Os substitutos ósseos são actualmente objecto de intensa investigação a nível mundial, com vista a ultrapassar as limitações decorrentes da colheita de enxerto ou do recurso a bancos de osso, para preencher defeitos ósseos. Além disso, a utilização de substâncias com capacidade osteogénica abre novas perspectivas no tratamento de fracturas, pseudartroses e nas artrodeses vertebrais. Dada a grande quantidade de informação existente sobre esta matéria, este artigo pretende não só rever conceitos gerais como também sumarizar o que de mais recente foi publicado na área da aplicação de substitutos ósseos para regeneração óssea.

Bone grafts are nowadays the subject of extensive research worldwide, aimed at overcoming limitations associated with the use of autografts or bone banks to fill bone defects. Additionally, the use of osteogenic substances opens new perspectives in the treatment of fractures, pseudarthroses and vertebral arthrodeses. Due to the large amount of information available in the area of bone grafts, this paper aims not only to revise general concepts but also to summarize what has been published recently in the area of bone substitutes for bone regeneration.

In the present study, mechanical properties of porous glass reinforced hydroxyapatite bioceramics were assessed by microhardness, bending and compression tests and fracture toughness determination. Porous discs were produced by a dry method using wax spheres as pore formers. Green bodies were sintered and the final microstructure of the composites consists of hydroxyapatite, alpha and beta tricalcium phosphate (alpha and <FONT FACE=Symbol>b</font>-Ca3(PO4)2)due to the reaction between the glassy phase and the hydroxyapatite matrix. The results of the mechanical tests showed that the glassy phase yielded higher fracture toughness and bending strength when comparing with literature data for single hydroxyapatite. There is a compromise between mechanical properties and the porosity level for bioceramics: for example, according to Weibull statistics for composites with 65% porosity the maximum bending stress level is 0.2 MPa for 100% survival probability whereas this stress level increases to 2.5 MPa for composites with 40%. However, only the 65% porosity composite samples seem to have the complete adequate morphology for bone ingrowth.