Nailbiting: frequency and association with root resorption during orthodontic treatment.

The purpose of the present investigation was to determine the incidence and intensity of nailbiting and its possible role in root resorption during orthodontic treatment. A sample of 1365 boys and girls, aged 13-15 years old, were investigated about their nailbiting habits. The possible effect of nailbiting on root resorption during orthodontic treatment was evaluated by radiographic examination of two groups, matched with regard to overjet, age, sex, length and type of orthodontic treatment with fixed orthodontic appliances, one group consisting of 21 severe nailbiters and the other a group of 21 patients without the habit. Replies to questionnaires distributed to 340 boys and girls showed that the incidence of nailbiting was 45 per cent. The habit of severe nailbiting among 1025 of the children investigated was registered in 14.3 per cent. There was no significant difference regarding the habit between boys and girls. The apical root resorption index was significantly higher in the severe nailbiters before (p less than 0.01) and after (p less than 0.001) orthodontic treatment.