Effect Of Fluoride Content On Mechanical Properties Of A New Nano-fluoride-containing Resin

Objective To evaluate the effect of fluoride content on mechanical properties,such as flexural strength,elastic modulus and micro-bonding strength, of a new Nano–fluoride-containing resin.Methods 3M Z350 and four composite resins(0wt%,10wt%,20wt%,30wt% of fluoride content) were divided into five groups(M,D0,D1,D2,D3).1).Flexural Test:Five kind of resins were used to make standard samples,(25±2)mm×(2±0.1)mm×(2±0.1)mm, five specimens per group. Flexural strength and elastic modulus of the specimens were assessed using a three-point bending test on a universal test machine.2).Micro-tensile Test: Twenty five human freshly extracted and non-caries-affected molars were randomly divided into the five groups(M,D0,D1,D2,D3). Sectioned the enamel of the teeth using a low-speed diamond blade and then the facial enamel surfaces of the crowns were abraded with 600-grit silicon carbide paper to expose flat, mid-coronal dentin surfaces.Z350 and four composite resins discs(3-5 mm thick) were cemented on the teeth. After 24 h storage in 0.9% saline solution at 37℃,teeth were sectioned with a cross-section of(1.0±0.2)mm2,ten specimens per group,prepared forμ TBSs. Observed fracture mode of the specimen under low magnification microscope.The dates of the two tests above were statistically analysed by ANOVA and post hoc multiple comparisons with Tukey`s HSD test using SPSS 19.0(α = 0.05).Results 1).Flexural test results show that there was no significantly different among all groups in flexural strength(P>0.05);but group D2 presented significantly higher elastic modulus values in comparison with all the other groups(P>0.05)except group D1.2). Micro-tensile test results show that group D3 presented significantly lower bond strength values in comparison with group D0(P<0.05),but there was no significantly different between D0 and D1 or D2(P>0.05);Group D2 and D3 presented significantly lower bond strength values in comparison with group M(P<0.05),but there was no significantly different among group D0,D1 or M(P>0.05). All specimens were broken from the adhesive surface.Conclusions 1).There was no significantly different between Z350 and the new Nano-fluoride-containing resin on the μ TBS when the content of fluoride was less than twenty percent; The flexural strength and modulus modulus were higher than the other groups when the content of fluoride was 20%. 2).When the fluoride content of the material exceeds a certain amount(20% in this experiment), there was significantly different of the effect of the fluoride content on the μ TBS,otherwise,there was no significantly different.