RESUMO
AIM: To evaluate the influence of additives on several physical and chemical properties of a novel endodontic cement based on calcium aluminate in comparison with mineral trioxide aggregate (MTA). METHODOLOGY: Manipulation tests, measurements of temperature, pH, ionic conductivity, compressive strength, apparent porosity, and pore size distribution were carried out on Gray-MTA (Angelus) and calcium aluminate cement (Secar-71, Kerneos) with and without various additives: a polymeric dispersant, CaCl(2) as plasticizer, and ZnO as radiopacifier. RESULTS: The calcium aluminate cement without additives had a setting time of approximately 60min, and when combined with Li(2) CO(3) it decreased to 10min. The material also released Ca(2+) ions and alkalinized the medium. Moreover, the addition of additives (dispersant, plasticizer, and radiopacifier) improved its properties resulting in a material with a viscosity of 57mPas, enhanced handling properties, a mechanical strength of 81MPa, a porosity of 4% and pores with small diameter (0.25µm). MTA had no temperature increase (that indicates setting) up to 400min, a mechanical strength of 34MPa, and porosity of 28% with pores 2.5µm in diameter. CONCLUSION: The novel cement set more rapidly, had better fluidity, improved handling properties, higher mechanical strength, and reduced porosity with lower pore size compared to Gray-MTA Angelus.
Assuntos
Compostos de Alumínio/química , Compostos de Cálcio/química , Cimentos Dentários/química , Materiais Restauradores do Canal Radicular/química , Fenômenos Químicos , Misturas Complexas/química , Força Compressiva , Combinação de Medicamentos , Humanos , Teste de Materiais , Óxidos/química , Silicatos/químicaRESUMO
Hydroxyapatite (HA) ceramic in a porous configuration is suggested as a drug release system. A new technique for the production of this material, based on the foaming of suspensions and in situ polymerization (gelcasting method), resulted in a material whose characteristics are likely to make it useful as an implantable drug delivery system. Three batches of HA ceramic with different porosities were characterized by X-ray diffraction and scanning electron microscopy (SEM). Pore size and shape as well as density were determined. In vitro experiments were performed in order to evaluate the dissolution behavior of cisplatin in the system. X-ray diffraction analysis showed that the final product consisted of a single phase, indicating that the sintering process had not affected the structure of the HA. Energy dispersive X-ray analysis (EDX) showed absence of impurities. Pore diameters were in the range 15--34 microm. SEM showed that the material presented a highly interconnected spheroidal porous network with open micropores and closed macropores. In vitro experiments showed significant differences in the release rate of cisplatin between three different porosities.