Expression patterns of nociceptin in rats following experimental tooth movement.

OBJECTIVES: To determine the expression levels of nociceptin following experimental tooth movement. MATERIALS AND METHODS: A total of 72 male Sprague-Dawley rats were divided into two groups: sham and experimental groups. For the experimental group, closed coil springs were used to mimic orthodontic force (80 g) between upper incisors and first molars, and the rats were killed at 0 hours, 4 hours, 12 hours, 1 day, 2 days, 5 days, 7 days, 10 days, and 14 days. All of these procedures were similar for the sham group, except for that no force was applied. The four rats killed at 0 hours without any intervention were used as the baseline control in each group. Trigeminal nucleus caudalis from both the ipsilateral and contralateral sides of force applications were obtained for immunostaining. RESULTS: Nociceptin was expressed in both the ipsilateral and contralateral sides of each group. Its expression levels started to increase on day 2, peaked on day 7, and returned to baseline on day 10 in the experimental group, while expression levels started to decrease on day 1 and returned to baseline on day 10 in the sham group. Moreover, the expression levels were similar between the ipsilateral and contralateral sides in each group. CONCLUSION: The expression levels of nociceptin were elevated following experimental tooth movement. The anesthetic agent used in this study (chloral hydrate) may have an antagonism with nociceptin. Due to bilateral innervation of anterior teeth and bilateral projection of nerve fibers, the expression levels of nociceptin were similar between ipsilateral and contralateral sides.

[The effects of orthodontic treatment on the morphology of temporomandibular joint of the adult with the low angle Class II malocclusions: a CT study].

OBJECTIVE: To analyze the effects on the morphology of temporomandibular joint (TMJ) of the adult with the low angle Class II malocclusions before and after orthodontic treatment comparatively. To provide the references for the orthodontic treatment of the adults. METHODS: 19 adult patients with low angle Class II malocclusions were chosen and treated with Damon self-ligating braces. The examinations of 16-slice spiral CT were taken before and after the orthodontic treatment. The parameters of skeletal morphology of TMJ were measured in the multiplanar reconstruction (MPR) images. The results were analysed statistically. RESULTS: The rate of condyles in a center position in the glenoid fossa after the treatment was 52.6%(20/38), and the rate of retrodisplacement was 31.6% (12/38). The position of the condyles before and after the orthodontic treatment had significant differences (P<0.05, chi2=4.41, chi2=5.32). The mean value of the anterior oblique angle of condyle decreased by 2.32 degrees +/- 1.78 degrees after treatment, meanwhile the average height of the condylar head increased by (1.07 +/- 0.29) mm. There were significant differences in both results before and after treatment (P<0.05). CONCLUSION: The orthodontic treatment can make the TMJ structures stable and beneficial to relieve the symptoms by moving the condyle forward, increasing the height and reconstructing the anterior oblique angle of condyle on adult patients with low angle Class II malocclusions.

Trigeminal expression of N-methyl-D-aspartate receptor subunit 1 and behavior responses to experimental tooth movement in rats.

OBJECTIVE: To test the hypothesis that peripheral N-methyl-D-aspartate (NMDA) receptors play a role in pain induced by experimental tooth movement. MATERIALS AND METHODS: Male Sprague-Dawley rats weighing between 200 g and 300 g were used in this study. Expression of NMDA receptors subunit 1 (NMDAR1) in the mandibular portion of the trigeminal ganglion (TG) was determined by Western blotting 4 hours and 1, 2, 3, 5, 7, and 14 days after tooth movement. Changes in the time taken by the rats on nocifensive behavior then effects of NMDA receptor antagonist MK-801 and force magnitude on these changes in behavior and NMDAR1 expression were evaluated. RESULTS: Experimental tooth movement led to a statistically significant increase in NMDAR1 expression at protein level from day 1 to 7 after force application initiating tooth movement. Time spent on nocifensive behavior dramatically increased from day 1 to 7. The rhythm in NMDAR1 expression in the TG and behavioral activities correlated well with the initial orthodontic pain responses. The magnitude of the nocifensive behavior and NMDAR1 expression were both force magnitude dependent and could be reduced by peripheral NMDA receptor antagonist MK-801. CONCLUSIONS: The hypothesis is accepted. Peripheral NMDA receptors are modulated by experimental tooth movement and involved in the development of tooth movement pain.

Behavioural responses and expression of P2X3 receptor in trigeminal ganglion after experimental tooth movement in rats.

OBJECTIVE: To explore the role of P2X(3) receptor in pain induced by experimental tooth movement. DESIGN: Male Sprague-Dawley rats weighing 200-300g were used. P2X(3) receptor distribution in the caudal one-third portion of the trigeminal ganglion (TG) was studied by IHC. Next, the changes of P2X(3) expression were detected by Western blotting 4h, 1d, 2d, 3d, 5d, 7d, 14d after tooth movement. We then developed a behaviour pain model associated with directed mouth wiping. Finally, the effect of TNP-ATP on nociceptive-like behaviour was evaluated. RESULTS: Our results showed that P2X(3) receptors were expressed mainly in small- and medium-sized cells and experimental tooth movement led to an increase in staining of mandibular P2X(3) receptors. In addition, following experimental tooth movement, the expression of P2X(3) receptor in TG was statistically significantly up-regulated from days 1 to 5, with a peak on day 3. It was also found that the time spent on directed mouth wiping was dramatically increased by experimental tooth movement from days 1 to 7. The rhythm change of P2X(3) receptor expression in TG and the mouth wiping behaviour were in concert with the initial orthodontic pain responses. The directed mouth wiping behaviour was modulated in a force-dependent manner and could be attenuated by peripheral and systemic morphine. Furthermore, peripherally administered TNP-ATP could exert an analgesic effect on this pain model. CONCLUSION: These results suggest that directed mouth wiping behaviour can be a reliable measurement of pain following experimental tooth movement in rats. The P2X(3) receptor is important in the development and maintenance of tooth movement pain and thus may be peripheral targets for analgesics in orthodontic pain control.

[Orthodontic treatment on primary dentition of a child with mandible fracture: a case report].

Fixed orthodontic treatment is rarely used on primary dentition. In this paper, a primary dentition child with mandible fracture was treated with orthodontic treatment appliance. The occlusal function was improved and the fracture was recoveried after treatment.