Functional Unit-Based Analysis Unveils the Skeletal Mandibular Effects of Class II Elastics Therapy in Adolescents.

BACKGROUND

This study sought to thoroughly assess the skeletal impacts of Class II elastics therapy on the developing mandible, highlighting three-dimensional changes in its functional units.

METHODS

Treatment records of 140 CBCT scans from 70 adolescent patients were retrospectively collected and assigned to one of two groups: the Class II elastics group (n = 35), in which class II elastics were performed on the stainless steel archwires for more than 12 months, and the control group (n = 35). Pre- and post-treatment cone beam computed tomography (CBCT) images were used to assess changes related to the skeletal facial pattern, functional units, and transverse parameters. An independent t-test was used to compare between the two groups.

RESULTS

In the Class II elastics group, the mandibular body unit length (IAF-MF) increased by 3.09 ± 3.16 mm from pre- to post-treatment, significantly larger than that in the control group (1.37 ± 3.14 mm). No other mandibular functional unit or transverse parameters demonstrated significant differences between the two groups.

CONCLUSIONS

Based on the single-center sample included in this study, the adolescent group receiving prolonged Class II elastics may have exhibited a greater increase in mandibular body unit length compared to the group with minimal elastic use. However, these findings cannot be generalized without further validation.