In situ reaction kinetic analysis of dental restorative materials

¹ Interdisciplinary Research Centre in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000, Pakistan
² Faculty of Dentistry, SEGi University, Kota Damansara PJU 5, Malaysia
³ Department of Mathematics, COMSATS Institute of Information Technology, Lahore 54000, Pakistan
⁴ Department of Materials Science and Engineering, The Kroto Research Institute, The University of Sheffield, Sheffield S3 7HQ, United Kingdom

^b e-mail: draskhan@ciitlahore.edu.pk

Received: 31 July 2013
Revised: 21 October 2013
Accepted: 18 November 2013
Published online: 16 December 2013

Abstract

The objective of this study was to evaluate in situ structural and thermal changes of dental restorative materials at periodical time intervals. The commercial materials included zinc oxide eugenol (ZOE), zinc phosphate type I (ZnPO₄), glass ionomer cement type II (GIC) and resin-based nano-omposite (Filtek Z350 XT). These materials were processed according to manufacturer’s instructions. For the structural analysis Fourier transform infrared spectroscopy (FTIR) was used at high resolution. TGA was used to evaluate thermal weight-loss. The FTIR spectra were collected at periodic time intervals. FTIR spectra showed that with time passing all materials exhibited an increase in peak intensities and a new appearance of shoulders and shifting of peaks for example, ZnPO₄ (P-O), ZOE (C═O, C═N, C-O-C), GIC (COO^–, C-H, Si-OH), composites (C═O, C═C, C═N, C-N-H). The peaks were replaced by bands and these bands became broader with time interval. Composites showed a degree of conversion and new peaks corresponded to the cross-linking of polymer composites. TGA analysis showed that significant changes in weight loss of set materials were observed after 24 h, where ZOE showed continuous changes in thermal degradation. The spectral changes and thermal degradation with time interval elucidated in situ setting behaviour and understanding of their bonding compatibility with tooth structure and change in relation to time.