Comparative Evaluation of the Effect of Different Types of Bleaching Dentifrices on Shear Bond Strength of Orthodontic Metal Brackets Bonded by Conventional Composite to Human Teeth: An In Vitro Study.

AIM: This study aims to evaluate and compare the effect of different types of bleaching dentifrices on the shear bond strength of orthodontic metal brackets bonded by light-cured composite adhesive to human teeth. MATERIALS AND METHODS: Forty-five human premolar teeth were randomly divided into three groups, receiving the following treatments: Group 1 (control group; teeth in this group were not bleached), Group 2 (teeth in this group were treated with active oxygen bleaching dentifrice), and Group 3 (teeth in this group were treated with peroxide bleaching dentifrice). Orthodontic brackets were bonded using a light-cured composite adhesive. A universal measuring device was used to assess the shear bond strength with a crosshead speed of 0.5 mm/min. One-way ANOVA, post hoc Tukey tests, and an independent t-test were used to analyse the data. RESULTS: There was a highly significant difference (p≤0.001) in the mean shear bond strength of orthodontic brackets bonded to untreated teeth as compared to teeth treated with bleaching dentifrice. There was no significant difference in the mean shear bond strength of orthodontic brackets bonded to teeth treated with peroxide bleaching dentifrice or active oxygen bleaching dentifrice. CONCLUSION: There was a significant reduction in the mean shear bond strength of orthodontic metal brackets when bonded to human teeth treated with bleaching dentifrices.

Comparative Evaluation of Effect of Micro-Osteoperforation and Mechanical Vibration on Rate of Orthodontic Tooth Movement in Young Adults With Bimaxillary Protrusion.

AIM: To evaluate and compare the rate of orthodontic tooth movement and root resorption by micro-osteoperforation (MOP) and mechanical vibration in young adults with bimaxillary protrusion. METHOD: Twenty patients having class I bimaxillary protrusion who required all first premolar extraction were allocated into two groups MOP (Group A) and mechanical vibration (Group B), with a 1:1 allocation ratio. After leveling alignment MOP was performed on either side of the arch, and vibration was applied on the contralateral side 20 mins per day. Canines were retracted with nickel-titanium coil springs, and Alginate impressions were taken every four weeks till 4 months. RESULT: The mean rate of retraction of canines of Group A was more than Group B. There was a statistically significant difference between Group A and Group B. (p=0.0120) Conclusion: The mean rate of retraction of canines treated by MOP was 1.15 mm per 4 weeks, and by mechanical vibration, 0.8mm per 4 weeks.