Occlusal and muscular changes following removal of orthodontic brackets

Aims: To evaluate the relationship between three parameters at band removal and at 3 and 6 months following completion of orthodontic treatment: centric slide (RCP-ICP); maximal voluntary bite force (MVBF); and muscle tenderness to palpation. Method: 41 orthodontic patients (22 females, 19 males) aged 17.4 ± 5.4 years, were examined immediately after band removal (T1) and at 3 (T2) and 6 (T3) months following completion of full edgewise orthodontic treatment. The sagittal distance between retruded contact position (RCP) and intercuspal contact position (ICP) was measured with a digital caliper; MVBF was recorded with a custom-made rubber tube, filled with water and tightly sealed with a manometer in one end; muscle tenderness was recorded by way of manual palpation of superficial masticatory muscles using the patient's own rating (0-3). Results: RCP-ICP increased significantly from 0.6 ± 0.3 mm (T1) to 0.8 ± 0.3 mm (T2), then decreased to 0.7 ± 0.3 mm (T3). MVBF increased significantly by an average 15% from T0 (few hours before band removal) to T1, and an additional 15% from T1 to T2. From T2 to T3, MVBF increased another 2%. The masseter showed a major decrease in sensitivity between T1-T2. At T2-T3 the masseter leveled while the temporalis continued a similar decrease as in T1-T2. Conclusions: RCP-ICP remained quite stable during the three time points, and within the normal range. Appliance removal enabled an immediate increase in MVBF, followed by an additional increase as uninterrupted function returned. Superficial masticatory muscle tenderness to palpation decreased from T1-T3.