Fractal analysis of mandibular trabecular pattern following protraction facemask therapy : A pilot study

To assess the remodeling effects of protraction facemask therapy on the trabecular pattern of the mandible and identify quantitatively the regions of the mandible undergoing maximum changes in the trabecular pattern.

The retrospective study was conducted in 30 subjects divided into two groups. The treatment group (group 1) consisted of 15 subjects with skeletal class III malocclusion treated with a facemask (mean age: 9.1 ± 2.1 years). Digital panoramic radiographs (OPG) were obtained before treatment (T0) and at the end of active facemask therapy (T1) with a mean duration of 16.1 ± 2.5 months. In all, 15 skeletal class I subjects who did not undergo any orthodontic treatment (mean age 9.1 ± 2.2 years) comprised the control group (group 2) who had two OPGs at a mean interval of 13.6 ± 2.2 months. The fractal dimensional (FD) value was calculated in three regions: angular, condylar, and corpus region.

Intragroup comparisons revealed a significant increase in the FD values in the right condylar (T0 = 1.2 ± 0.2; T1 = 1.4 ± 0.1) and left condylar (T0 = 1.2 ± 0.1; T1 = 1.4 ± 0.1) region (p < 0.05) and in the corpus region (FD values: right T0 = 1.2 ± 0.1, T1 = 1.4 ± 0.1; left T0 = 1.2 ± 0.1, T1 = 1.4 ± 0.1; p < 0.05). The intergroup comparison demonstrated that the treatment group showed greater changes compared with the controls in the condylar process (mean difference: right = 0.19, left = 0.20; p < 0.05) and the corpus region (0.172; p < 0.05).

FD analysis demonstrated that the condylar process and the corpus region underwent the most significant change in the trabecular pattern in subjects treated with protraction facemask therapy.