A Randomised 14-year Clinical Evaluation of 3 Ceramic Inlay Systems

Objectives: To evaluate the clinical quality of three different ceramic inlay systems, 20 patients were treated with one Cerec, one Mirage and one Empress inlay respectively, inserted in a randomly selected order in the lower jaw. All patients were also treated with one gold inlay.

Methods: In total, 35 premolars and 45 molars were treated with inlays. The inlays were examined independently by two calibrated examiners immediately after luting, 1 year, 3 years, 5 years, 8 years and 14 years after luting. The inlays were rated using the California Dental Association (CDA) quality evaluation system.

Results:A higher, but not statistically significant, survival rate was found for the gold inlays (85%) compared to the ceramic inlays (72.7 %). Gold inlays failed due to recurrent caries and to fractured tooth substance and ceramic inlays failed due to ceramic bulc fractures. The examination using the CDA-criteria showed an increased mismatch of color from 15% at baseline to 38% over 14 years. Inlays with slightly roughened surfaces increased from 0% to 62% over 14 years. A visible evidence of ditching along the margin increased from 5% to at most 92 % after 14 years. For the ceramic inlays an apparent discoloration of the margin between the tooth and the restoration increased from 0-5% at baseline to at most 80 %. Of the fractured ceramic inlays, 71 % had fractured after 5 years.

Conclusion: Gold inlays have a significantly higher survival rate over long periods of time compared to ceramic inlays. Ceramic failures are related to fractures of the ceramic material, whereas failures of gold inlays are related to the surrounding tooth substance. The majority of fractures appear after 5 years. Based on the CDA- criteria there was a significant deterioration from excellent conditions concerning surface texture and marginal adaptation.