| Objective:Dental restorative materials is one of the important content of areas of study. At present, despite the chemical, physical, mechanical and biology properties of the dental restorative materia are improved significantly, but the dental restorative materials with the biology active and close tooth body still is not used to clinical applications. This study aims to develop into a dental restorative and bioactive composite NHA materials which can reach the teeth bionics and be used for the teeth restorative. Through test its mechanical properties, provide the evidence for clinical application.And this material developed successfully will start a new way for defect repair teeth, and provide the evidence for the future of the clinical application.Methods:Part1:Prepare composite materials by different proportion of NHA in composite materials:The composite materials were composed of a visible light-curing monomer mixture as a matrix and NHA as a inorganic filler. The surface of the NHA particles was modified by using a silane coupling agent KH-570. The composite materials was divided into A、B、C、D four groups by the proportions of NHA (45wt%,50wt%,55wt%,60wt%) in composite materials, and each group production5specimens. Four groups of composites were prepared for curing depth, flextural strength and compressive strength. Compared the differences with the analysis of variance.Part2:Effects of light initiator system for mechanical properties of composite:The experiments included the surface of NHA was processed by silane coupling agent,KH-570.Then NHA was mixed with resin matrix(Bis-GMA and TEGDMA as single body) in the ratio of55:45.According to the photo-initiation system,the quality of camphorquinone(CQ) or DMAEMA in resin matrix were0.8wt%,1.0wt%,1.2wt%, respectively.Then three groups (group E,F,and G) of light-cured nano-hydroxyapatite composites were prepared, and each group production5specimens.Three groups of composites were prepared for curing depth, flextural strength and compressive strength. Compared the differences with the analysis of variance.Part3:Effects of thinner for mechanical properties of composite:This experiment composed three portions resin matrix according to the quality of8:2,7:3,6:4with Bis-GMA and TEGDMA. And they were mixed with NHA processed by KH-570in the ratio of45:55, Then three groups (H, I, and J) of light-cured nano-hydroxyapatite composites were prepared. Product5specimens of each group, and measured curing depth, flexural strength and compressive strength. Compared the differences with the analysis of variance.Part4:Detect the mechanical properties of composite after screened:According to the quality ratio of Bis-GMA and TEGDMA is7:3,resin matrix and NHA is45:55, and the quantities of CQ and DMAEMA in resin matrix are1wt%respective,we preparat the new-type nano-hydroxyapatite composite. Type A2Carisma was as control group(group B).Five test titles were made in each group.The cured depth, flexural strength, compressive strength, hygroscopy and dissolubility were monitored in each group. The differences between each group were compared by analysis of variance. Result:1. The proportion of NHA in composite materials has effect remarkably for its mechanical properties, when the quality precondition of NHA and resin matrix is55:45, the mechanical properties of the composite materials is optimal. It is worth noting, the curing depth of nano hydroxyapatite composite is reduced with the proportion of NHA in composite materials,but the compression strength and flexural strength is reduced after rose with it.2. New-type nano-hydroxyapatite composite cross section SEM after bended showed that, the section of composite material was composed of NHA treatmented by KH-570is fuzzy, and show ductile fracture. But the section of composite was composed of NHA without treatmented by KH-570has many irregular holes, and show brittle fracture. It clew that there is better organic union between NHA treatmented by KH-570and matrix.3. As the ratio of photoinitiator increased, the cured depth of new nanometer hydroxyapatite composite increased, while the compressive strength and flexural strength declined. When the photoinitiator proportion is1.0wt%, curing depth (1.60±0.46mm) can meet international standards requirement, and compression strength (216.93±1.18Mpa) and flexural strength (63.39±3.19Mpa) also are better.4. As the ratio of diluent increased, the cured depth of new nanometer hydroxyapatite composite was not alteration obvious in experiment groups, while the compressive strength and flexural strength declined after rose, when the quantity ratio of Bis-GMA and DMAEMA was7:3, compression strength (214.12±7.29Mpa) and flexural strength (64.19±0.86Mpa) also are better,and curing depth (1.57±0.50mm) can meet international standards requirement.5. Results showed that the cured depth is less than control group, and the hygroscopy and dissolubility are higher than the control group, and there were significant differences in the cured depth, hygroscopy and dissolubility as compared with control group respectively (P<0.05).But there were no significant differences in compressive strength and flexural strength as compared with control group (P>0.05).Conclusion:1. The degree of interface which is bonded of NHA surface treatmented by KH-570and organic matrix is better than the interface which is bonded of NHA surface without treatmented by KH-570and organic matrix. When the proportions of NHA in composite materials is45%～60%, Operating performance of experiment is good. And When the proportions of NHA in composite materials is55%, compression strength and flexural strength are highest. Mechanical properties is better.2. When the photoinitiator proportion is1.0wt%,and the quantity ratio of Bis-GMA and DMAEMA was7:3, the mechanical properties of new-type nano-hydroxyapatite composite is better.4. In nano-hydroxyapatite composite, there were no significant differences in mechanical strength as compared with cured resin composite(Type A2Carisma). But we also need further research hygroscopy and dissolubility of new-type nano-hydroxyapatite composite to improve it. |
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