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The Effects of Several Surface Preparation Methods on Shear Bond Strength of Orthodontic Brackets to Caries-like Lesions of Enamel

 
Farzaneh Ahrari
Assistant Professor, Dept. of Orthodontics, Dental School, Mashhad University of Medical Sciences
Mostafa Shahabi
Associate Professor, Dept. of Orthodontics, Dental School, Mashhad University of Medical Sciences
Horieh Moosavi
Assistant Professor of Restorative Dentistry, Dental Material Research Center, Dental School, Mashhad University of Medical Sciences
 Azade Gholami
Dentist, Dental School, Mashhad University of Medical Sciences


Objective:
This study aimed to evaluate the efficiency of several surface preparation methods for improving shear bond strength of brackets to demineralized enamel.
Methods & Materials:
Eighty premolars were selected and divided into 5 groups. Group 1 served as the control, while the remaining 4 groups were immersed in a demineralising solution (pH 4.8) for 12 weeks. In groups 1 (control) and 2 (demineralized/control) conventional acid etching was used. In group 3, a solution of 5% sodium hypochlorite (NaOCl) was applied on enamel surface for one minute after acid etching. The brackets in group 4 were bonded with Transbond Plus self-etching primer, and group 5 underwent treatment with a 2% sodium fluoride (NaF) gel, which was applied on the enamel surface for 4 minutes before etching. Shear bond strength (SBS) and adhesive remnant index (ARI) were determined in all groups, and surface morphology was examined under scanning electron microscope (SEM).
Results:
The mean SBS of acid-etched demineralised enamel was significantly lower than that of acid-etched sound enamel (p<0.05). Treatment of caries-like lesions with 5% NaOCl or self-etching primer failed to improve the bond strength. After NaF treatment and acid etching of demineralised enamel, both type 1 and type 2 etching patterns were observed and the resulting SBS was comparable to that of sound enamel (p>0.05).
Conclusion:
The application of 2% NaF on enamel caries before bracket bonding is an effective way for enhancing the bond strength.

Keywords:
Shear bind strength,Enamel,Demineralization,Bracket


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محل نشر یا ارائه:  کنگره 10 انجمن ارتودنتیست ها
سال ایرانی :  1391
موضوع:  ارتودنسی
Level:  Postgraduate

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