Five‐year results of a prospective randomised controlled clinical trial of posterior computer‐aided design–computer‐aided manufacturing ZrSiO4‐ceramic crowns

The aim of this prospective randomised controlled clinical trial was to evaluate the clinical outcome of shrinkage‐free ZrSiO₄‐ceramic full‐coverage crowns on premolars and molars in comparison with conventional gold crowns over a 5‐year period. Two hundred and twenty‐three patients were included and randomly divided into two treatment groups. One hundred and twenty‐three patients were restored with 123 ZrSiO₄‐ceramic crowns, and 100 patients received 100 gold crowns, which served as the control. All crowns were conventionally cemented with glass–ionomer cement. After an observation period of 6, 12, 24, 36, 48 and 60 months, the survival probability (Kaplan–Meier) for the shrinkage‐free ZrSiO₄‐ceramic crowns was 98·3%, 92·0%, 84·7%, 79% and 73·2% and for the gold crowns, 99%, 97·9%, 95·7%, 94·6% and 92·3%, respectively. The difference between the test and control group was statistically significant (P = 0·0027). The gold crowns showed a better marginal integrity with less marginal discoloration than the ceramic crowns. The most common failure in the ceramic crown group was fracture of the crown. The 60‐month results of this prospective randomised controlled clinical trial suggest that the use of these shrinkage‐free ZrSiO₄‐ceramic crowns in posterior tooth restorations cannot be recommended.