RETENTIVE STRENGTHS OF CAST GOLD CROWNS USING GLASS-IONOMER, COMPOMER, OR RESIN CEMENT

Purpose. The retention forces of a newly developed compomer cement (Dy ract Cem), a glass ionomer cement (Ketac Cem Aplicap), and a resin cem ent (F21) were examined. Material and methods. Cemented cast gold crow ns were removed along the path of insertion with a Zwick universal tes ting device. The impact of both a cured and a noncured additional bond ing layer that were applied to the inner surface of the crowns was exa mined 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 t he Dyract Cem group, respectively. The application of an additional bo nding layer to the inner surface of the crowns did not significantly i mprove the retentive strength of Dyract Cem; the respective mean stren gths were observed at 1.46 +/- 0.33 N/mm(2) for the uncured and at 1.7 0 +/- 0.76 N/mm(2) for the cured bonding layers. Conclusions. Dyract C em and Ketac Cem showed significantly higher retentive strengths than F21 (p < 0.001, Wilcoxon test, 5% level). No significant difference wa s found in bond strength between Ketac Cem and Dyract Cem.