||Fatigue resistance to experimental contraction in human craniofacial muscle groups
Aim: Hyperactivity or abnormal contractions of craniofacial muscles, e.g. bruxism, aretraditionally linked to pain and unpleasantness in the active muscles. The aim of thisstudy was to investigate the effects of different standardized craniofacial musclecontractions on perceived muscle symptoms. Materials and Methods: Sixteen healthyvolunteers (seven men, mean ± SEM, 25.7 ± 1.4 years and nine women, 24.9 ± 2.3years) performed six 5-minutes bouts of 20% maximal voluntary experimentalcontraction task of jaw-closing (Jaw), orbicularis-oris (O-oris), and orbicularis-oculi(O-oculi) muscles. Participants rated their perceived pain, unpleasantness, fatigue, andstress levels before, during, and after the contraction tasks on 0-10 Numeric RatingScales (NRS). Each muscle contraction task (= one session) was separated by at leastone week and the order of performed sessions was randomised in each participant. Datawere analysed using repeated measurements ANOVAs. Results: All muscle contractiontasks evoked significant increases in NRS scores of pain, unpleasantness, fatigue, andstress (P < .034). Jaw contractions were associated with higher NRS scores compared toO-oris and O-oculi contractions (P < .005) without differences between O-oris andO-oculi (P > .063). All craniofacial muscle symptoms had disappeared within a day (P> .469). Conclusion: The results showed that submaximal static contractions ofdifferent craniofacial muscle groups could evoke mild to moderate levels of transientsymptoms. Further studies are warranted to better understand the contribution ofspecific craniofacial muscle groups for the characteristic presentation ofmusculoskeletal pain conditions in the head.
Hokkaido University（北海道大学）. 博士(歯学)