Maximum bilateral masticatory forces in patients with and without pain

The objective of the present retrospective study, with 154 patients between 9 and 87 years of age, was to identify the maximum masticatory forces, which had been obtained with a bilateral measuring method, and to answer the question as to whether pain influences the symmetry of masticatory forces. The patients were categorized as 'with' or 'without' pain according to their patient files. The highest total bilateral force was 1,002 N; the mean was 376 ± 176 N. The average maximum unilateral chewing forces, i.e. either right or left, were 188 ± 103 N. The total asymmetry index over the entire patient population was 24.4 ± 17.2%. The total masticatory force was not influenced significantly by pain in the maxillofacial region (P > 0.05). By contrast, pain (P = 0.01) and gender (P = 0.01) did have a significant influence on the occurrence of masticatory asymmetry. The study results permit the conclusion that an increased asymmetry index in the masticatory system must be interpreted as a motor adaptation to a nociceptive input. The study is prefaced by some remarks about the clinical relevance and the possibilities of measuring masticatory forces. Keywords: Analysis of masticatory forces, masticatory asymmetry index, maxillofacial pain, TMD, UCM analysis, frequency analysis