Effects of a fluoride etchant and a phosphate primer on bonding of veneering composite to Ti–6Al–4V alloy for CAD/CAM restorations

Abstract

PurposeTitanium abutments and superstructures are commonly veneered or covered with esthetic materials. The present investigation was carried out to evaluate the effects of an experimental surface treatment using etchant and primer on bond strength between a resin composite and Ti–6Al–4V alloy. MethodsDisk-shaped Ti–6Al–4V alloy was machine milled, the surface was air abraded with alumina, and the alloy was chemically etched with 5wt% ammonium hydrogen fluoride (F-etch) for 30s. A phosphate primer (MDP-primer) was applied to the bonding area, and then a resin composite, with or without milled-fiber resin composite (FRC), was veneered on the specimen. Shear bond strengths were determined after thermocycling for 20,000 cycles. Bond strength data were analyzed by means of ANOVA and a multiple comparison test (α=0.05). The surface of Ti–6Al–4V alloy was observed using a scanning electron microscope before and after the etching procedure. ResultsNo-FRC/F-etch/MDP-primer exhibited the highest bond strength (28.2MPa), followed by No-FRC/No-etching/MDP-primer (24.2MPa), FRC/F-etch/MDP-primer (19.9MPa), FRC/No-etching/MDP-primer (17.8MPa), No-FRC/No-etching/No-primer (13.6MPa), while FRC/No-etching/No-primer (2.5MPa) resulted in the lowest value. Microphotographs showed that numerous micro and nano pits were created on the Ti–6Al–4V alloy surface modified with F-etch. ConclusionsThe bond strength between Ti–6Al–4V alloy and the veneering resin composite was the highest when the alloy surface was modified with alumina blasting, fluoride etchant, and phosphate primer successively.