Somatosensory changes in Chinese patients after coronectomy vs. total extraction of mandibular third molar: a prospective study.

OBJECTIVES: This study aimed to quantitatively compare the somatosensory function changes of inferior alveolar nerve (IAN) after mandibular third molar extraction with a surgery protocol of coronectomy, as opposed to the conventional method. MATERIALS AND METHODS: Patients with a lower third molar directly contacting IAN were recruited and assigned either to a test group (coronectomy group) or a control group (conventional extraction). A standardized quantitative sensory testing (QST) battery was performed for four times: one week before surgery and the second, seventh, and 28th days after surgery. Z-scores and the loss/gain coding system were applied for each participant. RESULTS: A total of 140 molars (test group: n = 91, control group: n = 49) were enrolled. The sensitivity of the mechanical detection threshold (MDT) and pressure pain threshold (PPT) significantly increased after surgery more than before surgery in both groups (P ≤ 0.001). After the surgery, the sensitivities of the cold detection threshold (CDT), cold pain threshold (CPT), and heat pain threshold (HPT) were significantly higher in the test group than in the control group (P ≤ 0.027). The risk of IANI was significantly larger (P = 0.041) in the test group than in the control group. CONCLUSIONS: QST was a sensitive way to detect somatosensory abnormalities even with no subjective complaint caused by surgery. Coronectomy had less influence on IAN function than conventional total extraction. CLINICAL RELEVANCE: The somatosensory function changes after mandibular third molar extraction were quantitatively studied, and coronectomy was proved a reliable alternation to reduce IAN injury rate.

Genistein Antagonizes 17ß-Estradiol Effects on Glutamate-Evoked Masseter Muscle Hypernociception in Rats.

Temporomandibular disorders (TMDs) predominantly affect women of reproductive ages, with pain as the main symptom. The aim of the present study was to examine the effects of 17ß-estradiol (E2) on glutamate-evoked hypernociception of masseter muscle and to examine whether genistein could antagonize the effects of E2 in female rats. Injection of glutamate into the masseter muscle dose-dependently decreased head withdrawal thresholds, a parameter for mechanical hypernociception. Head withdrawal thresholds in ovariectomized rats also decreased with increasing doses of E2 replacement, and were further aggravated by injection of glutamate (1M, 40µL) into the masseters. Genistein at doses of 7.5 and 15 mg/kg antagonized E2-induced hypernociception of masseter muscle, and at doses of 7.5, 15, and 30 mg/kg also antagonized E2 potentiation of glutamate-evoked hypernociception of masseter muscle. Genistein produced optimal antagonistic effects of E2 on nociception behavior at a dose of 15 mg/kg. On the molecular level, tyrosine phosphorylation of the NR2B subunit of the N-methyl-D-aspartate receptor (pNR2B) and phosphorylated mitogen-activated protein kinase (pERK1/2) were significantly upregulated in the hippocampus following glutamate injection and were further potentiated by E2 replacement. Genistein at dose of 15 mg/kg partially reversed E2-potentiated glutamate-evoked upregulation of pNR2B and pERK1/2 expression in the hippocampus. These results indicated that moderate doses of genistein could antagonize E2 enhanced glutamate-evoked hypernociception of masseter muscle possibly via N-methyl-D-aspartate receptor and ERK1/2 signaling pathways in the hippocampus.

[Data of the quantitative orofacial somatosensory functions of healthy subjects and its influence factors analysis].

OBJECTIVE: To establish the preliminary somatosensory data stratified by gender, age group, and sites in the trigeminal region through standardized quantitative sensory testing on healthy individuals, and to evaluate the effects of gender, age, and sites on somatosensory functions. METHODS: The standardised QST battery developed by the German Research Network on Neuropathic Pain consists totally of 13 different parameters. A total of 70 healthy individuals participated. The subjects were stratified into two groups according to age: younger group (16 female, 16 male, age 24-40 years old) and elder group (20 female, 18 male, age 41-69 years old). The test was performed bilaterally over the infraorbital, mental, and hand regions. RESULTS: The preliminary orofacial somatosensory data stratified by gender, age group, and sites were presented. Female were more sensitive than male for most of the parameters (P<0.05). Age had a significant effect on most of the parameters (P<0.05), the younger group was more sensitive compared with the elder group (P<0.01) for heat pain threshold (HPT): younger group (38.07±2.94) °C, elder group (39.85±3.52) °C; warmth detection threshold (WDT): younger group (1.40±0.74) °C, elder group (1.89±1.14) °C; mechanical detection threshold (MDT): younger group (0.73±1.66) mN, elder group (1.41±2.82) mN; pressure pain threshold (PPT): younger group (171.71±92.51) kPa, elder group (196.36±73.73) kPa; cold pain threshold (CPT): younger group (25.90±5.38) °C, elder group (21.64±6.78) °C; cold detection threshold (CDT): younger group (-0.97±0.55) °C, elder group (-1.36±0.90) °C, and wind-up ratio (WUR): younger group (3.33± 2.20), elder group (2.67±1.68). The inverse results were demonstrated for mechanical pain threshold (MPT): younger group (111.50±88.93) mN, elder group (104.49±94.94) mN; mechanical pain sensitivity (MPS): younger group (6.96±5.61), elder group (8.93±6.53), and vibration detection threshold (VDT): younger group (7.44±0.52) scale, elder group (7.55±0.48) scale (P<0.05). Somatosensory function was site dependent (P<0.001), the two trigeminal sites (infraorbital and mental) were more sensitive than the hand for CDT, HPT, WDT, thermal sensory limen (TSL), MDT, MPT, MPS, and PPT (P<0.001), but the inverse result was observed for VDT (P<0.001). CONCLUSION: The preliminary orofacial somatosensory data of Han Ethnicity stratified by gender, age group, and sites were established. The study evaluated the effects of gender, age and sites on orofacial somatosensory functions by employment standardized quantitative sensory testing.

[Comparison of self-controlled retruded approach and bimanual manipulation method on the relationship of incisal point displacement in the mandibular retruded contact position].

OBJECTIVE: To evaluate the relationship of incisal point displacements in the mandibular retruded contact position (RCP) between the self-controlled retruded approach and bimanual manipulation method. METHODS: Twelve healthy young volunteers were selected. The RCP was guided through the self-controlled retruded approach and bimanual manipulation method. The track of the incisal point was recorded, using the mandibular movement trace recording system. The movement direction of the incisal point in horizontal plane was observed. The distance between the incisal point of the RCP and intercuspal contact position (ICP) was measured. RESULTS: Except one volunteer's incisal point movement direction of the RCP was oblique, others were straight toward posterior. The displacements of the incisal point from the ICP to RCP guided through self-controlled approach and bimanual manipulation method were (1.15 ± 0.64) mm, (0.98 ± 0.29) mm respectively. There was no statistical significance between the two methods (P > 0.05). CONCLUSION: The displacements of the incisal point from the ICP to RCP guided through self-controlled approach and bimanual manipulation method are approximately the same.