habit reversal versus object manipulation training for treating nail biting: a randomized controlled clinical trial.

objective: this is a parallel, three group, randomized, controlled clinical trial, with outcomes evaluated up to three months after randomization for children and adolescents with chronic nail biting. the current study investigates the efficacy of habit reversal training (hrt) and compares its effect with object manipulation training (omt) considering the limitations of the current literature . method: ninety one children and adolescents with nail biting were randomly allocated to one of the three groups. the three groups were hrt (n=30), omt (n=30), and wait-list or control group (n=31). the mean length of nail was considered as the main outcome  results: the mean length of the nails after one month in hrt and omt groups increased compared to the waiting list group (p<0.001, p<0.001, respectively). in long term, both omt and hrt increased the mean length of nails (p<0.01), but hrt was more effective than omt (p<0.021). the parent-reported frequency of nail biting did show similar results as to the mean lengt  of nails assessment in long term. the number of children who completely stopped nail biting in hrt and omt groups during three months was 8 and 7, respectively. this number was zero during one month for the wait-list group . conclusion: this trial showed that hrt is more effective than wait-list and omt in increasing the mean length of nails of children and adolescents in long terms.