Correlation between occlusal contacts and masticatory muscle activity: A comparative study of cotton and wax normalization methods showing improved repeatability and comfort

• Published in: Archives of oral biology Vol. 171; p. 106163
• Main Authors: Biasuz, Claudia Adriana Abrão, Baptista, Rafael Reimann
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2025
• Subjects: Adult; Cross-Sectional Studies; Dental Occlusion; Electromyography; Electromyography - methods; Female; Humans; Male; Malocclusion; Masseter muscle; Masseter Muscle - physiology; Masticatory muscles; Masticatory Muscles - physiology; Occlusal adjustment; Reproducibility of Results; Temporal Muscle - physiology; Temporomandibular joint disorders; Waxes; Young Adult; Occlusal adjustment; Malocclusion; Electromyography; Temporomandibular joint disorders; Masticatory muscles; Masseter muscle
• ISSN: 0003-9969; 1879-1506; 1879-1506
• DOI: 10.1016/j.archoralbio.2024.106163

This study aimed to correlate occlusal marks on posterior teeth and cusp tips, recorded using an analog qualitative method, with digital evaluations of masseter and temporal muscle activity through electromyography indexes, comparing two normalization techniques (cotton and wax) using the standardized Percentage Overlap Coefficient of the Anterior Temporal muscle and Percentage Overlap Coefficient of the Masseter muscle indexes. This is a comparative cross-sectional observational study. Occlusal contact and electromyography records of the anterior temporal and masseter muscles were detected in 30 individuals with an average age of 34.9 years. During the electromyography examination, two repetitions of normalization were performed, each with maximum voluntary clenches of 5 seconds on cotton and on wax. The average electromyography amplitude was calculated from three repetitions for each material. According to the average obtained for each pair of muscles, the muscle activity index was calculated and correlated to the number of contacts, which were converted into percentages. Normalization with cotton showed a positive correlation between occlusal contacts and muscle activity (rs = 0.465, p = 0.010). The mean muscle activity index for cotton was 79.4 ± 13.9 for the masseter and 83.3 ± 9.2 for the temporal muscle, with no significant difference between the two muscles (p = 0.195). Normalization with wax showed better intra-subject repeatability with less than 5 % variation (masseter: 4.9 %, temporal: 4.2 %). There was no significant difference in muscle contraction between the different normalization materials (p = 0.902). Both normalization methods demonstrated a variation of less than 10 %, with wax being considered more comfortable by the participants, indicating occlusal and muscular adaptation to the different methods. The results showed a positive correlation between posterior occlusal contacts and masticatory muscle activity, especially with cotton normalization, suggesting that occlusal contacts significantly influence muscle activity, potentially leading to muscle fatigue or hyperactivity. •Cotton normalization shows a positive correlation between occlusal contacts and masseter muscle activity.•Wax normalization provides better intra-subject repeatability, with less than 5 % variation.•No significant difference in muscle contraction between cotton and wax normalization methods.•Deep bite type is significantly associated with increased temporal muscle activity when using wax normalization.•Occlusal contacts play a crucial role in influencing masticatory muscle activity, potentially leading to muscle fatigue or hyperactivity.