Effect of surface treatments on titanium alloy bonding to lithium disilicate glass-ceramics

The esthetic challenges of using all-titanium alloy abutments have led to the increasing use of prefabricated titanium inserts bonded to tooth-colored abutments and fixed dental prostheses. Optimal bonding protocols related to the titanium alloy treatment have not been established.

The purpose of this in vitro study was to evaluate the effects of different surface treatments and cementation procedure combinations of titanium-6aluminum-4vanadium alloy (Ti6Al4V) disks on the bond strength of lithium disilicate glass-ceramics.

A total of 100 computer-aided designed and computer-aided manufacturing (CAD-CAM) Ti6Al4V disks (4×6.6 mm) were used. As-milled specimens, without surface treatment, were used as controls. Surface treatment variables including alumina airborne-particle abrasion (50 μm, 0.4 MPa, 10 seconds, at 20-mm distance), ceramic etchant gels (5% and 9.5%), and buffered hydrofluoric (HF) acid etching, and etching times (30 and 90 seconds) were assessed. Heat-pressed lithium disilicate disks were fabricated and bonded with resin cements onto the treated surfaces (10 groups; n=10/group) according to the manufacturers' instructions. After 5000 cycles of thermal cycling, a shear bond strength test was conducted using a universal testing machine and a customized fixture with crosshead speed of 5 mm/min. ANOVA and Tukey honest significant differences tests were used for statistical analysis (α=.05). Representative specimens were observed using stereomicroscopy and scanning electron microscopy to determine the surface patterns after different treatments.

The mean ±SD bond strength values ranged from 13.1 ±6.9 MPa to 53.0 ±9.7 MPa. Statistically significant higher shear bond strength values were obtained using airborne-particle abrasion alone or etching with 9.5% HF for 30 seconds without airborne-particle abrasion (P<.05). Resin cements tested in this study had a similar effect on the bonding strength values (P>.05).

Individual treatments with alumina airborne-particle abrasion alone or etching with 95% HF for 30 seconds improved shear bond strength. However, combining alumina airborne-particle abrasion with different HF etching procedures did not.