The impact of chitosan in experimental resin with different photoinitiator systems

to investigate the effect of different concentrations of chitosan added to experimental resins containing either BAPO or camphorquinone (CQ) as photoinitiators, regarding degree of conversion (DC), flexural strength (FS), flexural elastic modulus (E), Knoop microhardness (KHN), cytotoxicity, genotoxicity and antimicrobial activity. Experimental resins with polymeric matrix of BisGMA and TEGDMA was added either 0.5 wt% BAPO or 0.5 wt% camphorquinone/0.2% amine along with and chitosan concentrations of 0.5%; 1.0% or 2.0%. Degree of conversion was measured using Fourier transformed infrared spectroscopy. Flexural strength and elastic modulus were obtained through three-point bending test and Knoop microhardness was measured in a microidenter. Direct cytotoxicity was performed in human keratinocytes and genotoxicity test was done in murine macrophages cells. Antimicrobial activity was acessed against Staphylococcus aureus and Streptococcus mutans through the inhibition halo. Data were analyzed using two-way ANOVA and Tukey teste (α = 0.05). The materials containing photoinitiator BAPO showed higher values of DC, FS, E, and KHN compared to resins with CQ. The addition of chitosan did not affect the properties of these materials. However, in resins containing CQ, the addition of chitosan improve these properties compared to control group. For the groups containing BAPO the chitosan reduced cytotoxicity and genotoxicity compared to materials with camphorquinone. The materials with 1.0% and 2.0% chitosan showed increased antibacterial activity in the materials containing BAPO as photoinitiator for both bacteria. The alternative photoinitiator BAPO and chitosan can improve physical and biological properties of photoactivated resins when compared with the materials with photoinitiator camphorquinone.