title: Experimental occlusal interference induces long-term masticatory muscle hyperalgesia in rats.
abstract: Temporomandibular joint or related masticatory muscle pain represents the most common chronic orofacial pain condition. Patients frequently report this kind of pain after dental alterations in occlusion. However, lack of understanding of the mechanisms of occlusion-related temporomandibular joint and muscle pain prevents treating this problem successfully. To explore the relationship between improper occlusion (occlusal interference) and masticatory muscle pain, we created an occlusal interference animal model by directly bonding a crown to a maxillary molar to raise the masticating surface of the tooth in rats. We raised the occlusal surface to three different heights (0.2, 0.4, and 0.6mm), and for one month we quantitatively measured mechanical nociceptive thresholds of the temporal and masseter muscles on both sides. Results showed a stimulus-response relationship between the height of occlusal interference and muscle hyperalgesia. Removal of the crown 6 days after occlusal interference showed that the removal at this time could not terminate the 1 month duration of mechanical hyperalgesia in the masticatory muscles. Lastly, we systemically administered NMDA antagonist MK801 (0.2, 0.1, and 0.05 mg/kg) to the treated rats and found that MK801 dose dependently attenuated the occlusal interference-induced hyperalgesia. These findings suggest that occlusal interference is directly related to masticatory muscle pain, and that central sensitization mechanisms are involved in the maintenance of the occlusal interference-induced mechanical hyperalgesia.
authors.affiliation: Department of Prosthodontics, Peking University School & Hospital of Stomatology, 22 Zhong Guan Cun South Avenue, Beijing 100081, PR China Center for TMD & Orofacial Pain, Peking University School & Hospital of Stomatology, 22 Zhong Guan Cun South Avenue, Beijing 100081, PR China Department of Anesthesiology, University of Utah, Salt Lake City, UT 84132-2304, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Cao
authors.forename: Qiu-Fei
authors.initials: QF
authors.lastname: Xie
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.forename: Alan R
authors.initials: AR
authors.lastname: Light
authors.forename: Kai-Yuan
authors.initials: KY
authors.lastname: Fu
mesh_terms: D000344:Afferent Pathways / Q000503:physiopathology; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D002908:Chronic Disease; D003442:Crowns / Q000009:adverse effects; D004195:Disease Models, Animal; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005157:Facial Pain / Q000209:etiology / Q000503:physiopathology*; D006930:Hyperalgesia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008310:Malocclusion / Q000150:complications*; D008340:Mandibular Nerve / Q000503:physiopathology; D008410:Masticatory Muscles / Q000294:innervation* / Q000503:physiopathology*; D008963:Molar / Q000473:pathology / Q000601:surgery; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism; D013995:Time
chemical_list: D000700:Analgesics; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate