A cross-sectional study of developing resting masseter activity in different angle classifications in adolescence

Area of Science:

• Orthodontics and Dental Morphology
• Biomedical Engineering
• Human Physiology

Background:

• Understanding the relationship between muscle activity and craniofacial development is crucial in orthodontics.
• Masseter muscle resting activity patterns may offer insights into skeletal classifications.
• Electromyography (EMG) is a key tool for assessing neuromuscular function.

Purpose of the Study:

• To investigate if resting masseter muscle activity characterizes different Angle's classifications in adolescents.
• To analyze age-related changes in masseter EMG activity based on gender and Angle's classification.
• To determine if EMG patterns can distinguish anteroposterior mandibular positions.

Main Methods:

• Electromyographic (EMG) activity of masseter muscles was recorded in 172 subjects (64 boys, 108 girls) aged 10–18.
• Polynomial regression models (first and second order) were used to analyze age-related EMG changes.
• Data were stratified by gender and Angle's classification (Class I, II, III).

Main Results:

• Class I subjects showed positive second-order polynomial trends for EMG activity.
• Class II and III subjects exhibited first-order polynomial trends.
• EMG levels were lower in Class III compared to Class II subjects.

Conclusions:

• Resting masseter muscle activity patterns are characteristic of different Angle's classifications.
• EMG development in masseter muscles can help differentiate anteroposterior mandibular positions.
• These findings contribute to understanding the neuromuscular basis of malocclusions.