Cerebral activation during unilateral clenching in patients with temporomandibular joint synovitis and biting pain: an functional magnetic resonance imaging study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Functional magnetic resonance is a non-invasive method that can examine brain activity and has been widely used in various fields including jaw movement and pain processing. Temporomandibular disorder (TMD) is one of the most frequent facial pain problems. The objective of this study was to investigate the brain activities using functional magnetic resonance imaging (fMRI) during unilateral maximal voluntary clenching tasks in the TMD synovitis patients with biting pain.</p><p><b>METHODS</b>Fourteen TMD synovitis patients with unilateral biting pain and 14 controls were included in the study. Contralateral biting pain was defined as right molar clenching causing left temporomandibular joint (TMJ) pain. Ipsilateral biting pain was defined as right molar clenching causing right TMJ pain. Symptom Check List-90 (SCL-90) was administered to the patients and controls. Independent sample t-test was used to compare the SCL-90 subscales between the two groups. Unilateral clenching tasks were performed by the patients and controls. Imaging data were analyzed using SPM99.</p><p><b>RESULTS</b>Patients were divided into contralateral TMD biting pain group (n = 8) and ipsilateral TMD biting pain group (n = 6). The SCL-90 subscales were significantly different between the two groups for somatization, depression, anxiety, phobic anxiety, and paranoid ideation. Group analysis of the controls demonstrated brain activations in the inferior frontal gyrus, precentral gyrus, middle frontal gyrus, superior temporal gyrus, and insular. The areas of activation were different between right and left clenching task. In TMJ synovitis patients with contralateral or ipsilateral biting pain, the group analysis showed activations in the inferior frontal gyrus, superior temporal gyrus, medium frontal gyrus, precentral gyrus, and anterior cingulate cortex.</p><p><b>CONCLUSIONS</b>The inferior frontal gyrus and precentral gyrus play essential roles during the unilateral clenching task. Activation of anterior cingulate cortex in the synovitis patients with biting pain was associated with higher levels of psychological distress.</p>

Investigation on disc position of the temporomandibular joint in asymptomatic volunteers by magnetic resonance imaging / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the types of disc position of the temporomandibular joint (TMJ) and their relationship with age and gender in asymptomatic volunteers by magnetic resonance imaging (MRI).</p><p><b>METHODS</b>A total of 100 asymptomatic volunteers were divided into 5 groups (11-, 21-, 31-, 41-, 51 - 60 years old), 10 male and 10 female were included in each group. A total of 200 TMJs were scanned with Siemens Trio Tim 3.0T MRI system oblique-sagittally at closed- and open-mouth positions. Visual evaluation of MR images were performed on 3 neighbour slices of each TMJ (lateral, central, medial).</p><p><b>RESULTS</b>There was a normal disc-condyle relationship in 59 of the 100 asymptomatic subjects. The normal disc position, anterior disc displacement and insidious anterior disc displacement (IADD) were observed in 140 (70.0%), 14(7.0%) and 46(23.0%)joints respectively, which showed no significant differences among different age groups or between genders (P > 0.05). The maximum mouth opening of the 100 asymptomatic volunteers was (46.3 +/- 5.5) mm, with no significant difference among the various types of disc position (P > 0.05).</p><p><b>CONCLUSIONS</b>Disc displacement does exist in the asymptomatic volunteers, however, its occurrence is not associated with age and gender. IADD is the main type of the disc displacement in asymptomatic volunteers. There is no close relationship between the imaging manifestation of the disc displacement and clinical symptoms.</p>

Effect of chewing-side preference on activation of parahippocampal gyrus during clenching task / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To explore effects of chewing-side preference (CSP) on cerebral cortical response during clenching task with functional magnetic resonance imaging (fMRI).</p><p><b>METHODS</b>Seven patients with left CSP and 7 patients with right CSP were selected to perform the maximum voluntary clenching in intercuspal position, and block designed blood oxygenation level-dependent (BOLD) fMRI scan covering the whole brain was carried out.</p><p><b>RESULTS</b>There was activation in the parahippocampal gyrus in the four patients among seven with left CSP. But there was no activation in the parahippocampal gyrus among the patients with right CSP.</p><p><b>CONCLUSIONS</b>This research shows that the parahippocampal gyrus, which is associated with human memory and study, is activated during clenching task in the patients with left CSP.</p>

The biochemical changes of hippocampus in patients before and after denture restoration: a preliminary 1H-magnetic resonance spectroscopy study / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the effects of reconstruction of lost occlusal support on the biochemical changes of nervous system.</p><p><b>METHODS</b>The changes of central nervous system metabolic compounds within hippocampus body were measured with proton magnetic resonance spectroscopy ((1)HMRS) before and after denture restoration (six weeks) in seven patients with prolonged loss of occlusal support.</p><p><b>RESULTS</b>(1)HMRS indicated that Cho/Cr decreased by 11.9% (P < 0.05) six weeks after denture restoration, MI/Cr decreased by 28.8% (P < 0.05), and NAA/CR increased by 4.8% (P > 0.05) within hippocampus body.</p><p><b>CONCLUSIONS</b>Recovery of occlusal support facilitates improvement of neuron functions in patients' hippocampus, which may help improve the functions of nervous system.</p>