Síntese e caracterização de novo monômero derivado do líquido da casca da castanha de caju (LCC) e seu efeito na oclusão de túbulos dentinários

Abstract

Dentin hypersensitivity is a common health problem associated with exposed dentin surfaces, and tubular occlusion is an effective treatment strategy. In the context of the research of molecules with a long carbonic chain for the production of fine chemicals from natural and renewable sources, the cashew nut shell liquid (CNSL) appears as a biomass rich in phenolic compounds. In this regard, the synthesis of a novel monomer derived from natural compounds could produce improved biocompatible desensitizing agents. The aims of this study were to synthesize, to characterize and to evaluate the effects on tubular occlusion of new monomer derived from CNSL, also studying the effects of acid challenge on dentin surfaces treated with different desensitizers. The intermediary cardanol-epoxy (CNE) was synthesized through hydrogen peroxide epoxidation of CNSL, followed by synthesis of cardanol-methacrylate-epoxy (CNME) through methacryloyl chloride esterification. Products were purified through chromatography column and characterized by Fourier Transform Infrared Spectrometry, 13C and 1H Nuclear Magnetic Resonance. Resinous dentin desensitizers were formulated containing either unsaturated cardanol (CNU), CNE or CNME. Dentin disks were divided into seven groups: SL - Smear-layer, EDTA - EDTA-treated only, GLUMA - Gluma Desensitizer (commercial desensitizer), OCB - One Coat Bond SL (commercial adhesive), CNU - CNU desensitizer, CNE - CNE desensitizer and CNME - CNME desensitizer. Dentinal fluid rate (DFF) was obtained using a Flodec equipment and tubular occlusion employing a scanning electron microscope (SEM), before and after acid challenge. Data of DFF were submitted to two-way ANOVA and Tukey’s test (p<0.05). GLUMA showed the lower reduction in DFF when compared to the other products, which were statistically similar. Even after the acid challenge, CNME presented the most homogenous and occluded surface. Furthermore, CNE and CNU were partially removed, GLUMA was completely removed and OCB keep an occluded, but irregular surface. CNME showed a significant reduction of DFF and a homogenous occluded surface, suggesting that it may be an effective and acid-resistant treatment option for dentine hypersensitivity from a renewable source.