A Study Of Bond Strength Between Various Base Metal Brackets And Different Adhesives In Vitro

ObjectiveThe metal brackets are most usually used in clinic at present. Bond failure not only affects the course of orthodontic therapy indirectly, but also increases the work strength of the orthodontist and the burden of the sufferer directly. Aiming at the phenomenon of orthodontic bracket dropping during the fixation orthodontics , this study is going to compare the shear bond strength between metal brackets with various bases and different type adhesives in vitro, and to search the ideal combinations for the satisfied clinical need.Materials and MethodsFour kinds of metal brackets: meshy base metal bracket ( Xihu, Hang-zhou) ,concave base metal bracket(3B, Hangzhou) .groove base metal bracket (Shenyang) ,APC metal bracket(3M, U. S. ).Three kinds of adhesives;Jingjin Enamel Adhesive (Tianjin) , no - mix orthodontic direct bonding system (Xihu, Hangzhou) , Transbond XT(3M, U. S.).One hundred recently extracted human premolars were bonded with various bracket/adhesive combinations. All samples were immersed in artificial saliva at room temperature for 24 hours, then subjected to thermal cycling (0℃, and 55℃) for 750 complete cycles before debonding. Data relating to bond strength were analyzed using two - way ANOVA. After debonding, specimens were examined under a stereomicroscope at 2 magnification in order to assess adhesive remnants on tooth surfaces using the Adhesive Remnant Index (ARI).Results1. The metal bracket with meshy base produced higher bond strength than concave and groove base metal brackets, P <0. 01.2. Bond strength of 3 adhesives had no statistics difference, P >0.05.3. The meshy bracket/Transbond XT combination produced higher bond strength ,P<0.05.4. APC bracket produced the highest bond strength, P<0.05.5. After debonding, in the group of Jingjin Enamel Adhesive almost 63.4% of the sample had a scores of 2 or3;in the groups of no - mix orthodontic direct bonding system and Transbond XT, however, 73. 3% and 70% of the sample had a scores of 0 or 1 respectively. To the group of APC bracket, ARI scores are all 0 or 1, including one enamel crack.Conclusions1. All combinations of metal brackets and adhesives could satisfy the need of clinic;the metal bracket with meshy base produced higher bond strength;2. APC bracket produced the highest bond strength;3. Bond strength of 3 adhesives had no difference;4. The interact existed between various base metal brackets and different types of adhesives, and the combination of metal bracket with meshy base and Transbond XT produced higher bond strength.