A bond strength study of luted castable ceramic restorations

Accurate intracoronal castings can be produced using a castable ceramic--DICOR--for which there is a need to identify a suitable luting cement. The aim of this investigation was to evaluate the bond strength of three glass-ionomer luting cements and one resin cement to treated and untreated DICOR, enamel, and dentin surfaces. Forty "cerammed" DICOR specimens were assigned to four groups: (1-3) grit-blasting and bonding to each of the three glass-ionomer cements; and (4) acid-etching, silane coating, and bonding to the resin cement. Seventy enamel specimens were assigned to seven groups: (1-3) no etching and bonding to each of the glass-ionomer cements; (4-7) acid-etching and bonding to the glass-ionomer cements and the resin cement. Seventy dentin specimens were assigned to seven groups: (1-4) bonding to each of the three glass-ionomer cements and the resin cement; (5-7) polyacrylic acid preconditioning and bonding to each of the three glass-ionomer cements. The mean resin cement bond strengths (MN/m2) to DICOR (9.4) and to etched enamel (10.7) were significantly greater (p less than 0.01) than those of the glass-ionomer cements (DICOR, 0.8-1.2; enamel, 0.4-0.9). Preconditioning of enamel and dentin significantly increased (p less than 0.05) the bond strengths to the glass-ionomer cements. The mean bond strength of the resin cement to untreated dentin (4.3) was significantly higher (p less than 0.05) than the glass-ionomer bond strengths to untreated dentin (1.0-1.7) and to preconditioned dentin (2.1-3.3). The high bond strengths achieved with the resin cement are encouraging. Selected surface treatment of DICOR, enamel, and dentin prior to luting should be clinically useful.