Evaluation of the degradation of two bioabsorbable interference screws: an in-vivo study in sheep

Purpose: To evaluate in-vivo degradation of two bioabsorbable interference screws. Methods: Twenty-two crossbred Santa Inês ewes were used. A poly-DL-lactide (PDLLA) screw (70%/30%) was inserted in the right pelvic limb, and a PDLLA screw (70%) + ß-tri-calcium phosphate (ß-TCP) (30%) in the left pelvic limb. Animals were euthanized at one, four, seven and a half and 18 months after surgery. Plain radiography, computed tomography (CT), microCT, and histological analysis were accomplished. Results: PDLLA screw was hypodense at all evaluation moments, but with progressive density increase along the central axis, whereas PDLLA/ß-TCP was initially hyperdense and progressively lost this characteristic. No adverse reactions were observed on histological evaluation. Conclusions: The inclusion of ß-TCP favors screw degradation since the PDLLA/ß-TCP screws evidenced a more intense degradation process than the PDLLA screws at the last evaluation. PDLLA screws showed higher bone production, evident around the screw thread, inside the lateral perforations, and in the central canal, whereas the PDLLA/ß-TCP screws presented less bone tissue at the implantation site.

Experimental dry socket: microscopic and molecular evaluation of two treatment modalities / Alveolite experimental: análise microscópica e molecular de duas modalidades de tratamento

PURPOSE: To evaluate two treatment modalities of dry socket in rats and to discuss the first findings of the molecular analysis in this experimental model. METHODS: 84 rats underwent a tooth extraction were divided in 4 groups: I-uninfected socket (control), II-infected socket without any treatment, III-infected socket treated with irrigation of 2% sodium iodide and 3% hydrogen peroxide solution, IV-infected socket submitted to curettage, irrigation with physiological saline solution and fulfilled with metronidazole paste as base. The groups were subdivided in postoperative sacrifice periods: 6/15/28 days. A quantitative and a qualitative microscopic analysis was performed. Also, a quantitative analysis was performed using a RealTimePCR to evaluate the genes expression in the wound healing: Collagen Type I/COL-I, vascular endothelial growth factor/VEGF, osteocalcin/OCN, alkaline phosphatase/ALP, runt-related transcription factor 2/RUNX2 and tumor necrosis factor alpha/TNF-α. RESULTS: The group I showed higher bone formation, followed by groups IV, III, II respectively. The group II presented higher inflammatory infiltrate and the wound healing was delayed compared with other groups. It was obtained a significant positive correlation between bone neoformation and the expression of OCN and RUNX2, inflammatory infiltrate with TNF-α and a negative correlation between bone neoformation and TNF-α. CONCLUSION: No significant difference was found between the treatments.(AU)

OBJETIVO: Avaliar duas modalidades de tratamento da alveolite em ratos e discutir os primeiros achados de uma análise molecular neste modelo experimental. MÉTODOS: 84 ratos foram submetidos a uma extração dentária e foram divididos em quatro grupos: I- alvéolo não infectado (controle), II- alvéolo infectado sem tratamento, III- alvéolo infectado tratado com irrigação de iodeto de sódio a 2% e solução de peróxido de hidrogênio a 3%, IV- alvéolo infectado submetido à curetagem, irrigação com solução salina fisiológica e preenchimento com pasta a base de metronidazol. Os grupos foram subdivididos em períodos de sacrifício pós-operatório: 6/15/28 dias. Uma análise quantitativa e qualitativa microscópica foi realizada. Além disso, uma análise quantitativa foi realizada utilizando RealTimePCR para avaliar a expressão de genes no reparo alveolar: o colágeno tipo I / COL-I, o fator de crescimento endotelial vascular / VEGF, osteocalcina / OCN, fosfatase alcalina / ALP, fator de transcrição runt relacionados 2 / RUNX2 e fator de necrose tumoral alfa / TNF-α. RESULTADOS: O grupo I mostrou maior formação óssea, seguido pelos grupos IV, III, II, respectivamente. O grupo II apresentou maior infiltrado inflamatório e a cicatrização foi atrasada em comparação com outros grupos. Foi obtida uma correlação positiva entre a neoformação óssea e a expressão de OCN e RUNX2, infiltrado inflamatório com TNF-α e uma correlação negativa entre a neoformação óssea e TNF-α. CONCLUSÃO: Nenhuma diferença significativa foi encontrada entre os tratamentos.(AU)