Correlation of masticatory muscle activity and occlusal function with craniofacial morphology: a prospective cohort study

Objectives: Masticatory function, including masticatory muscle activity and occlusal function, can be affected by craniofacial morphology. This study aimed to investigate the relationship between craniofacial morphology and masticatory function in participants who had completed orthodontic treatment at least two years before and had stable occlusion. Materials: and Methods: Fourty-two healthy participants were prospectively enrolled and divided into three vertical cephalometric groups according to the mandibular plane angle. Masticatory muscle activity (MMA) in the masseter and anterior temporalis muscles was assessed using surface electromyography. The occlusal contact area and occlusal force (OF) were evaluated using the Dental Prescale System. Masticatory muscle efficiency was calculated by dividing MMA by OF. The craniofacial morphology was analyzed using a lateral cephalogram. The masticatory function was compared using one-way analysis of variance. Pearson correlations were used to assess the relationships between craniofacial morphology and masticatory function. Results: : The hypodivergent group had the lowest MMA and the highest efficiencies in the masseter and anterior temporalis muscle ( p < 0.05). MMA showed a positive relationship with mandibular plane angle, whereas the occlusal function demonstrated a negative relationship ( p < 0.05). The anterior temporalis muscle activity negatively correlated with ramus height ( p < 0.05). Conclusions: : Vertical craniofacial morphology was related to masticatory function in participants with normal occlusion after orthodontic treatment. Participants with hypodivergent facial profiles may have low MMA and high occlusal function, resulting in good masticatory muscle efficiency. Clinical relevance: Vertical craniofacial morphology is an important factor to consider in orthodontic diagnosis and prosthetic treatment planning.