Effect of chemical surface treatment of titanium on its bond with dental ceramics.

Statement of Problem: Airborne-particle abrasion of titanium is a clinically accepted method of surface preparation. As a side effect of airborne-particle abrasion, particles of the abrasive material get embedded into the surface. How particle presence or removal from the titanium surface affects the strength of the titanium-ceramic bond is unclear.
Purpose: The purpose of this in vitro study was to determine the effect of removing Al ₂ O ₃ particles embedded into the surface by means of chemical surface treatment on the strength of the titanium-ceramic bond.
Material and Methods: Titanium (TritanCpTi 1, Dentaurum, 99.5% Ti) disks were airborne-particle abraded with 110 μm Al ₂ O ₃ at a pressure of 0.4 MPa and an angle of approximately 45 degrees. The surface was etched chemically using 1 of 8 reagents, and the veneering ceramic applied and fired. The strength of the metal-ceramic bond was determined using the shear strength test. Further, the effect of thermal fatigue on the bond strength was evaluated. The results were analyzed with 2-way ANOVA and the Tukey honest significant difference (HSD) test (α=.05). Fractographic investigations and microscopic tests were also performed to determine the quality of the titanium-ceramic bond.
Results: Effective etching of the titanium surface and removal of Al ₂ O ₃ particles included a 30% water solution of HNO ₃  + 3% HF, a mixture of HNO ₃  + HF + glycerin, a 4% solution of HF in H ₂ O ₂ , and a 4% solution of HF in H ₂ O. A statistically significant difference (of about 50%) in bond strength was found between the groups subjected to chemical etching and the control group (P<.05). Additionally, a statistically significant difference (about 25%) was found after thermocycling (P<.05).
Conclusions: Removing the Al ₂ O ₃ particles embedded into the titanium surface after airborne-particle abrasion lowers the strength of the titanium-ceramic bond (P<.05). Thermocycling also weakens the strength of the titanium-ceramic bond, regardless of the surface preparation (P<.05).
(Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)