title: Spontaneous neural activity alterations in temporomandibular disorders: a cross-sectional and longitudinal resting-state functional magnetic resonance imaging study.
abstract: The involvement of the central nervous system in the pathophysiology of temporomandibular disorders (TMD) has been noticed. TMD patients have been shown dysfunction of motor performance and reduced cognitive ability in neuropsychological tests. The aim of this study is to explore the spontaneous neural activity in TMD patients with centric relation (CR)-maximum intercuspation (MI) discrepancy before and after stabilization splint treatment. Twenty-three patients and twenty controls underwent clinical evaluations, including CR-MI discrepancy, Helkimo indices and chronic pain, and resting state functional magnetic resonance imaging scans at baseline. Eleven patients repeated the evaluations and scanning after the initial wearing (T1) and 3months of wearing (T2) of the stabilization splint. The fractional amplitude of low-frequency fluctuation (fALFF) was calculated to compare the neural functions. At baseline, the patients showed decreased fALFF in the left precentral gyrus, supplementary motor area, middle frontal gyrus and right orbitofrontal cortex compared with the controls (P<0.05, AlphaSim corrected). Negative correlations were found between the fALFF in the left precentral gyrus and vertical CR-MI discrepancy of bilateral temporomandibular joints of patients (P<0.05, two-tailed). At T2, the symptoms and signs of the patients were improved, and a stable condylar position on the CR was recovered, with increased fALFF in the left precentral gyrus and left posterior insula compared with pretreatment. The fALFF decrease in the patients before treatment was no longer evident at T2 compared with the controls. The results suggested that TMD patients with CR-MI discrepancy showed significantly decreased brain activity in their frontal cortexes. The stabilization splint elicited functional recovery in these cortical areas. These findings provided insight into the cortical neuroplastic processes underlying TMD with CR-MI discrepancy and the therapeutic mechanisms of stabilization splint.
authors.affiliation: State Key Laboratory of Oral Disease, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041,China. Electronic address: heshushu-03@163.com.
authors.forename: S-S
authors.initials: SS
authors.lastname: He
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China. Electronic address: charlie_lee@qq.com.
authors.forename: F
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Oral Disease, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041,China. Electronic address: 244182068@qq.com.
authors.forename: F
authors.initials: F
authors.lastname: Song
authors.affiliation: State Key Laboratory of Oral Disease, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041,China. Electronic address: 68072870@qq.com.
authors.forename: S
authors.initials: S
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Oral Disease, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041,China. Electronic address: 181060451@qq.com.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Chen
authors.affiliation: Department of Psychiatry, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China. Electronic address: 43961554@qq.com.
authors.forename: N
authors.initials: N
authors.lastname: He
authors.affiliation: State Key Laboratory of Oral Disease, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041,China. Electronic address: shujuanzou@aliyun.com.
authors.forename: S-J
authors.initials: SJ
authors.lastname: Zou
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China. Electronic address: julianahuang@163.com.
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Huang
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China. Electronic address: Lusuwcums@tom.com.
authors.forename: S
authors.initials: S
authors.lastname: Lui
authors.affiliation: Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China. Electronic address: qiyonggong@hmrrc.org.cn.
authors.forename: Q-Y
authors.initials: QY
authors.lastname: Gong
authors.affiliation: State Key Laboratory of Oral Disease, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041,China. Electronic address: songchen882002@hotmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Chen
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology; D001931:Brain Mapping; D003430:Cross-Sectional Studies; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D020127:Recovery of Function; D013165:Splints; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult
keywords: centric relation; chronic pain; functional magnetic resonance imaging; neuronal plasticity; occlusal splints; temporomandibular disorders