Hydroxyapatite-lignin composite as a metallic implant-bone tissue osseointegration improver: experimental study in dogs/Composito de hidroxiapatita sintetica e lignina como promotor de osseointegracao entre implante metalico e tecido osseo: estudo experimental em caes

The study aimed to evaluate biocompatibility, osteoconduction and osseointegration of a pasty composite of hydroxyapatite (20%) and lignin (80%) as a promoter of metal implant and bone tissue integration. An intramedullary Schanz pin was implanted in both tibias of fifteen bitches. In the left tibia, the pin was coated with the biomaterial at the time of surgery Marrow cavity was also filled with the biomaterial. Right limb did not receive the biomaterial, then constituting the control group. Tibias were harvested from five animals at 8, 60 and 150 days after surgery; three of them were analyzed by histological and biomechanical assessment and the two remaining tibias by X-ray diffraction. Results showed that the biomaterial is biocompatible, with osteoconductivity and osseointegration properties. Histological analysis and diffractograms showed the presence of hydroxyapatite in samples in all periods, although the presence of organic material of low crystallinity was variable. There was no statistical difference in the forces required for removal of the intramedullary pin between times or treatments. Although the biomaterial showed biocompatibility, osteoconductivity and osseointegration, it was not able to promote a better intramedullary pin anchorage. Key words: biomaterial, biocompatibility, osseointegration, osteoconduction, tissue regeneration. O trabalho objetivou avaliar a biocompatibilidade, a osteoconducao e a osseointegracao de um composito pastoso de hidroxiapatita (20%) e lignina (80%) como promotor de integracao entre implante metalico e tecido osseo. Um pino intramedular de Schanz foi implantado em ambas as tibias de quinze cadelas. Na tibia esquerda, o pino foi coberto com o biomaterial no momento da cirurgia. A cavidade medular tambem foi preenchida com o biomaterial. O membro direito nao recebeu o biomaterial, constituindo assim o grupo controle. As tibias foram coletadas de cinco animais aos oito, 60 e 150 dias apos a cirurgia, sendo tres encaminhadas para avaliacao histologica e biomecanica e as duas restantes, para difracao de raios X. Os resultados revelaram biocompatibilidade do material, com propriedades de osteoconducao e osseointegracao. As analises histologicas e os difratogramas mostraram presenca da hidroxiapatita no tecido em todos os periodos avaliados, embora a presenca de material organico de baixa cristalinidade tenha sido variavel. Nao houve diferenca estatistica na forca necessaria para remocao do pino intramedular entre