Effect of brushing with sonic and counterrotational toothbrushes on the bond strength of orthodontic brackets

The purpose of this study was to evaluate the effect of brushing with both a sonic and mechanical counter rotary power toothbrush on the bond strength of orthodontic brackets. Forty-five extracted teeth were divided into thre e random groups and had orthodontic brackets bonded to them. One group was brushed with a counterrotational toothbrush, the Interplak, one group with a sonic toothbrush, the Sonicare, and a third group was not brushed and was held as a control. After the equivalent of 2 years brushing, the teeth wer e placed in an Instron machine and the shear force to remove the brackets w as recorded. Group 1, the counter rotary power brush, had a mean of 107.5 k g/cm2, the second group, the sonic brush, had a mean of 79.7 kg/cm2, and th e control group had a mean of 125.4 kg/cm2. Single factor analysis of varia nce followed by the Fisher-Hayter Multiple Comparison Procedure showed a st atistically significant difference between the sonic power brush and the co ntrol (P<.01), but no significant difference between the counter rotary and the control (P > .05). There was no significant difference between the two power brushes (P > .05).