Synthesis and characterization of a newmethacrylate monomer derived from the cashewnut shell liquid (CNSL) and its effect on dentinaltubular occlusion

Abstract

Objective. The aim of this study was to synthesize, to characterize and to evaluate the effectson tubular occlusion of new monomer derived from cashew nut shell liquid (CNSL), alsostudying the effects of acid challenge (AC) on dentin surfaces treated with desensitizers.Methods. The intermediary cardanol-epoxy (CNE) was synthesized through epoxidation ofCNSL, followed by synthesis of cardanol-methacrylate-epoxy (CNME) through methacry-loyl chloride esterification. Products were purified through chromatography column andcharacterized by Fourier transform infrared spectrometry and 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, OCB — One Coat Bond, CNU — CNUdesensitizer, CNE — CNE desensitizer and CNME — CNME desensitizer. Dentinal fluid rate(DFF) was obtained using a Flodec equipment and tubular occlusion employing a scanningelectron microscope (SEM), before and after AC. Data of DFF were submitted to two-wayANOVA and Tukey’s test (p < 0.05).Results. GLUMA showed the lower reduction in DFF when compared to the other products,which were statistically similar. Even after AC, CNME presented the most homogenousand occluded surface, while CNE and CNU were partially removed, GLUMA was completelyremoved and OCB keep an occluded, but irregular surface.Significance. CNME showed a great reduction of DFF and a homogenous occluded surface,suggesting that it may be a suitable and acid-resistant treatment option for dentine hyper-sensitivity.