Objectives:hydrothermal ceramics present high translucency, and allegedly high surface smoothness due to the formation of a hydroxilic film (silicon hydroxide), that may be able to obliterate Griffith's microfissures caused by mechanical wear. The goal of this work was to evaluate the ions modifications in the bulk of a conventional feldspathic ceramic system and of a hydrothermal ceramic. Methods: twenty four crowns were made, twelve built with a conventional ceramic (Duceramplus®, Degussa Dental, Germany), baked on a low gold alloy (Degubond 4 ®, Degussa Dental), twelve with a hydrothermal ceramic (Duceragold ®, Degussa Dental) baked on a high gold alloy (Degunorm ®, Degussa Dental), according to the manufacturer's instructions. All the samples were sectioned in two parts along their longitudinal axis with a diamond rotating disk. Three samples for each group served as controls, while the others were divided in three groups and immersed in acid (pH 5.34), alkaline (pH 9.39), and neutral (pH 7.16) artificial saliva for 40 days. Then the ceramic layer of each half sample was examined with Proton Induced X-Ray Emission (PIXE ě-Beam) to evaluate possible modifications in ions distribution, due to the immersion in saliva at different pH values. The other halves were evaluated with X-Ray Fluorescence - Energy Dispersive Microscopy (XRF-EDF) at the scanning electron microscope. Results: maps showing elements location were obtained with both the microprobe techniques. No ions modifications were found in feldspathic masses, with both techniques. On the other hand, in the hydrothermal ceramics, after immersion in artificial saliva, modifications of silicon distribution were detected with both microprobes. Conclusions: these data suggest that hydrothermal ceramics may self-repair surface microfissures by formation of a silicon hydroxide layer.

Back to the Dental Materials: III - Ceramics and Cements Program
Back to the IADR/AADR/CADR 80th General Session (March 6-9, 2002)

Top Level Search