Life Sciences Commons^™

Properties Of A New Dental Porcelain, T. K. Vaidyanathan, J. Vaidyanathan, A. Prasad

Scanning Microscopy

A high strength dental porcelain OPTEC, HSP™ has recently been introduced for use in the fabrication of crowns, three-unit anterior bridges with a single pontic, inlays, on lays, veneers, etc., without a metal substrate. This investigation reports the results of our research involving the characterization of the structure properties and thermally induced transformations of this porcelain. It has been found that the material possesses superior strength and other properties relative to conventional porcelains. The improved properties appear to result from the presence of a very fine and relatively dense distribution of leucite crystals. Scanning electron microscopy indicates, however, that the …

Morphology And Chemical Composition Of Dental Calculi Mainly Composed Of Whitlockite, Toshiro Sakae, Hirotsugu Yamamoto, Hiroyuki Mishima, Takashi Matsumoto, Yukishige Kozawa

Scanning Microscopy

The morphology and chemical composition of two subgingival calculus samples, which were composed of magnesium-whitlockite with a Mg/Ca molar ratio of approximately 0.1 as shown by X-ray powder diffraction, were analyzed semiquantitatively using energy-dispersive spectroscopy (EDS) combined with scanning electron microscopy (SEM). The Ca/P molar ratio values for 33 EDS-analyzed materials ranged from 1.24 to 2.03 with an average of 1.49, and the (Mg+Ca)/P molar ratio values ranged from 1.43 to 2.28 with an average of 1.63. The average Mg/Ca molar ratio was 0.10, a value very close to that obtained by X-ray diffraction analysis.

The EDS-analyzed materials were grouped …

Solution-Mediated Transformation Of Octacalcium Phosphate (Ocp) To Apatite, R. Z. Legeros, G. Daculsi, I. Orly, T. Abergas, W. Torres

Scanning Microscopy

OCP crystals were hydrolyzed in solutions containing Ca²⁺, Mg²⁺, HPO₄^2-, CO₃^2-, F^-, citrate or P₂O₇ ions. Products of hydrolysis were analyzed using scanning (SEM) and transmission (TEM) electron microscopy, infrared spectroscopy and x-ray diffraction.

Results demonstrated that the OCP to Apatite (AP) transformation is influenced by: (1) types of ions in solution: inhibited by Mg²⁺, citrate or P₂O₇^4-; facilitated by F^-, CO₃^2-, HPO₄^2- or Ca²⁺ ions; (2) ionic concentrations; (3) …