Retentive strengths of cast gold crowns using glass ionomer, compomer, or resin cement

Abstract

Purpose. The retention forces of a newly developed compomer cement (Dyract Cem), a glass ionomer cement (Ketac Cem Aplicap), and a resin cement (F21) were examined. Material and methods. Cemented cast gold crowns were removed along the path of insertion with a Zwick universal testing device. The impact of both a cured and a noncured additional bonding layer that were applied to the inner surface of the crowns was examined across the Dyract Cem group. Results. The mean adhesive strength was measured at 2.36 ± 0.69 N/mm 2 in the Ketac Cem group, at 0.60 ± 0.28 N/mm 2 in the F21 group, and at 1.85 ± 0.94 N/mm 2 in the Dyract Cem group, respectively. The application of an additional bonding layer to the inner surface of the crowns did not significantly improve the retentive strength of Dyract Cem; the respective mean strengths were observed at 1.46 ± 0.33 N/mm 2 for the uncured and at 1.70 ± 0.76 N/mm 2 for the cured bonding layers. Conclusions. Dyract Cem and Ketac Cem showed significantly higher retentive strengths than F21 ( p < 0.001, Wilcoxon test, 5% level). No significant difference was found in bond strength between Ketac Cem and Dyract Cem. (J Prosthet Dent 1998;79:472-6.)