Microstructure, composition, and etching topography of dental ceramics.
OBJECTIVE
Topographic analysis of etched ceramics provides qualitative surface structure information that affects micromechanical retention mechanisms. This study tested the hypothesis that the etching mechanism changes according to the type of etchant and the ceramic microstructure and composition.


METHODS
Quantitative and qualitative analyses of 15 dental ceramics were performed using scanning electron microscopy, back-scattered imaging, X-ray diffraction, optical profilometry, and wavelength dispersive spectroscopy based on Phi-Rho-Z correction. All ceramic specimens were polished to 1 micron with diamond compound, and the following etchants and etching times were used: ammonium bifluoride (ABF) for 1 minute, 9.6% hydrofluoric acid (HF) for 2 minutes, and 4% acidulated phosphate fluoride (APF) for 2 minutes.


RESULTS
HF produced an irregular etching pattern in which pores were the characteristic topographic feature. ABF-etched ceramic surfaces showed mostly grooves, and APF etchant caused a buildup of surface precipitate. Core ceramics showed less topographic change after etching because of their high alumina content and low chemical reactivity.


CONCLUSIONS
The observations suggest that the etching mechanism is different for the three etchants, with HF producing the most prominent etching pattern on all dental ceramics examined.
Della Bona
Alvaro
A
School of Dentistry, University of Passo Fundo, PO Box 611/613, Passo Fundo, RS, 99001-970 Brazil. adellabona@via-rs.net
Anusavice
Kenneth J
KJ
D000134:Acid Etching, Dental / Q000379:methods*; D000149:Acidulated Phosphate Fluoride; D064751:Ammonium Compounds; D003776:Dental Porcelain / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D005459:Fluorides; D006358:Hot Temperature; D006858:Hydrofluoric Acid; D008855:Microscopy, Electron, Scanning; D000644:Quaternary Ammonium Compounds; D012542:Scattering, Radiation; D013057:Spectrum Analysis / Q000379:methods; D013499:Surface Properties; D014961:X-Ray Diffraction
D064751:Ammonium Compounds; D000644:Quaternary Ammonium Compounds; D003776:Dental Porcelain; D000149:Acidulated Phosphate Fluoride; C024822:ammonium fluoride; D005459:Fluorides; D006858:Hydrofluoric Acid