Abstract:

Objective: To discuss the bonding strengths of commonly used three kinds of orthodontic adhesives under the dry and artificial saliva conditions,and to evaluate their bonding properties and provide the reference for clinical application. Methods: A total of 60 premolars removed for the orthodontic treatment were collected and randomly divided into 3M light curing adhesive group,3M chemical curing adhesive group, and Hangzhou West Lake enamel adhesive group,and there were 20 premolars in each group;then the each group was divided into two sub-groups with 10 premolars.A1 group was dry condition + metal brackets + 3M light curing adhesive,and A2 group was artificial saliva condition + metal brackets + 3M light curing adhesive; B1 group was dry condition + metal brackets + 3M chemical curing adhesive,and B2 group was artificial saliva condition+metal brackets + 3M chemical curing adhesive;C1 group was dry condition + metal + Hangzhou West Lake enamel adhesive,and C2 group was artificial saliva condition + metal brackets+ Hangzhou West Lake enamel adhesive.The electronic universal mechanical testing machine was uesd to test the bond strengths of orthodontic adhesives in various groups under the dry or artificial saliva conditions. The microscope was used to observe the adhesive remnant index(ARI) of orthodontic adhesives on the surface of the teeth, which was bonded with metal brackets;the scanning electron microscope was used to observe the surface morphology of the teeth detached from metal brackets. Results: Under both dry and artificial saliva conditions,the bonding strength of orthodontic adhesives in 3M light curing adhesive group was higher than those in 3M chemical curing adhesive and Hangzhou West Lake enamel adhesive groups(P<0.05); the bonding strength of orthodontic adhesives in 3M light curing adhesive group under the dry condition was higher than that under artificial saliva condition. Under the saliva condition, the bonding strengths of orthodontic adhesives in varous groups had no significant differences(P>0.05);the ARI of premolars in 3M light curing adhesive group was lower than those in other two groups(P<0.05).The testing results of scanning electron microscope showed that compared with the other two groups,the surface of premolars in 3M light curing adhesive group was more regular and flat without obvious cracks and enamel stripping. Conclusion: Under different conditions,the bonding strengths of three kinds of orthodontic adhesives can meet the requirements of clinical orthodontics,and the bonding properties of orthodontic adhesives of 3M light curing adhesive is better than the other two kinds of orthodontic adhesives.

Key words: orthodontic adhesives, bonding properties, scanning electron microscope, metal brackets, bonding strength