title: Muscular activity during isometric incisal biting.
abstract: This study attempted to estimate TMJ loading during incisal loading using a custom load-cell device and surface electromyographic (sEMG) recordings of the main jaw closers to assess the outcome correlation. Study participants were 23 healthy volunteers. The incisal loads having submaximal and mean intensity were recorded using a calibrated electronic load cell; simultaneously, surface electromyography (sEMG) of the right and left masseter and temporalis muscles was recorded. Readings of the resting, clenching in maximal and submaximal intercuspal positions and mean (50%) incisal loads were recorded. Clenching sEMG activity was used as a reference for normalization. The mean (SD) submaximal incisal load recorded was 498 (305.78)N, and the mean at 50% of the submaximal load was 268.93 (147.37)N. Mean (SD) sEMG activity during submaximal clenching was 141.23 (87.76)μV, with no significant differences between the four muscles. During submaximal voluntary incisal loading, the normalized mean sEMG activity was 49.99 (34.54)µV %, and 27.17(15.29)µV % during mean (50%) effort. The incisal load was generated mainly by the masseter muscles, as these showed a positive correlation during mean but not during submaximal effort. In the edge-to-edge jaw position, the mean incisal load effort seems to be physiological, but excessive TMJ loads can be expected from chronic or excessive incisal loading. In conclusion, incisal loads require the activity of the masseter muscles, which show a positive correlation between sEMG activity and effective incisal loads during mean, but not during submaximal, effort, and the masseter muscles are dominant over the temporalis muscles during submaximal incisal biting.
authors.affiliation: Department of Stomatology, Faculty of Medicine and Odontology, University of Santiago de Compostela, Santiago de Compostela, La Coruña, Spain. Electronic address: urbano.santana@usc.es.
authors.forename: Urbano
authors.initials: U
authors.lastname: Santana-Mora
authors.affiliation: Department of Stomatology, Faculty of Medicine and Odontology, University of Santiago de Compostela, Santiago de Compostela, La Coruña, Spain.
authors.forename: Arturo
authors.initials: A
authors.lastname: Martínez-Ínsua
authors.affiliation: Department of Stomatology, Faculty of Medicine and Odontology, University of Santiago de Compostela, Santiago de Compostela, La Coruña, Spain.
authors.forename: Urbano
authors.initials: U
authors.lastname: Santana-Penín
authors.affiliation: Biomaterials Group, Aragon Institute of Engineering Research, University of Zaragoza, Spain.
authors.forename: Amaya P
authors.initials: AP
authors.lastname: del Palomar
authors.affiliation: Biomaterials Group, Aragon Institute of Engineering Research, University of Zaragoza, Spain.
authors.forename: José C
authors.initials: JC
authors.lastname: Banzo
authors.affiliation: Department of Stomatology, Faculty of Medicine and Odontology, University of Santiago de Compostela, Santiago de Compostela, La Coruña, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Mora
mesh_terms: D000328:Adult; D001732:Bite Force; D004576:Electromyography; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007537:Isometric Contraction; D007568:Jaw / Q000502:physiology*; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D009142:Musculoskeletal Physiological Phenomena; D013703:Temporal Muscle / Q000502:physiology*; D016474:Weight-Bearing; D055815:Young Adult
keywords: Bite forces; EMG; Loads; TMJ; Temporomandibular disorders