[Monomer conversion effect of post-cure treatment on light-cured composite resin]

To study the influence of post-cure treatment on the monomer conversion of 3 light-cured composite resins.

Three kinds of light-cured composite resin: CHARISMA, DenFilTM Flow and nano-hydroxyapatite composite resin were double-side cured for 40 s. The materials without any secondary treatment were used as control group (group A). Group B were lighted in Translux CU light cure case for 5 min. Group C were subjected to post-cure heat treatment for 7.5 min at 140 degrees centigrade and Group D were post heated in 132 degrees centigrade and pressured 0.2 MPa for 6.5 min. Degree of conversion (DC) of all the samples was measured by Fourier transform infrared spectroscopy (FTIR). The data was analyzed using SPSS 13.0 software package.

The monomer conversion of light-cured composite resins improved at different degree after post-cure treatment, and group C was the most favorable group(P<0.05). Compared with the control group, group B and C had significant differences (P<0.05) except when the DenFilTM Flow and CHARISMA were lighted for 5 minutes (P>0.05). Among the experimental groups, there was no significant difference between each group of DenFilTM Flow groups, CHARISMA illumination and hot-pressing groups, and n-HA composite resin illumination compared with 140 degrees centigrade groups.

Post-cure treatment can increase the monomer conversion of light-cured composite resin so as to improve material performance, particularly for the heat treatment for 7.5 min at 140 degrees centigrade.