| Tooth avulsion is one of the most serious of all dental injuries. It defined as the complete displacement of a tooth from its original alveolar socket. The periodontal ligament(PDL) is severed, and fracture of the alveolus may occur. It usually has an unfavorable outcome due to its high rate of root resorption. There are a lot of researches mainly focused on how to preserve the activity of periodontal membrane of avulsed teeth and to deal with its root surface, such as using propolis, milk and HBSS to storage avulsed tooth, or using laser, enamel matrix proteins and fluoride solutions to deal with the surface of the tooth, but the outcome was still less than satisfactory. Some researchers try to use periodontal ligament stem cells as seed cells for tooth reimplantation in recent years. However, most of these studies were conducted in vitro or in animal models. Although some of them have obtained the encouraging result, the PDLSCs has not been applied in clinical due to the ethical limitation and time restricted.The content of this item includes two parts summarized as followingPart 1: A retrospective study about clinical character and periodontal ligament healing of avulsion in permanent teethA retrospective analysis was performed of the dental records of 131 patients who had visited the Emergency Department of our hospital from April 2012 to April 2014. We follow the IADT guidelines. The information on the patient's age, gender, the causes of tooth avulsion, number of avulsed permanent teeth, accompany injuries, transport media and the period of delayed reimplantation were collected. The clinical features of avulsed tooth were investigated and the factors related to root resorption were analyzed. Conclusion: The periodontal healing of avulsed tooth were mainly affected by the time elapsed from the socket and the maturity of the root. No correlation was found between the root surface resorption and the injury of adjacent tooth, as well as alveolar fracture. Besides, the length of the dry extra-alveolar storage period is the main factor affecting the periodontal prognosis. Therefore, it was necessary to enhance the patient's consciousness of timely treatment to save more avulsed teeth.Part 2:The clinical study of using platelet-rich fibrin for delayed reimplantation of avulsed toothAccording to Part 1 and our previous animal study, we using autologous PRF as a graft for avulsed tooth in clinical. The patients were stratified-block randomized and divided into 2 groups, whose tooth was reimplantated combined with autologous PRF or with nothing. The clinical examination, computed radiography, CBCT and self-examination were performed to evaluate the periodontal healing of reimplanted teeth. Conclusion: The use of PRF could significantly promote the periodontal healing and reduce the root surface resorption of avulsed tooth.Summary: We found that root development stage and extra-oral time were the main factors affecting the periodontal healing of avulsed tooth. If kept dry and extra-oral for a long time, the avulsed tooth hardly reached favorable periodontal healing. The common denominator for all these factors related to PDL healing appeared to be the survival of the PDL cells. A longer time was needed for fixation if accompany injury such as alveolar fracture or injury of the adjacent tooth occurred, but showed no correlation with root resorption. It was necessary to raise the patient's awareness of timely treatment to save more avulsed teeth. In conclusion, we proved that PRF, enriched with growth factors and leucocytes, could promote periodontal wound healing and periodontal ligament regeneration of following delayed reimplantation of avulsed teeth, and reduce the pathological resorption effectively. Although the availability of PRF still need to be proved by more cases, at least, the application of PRF has brought new hopes for avulsed tooth. |
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