Platelet-rich fibrin improves the osteoneogenesis in non-critical defects in calvaria: a histological and histometric study.

PURPOSE: The aim of this study was to evaluate the effect of platelet-rich fibrin (PRF) and autograft on non-critical bone repair. METHODS: Four bone defects (8.3 × 2 mm) were produced on the calvarium of 15 rabbits. The surgical defects were treated with either autograft, autograft associated to PRF, PRF alone, and sham. Animals were euthanized on the second, fourth or sixth posteoperative week. Histological analyses for presence of bone development on deffect was evaluated comparing the groups treated with autograft and without the autograft separately within the same period. Mann-Whitney's tests were used to compare the percentage of bone repair in each post-operative period for autograft × autograft + PRF groups and also for control × PRF groups (α = 5%). RESULTS: No differences were observed between the groups that received autograft and autograft associated to PRF on the second and fourth postoperative week, but areas treated with PRF demonstrated significant osteogenesis when compared to sham group on the fourth and sixth weeks. The groups that received PRF (with autograft or alone) demonstrated an enlarged bone deposition when compared to their control group. CONCLUSIONS: The use of PRF may influence bone repair and improve the bone deposition in late period of repair demonstrating osteoconductive and osteogenic properties.

Platelet-rich fibrin improves the osteoneogenesis in non-critical defects in calvaria: a histological and histometric study

ABSTRACT Purpose: The aim of this study was to evaluate the effect of platelet-rich fibrin (PRF) and autograft on non-critical bone repair. Methods: Four bone defects (8.3 × 2 mm) were produced on the calvarium of 15 rabbits. The surgical defects were treated with either autograft, autograft associated to PRF, PRF alone, and sham. Animals were euthanized on the second, fourth or sixth posteoperative week. Histological analyses for presence of bone development on deffect was evaluated comparing the groups treated with autograft and without the autograft separately within the same period. Mann-Whitney's tests were used to compare the percentage of bone repair in each post-operative period for autograft × autograft + PRF groups and also for control × PRF groups (α = 5%). Results: No differences were observed between the groups that received autograft and autograft associated to PRF on the second and fourth postoperative week, but areas treated with PRF demonstrated significant osteogenesis when compared to sham group on the fourth and sixth weeks. The groups that received PRF (with autograft or alone) demonstrated an enlarged bone deposition when compared to their control group. Conclusions: The use of PRF may influence bone repair and improve the bone deposition in late period of repair demonstrating osteoconductive and osteogenic properties.

BONE HEALING OF DEFECTS IN CALVARIA USING RICH FIBRIN IN PLATELETS AND LEUKOCYTES: STUDY IN RABBITS / CICATRIZAÇÃO ÓSSEA DE DEFEITOS EM CALVÁRIA UTILIZANDO FIBRINA RICA EM PLAQUETAS E LEUCÓCITOS: ESTUDO EM COELHOS

Introduction: L-PRF (platelet and leukocyte-rich fibrin) is a concentrate of platelets and leukocytes in a fibrin network, obtained by autologous centrifugation collected at the time of the operation. It offers the advantages of low cost, easy preparation, simple acquisition and ability to accelerate the healing of soft and hard tissues. Objective: To evaluate the bone repair of non-critical defects in rabbit calvaria using L-PRF alone and in association with particulate autogenous bone. Method: Fifteen rabbits were used with blood collected and immediately centrifuged. Four non-critical defects measuring 8 mm in diameter were performed and filled with: 1) particulate autogenous bone; 2) particulate autogenous bone + L-PRF; 3) L-PRF only; and 4) without graft. They were sacrificed after 2, 4 and 6 weeks with the samples analyzed histologically and histomorphometrically comparing the regenerated areas. Results: At 2 weeks there was a statistical difference between groups 1 and 3; at 4 weeks there was between groups 2 and 4; and at 6 weeks between groups 1 and 4 and between 3 and 4. There was significant bone and proportional gain between 2 and 6 weeks for the L-PRF group. Conclusion: L-PRF alone had a positive and proportional effect on bone formation over the weeks.

Introdução: O L-PRF (fibrina rica em plaquetas e leucócitos) é concentrado de plaquetas e leucócitos em uma rede de fibrina, obtido pela centrifugação autóloga coletada no momento da operação. Oferece como vantagens o baixo custo, fácil preparo, de simples obtenção e com capacidade de acelerar a cicatrização de tecidos moles e duros. Objetivo: Avaliar o reparo ósseo de defeitos não críticos em calvária de coelhos utilizando o L-PRF isoladamente e em associação com osso autógeno particulado. Método: Foram utilizados 15 coelhos com sangue coletado e imediatamente centrifugado. Foram realizados 4 defeitos não críticos de 8 mm de diâmetro e tratados com preenchimento por: 1) osso autógeno particulado; 2) osso autógeno particulado + L-PRF; 3) somente L-PRF; e 4) sem enxerto. Foram sacrificados após 2, 4 e 6 semanas com as amostras analisadas histologicamente e histomorfometricamente comparando as áreas regenerada. Resultados: Com 2 semanas houve diferença estatística entre os grupos 1 e 3; com 4 semanas entre os grupos 2 e 4; e com 6 semanas entre os grupos 1 e 4 e entre 3 e 4. Houve ganho ósseo e proporcional significativo entre 2 e 6 semanas para o grupo de L-PRF. Conclusão: O L-PRF isoladamente teve efeito positivo e proporcional na formação óssea no decorrer das semanas.

Avaliação in vitro da força de ativação da mola de ancoragem utilizada na técnica Straight-Wire - sistema versátil - em diferentes ligas e calibres / In vitro evaluation of the activation force of the spring anchor technique used in the Straight-Wire - versatile system - in different alloys and gauges

O controle de ancoragem é uma das chaves do sucesso em Ortodontia. Existem vários métodos para aumentar ou diminuir a ancoragem de um dente ou grupo de dentes. As molas de ancoragem da técnica Straight-wire Sistema Versátil são molas confeccionadas no próprio consultório, fáceis de instalar, que independem da colaboração do paciente, e tem como função aumentar a ancoragem posterior, permitindo maior movimento mesial dos dentes anteriores. Assim sendo, o presente trabalho estudou a liberação da força das molas de ancoragem confeccionadas em diferentes fios ortodônticos (Aço, TMA e Elgilloy), de diferentes calibres e marcas comerciais, quando tensionadas até 7 mm (avaliada a cada mm) ou até 500 g de força, com a finalidade de utilizá-las para a retração dos dentes anteriores. Desta maneira pode-se escolher os melhores protocolos para a retração dos dentes, considerando que ativações entre 2 e 3 mm são mais fáceis de visualizar, que quanto maior a necessidade de ativação melhor a relação carga/deflexão oferecida, e que para a retração dos dentes anteriores superiores são necessários aproximadamente 300 g de força e para os dentes anteriores inferiores são necessários aproximadamente 240 g de força. Assim sendo, o melhor protocolo para liberar a força desejada para a retração dos dentes ântero-superiores é a mola confeccionada com fio TMA Morelli 0,017" x 0, 025" quando ativada em 3 mm e para os dentes ântero-inferiores é a mola confeccionada com fio Elgilloy Morelli 0,017" x 0,025" quando ativado em 2 mm. Utilizando o protocolo acima estabelecido, além do aumento da ancoragem, haverá maior facilidade de visualização da ativação do sistema de forças, melhor controle das forças utilizadas e melhor relação carga/deflexão do fio, tornando a técnica Straight-wire Sistema Versátil ainda mais segura e simples de realizar.

The anchorage control is one of the keys of successful orthodontics. There have been developed several methods to increase or decrease the anchorage of a tooth or a group of teeth.The anchorage springs from Straight-wire Versatile System technique are springs which are made at the office. They are easy to install, do not depend on the patient’s collaboration, and have as their function to increase the posterior anchorage, allowing a greater mesial movement of the anterior teeth. Thus, the present work studied the strength release of the anchorage springs made of different orthodontic wires (Steel, TMA and Elgilloy), different calibers and commercial brands, when tensed up to 7 mm (with graduation in each of them) or up to 500g strength, used to retrain anterior teeth. This way, it is possible to choose the best protocols to retrain teeth, taking into consideration activations between 2 and 3 mm, which are easier to visualize, that the bigger the activation necessity, the better the relation load/deflexion offered. Then, in order to retrain superior anterior teeth it is necessary aproximately 300g strength and to retrain superior anterior teeth, 240g strength is needed. In this sense, the best protocol to release the desired strength for retraining anterior superior teeth is the one made of TMA Morelli 0,012” x 0,025” wire when activated in 3 mm and, for anterior inferior teeth, the spring suggested is the one made with Elgilloy Morelli 0,017” x 0,025” wire, when activated in 2 mm. By making use of the such protocol, there will be - besides the anchorage increase - an easier visualization of the strength system activation, a better control of the used forces and a better load/deflexion relation of the wire, transforming the Straight-wire Versatile System into an even safer and easier technique to apply.