The value of bone mineral density and bone resorption markers around the mini-screw implant in the orthodontic treatment / 中国基层医药

Objective To investigate the value of bone mineral density and bone resorption markers around the mini-screw implant in the orthodontic treatment.Methods 178 orthodontic patients were prospectively collected.According to the organization condition around the mini-screw implant loaded,all patients were assigned into stable group (n =160) and loose group (n =18).The levels of interleukin-1 β (IL-1 β) and matrix metalloproteinase-9 of the liquid around the mini-screw implant were detected at 1,2 and 3 months after loading.Moreover,the bone miner al density around the mini-screw implant before and after loading were studied as well.Results Compared with the stable group,the loose groups at 1,2 and 3 months after loading got significantly higher levels of IL-1β [(35.48 ± 4.39)pg/mL vs.(29.48 ±3.92)pg/mL,t =3.348,P =0.004;(41.45 ±5.39)pg/mL vs.(26.29 ±4.12)pg/mL,t =6.493,P =0.000;(54.39 ± 12.82) pg/mL vs.(23.58 ± 3.62) pg/mL,t =11.589,P =0.000].Compared with the stable group,the loose group at 1,2 and 3 months after loading got significantly higher levels of MMP-9[(5.68 ± 3.54) ng/mL vs.(1.74 ± 0.88) ng/mL,t =8.496,P =0.000;(6.84 ± 2.82) ng/mL vs.(1.25 ± 0.62) ng/mL,t =9.835,P =0.000;(9.84 ± 4.39) ng/mL vs.(1.21 ± 0.58) ng/mL,t =12.548,P =0.000].Compared with the sta ble group,the loose group got significantly lower levels of bone mineral density of maxillary bones around the miniscrew implant before and at 3 months after loading[(620.48 ±67.82) HU vs.(694.39 ±84.58)HU,t =2.459,P =0.015;(597.39 ± 58.93) HU vs.(693.59 ± 83.29) HU,t =2.909,P =0.008].Conclusion The decrease of bone mineral density around the mini-screw implant is related to the loosening of the mini-screw implant,and IL-1 β and MMP-9 of the surrounding fluid can reflect the peripheral inflammation.

Participation of Peripheral P2X Receptors in Orofacial Inflammatory Nociception in Rats

The present study investigated the role of peripheral P2X receptors in inflammatory pain transmission in the orofacial area in rats. Experiments were carried out on male Sprague-Dawley rats weighing 220 to 280 g. Formalin (5%, 50 microL) and complete Freund's adjuvant (CFA, 25 microL) was applied subcutaneously to the vibrissa pad to produce inflammatory pain. TNP-ATP, a P2X(2,2/3,4) receptor antagonist, or OX-ATP, a P2X(7) receptor antagonist, was then injected subcutaneously at 20 minutes prior to formalin injection. One of the antagonists was administered subcutaneously at three days after CFA injection. The subcutaneous injection of formalin produced a biphasic nociceptive behavioral response. Subcutaneous pretreatment with TNP-ATP (80, 160 or 240 microg) significantly suppressed the number of scratches in the second phase produced by formalin injection. The subcutaneous injection of 50 microg of OX-ATP also produced significant antinociceptive effects in the second phase. Subcutaneous injections of CFA produced increases in mechanical and thermal hypersensitivity. Both TNP-ATP (480 microg) and OX-ATP (100 microg) produced an attenuation of mechanical hypersensitivity. However, no change was observed in thermal hypersensitivity after the injection of either chemical. These results suggest that the blockade of peripheral P2X receptors is a potential therapeutic approach to the onset of inflammatory pain in the orofacial area.

Effects of Peripheral Inflammation on Brain-Derived Neurotrophic Factor and TrkB in Rat Dorsal Root Ganglia and Spinal Cord / 대한해부학회지

Recent study showed that peripheral inflammation induced an increased expression of brain-derived neurotrophic factor (BDNF) mRNA which was mediated by nerve growth factor in the dorsal root ganglion (DRG). Therefore, it is conceivable that peripheral inflammation may induce an increase in BDNF synthesis in DRG and consequently enhance the level of BDNF in the spinal cord and that gene expression of trkB mRNA may be altered. In the present study, we evaluated changes in BDNF-immunoreactivity and trkB mRNA in the DRG and spinal cord by means of immunohis-tochemistry and RT-PCR, respectively, following peripheral tissue inflammation produced by intraplantar injection of Freund's adjuvant into rat paws. In addition, coexistence of BDNF and preprotachykinin (PTT) mRNAs, BDNF and CGRP mRNAs or BDNF and trkB mRNAs in the DRG following inflammation was observed by means of in situ hybridization. The results obtained were as follows; 1. Inflammation induced a significant increase of the number of BDNF-immunoreactive (IR) neurons in the ipsilateral DRGs. The increase was observed 1 and 3 days after injection of adjuvant, and the levels had returned to normal by 7 days. In the spinal cord, inflammation also induced an elevation in the expression of BDNF-IR terminals in the medial superficial layers of the ipsilateral dorsal horn and in lamina V 1 and 3 days after injection. 2. There was significant increase of truncated trkB (t-trkB) mRNA in the ipsilateral DRG 3 days following inflammation. Changes in the expression of trkB mRNA in the DRG or trkB and t-trkB mRNAs in the spinal cord were not observed. 3. Many neurons showed increased coexistence of BDNF and PTT mRNAs or BDNF and CGRP mRNAs in the DRG following inflammation. 4. Few neurons showed coexistence of BDNF and trkB mRNAs in the DRG following inflammation. The results suggest a paracrine function for BDNF within the DRG in addition to an important role related with nociception following peripheral inflammation.

Change in the Synthesis of Brain-Derived Neurotrophic Factor in the Dorsal Root Ganglion Following Peripheral Inflammation / 대한해부학회지

It is well known that nerve growth factor (NGF) may serve as a link between inflammation and hyperalgesia. However, there is little information whether brain-derived neurotrophic factor (BDNF), another family of neurotrophin, may related with nociception. In the present study, in situ hybridization was used to evaluate i) the change in the level of BDNF mRNA, ii) colocalization of the trkA mRNA and BDNFmRNA and iii) colocalization of the preprotachykinin (PTT)mRNA and BDNFmRNA following peripheral inflammation produced by an intraplantar injection of Freund's adjuvant into the rat paws. The results obtained were as follows: 1. Peripheral tissue inflammation significantly increased BDNFmRNA levels in the DRG. 2. Many neurons expressing trkAmRNA showed increased expression of BDNFmRNA following peripheral inflammation. 3. Many neurons expressing PTT mRNA showed increased expression of BDNFmRNA following peripheral inflammation. 4. Intraplantar injection of antibody to NGF together with Freund's adjuvant prevent the increase in BDNFmRNA. The present results indicate that the peripheral inflammation induces an increased synthesis of BDNF which is mediated by NGF and BDNF coexist with substance P in the DRG and that BDNF may play an important role related with nociception.