Physical and Mechanical Evaluation of Dental Resin Composite After Modification with Two Different Organo-Modified Montmorillonite Nanoclay

Abstract

The aim of this study was to evaluate resin composite restorative material after modification with two types of organo-modified MMT nanoclay; an experimentally prepared polymethyl-methacrylate modified MMT nanoclay (PMMA/MMT) and a commercially available dimethyl di-hydrogenated tallow quaternary ammonium modified MMT (Cloisite20A). Three different concentrations (0.5wt%, 1wt% and 1.5wt%) of each organo-modified nanoclay were used and evaluated regarding their effect on degree of conversion (DC), microhardness, flexural properties and color change of resin composite. The experimental MMT was synthesized by the sol-gel technique, then organo-modified by polymethyl methacrylate (PMMA) by graft polymerization. X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS) and transmission electron microscope (TEM) were employed for phase identification, chemical characterization, particle size analysis and morphological characterization of unmodified MMT, PMMA/MMT and Cloisite20A nanoclays. A total of 316 specimens were used in this study. Two hundred and forty modified resin composite specimens were prepared and divided into 6 groups according to the type and the concentration of nanoclay used for resin composite modification. Forty unmodified resin composite specimens were used as the control group. Moreover, for evaluation of nanoclay dispersion in resin composite matrix, 36 specimens of resin composite modified with PMMA/MMT and Cloisite20A in 0.5wt%, 1wt% and 1.5wt% concentrations were prepared.