| Objective:Light-cured composite resin is a kind of dental material which has been widely used in dental restoration. But the residual monomers of dental filling materials have outstanding effects on the mechanical and biological properties of these materials, and the widely use is limited in dental restorations. The inorganic component of a new nano-hydroxyapatite composite resin is n-HA, which has excellent mechanical properties and biocompatibilities, and it has wide clinical prospect. This study aims to provide different solutions for n-HA composite material, CHARISMA(?) and DenFilTM Flow composite resins, determine the degree of monomer conversion (DC) and compare their differences, and to analyze the influence of factors to the monomer conversion rate. Looking at ways that we can enhance synthetic function of the new material, which could be better suited for clinical appliance.Methods:Part1:Prepare composite materials by different proportion of n-HA in composite materials: The composite materials were composed of a visible light-curing monomer mixture as a matrix and n-HA as a inorganic filler. The surface of the n-HA particles was modified by using a silane coupling agent KH-570. The quality of n-HA in composite materials were 45wt%,55wt%,65wt %,75wt%, respectively.Part2:Effects of the content of inorganic fillers for monomer conversion of n-HA composite resin:The composite materials was divided into A、B、C、D four groups by the proportions of n-HA (45wt%,55wt%,65wt%,75wt%) in composite materials, and each group production 5 specimens. The IR spectra of composite resins were determined and the degree of conversion was calculated. Compare the differences through variance analysis.Part3:Effects of post-cure treatment for monomer conversion of composite materials:Three kinds of light-cured composite resin:nano-hydroxyapatite composite resin that consists of 55wt% n-HA, CHARISMA(?), DenFilTM Flow were double-side cured for 40 seconds.20 samples were made and randomly divided into four groups. The materials without any secondarily treatment as control group (group E), the samples were lighted in Translux(?) CU light cure case for 5 minutes (group F), the specimens were subjected to post-cure heat treatment for 7.5 min at 140℃ (group G) and the remaining materials were post heated in 132℃ and pressured 0.2 MPa for 6.5 min (group H). The IR spectra of composite resins were determined and the degree of conversion was calculated. Compare the differences through variance analysis.Result:1. The new nano-hydroxyapatite composite resins by different proportion of n-HA were successfully produced with better color and plasticity.2. The proportion of n-HA in composite materials has a certain influence on the monomer conversion, when the quality of n-HA is 65wt%, the conversion of the composite materials is optimal (48.56±1.54)%. The monomer conversion of nano-hydroxyapatite composite is reduced after rose with the proportion of n-HA in composite materials. The DC of nano-hydroxyapatite composite when the quality of n-HA is 55wt% is (29.72±2.17)%.3. The monomer conversion of light-cured composite resins were improved at different degree after the post-cure treatment, and the group G is most favorable (P<0.05). Compared with the control group, group F and H have significant differences (P<0.05) except DenFilTM Flow and CHARISMA(?) were lighted for 5 minutes (P>0.05). In the three experimental groups, there were no statistical differences between each group of DenFilTM Flow groups, CHARISMA(?) illumination and hot-pressing groups, n-HA composite resin illumination compared with 140℃ groups.4. The monomer conversion rate of these three kinds of composite resin is not the same. The DC of materials are processed by the three experimental groups have significant differences (P<0.05) expect CHARISMA(?) and DenFilTM Flow in hot-pressing groups and 140℃ groups.Conclusion:1. The degree of conversion can be affected by the content of inorganic fillers. When the quality of n-HA is 65wt%, the conversion of the composite materials is optimal.2. 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℃.3. After the traditional solidification, the DC of n-HA composite resin is lower than CHARISMA(?) and DenFilTM Flow. But the transformation efficiency can be obviously raised by using post-cure treatment.4. The materials are lighted for 5 minutes after solidification could be high clinical value to dental direct restoration, however, the properties of indirect restorative materials can be improved though heat and pressure. |
PDF Full Text Request