| Objectives Chosen four kinds of dental restorative material frequently-used, proceed friction and wear experiments against natural tooth enamel /dentine. Investigate and evaluate the wear resistance between the nature enamel/dentine and four kinds of dental restorative material in vitro, provides appropriate reference and experimental basis for clinical.Methods With natural tooth enamel/dentin cusp unworn as the research object, porcelain ceramic, glass ceramics, zirconia, pure titanium highly polished as the friction pair.Divided enamel/dentine into a treatment group which enamel/dentine cusp grind four kinds of dental restorative material respectively and a control group which enamel/dentine cusp grind enamel/dentine plane. Make the enamel/dentin cusps in sliding against porcelain ceramic, glass ceramic, zirconia, pure titanium respectively on a loading wear test which needed to be done using UMT-2 friction and wear testing machine. The way of friction movement was reciprocating motion. Set vertical load on 15 N, cycle times were 6000,displacement was 1mm, 2 Hz frequencies. Treated it is possible to conclude that the change of the parameters such as friction coefficient curve. Surface morphology of tooth cusps and materials was observed by a scanning electron microscopy(SEM) before and after the abrasion experiment. Roughness of tooth enamel/dentine and materials were measured by the surface roughometer, and surface hardness was monitored by HVS-50 Z type automatic turret digital display vicars hardness instrument. Mass loss of enamel/dentine cusps after abrasion test was measured by electronic scales.Results 1 After friction experiment, the microscopic morphology of tooth enamel cusp surface under electron microscope have scratches and loose particles. among the control group, glass-ceramic group and pure titanium group, the tooth tips' surface appeared a lot of debris and fatigue crack. The tooth tips' surface of polymer ceramic group was more smooth than other groups. The tooth tips' surface of zirconia group was severe wear,had furrows exist.By spss17.0 to examine the enamel tooth tips' mass loss after abrasion experiment between experimental group and control group. There was statistically significant difference between the experimental group and control group(P=0.000, <0.05). It's not all the equivalent of mass loss between four kinds of materials and the control group against enamel tips. Using correlation analysis conduct the connection between mass loss and materials' hardness for each experimental groups' enamel tooth cusps( r=0.979, > 0.8, P=0.004, < 0.05), significant positive correlation, so there were significant positive correlation between mass loss of tooth cusp and hardness of materials,with the increase of hardness, the mass loss also increases. Mass loss of enamel cusps grinding glass ceramics was the closest to the control group.2 After friction experiment, the microscopic morphology of tooth dentine cusp surface under electron microscope have scratches and loose particles. Between control group and polymer ceramic group, the tooth tips' surface appeared visible deformation form of dentin tubule. The tooth tips' surface of glass-ceramic group, pure titanium group and zirconia group were severe wear,dentin tubule invisible, there are a lot of debris and furrows in the wear area. By spss17.0 to analyze the dentine tooth tips' mass loss after abrasion experiment between experimental group and control group. There was statistically significant difference between the experimental group and control group(P=0.000,<0. 05). It's not all the same of mass loss between four kinds of materials and the control group against dentine tips. Using correlation analysis conduct the connection between mass loss and materials' hardness for each experimental groups' dentine tooth cusps(r=0.846, >0.8, P=0.147, >0.05), significant positive correlation, so there were significant positive correlation between mass loss of tooth cusp and hardness of materials,with the increase of hardness, the mass loss also increases. Mass loss of dentine cusps grinding polymer ceramic was the closest to the control group.Conclusions Different material causes being different surface abrasion to enamel/ dentin.Analyze materials' wear resistance of the wear morphology, material hardness and mass loss of the tooth cusp. The wear resistance of glass ceramic match with the performance of enamel, the abrasion resistance of porcelain ceramic match with the performance of dentine. Therefore, in clinical, glass ceramic is appropriated to be chosen as the restoration material, if the jaw teeth enamel existing. And porcelain ceramic is appropriated to be determined for the restoration material when the jaw teeth exposed dentine. |
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