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

Abstract

Statement of problem: 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.

Purpose: 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.

Material and methods: 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.

Results: 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).

Conclusions: 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.