Effect of Light Curing Tip Distance and Immersion Media on the Degree of Conversion, Sorption and Solubility of Methacylate and Silorane-Based Composites - Abstract
The purpose of this study in vitro was evaluate the degree of conversion (DC%), sorption (Sp) and solubility (Sl) of a methacrylate composite (Filtek™ Z250) and silorane-based composite (Filtek™ P90) cured in three curing tip distances (0 mm, 3 mm and 6 mm) with LED of second generation and immersed in artificial saliva (AS), Plax FeshMint (PFM), Plax Alcohol-Free (PAF) and Plax Whitening (PW). The methodology was based on the ISO 4049/2009 standard and five repetitions (n=5) were made for each group. Specimens (6mm in diameter and 1mm thick) were prepared and initially the degree of conversion (DC%) of discs was obtained by using an FT-IR spectrometer. After, the specimens were placed in a desiccator at 37ºC and to be weighed until a constant mass
(m1) was obtained. The discs were immersed separately into the 4 media for 30 days. Twice a day, for two minutes, the samples were immersed in 2 ml of three mouthrinses. A control group was maintained in artificial saliva. After the period the discs was reweighed (m2). The reconditioning in the desiccator was done until a constant mass (m3) was obtained. The dates of DC% were analyzed by analysis of variance (ANOVA) in split plots and methacrylate-based composite showed significant higher DC than silorane-based composite and there is no statistical difference in DC between top and bottom surfaces. The sorption data were submitted to three-way ANOVA and Tukey’s Test at a 5% level of significance and the rate of sorption-based composite silorane (P90) was significantly
lower than the methacrylate-based composite (Z250). Moreover, the artificial saliva did not affect the increase in rate of sorption in any of the photoactivation distances. In 3 mm and 6 mm light distance, the mouthwash Plax Whitening caused the increase of sorption for the two composites. The solubility date were analyzed by Kruskal-Wallis’s Test (p=0,05) and Dunn’s Test, since a non-normal date distribuition was observed. The values were negative, which means that there was mass gain. It may be concluded that the curing tip distance affect the degree of conversion and sorption only when cured to 6mm, however not influenced by the type of mouthwash. The solubility test demonstrated negative data, masking the real solubility..