Comparative Research On The Rebonding Of Three Different Kinds Of Bottom Plate Brackets And Brackets After Falling Off By Sandblasting

Objective:To discuss the bond strength,under artificial saliva conditions,of three different kinds of metal bottom plate brackets and three different kinds of brackets after falling off by sandblasting that was commonly used in orthodontic and to evaluate its bonding performance which provide reference for clinical application.Methods:Collect 60 premolar teeth that was extracted because of orthodontic treatment and divide them into there groups randomly with 20 premolar teeth in each group: group A: the group of Xinya brackets;group B: the group of MBT brackets;group C : the group of TOMY brackets.Then the teeth were randomly divided into 6 groups after the brackets falling off,A1,A2;B1,B2;C1,C2.Choose again 10 new Xinya brackets,10 new MBT brackets,10 new TOMY brackets respectively.10 brackets were randomly selected from each group in the three groups that were treated by sandblasting.Test the shear strength by universal electronic mechanical testing machine in each group,and observe the residual adhesive index(ARI)in each group.Scanning electron microscope(SEM)was used to observe the morphologies of three types of brackets and three different kinds of bottom plate brackets after falling off by sandblasting.Results:1、Under the condition of artificial saliva,the shear strength of three different brackets is different,TOMY group was larger than the Xinya group and the MBT group(p<0.05),and the MBT group was less than the new Xinya group(p>0.05).2 、 Under the condition of artificial saliva,the shear strength brackets after falling off by sandblasting,the three groups were all increased,among the TOMY group and MBT group(P<0.05),while the Xinya group(P>0.05).3、Under the condition of artificial saliva,three groups of ARI scores were scored,and the Xinya group was larger than the MBT group and the MBT group is larger than the TOMY group.Brackets after falling off by sandblasting,the three ARI score decreased.However,there was no statistical difference between the groups.4 、 Scanning electron microscopy(SEM)observed that all three brackets are grid,and the bottom of the TOMY are more compact and regular.After sandblasting,the sand grains are all embedded in the net,and MBT and TOMY are more distributed in the bottom of the net.5、Scanning electron microscopy shows that the network bottom part of the Xinya groove is severely damaged after the second sandblasting.While the other two groups of brackets did not see obvious abnormalities.Conclusion:1.The adhesion strength of the three different types of backets can meet the clinical needs,but the TOMY group has signficantly better adhesion strength and ARI than the other two groups.2.After three types of brackets after falling off by sandblasting,the bond strength increased,and the bonding strength of TOMY and MBT group increased obviously.3.With the increase of sandblasting frequency,the bottom plate may be damaged,and the Xinya brackets should avoid repeated use.