%A   Mohamad,  D
%A   Young, R.J. 
%A   Mann, A.B. 
%A   Watts, D.C. 
%O This article is based on a dissertation submitted to
the Manchester Materials Science Centre, UMIST, in partial requirements for the MSc degree.
%J Archives of Orofacial Sciences
%T Post-polymerization of dental resin composite evaluated with nanoindentation and micro-Raman spectroscopy
%X The aim of the study was to evaluate post-polymerization of resin composite by measuring NanoHardness (H), Young?s Modulus (E) and Degree of Conversion (DC) using nanoindentation and Micro-Raman spectroscopy. For this purpose a computer-controlled NanoIndenter?  and a Renishaw 1000 Raman Spectrometer fitted with an Olympus microscope attachment, operated at 638 nm, were used. A light- activated resin composite was used in this study, (Z250, 3MESPE). Sub-groups (n=3) of specimens were irradiated for 20, 30, 40 s. All samples for nanoindentation were polished metallographically and typically 50 nano-indentations were performed per specimen. After curing and polishing, half of the samples were tested immediately (Group 1); the others after being stored dry at 37 ?C for 7 days (Group 2) to allow scope for post-polymerization. H values ranged from 1.08 to 1.40 GPa for Group 1, and from 1.64 to1.71 GPa for Group 2. E values in Group 1 ranged from 19.60 to 19.94 GPa and for Group 2, from 21.42 to 22.05 GPa. DC values ranged from 55 to 66.39%, and 60.90 to 66.47% for Group 1 and Group 2 respectively. All values obtained shown significant different between Groups 1 and 2 (p<0.05); ie as a result of any (further) monomer post- polymerization. The consistently greater H, E and DC values in Group 2 suggest that network stabilization may occur partly by mechanisms supplementary to monomer conversion per se. This could include annealing of the polymer chain segments.
%K Nanoindentation, dental composite, Young?s modulus, hardness, degree of conversion
%P 26-31
%V 2
%D 2007
%I School of Dental Sciences, Universiti Sains Malaysia
%L myais1601