Evaluation of Electromyographic Activity of Orbicularis oris Muscle in Cleft Lip and Palate Patients: A Systematic Review and Meta-analysis.

ObjectiveThis systematic review and meta-analysis aimed to evaluate electromyographic (EMG) activity of the orbicularis oris muscle in children, adolescents, and young adults with repaired cleft lip and/or palate (CLP), compared to noncleft controls.DesignSystematic review and Meta-analysis.Patients and ExposuresPatients with CLP.ComparisonPatients without CLP.Main Outcome MeasuresElectrical activity of orbicularis oris muscle at rest and during swallowing salaiva, lip compression, and articulation of bilabial phonemes (/pa/, /ba/, and /ma/).Methods & MaterialsObservational studies reporting quantitative surface EMG outcomes of the orbicularis oris in participants with repaired CLP and noncleft controls were included. Data extraction and risk of bias assessment were performed independently by two reviewers; certainty of evidence was evaluated with Grading of Recommendations, Assessment, Development and Evaluation, and heterogeneity was assessed with I2.ResultsA comprehensive literature search was conducted across five databases (MEDLINE, Web of Science, EMBASE, Scopus, CENTRAL) from their inception until February 2025. Eligible observational studies based on the PECO question were selected and assessed for bias using the ROBINS-E tool. Random-effects meta-analyses were used to pool mean differences. Finally, six studies met the inclusion criteria. Pooled findings showed significantly higher orbicularis oris EMG amplitudes in tasks requiring strong lip seal-saliva swallowing, lip compression, and the bilabial phenome /pa/-among participants with repaired CLP relative to controls. In contrast, EMG activity at rest and certain other bilabial phonemes (/ba/ and /ma/) showed borderline or nonsignificant differences. Heterogeneity was generally moderate to high, reflecting methodological diversity among studies.ConclusionsChildren with repaired CLP exhibit elevated orbicularis oris muscle activity during tasks demanding strong lip closure. This may represent a compensatory mechanism to overcome structural alterations or scarring. Although such hyperactivation can enhance oral function (eg, swallowing and speech), it might also have long-term implications for maxillary growth or soft-tissue scarring.