SILVEIRA, O. C.; http://lattes.cnpq.br/5037512670609043; SILVEIRA, Olimpia Crispim da.
Résumé:
The technological development in dental ceramics engineering has led to the introduction of new systems, which use a ceramic core to replace the metal infrastructure. Researches have been dedicated to the study of reinforcement of these new infrastructures in order to improve their strength and processability. The aim of this study was to developed systems of alumina in infiltrated with poly (methyl methacrylate) and evaluates its microstructure and mechanical resistance, with prospect for application in dentistry. It was studied four aluminas from different suppliers: Alglass (AG), Alcoa (AC), In-Ceram (IC) and Vitro Ceram (VC). These aluminas were characterized by particle size and mineralogical composition. Specimens were made in prismatic-shaped (30 mm x 5 mm x 4 mm), according to the specifications of ISO 6872-1998, sintered at 1400 oC and submitted to polymer infiltration at low and high pressure for periods of 6 and 12 h. The samples were analyzed in relation to porosity and bulk density by the Archimedes method. The specimens were submitted to characterization by scanning electron microscopy (SEM), optical microscopy (OM) and mechanical tests of flexural resistance in three points and microhardness. The results of mechanical resistance and microhardness were evaluated considering a 5% level of statistical significance. The infiltration of the polymer in the porous substrate of sample VC for a period of 12 h obtained the best results of flexural resistance (119.37 MPa ± 23.64) and microhardness (1055.10 HV ± 111.01). The sample prepared with Alcoa alumina obtained the smallest mechanical bending results (15.72 MPa ± 1.03) and hardness (462.60 HV ± 0.70) with 12 h infiltration. The results of flexural strength and microhardness of Alcoa and Alglass samples showed no statistically significant differences in all conditions. The sample of Vitro Ceram was presented the best performance when infiltrated in low and high pressure by the time of 12 h and meets the values of hardness and bending resistance (100 MPa) established by ISO 6872, and can be used for infrastructure applications in fixed prosthesis.
