An evaluation of the technique sensitivity of a hydrothermal low-fusing dental ceramic

OBJECTIVES: To investigate the technique sensitivity in the manipulation of Duceram Low-Fusing Ceramic, a hydrothermal dental veneering material by employing bi-axial flexure tests. METHODS: Disc shaped specimens of Duceram-LFC dentine powder were condensed from varying powder contents manipulated with 0.33 ml of liquid. Bi-axial flexure (ball-on-ring) testing was employed to determine the mean bi-axial flexure strength, standard deviations and Weibull modulus (m). Apparent solid density and apparent porosity were also measured. RESULTS: Mean bi-axial flexure strengths and standard deviations of specimens condensed from 0.82 g of powder were 66.47 and 9.62MPa (m=7.23, 1.32) compared with 59.12 and 13.62 MPa (m=4.19, 0.77) and 63.91 and 14.51MPa (m=4.46, 0.81) for powder contents of 0.78 and 0.86 g, respectively. A decrease in apparent solid density and an increase in apparent porosity were also associated with increasing or decreasing the powder content of slurry consistencies. CONCLUSIONS: A slurry consistency was identified for Duceram-LFC specimens where the reliability of fracture strength data increased. The technique sensitivity in the manipulation of Duceram-LFC would appear to be confirmed due to the relatively small amount of powder required to complete the transition from a 'fluid' to a 'thick' slurry consistency compared with a conventional veneering dental porcelain.