Preliminary Evaluation of Titanium Tetrafluoride as an Alternative Ceramic Etchant to Hydrofluoric Acid

Purpose: The etching of dental ceramics with a glassy matrix by means of hydrofluoric acid (HF) is highly effective and after the application of a silane coupling agent, a strong link between the adhesive and the ceramic is achieved. The purpose of this study was to investigate whether aqueous titanium tetrafluoride (TiF4) solution could be used as an alternative ceramic etchant or not. Materials and Methods: Seventy lithia-based all-ceramic specimens (IPS Empress 2, Ivoclar Vivadent) (diameter: 4 mm, height: 4 mm) were prepared and ultrasonically cleaned for 15 min in ethanol and deionized water, then divided into 1 control and 4 experimental groups (n = 14/group). The control group was acid etched with 4.9% HF for 20 s as described by the manufacturer. The experimental groups were treated with 2.5% TiF4 solution for 60 s, 2.5% TiF4 solution for 120 s and 5% TiF4 solution for 60 s, as well as 5% TiF4 solution for 120 s. Seven of the ceramic specimens in each group were luted to the other seven by a dual-curing cement (Variolink II, Ivoclar Vivadent,) with silane application (Monobond-S). After storage of luted specimens in deionized water at 37°C for 24 h, the specimens were embedded in plastic holders with cyanoacrylate, and the shear-bond strength (SBS) tests were performed with a Shimadzu universal testing machine at a crosshead speed of 0.5 mm/min. A one-way ANOVA and Bonferroni correction, followed by the Tukey test, were applied for statistical analysis. Scanning electron microscopic examination was performed to evaluate the pattern of debonding. Results: Significantly higher SBS values (p = 0.05) were obtained for the control group (28.71 ± 9.74). The SBS for 2.5%-60 s (25.25 ± 5.13) and 2.5%-120 s TiF4 (22.65 ± 5.68) were significantly higher than 5%-60 s (16.77 ± 3.92) and 5%-120 s TiF4 (18.54 ± 3.52) groups (p = 0.05). Differences between 60- and 120-s groups irrespective of TiF4 concentrations were insignificant (p > 0.05). Conclusion: Aqueous TiF4 solution exhibited similar shear bond strength values in comparison to commonly used HF and can be considered as an alternative ceramic etchant within the limitations of this preliminary report. Keywords: acid etching, titanium tetrafluoride, lithium disilicate, composite resin