Assessment of the effects following different mandibular incisors intrusive mechanics for treatment of orthodontic patients with deep bite; A randomized clinical trial.

OBJECTIVE: Assessment of total root volume, root length, labial bone height, and amount of intrusion for three different intrusive mechanics; orthodontic miniscrews, utility arch, and the nitinol reverse curve archwire (RCA). PATIENTS AND METHODS: Twenty-one deep bite orthodontic patients (male and female, age range 12-16 years old), were involved in the current study. According to the method of intrusion for lower incisors, the patients were randomly subdivided into three groups; Group (A): patients received an intrusive force delivered by elastics from two mini-screws between mandibular lateral incisor and mandibular canine. Group (B): patients received an intrusive force delivered by intrusive utility arch. Group (C): patients received an intrusive force delivered by RCA. Cone beam computed tomography (CBCT) was taken just before and after completion of intrusion of the lower anterior segment. Statistical analysis was done with Statistical Package for Social Sciences (SPSS) version 18; Bonferroni's post hoc test was used for pair-wise comparisons when the ANOVA test is significant. The significance level was set at P ≤ 0.05. RESULTS: A statistically significant difference in root length reduction was found among the three groups. Post hoc analysis revealed no significant difference between group A and group B with mean difference (-0.97 mm, -0.93 mm). However, root length reduction in group A and group B was significantly greater than that of group C, which showed the least mean difference (-0.81 mm) in root length reduction. CONCLUSIONS: The nitinol RCA produce adverse effects as a root resorption and reduction of labial bone height during intrusion of the lower anterior segment more than that produced by the orthodontic miniscrews with elastics and utility arch as intrusive mechanics.