Outcomes of two-phase orthodontic treatment of deepbite malocclusions

The objective of this prospective controlled study was to assess the outcomes of two-phase treatment of deepbite patients revaluated at the end of circumpubertal growth, 1 year after the end of a phase-2 treatment.

A sample of 58 subjects with deepbite (mean age 9.7 years, overbite greater than 4.5 mm) was treated consecutively with a two-phase protocol. Lateral cephalograms were taken before treatment (T1), at the completion of phase 1 (T2), and 1 year after the completion of phase 2 with fixed appliances (T3, mean age 15.8 years). The T1-T2, T2-T3, and T1-T3 changes were compared with those of the 29 subjects (mean age at T1 = 9.1 years) with untreated deepbite (t-tests for independent samples). Prevalence rates for improved overbite during the T1-T3 interval and for corrected overbite at T3 were contrasted in the treated vs untreated groups (z tests on proportions).

Overbite was reduced by 1.9 mm in the treated group as a result of overall treatment; this group also displayed a significant reduction in the interincisal angulation (-6.6°) due to a significant proclination of upper incisors (4.1°) and a significant increase in the projection of the lower incisors (2.0 mm).

The average amount of deepbite correction 1 year into retention was modest, and it was mainly due to a significant proclination of the incisors. The prevalence rate of subjects with a corrected overbite in the treated sample at T3 (74%) was not significantly different from that of the untreated sample (52%).