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Tooth Replantation: Use of active stabilization as a new protocol to improve periodontal repair


Achieving success after tooth replantation is still considered a great challenge in dentistry due to the high incidence of progressive root resorption after this procedure. The current level of scientific evidence for the stabilization of traumatized teeth reinforces the importance of using a flexible splinting that exerts a mechanical stimulus while allowing the physiological movement of the injured tooth during repair in order to prevent the occurrence of ankylosis. Considering that orthodontic movement consists in the application of controlled forces to the teeth, this therapy for replanted teeth could be a promising and innovative technique in Dental Traumatology, providing a better prognosis for periodontal repair. Thus, the objective of this project is to evaluate the effect of controlled physiological function to periodontal repair using active and passive stabilizations with brackets and orthodontic wires in replanted dogs teeth. For this purpose, 30 upper and lower premolars of 3 dogs (totaling 60 root canals) will be submitted to endodontic treatment and surgical procedures for root resection and atraumatic extraction. The roots will be randomly distributed in four Groups: I (n = 20): 20-minute extra-alveolar time and passive stabilization with orthodontic brackets and orthodontic wire; II (n = 20): 20-minute extra-alveolar time, stabilization with orthodontic brackets and orthodontic wire and activation with elastic ligatures; III (negative control; n = 10): immediate replantation and passive stabilization; IV (positive control; n = 10): 90-minute extra-alveolar time and passive stabilization. Two weeks later (14 days), the orthodontic appliance will be removed from the teeth of all groups. After 4 months, the animals will be euthanized and the maxillas and mandibles containing the roots will be submitted to histotechnical processing. The sections will be stained with hematoxylin and eosin for descriptive and semi-quantitative analysis of the histopathological features of the periodontal ligament and for quantitative analyses of the percentage of ankylosis, inflammatory resorption area and count of neutrophils. In addition, indirect immunofluorescence assay will be performed to evaluate the expression of neuronal regeneration marker (neurotrophin); Tunnel method and DAPI staining will be used for quantification of apoptotic cells; tartrate-resistant acid phosphatase (TRAP) histoenzymology will be used for osteoclast counting; Picrosirius staining will be used for the characterization of collagen fibers in the periodontal ligament and; immunohistochemical analysis for the identification of macrophages, neutrophils, T CD4+ lymphocytes and T CD8+ lymphocytes. The results will be submitted to the appropriate statistical analysis with 5% significance level. (AU)

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