Influence of surgical orthodontic treatment on masticatory function in skeletal Class III patients

Abstract

Skeletal Class III patients exhibit malocclusion characterised by Angle Class III and anterior crossbite, and their occlusion shows total or partially lateral crossbite of the posterior teeth. Most patients exhibit lower bite force and muscle activity than non-affected subjects. While orthognathic surgery may help improve masticatory function in these patients, its effects have not been fully elucidated. The aims of the study were to evaluate jaw movement and the electromyographic (EMG) activity of masticatory muscles before and after orthognathic treatment in skeletal Class III patients in comparison with control subjects with normal occlusion. Jaw movement variables and EMG data were recorded in 14 female patients with skeletal Class III malocclusion and 15 female controls with good occlusion. Significant changes in jaw movement, from a chopping to a grinding pattern, were observed after orthognathic treatment (closing angle P < 0.01; cycle width P < 0.01), rendering jaw movement in the patient group similar to that of the control group. However, the grinding pattern in the patient group was not as broad as that of controls. The activity indexes, indicating the relative contributions of the masseter and temporalis muscles (where a negative value corresponds to relatively more temporalis activity and vice versa) changed from negative to positive after treatment (P < 0.05), becoming similar to those of control subjects. Our findings suggest that orthognathic treatment in skeletal Class III patients improves the masticatory chewing pattern and muscle activity. However, the chewing pattern remains incomplete compared with controls.

Relationships of maxillofacial morphology and malocclusion with handgrip strength in adult women

“…To measure MOF, we used the dental prescale system. This method is calculated using OCA, which is reported to give excellent quantitative as one of the evaluation methods for occlusion . In this study, to evaluate both malocclusion and MOF, the dental prescale system was used, as it is the most suitable method for measurement of MOF and OCA.…”

“…The goal of orthodontic treatment is to improve dentofacial aesthetics and function . It has been reported that masticatory function such as masticatory chewing pattern, masticatory muscle activity, maximum occlusal force (MOF) and occlusal contact area (OCA) improved after orthodontic treatment …”

Short-term changes in muscle activity and jaw movement patterns after orthognathic surgery in skeletal Class III patients with facial asymmetry

“…Wang et al14 reported that the mandibular movement tracings in skeletal Class III patients changed to become similar to those in the control group 6 months after OGS. Kubota et al13 also reported that OGS improved the masticatory chewing pattern in Class III patients. However, others have shown that there were no significant changes in the masticatory rhythm and chewing pattern after OGS in Class III patients 1516…”

“…Others also reported that the EMG activity levels of the masseter and temporalis muscles recovered to the presurgical levels at 6 months after OGS 1011. Previous studies have reported that surgical correction in skeletal Class III patients improved the balance of masticatory muscles on both sides and changed the temporalis-dominant pattern to the masseter-dominant pattern 1213. Wang et al14 reported that the mandibular movement tracings in skeletal Class III patients changed to become similar to those in the control group 6 months after OGS.…”

Temporomandibular joint positional change accompanies post‐surgical mandibular relapse—A long‐term retrospective study among patients who underwent mandibular advancement

“…However, skeletal stability after surgical‐orthodontic treatment has always been a major concern. As a result, evidence‐based studies focusing on skeletal stability will be of interest to both orthodontists and oral surgeons …”