Comparison On Shear Bond Strength Of Bracket With Primer Under Different Treatment-an In-vitro Study

Objective:The purpose of this study was to compare the different treatment of hydrophobic primer on tooth and bracket base on shear bond strength (SBS), and to provide coherent reference for clinical practice.Methods:All the samples were divided into four groups according to different treatment of primer on tooth and bracket base. Group 1:both tooth and bracket base were not air-thinned after primer painting; Group2:primer on bracket base was air-thinned but not for tooth; Group3:primer on tooth was air-thinned but not for bracket base; Goup4:both tooth and bracket base were air-thinned after primer painting. After etching and drying, all brackets were bonded to teeth using A and B hydrophobic adhesive,according to the groups which mentioned above.The SBS was tested at 30min and 24h by Instron appliance. Evaluated the adhesive remnant index (ARI) by observing the surface of the teeth after debonding. All statistics were analysed by SPSS15.0 software.Results:(1) The SBS of group 1 was higher than group 4, whatever using A or B adhesive at 30min and 24h (P<0.05), and there was no significant difference between the rest groups (P>0.05). (2) The SBS at 24h was significantly higher than 30min in both of the adhesives (P<0.01). (3) There was no significant difference of ARI in all groups.Conclusions:(1) The adhesive strength of bracket which hydrophobic primer was not air-thinned both on tooth and bracket base was higher than primer air-thinned both on tooth and bracket base. (2) The adhesive strength of bracket which hydrophobic primer was air-thinned both on tooth and bracket base was similar to the primer only air-thinned on tooth or bracket base. (3) The shear bond strength in 24h was higher than 30min.