for survival data. The incidence-free survival probabilities were then assessed using Kaplan–Meier analysis. A proportional hazard model (Cox) was used to test the treatment effect.
Results
After an observation period of 6, 12 and 24 months, the prospective survival rates (Kaplan–Meier) for the KaVo Everest HPC crowns were 97.9%, 95.1% and 89.8%, and for the gold crowns were 100%, 94.8% and 92.7%, respectively. There were no significant differences between the two groups (P 0.2). The 1-year failure rates were 4.9% for the KaVo Everest HPC crowns and 5.2% for the gold crowns. The 1-year cumulative risks for loss of vitality, secondary caries, fractures, loss of crown and extraction of abutment of the analysed abutments (88) were 8.9%, 0%, 0%, 1.1% and 1.1%, respectively, for the gold crowns and 2.8%, 0%, 4.7%, 0% and 0.9%, respectively, for the ceramic crowns (107 analysed abutments). No perfect marginal fit was shown by 49.5% of the evaluated ceramic crowns and 26.1% of the gold crowns.
Conclusions
The 12-month results indicate that Everest HPC crowns are suitable for posterior restorations, provided that an adequate tooth reduction is possible. The marginal fit shows potential for improvement.
Similar content being viewed by others
Log in or create a free account to read this content
Gain free access to this article, as well as selected content from this journal and more on nature.com
or
References
Higgins JPT, Green S (editors). Cochrane Handbook of Systematic Reviews for Interventions. Version 5.0.1. The Cochrane Collaboration 2008; section 8.10.2.
Montrori VM, Guyatt GH . Intention-to-treat principle. Can Med Assoc J 2001; 165: 1339–1341.
Greenberg BL, Kantor ML . The clinician's guide to the literature. J Am Dent Assoc 2009; 140: 48–54.
Author information
Authors and Affiliations
Additional information
Address for correspondence: Dr Birgit Encke, Department of Prosthodontics, School of Dentistry, University Medical Centre, Hugstetterstrasse 55, D-79106 Freiburg im Breisgau, Germany. E-mail: birgit.encke@uniklinik-freiburg.de
Encke BS, Heydecke G, Wolkewitz M, Strub JR. Results of a prospective randomised controlled trial of posterior ZrSiO4-ceramic crowns. J Oral Rehabil 2009; 36: 226–235
Rights and permissions
About this article
Cite this article
Abt, E. Computer-aided design/ computer-aided manufacturing crown survival rates. Evid Based Dent 11, 25–26 (2010). https://doi.org/10.1038/sj.ebd.6400709
Published:
Issue date:
DOI: https://doi.org/10.1038/sj.ebd.6400709
