| Traumatic and surgical wounds are frequently happening in the oral cavity. One of the most common oral wounds is the extraction socket wound after tooth removal. Oral tissue wound healing is an intricate process involving series of biologic events that tissue repair and remodeling in response to injury. The healing process is greatly influenced by a variety of systemic and local factors. Stromal-cell-derived factor 1 (SDF-1) is an active chemokine for injured myocardium repair and SDF-1/CXCR4 signaling pathway might play an important role in repairing injured blood vessel and tissue by promoting host cells recruitment and angiogenesis.Objective:To observe the expression and distribution of SDF-1 in the soft and hard tissue of tooth extraction.Methods:Fouty two 6-8 week-old male Wistar rats were used in this study and they were randomly divided into A and B groups. According to the different time after tooth extraction, each group randomly divided into six sub-groups at 0,1,2,4,7,10,14 days after tooth extraction respectively. The experimental animals were anaesthetized with pentobarbital sodium and the left mandible first molar was extracted. The rats were killed at 0,1,2,4,7,10 and 14 days after tooth extraction. Group A was for HE and immune-histochemical staining to observe the SDF-1 expression and distribution in different healing stages after tooth extraction; Group B was for SDF-1 mRNA quantitative evaluation by real-time fluorescent quantitative PCR.Results:Immuno-histochemical staining showed the SDF-1 protein was strongly expressed at the the gingival tissues around tooth extraction wound early than normal gingival, mainly especially in the cytoplasm and intercellular substance of the stratum spinosum and stratum basale, and stained more obvious closer to the stratum basale; Blood clots in the tooth socket white blood cells and fibrin dyeing, residual periodontal ligament with the expression of SDF-1.4 days after tooth extraction, the expression of SDF-1 in the stratum basale become more evident, and it is also positive inside endothelial cells of granulation tissues. The flange and the tooth socket of students can be seen in the granulation tissue of vascular endothelial cells and fibroblasts positive expression of proliferation activity.7 days after tooth extraction, the staining becomes uniform in the gingival epithelium, and visible positive staining of vascular endothelial cells in lamina propria; Freshman class tooth socket bone dyeing relatively obvious 10 days after tooth extraction, the characteristics is similar to the normal gingiva. The tooth socket basic fill up with cancellous bone, cancellous bone cell staining deep inside.RT-PCR test results showed that SDF-1mRNA underwent a biphasic expression change during gingival wound healing. SDF-1 mRNA level peaked at the first day after tooth extraction (p<0.01) but decreased 2 days after tooth extraction. However, the SDF-1 mRNA level increased again to a peak on the fourth day and then returned to a normal level 10 days later (p>0.05). In the hard tissues, SDF-1 mRNA expression level was higher on the first and second day after tooth extraction than normal level, to the peak on the fourth day, and then decline gradually.To 14 days after tooth extraction, SDF-1 mRNA expression level was smooth, but still slightly higher than normal control level.Conclusions:The expression of SDF-1 was ever increasing in the early healing stage after tooth extraction and it indicated that it mayparticipated in the hard and soft tissue healing process after tooth extraction As the difference of hard and soft tissue healing mechanism, the expression and the distribution of SDF-1ws different. So SDF-1 may play a role in tissue healing process after tooth extraction. |
