Bond failure after rebonding for newly placed brackets can be reduced by appropriate enamel surface treatment. This in vitro study investigated the effect of two enamel surface treatments on the bond strength of metallic brackets in the rebonding process. After debonding the brackets and removing the residual adhesive on the enamel surface of 50 upper premolar teeth, the teeth were divided into two equal groups. In the first group, the enamel surface was etched with phosphoric acid 37 per cent, and in the second group, the teeth were sandblasted prior to acid etching. After bonding of the new brackets, the shear bond strength (SBS), probability of bond failures, and adhesive remnant index (ARI) were determined and compared with the t-test, Weibull analysis, and chi-square test. Mean SBS in both groups did not differ significantly (P = 0.081). Most bond failures occurred with ARI scores of 2 and 3, and the difference between the two groups was statistically significant (P < 0.001). Weibull analysis showed that for a given stress, the probability of failure differed between groups. Enamel surface preparation with sandblasting prior to acid etching did not significantly improve SBS in bracket rebonding and left more residual adhesive remnants on the enamel surface.

Background and Aim: The aim of the present study was to evaluate the cephalometric changes in Class II division 1 mandibular deficient patients treated with Farmand functional appliance. Methods and Materials: Twenty-seven subjects (17 girls and 10 boys) with the mean age of 11.1±1.4 years were involved in the present study. All the subjects were treated with Farmand functional appliance. Paired t-test and Wilcoxon test were used to evaluate the data. The significance level was set at P<0.005. Results: A skeletal Class I relationship and a marked reduction in the overjet were achieved with the use of Farmand appliance. ANB decreased significantly by 3.2±1.7 degrees, while SNB increased from 74.3 ±1.7 degrees to 77.6±2.3 degrees (P<0.001). Conclusion: The results showed that Farmand functional appliance is effective in the treatment of mandibular deficiency in patients with Class II division 1 malocclusion.