Effect of orthodontic appliances on masticatory muscle activity

There is limited and conflicting evidence regarding the impact of orthodontic appliances on masticatory muscle activity (MMA), jaw function, and oral parafunctional behaviours. Investigations in this field frequently utilise surface electromyography (sEMG) to analyse changes in muscle contractile activity. Fixed orthodontics appliances have been associated with significant reductions in MMA post archwire activation. Conversely, elevations in masseter and digastric muscle activity have been reported in response to removable functional appliances. Research into the effect of clear aligner therapy (CAT) on MMA is still in its infancy with few studies published. There is a lack of agreement on whether MMA increases or diminishes in response to CAT though there is evidence this relationship may change over time due to muscle adaptation. The impact of CAT on temporomandibular disorder (TMD) symptoms is unclear, particularly how pre-existing risk factors for TMD may alter and individual's response.