Electromyographic Assessment of Muscle Activity in Different Malocclusions in Adults: A Systematic Review and Meta-Analysis

AimMalocclusion affects nearly half of the global population and is recognized by the World Health Organization as a major oral health concern. Orofacial muscles play a crucial role in occlusion and dentofacial development, and their dysfunction may contribute to the development or progression of malocclusion. Electromyography (EMG) provides a reliable method for assessing masticatory muscle activity. However, the current evidence regarding muscle activity patterns across different malocclusion classes remains inconsistent. This systematic review and meta-analysis aimed to evaluate the electromyographic activity of masticatory muscles in individuals with different classes of malocclusion.MethodsThis systematic review was conducted in accordance with the PRISMA ۲۰۲۰ guidelines and registered in PROSPERO (CRD۴۲۰۲۴۵۹۵۶۸۶). Comprehensive searches were performed in MEDLINE, Scopus, EMBASE, Web of Science, and Cochrane CENTRAL up to September ۲۰۲۵ without language or date restrictions. A total of ۱,۶۲۷ records were screened. Eligible studies included adult participants with sagittal malocclusions assessed using surface electromyography (sEMG). Studies involving pediatric populations, patients with systemic or craniofacial disorders, and interventional designs were excluded. Data extraction and risk‑of‑bias assessment using the NOS‑XS tool were conducted independently by two reviewers. Random‑effects meta‑analyses were performed in R to compare masseter and temporalis muscle activity during maximum voluntary clenching, chewing, and rest. Heterogeneity and publication bias were assessed using Cochrane-recommended methods.ResultsEighteen studies involving ۷۲۴ participants met the inclusion criteria. The overall risk of bias ranged from low to moderate. Meta‑analysis revealed no significant differences in muscle activity among malocclusion classes during chewing. During maximum voluntary clenching, individuals with Class III malocclusion exhibited significantly lower masseter and temporalis muscle activity compared with those with Class I malocclusion, although heterogeneity was substantial. At rest, temporalis muscle activity was significantly lower in Class II than in Class III malocclusion, while masseter activity showed no consistent differences between groups.ConclusionEMG evidence indicates that masticatory muscle activity may vary across different malocclusion classes. However, considerable heterogeneity among studies and the limited number of available investigations warrant cautious interpretation of these findings. Well‑designed studies with larger sample sizes and standardized EMG protocols are needed to provide more definitive evidence.

کلیدواژه ها:

Electromyography ، Malocclusion ، Masticatory Muscles ، Angle&rsquo ، s Classification