Abstract
The perioral muscles play an important role in the establishment of natural retention, and their functional assessment is necessary in the treatment of jaw deformities for not only the diagnosis before treatment but also ensuring postoperative stability.
In this study, we measured the maximum upper and lower lip pressures before and after treatment in 3 patients who underwent orthodontic treatment and 2 who underwent surgical orthodontic treatment for malocclu-sion accompanied by skeletal abnormalities. As a result, anterior occlusion remained stable after retention in the 4 patients in whom the balance between the lip pressures was better after than before treatment. However, relapse was noted in the 1 patient in whom no improvement was noted in the balance between the lip pressures after surgical orthodontic treatment.
