DEVELOPING AN OPTIMUM ETCHING SYSTEMFOR DIFFERENT PORCELAIN RESTORATIONS

Abstract

Two different chemical etchants were prepared to be used for etching of different all porcelain restorations. The first etchant was prepared from a mixture of hydrofluoric acid and boric acid. The second etchant was prepared thermally by partial dehy ration of orthophosphoric acid to produce pyrophosphoric one. The effects of the newly developed etchants, as well as three commercial etchants (APF, SE and OP) on three porcelain systems (1\llirage-Vitadure-Duceram), used for construction of all porcelain restorations were evaluated.

X-ray fluorescence analysis, as well as x-ray diffraction tests were carried out, to characterize chemically and mineralogically the three tested porcelain systems.

Scanning electron microscopy was used to examme the surface morphological effects of the newly developed etchants, as well as the three commercial etchants (APF, SE and OP) on the three studied porcelain systems. After etching process, the surface of each porcelain was silanated and then bonded to luting composite resin cement. The widely used shear bond strength test was used to assess the adhesion quality of the assemblies through which the proper etching time of each newly developed etchant was obtained. The assessment was extended to investigate, on comparative basis, the effect of the newly developed etchant on the fracture toughness as well as translucency and color difference of the treated porcelain. Specimens of the three commercially porcelain systems were made, and etched with the different etchants used in the study. The scanning electron microscopy revealed that, etch patterns were noticeably different for the three porcelain systems.