Evaluation of fluoride solutions under the superficial cast titanium

Objectives: This in vitro study investigated the superficial behaviour of commercially pure titanium(grade 2, ASTM) cast, under the action of different fluoride dental solutions, throught the analysis of corrosion grade under an optical microscope (OM) and the superficial roughness. Methods: All specimens received the standard metallography procedure for titanium, and were divided into the following groups, according to the attack solution received: Gr1-synthetic saliva with pH 7.0(control), Gr2-1.23% acidulated phosphate fluoride gel pH 3.5, Gr3-2% NaF gel pH 6.5, Gr4-0.05% NaF solution pH 4.0, and Gr5-0.05% NaF solution pH 7.5. The specimens were exposed to these solutions for 1, 4, 8, and 16 minutes, and between each of these times they were immersed in synthetic saliva for 24 h. The surfaces of samples were observed under OM at each interval time. The images of 100x in OM were classified by means of scores which ranged from 0 to 4, according to corrosion grade. The rugosity were analysed using the RA parameter. Results: The results of OM analysis were statiscally treated by means of Chi-square test and of rugosity through Snededor “F” and Bonferroni test (p<0.05), mean and SD = Gr1=0.25±0.08; Gr2=0.52±0.12; Gr3=0.25±0.16; Gr4=0.25±0.11; Gr5=0.27±0.12. There was a significant difference in the grade of corrosion among the fluoride solutions used, with the exception of Gr4 and Gr5, which showed a similar behavior and the smallest corrosion grades, and these had a significant increase in their final time. Gr2 presented the most severe corrosion grade and with no difference between the times. The corrosion grade of Gr3 increased according to time. As for roughness, Gr2 was the only one which had a significant increase in the superficial roughness. Conclusion: The fluorided solutions of dental use are harmful to surface of cast titanium, mainly gels with high fluoride concentration.