Masticatory Muscle Function in Growing Patients with Unilateral Posterior Crossbite: A Case-Control Study Combining...

Area of Science:

• Orthodontics
• Craniofacial Development
• Biomedical Engineering

Background:

• Unilateral posterior crossbite (UPXB) is a common malocclusion in growing individuals.
• UPXB is linked to mandibular deviation and asymmetric masticatory function.
• The relationship between UPXB and masticatory muscle activity is not fully understood.

Purpose of the Study:

• To evaluate masticatory muscle activity and viscoelastic properties in growing patients with UPXB.
• To compare these properties between UPXB patients and those with normal occlusion.
• To investigate potential neuromuscular asymmetries in UPXB.

Main Methods:

• Case-control study involving 140 growing patients (80 UPXB, 60 controls).
• Surface electromyography (sEMG) assessed masseter and temporalis muscle activity.
• Myotonometry evaluated muscle viscoelastic properties in mesofacial subjects.

Main Results:

• Limited differences in muscle viscoelastic properties between groups.
• No significant differences in maximum voluntary contraction during intercuspation.
• Increased activity in the crossbite-side masseter during contraction and mastication in UPXB patients.

Conclusions:

• UPXB is associated with condition-dependent alterations in masticatory muscle activity.
• Findings suggest functional adaptations rather than generalized neuromuscular asymmetry.
• Early diagnosis of UPXB is important for understanding craniofacial development.