This study showed the effects of sintering temperature and atmospheric pressure on the density, tensile strength, and microstructure of porcelain enamels. Although the densities of the opaque porcelains were higher, they were weaker than the gingival porcelains. Gingival porcelains also glazed and sintered at lower temperatures than the opaque porcelains.

Dental Porcelain↗

PubMedDate not supplied

Adsorption of Streptococcus mutans on chemically treated hydroxyapatite.

Adsorption of Streptococcus mutans on hydroxyapatite and chemically treated hydroxyapatite was studied. Zeta potentials of the surfaces were measured. Chemically treated hydroxyapatite gave higher zeta potentials and lower S mutans adsorption.

Adsorption↗

PubMedDate not supplied

Differential effect of secondary aqueous humor from rabbit and cat on DNA synthesis of cultured bovine corneal endothelial cells.

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Animals↗

PubMedDate not supplied

Fracture strength of glass infiltrated-magnesia core porcelain.

PURPOSE: This study determined the fracture strength of magnesia-core porcelain after using a glass infiltration firing technique. MATERIALS AND METHODS: Eighty refractory dies were replicated from a stainless steel master die milled to the dimensions of a maxillary premolar that had been prepared for a porcelain crown. The core porcelain was applied to the refractory dies using traditional condensation methods, and then formed into standardized copings using a centrifugal sculpturing device. The copings were vacuum-fired from 593 degrees C to 1 of 8 high temperatures. Five copings per temperature were then coated with a glass-infiltrate and ground back to a standard thickness. The finished copings were bonded to a duplicate die with an adhesive resin luting system and placed in an Instron testing machine and loaded to fracture. RESULTS: Analysis of variance and Student-Newman-Keuls tests demonstrated significant differences among treatments and temperatures (P < 0.05). A significant increase in fracture strength was observed after glass infiltration of the magnesia-core porcelain. Sintering the copings to 871 degrees C or 899 degrees C prior to glass infiltration gave the highest fracture load values. CONCLUSION: Glass infiltration significantly increased the fracture strength of the magnesia-core porcelain.

Analysis of Variance↗