Recebido em 21/9/98; aceito em 10/2/00 BIOCERAMICS: TENDENCIES AND PERSPECTIVES OF AN INTERDISCIPLINARY AREA.The need for new materials to substitute injured or damaged parts of the human body has led scientists of different areas to the investigation of bioceramics since the 70's, when other materials in use started to show implantation problems. Bioceramics show some advantages like being the material that best mimics the bone tissue but also, present low mechanical strength due to its ceramic nature. This paper presents a general view about the topic.Keywords: bioceramics; biomaterials; calcium phosphate. DIVULGAÇÃO INTRODUÇÃOO aumento da expectativa de vida do homem, como conseqüência dos avanços da medicina, da maior preocupação com a alimentação e do conforto gerado pela assim denominada "vida moderna", tem resultado no aumento da população de idosos e, conseqüentemente, das doenças relacionadas à velhice. Dentre os diversos males que afetam a estrutura óssea, a osteoporose e a perda de massa óssea têm sido intensamente estudados devido a seus efeitos devastadores na qualidade de vida das pessoas. Os problemas de estrutura óssea não são apenas "doença de velhos", eles também atingem indivíduos jovens em sua fase mais produtiva, em decorrência de acidentes, notadamente os automobilísticos e os de trabalho.A magnitude destes problemas de saúde junto à população tem levado pesquisadores, principalmente dos países mais desenvolvidos, à procura de materiais que possam substituir de forma apropriada os ossos danificados.Os materiais utilizados na substituição de ossos enquadram-se em uma classe denominada de biomateriais 1,2 e devem apresentar propriedades físicas e biológicas compatíveis com os tecidos vivos hospedeiros, de modo a estimular uma resposta adequada dos mesmos. Tais propriedades caracterizam a biocompatibilidade 2,3 . Os materiais sintéticos utilizados para estes fins podem ser metais, polímeros, compósitos, cerâmicas e vidros.Em geral, biomateriais utilizados na reposição dos chamados tecidos moles são muito diferentes daqueles usados na substituição de tecidos duros (ossos e dentes). Para os tecidos duros, dependendo do esforço mecânico a que são submetidos, alguns materiais podem ser mais apropriados que outros, devido à sua maior resistência. A Tabela 1 relaciona algumas aplicações de biomateriais sintéticos.A diversidade das aplicações dos biomateriais mostrada pela Tabela 1, assim como o amplo espectro de sua composição química e a necessidade de formas e morfologias apropriadas para sua utilização, fazem da pesquisa nesta área do conhecimento um trabalho de característica eminentemente interdisciplinar, envolvendo fatores que definem o sucesso de suas aplicações, tais como: rotas de síntese, processamento em formas variadas, qualidade e esterilidade clínica e resposta do tecido hospedeiro. Desta forma, o desenvolvimento de biocerâmicas e de próteses constituídas destes materiais deve ocorrer sob as mesmas condições de interdisciplinaridade que determinam o desenvolvimento de qualquer outro b...

No abstract

No abstract

No abstract

No abstract

Objectives: In regenerative medicine, surface engineering of bioinert synthetic materials is often required in order to introduce bioactive species that can promote cell adhesion, proliferation, viability and enhanced ECM‐secretion functions. The aim of this work is to study cell interaction with alumina‐modified surfaces. Material and methods: In this work, chemical properties of alumina surface were changed by a reaction at the surface of alumina with low molecular weight dicarboxylic acid, which produced carboxyl groups. Results: These carboxyl groups were able to complex with Ca2+ on the surface, forming sites of precipitation for calcium phosphates that make alumina biocompatible, as indicated by cell culture of pre‐osteoblasts (MC3T3‐E1 cell line). Conclusions: The procedure presented in this work shows that the insertion of specific functional groups on the surface of alumina increases cell interaction with the surface of alumina. This knowledge can be important in oral science and orthopedics, for the construction of prosthesis.

The consumption of alcohol or nicotine is harmful to the integrity of bone tissue, hindering or even impeding the fixation and maintenance of bone implants. The aim of the present work was to evaluate the effects of ethanol and nicotine, when consumed alone and simultaneously, on both bone mechanical resistance and bone neoformation around hydroxyapatite implants. Twenty rats were divided into four groups: control (CT), alcohol (A), nicotine (N) and nicotine + alcohol (N + A). After 4 weeks of alcohol and/or nicotine consumption, dense (HAD) and porous (HAP) bodies were respectively implanted in a surgically produced bone defect in the right and left tibiae. After the surgeries, the animals continued to consume alcohol and/or nicotine. After ninety days, the animals were sacrificed and the tibiae and femurs were isolated for histological processing and mechanical assays. All the animals presented newly formed bone tissue close to the HAD and HAP ceramic bodies. The animals of the N + A group presented a smaller volume of neoformed bone. Group A animals presented smaller bone volume around the implants in relation to the animals from group N. Bone resistance to mechanical loads was smallest in animals from the N + A group, followed (in order) by the A and N groups. Thus, it can be concluded that nicotine or alcohol consumption produced negative effects on bone mechanical resistance and on the osteogenesis around the HAD and HAP implants. In addition, the simultaneous consumption of the two substances intensified their harmful effects.

The effects of adding Nb 2 O 5 on the physical properties and glass structure of two glass series derived from the 45S5 Bioglass ® have been studied. The multinuclear 29 Si, 31 P, and 23 Na solid-state MAS NMR spectra of the glasses, Raman spectroscopy and the determination of some physical properties have generated insight into the structure of the glasses. The 29 Si MAS NMR spectra suggest that Nb 5+ ions create cross-links between several oxygen sites, breaking Si-O-Si bonds to form a range of polyhedra [Nb(OM) 6 -y (OSi) y ], where 1 ≤ y ≤ 5 and M = Na, Ca, or P. The Raman spectra show that the Nb-O-P bonds would occur in the terminal sites. Adding Nb 2 O 5 significantly increases the density and the stability against devitrification, as indicated by DT(T x -T g ). Bioglass particle dispersions prepared by incorporating up to 1.3 mol% Nb 2 O 5 by replacing P 2 O 5 or up to 1.0 mol% Nb 2 O 5 by replacing SiO 2 in 45S5 Bioglass ® using deionized water or solutions buffered with HEPES showed a significant increase in the pH during the early steps of the reaction, compared using the rate and magnitude during the earliest stages of BG45S5 dissolution.