Results of a prospective randomized controlled trial of posterior ZrSiO₄-ceramic crowns

Authors: ENCKE, B. S.¹; HEYDECKE, G.²; WOLKEWITZ, M.³; STRUB, J. R.¹

Source: Journal of Oral Rehabilitation, Volume 36, Number 3, March 2009 , pp. 226-235(10)

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Abstract:

Summary

The aim of this randomized controlled clinical trial was to evaluate over a 5-year period, the clinical outcome of shrinkage-free ZrSiO₄-ceramic (KaVo Everest HPC^®) full coverage crowns on posterior teeth in comparison with conventional gold crowns that served as the control. This study reports results of a 5-year study protocol up to 24 months. Patients totalling 224 were randomly divided into two treatment groups. Of these, 123 patients were restored with 123 Everest HPC^® crowns, fabricated by the Kavo Everest computer-aided manufacturing (CAM) procedure and 101 patients received 101 gold crowns, but two were excluded from analysis. All crowns were conventionally cemented with glass-ionomer cement. 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 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 analyzed 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 analyzed abutments). No perfect marginal fit was shown by 49·5% of the evaluated ceramic crowns and 26·1% of the gold crowns. Only 1·9% of the KaVo Everest HPC^® crowns had a marginal crevice. In conclusion, Everest HPC^® crowns with an adequate occlusal tooth reduction of >1·5 mm are suitable for posterior restorations, but the marginal fit shows a potential for improvement.

Keywords: randomized controlled clinical trial; ZrSiO4 ceramics; posterior crowns; survival rates; biological and technical complications

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2842.2008.01918.x

Affiliations: 1: Department of Prosthodontics, School of Dentistry, University Medical Center Freiburg, Freiburg, Germany 2: Department of Prosthodontics, School of Dentistry, University Hospital, Hamburg-Eppendorf, Germany 3: Institute of Medical Biometry and Medical Informatics, University of Freiburg, Freiburg, Germany

Publication date: 2009-03-01