Post-pubertal effects of the Face Mask Protocol with and without Bite Block appliance in the orthopedic treatment of Class III malocclusion: a comparative evaluation

The purpose of this retrospective study was to compare the dento-skeletal changes observed in growing Class III patients treated with the Face Mask Protocol (FMP) with and without Bite Block (BB).

Thirty subjects (12 f, 18 m) who underwent FM/BB therapy were compared to a matched group (FM) of 29 patients (15 f, 14 m) treated without BB. All patients were evaluated before treatment (T0), at the end of active treatment (T1), and at a post-pubertal follow-up observation (T2). A control group (CG) of 20 subjects (10 f, 10 m) with untreated Class III disharmony was used for the comparison of post-pubertal changes. Intergroup statistical comparisons were performed with the independent samples t-test (P < .05).

The comparison between treated samples showed a significant improvement of SN^GoGn (FM/BB vs FM, -2.1°), Overbite (FM/BB vs FM, +1.2 mm), and vertical position of lower molars FM/BB vs FM, -3 mm). When compared with the controls, both treated groups revealed a significant improvement of SNA (FM/BB, +1.8°; FM +2.1°), ANB (FM/BB +1.6°, FM +2.4°), gonial angle (FM/BB -4.9°; FM -4°), incisor inclination (Upper, FM/BB +1.7°, FM +2.3°; Lower, FM/BB -2.5°, FM -2.7°), and Overjet (FM/BB +3.2 mm; FM +4 mm). Improvement of SN^GoGn (-2.1°), Overbite (+1.8 mm), and vertical position of lower molars (-3.8 mm) were observed when FM/BB was compared with CG.

Limitations are related to the difficulty to recruit a larger contemporary long-term control group due to ethical reasons.

Both FM protocols induced favorable changes in the treatment of Class III malocclusion with a good post-pubertal stability. The BB allows a more efficient control of the vertical skeletal relationship.