Stomatognathic Functional Adaptation in Patients With Unilateral Cleft Lip and Palate: A T-Scan, Surface Electromyography and Joint Vibration Analysis Study

Abstract

Objective To compare the temporomandibular joint (TMJ) health, occlusal load distribution, masticatory efficiency and masticatory muscle function in patients with unilateral cleft lip and palate (UCLP) against age- and gender-matched noncleft controls, using a multimodal assessment approach. Design A cross-sectional comparative study. Settings All measurements were performed by 2 calibrated examiners. Patients In total, 19 UCLP patients (Group 1) and 19 noncleft controls (Group 2). Main Outcome Measure Occlusal load distribution was evaluated using computerised occlusal analysis (T-Scan). Surface electromyography (sEMG) of the anterior temporalis and masseter muscles was recorded at rest, during chewing and at maximum voluntary clenching (MVC). Masticatory efficiency was assessed using colorimetric analysis, and TMJ function was evaluated using joint vibration analysis (JVA). Results Occlusal timing parameters were comparable between groups. During maximum bite force (MBF), Group 1 demonstrated significantly lower MBF on the cleft side (38.64 ± 7.00%) than Group 2 (51.48 ± 4.63%). At MVC, normalised sEMG activity was significantly higher bilaterally in Group 1 compared with controls for both muscles. Masticatory efficiency was significantly reduced in Group 1 (optical density 0.42 ± 0.15 vs 0.76 ± 0.15). JVA showed significantly elevated noncleft-side total integral in Group 1 versus Group 2, and integral <300 Hz on the noncleft side, while the significantly elevated integral >300 Hz on the noncleft side also persisted. Conclusion UCLP patients exhibit significant occlusal force asymmetry, reduced masticatory efficiency and a task-dependent pattern of masticatory muscle recruitment. TMJ vibrational alterations were predominantly of low frequency, suggestive of structurally forced load redistribution and neuromuscular compensation.