The Effects Of Different Etching On Bonding Strength

Objective The aim of the study was to investigate the effects of different etching time on bonding strength to guide its clinical use.Methods 180 human extracted premorlars were selected as samples and randomly, evenly divided into four groups. Every group has 45 experimental samples. Every group was bonded with metallic brackets at different etching time. The tooth specimen was stored in water at 37℃for 24 hours. After 24 hours, the bonding strength was tested by WDW3050 electron testing machine after 24 hours. The Adhesive Remnant Index (ARI) was scored after debonding.Result The bonding strength for 15 seconds etching time was weaker than that for 30 seconds. There were statistically significant differences between them. But there were no statistically significant differences between 30 seconds, 45 seconds and 60 seconds. In vitro the means of the bonding strength in 30 second has reached 6.675 Mpa. The Adhesive Remnant Index (ARI) was increased gradually as the etching time increase.Conclusion Eteching for 30 seconds could provide enough bond strength for orthodontic practice. Therefore, in orthodontic clinical practice 30 seconds were the best etching time. Brackets could be removed easily in clinic by means of 30 second etching time.