Efeito do processamento e da inclusão de fibras nas propriedades mecânicas e ópticas de uma porcelana odontológica / The effect of processing methods and fibers incorporation on the optical and mechanical properties of a dental porcelain

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

15/08/2011

RESUMO

The objective was to evaluate the processing methods (conventional sintering and heat pressing) and fibers incorporation on the microstructure, mechanical properties (flexural strength f, and Weibull parameters m, 0 e 5%), slow crack growth parameters (n e f0) and contrast ratio (CR), translucency parameter (TP), opalescence parameter (OP) optical properties. Potassium Titanate fibers were mixed with a feldspathic porcelain, and then processed with conventional sintering and heat pressing (with or without fibers). A pilot study was carried out varying the sintering and heat pressing temperature with 5 or 10 wt% of fibers. The selected groups were the control group (CG), conventionally sintered processes following manufactures recommendations; conventionally sintered with fibers (SF); heat pressed without fibers (HP) and heat pressed with fibers (HPF). The hypothesis were: 1) The incorporation of fibers to the conventionally processed porcelain would improve the mechanical properties and slow crack growth parameters and would not affect the optical properties; 2) heat pressing the porcelain without fibers would improve the mechanical properties and slow crack growth parameters and would not affect the optical properties. 3) heat pressing the porcelain with fibers would improve the mechanical properties and slow crack growth parameters and would not affect the optical properties. Specimens were tested for biaxial flexural strength in water. Weibull analysis was used to determine m, 0 and 5% and the dynamic fatigue test was used to determine n e f0 values. The SF group showed percentage of porosity two times higher than the CG, higher values of f, but had no improvement on the Weibull parameters m, 0 and 5% values and slow crack growth parameters n and f0. It presented significant optical changes reaching 100% of opacity. The first hypothesis was partially accepted because there was increase only in f. The HP group presented 10 times lower porosity than CG. It showed higher values of f, and 0 but had no improvement on m and 5%. The HP group also showed higher values of n and f0 and significantly higher TP, and lower CR and OP. The second hypothesis was partially accepted as well because there were mechanical properties increases and changes in optical properties. The HPF group showed porosity two times higher than the CG, higher values of f, and showed an improvement on the Weibull parameters 0 and 5% and slow crack growth parameters n and f0. It presented significant changes OP.

ASSUNTO(S)

cerâmicas odontológicas dental ceramics fibers fibras processamento sinterig process

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