The Effect Of Irradiation On Micro-leakage And Microscopic Morphological Of Different Filling Materials

Objective: To analyze and compare the effects of irradiation on the dentin and adhesive property of different filling materials through the measurement of micro-leakage depth of different filling materials before and after the irradiation, comparison and micro-form observation, so as to provide theoretical basis for the selection of appropriate filling materials in the clinical operation.Method:1 Sample collection and grouping60 freshly extracted premolars were selected, cavities were prepared with the size of 3 mm*3 mm which were on the labial side, and the depth should reach 1 mm below the enamel-dentinal junction. All samples were randomly divided into the experimental group(A) and control group(B), and then divided into three subgroups at random, namely A1, A2, A3 and B1, B2,B3, with ten samples in each group.2 Sample processingGroup A1 and B1 were filled with strengthen glass-ionomer(FX-II), A2 and B2 were filled with composite resin(Filtek Z350), cavity were treated with infiltration resin in A3 and B3 group and then filled with Filtek Z350. All sample teeth were kept in 37℃ water for 7 days, and then 500 times of thermocycle were carried out. The teeth in group A were irradiated fractionally up to 70 Gy, once a day and 2.0Gy a time. Then, all samples of Group A and B shall be placed in methylene blue solution with 2.0% of mass fraction, for dying for 48 hours.3 Observation and data analysisAll the teeth were cut through the filling center with the direction of perpendicular to the surface of obturator, vertical to the long axis of the teeth. Finally, measuring micro-leakage used by microscope and microstructure were observed SEM.Result:1.Micro-leakage depthAccording to the Scheirer-Ray-Hare inspection result:the interactive function of the impact of irradiation and filling materials on the depth of micro-leakage is of no statistical significance(H=4.53, P=0.104), the main effect of the impact of irradiation on the depth of micro-leakage is of no statistical significance(H=2.23, P=0.135), and the main effect of the impact of filling materials on the depth of micro-leakage is of statistical significance(H=11.56, P=0.003)According to LSD inspection result:the difference in the micro-leakage depth after the filling of FX-Ⅱgroup and Z350 group is of no statistical significance(LSD-t=1.226, P=0.213), the difference in the micro-leakage depth after the filling of infiltration resin group and FX-II group is of great statistical significance(LSD-t=2.403, P=0.017), and the difference in the micro-leakage depth after the filling of infiltration resin group and z350 group is of great statistical significance(LSD-t=3.881, P<0.001).2. SEM observationThe grains of filling materials in Group A1 and B1 are large, and intervals can be seen on interface after amplifying;the grains of filling materials in Group A2 and B2 are of medium size, and there is resin tags close to the dentinal tubule,and the materials grains in the bonding interface in Group A3 and B3 are the smallest, with more resin tags than the filling with Z350. In the experimental group, the dentinal tubule is round and blunt in the edge with wrinkles, the dentin around the tubule is outstanding, and the dentin in incision surface is uneven.Conclusion:1.Radiotherapy treatment had no effect on the micro-leakage depth of different filling materials.2.Micro-leakage of different filling materials were different, FX-Ⅱgroup had no statistical significance compare with Z350 group, infiltration resin group had the best degree.