Introduction: Titanium is known to be attacked by fluoride ions, especially at low pH. To overcome this problem, titanium-chromium alloys are promising candidates. The aim of this study was to investigate the influence of corrosive pretreatment on the metal-porcelain bond strength of TiCr20 compared to commercial pure titanium.
Material and Methods: From each alloy, 20 strips (25 × 3 × 0.5 mm3) were cast, sandblasted and veneered with Ceramotion Ti (Dentaurum, Ispringen) according to the manufacturer's instructions. For the immersion test, 0.9% saline solution was used, which was adjusted to pH 5 with lactic acid and to 1400 ppm F- with addition of NaF. Each sample was placed in a 15 ml tube, filled with 5 ml of electrolyte, and stored at 37 °C in a heating cabinet. Over a period of 7.5 days, the electrolytes were changed daily and Ti release was analyzed by ICP-OES (Optima 4300 DV, Perkin Elmer). The bond strength was calculated according to ISO 9693-1:2012 without and after 7.5 days of corrosion.
Results: Bond strength values without and after 7.5 days of corrosion were 43.0 ± 4.4 MPa and 31.2 ± 2.8 MPa for titanium, and 35.5 ± 3.3 MPa and 29.5 ± 1.6 MPa for TiCr20, respectively.
The accumulated Ti release after 7.5 days of immersion was 8.89 ± 1.38 μg/cm2 for TiCr20 and 17.24 ± 2.84 μg/cm2 for titanium.
• Bond strength was higher for titanium than for TiCr20.
• The decrease in bond strength due to corrosion was 27.4 % (Ti-cp) and 11.9 % (TiCr20).
• In comparison with titanium, TiCr20 showed a higher corrosion resistance in fluoride-containing electrolyte.
• Due to the fluoride corrosion effect, the bond strength of both alloys decreased, but all values were above the 25 MPa required by the ISO 9693-1:2012.
Acknowledgment: Special thanks to Dentaurum for casting the samples.