A Study For The Biomechanics Of Metallic Orthodontic Bracket Of Multiple Bonding

Objective: The purpose of this study was to observe the biomechanics of metallic orthodontic bracket during multiple bonding. Methods: Investigate the influence of two diffrent base designs and adhesives on the bond strength of metallic orthodontic bracket. Then select the better bracket and adhesive to the multiple bonding, the dislodged brackets were recycled by thermal treatment and electropolishing. The bonding brackets were exposed to artificial saliva to mimic the true situation. The bond strength and the friction were tested by the tester. Observe the change of the bracket base and the slot base by using SEM, with whose help the slot size were tested and then the statistics of the slot related indexes were made. Results: The shearing bond strength and the tensil bond strength of simple foil mesh bracket were both greater than horizontal retention groove base bracket. The adhesive factor and the interaction between the base and the adhesive had little effect on the bond strength of bracket. During the test of multiple bonding, the fist bond strength was greast, with the times of bonding increased, the bond strength significantly decreased; the slot size became wider, the bracket width became shorter, the bracket index and the bracket engage index decreased, the critical contact angle increased; the base of the slot became more wearing, the friction between the bracket and the are wire increased. Conclusions: The bond strength of simple foil mesh bracket with micro-etch base is greater than horizontal retention groove base bracket. The bond strength of the metallic orthodontic bracket significantly decreased with the times of bonding increased, but the bond strength can still be clinic available after 4 times bonding. The...