Reporting microhardness data in scientific publications.
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Hardness↗
Biomedical subjects
R Pober
Publications and source records attributed to R Pober.
Flexural strength of an infused ceramic, glass ceramic, and feldspathic porcelain.
In-Ceram material is a relatively new all-ceramic restorative material with improved properties that require research. The clinical selection of restorative materials is based on a number of parameters such as esthetics, fit, and strength. This study determined the flexural strength of In-Ceram system components and compared the core material with conventional feldspathic ceramics and with Dicor all-ceramic restorative material. Four-point flexural strength values of bend bars of each ceramic were 18.39 +/- 5.00 MPa for In-Ceram sintered alumina, 76.53 +/- 15.23 MPa for In-Ceram infusion glass, and 236.15 +/- 21.94 MPa for In-Ceram infused alumina core. Flexural strength of self-glazed feldspathic porcelain was 69.74 +/- 5.47 MPa, as-cast Dicor ceramic 71.48 +/- 7.17 MPa, and polished Dicor ceramic was 107.78 +/- 8.45 MPa.
Aluminum Oxide↗
Flexural strength of feldspathic porcelain treated with ion exchange, overglaze, and polishing.
Feldspathic porcelains, which are used in the construction of porcelain-fused-to-metal (PFM) restorations, have an inherent weakness because of their brittle nature and processing flaws. A relatively new product, the Tuf-Coat ion exchange system, claims to substantially strengthen feldspathic porcelains. This study compared the strengthening effect of the Tuf-Coat system with that of surface treatments such as overglazing, polishing, and finishing. Bend bars of Vita VMK 68 porcelain were made and randomly assigned to eight different surface treatment groups to examine these effects. The flexural strengths revealed that although Tuf-Coat treatment strengthened the porcelain, it was not significantly different from overglazing, and the strengthening effect was lost if the porcelain was subsequently self-glazed or finished.
Analysis of Variance↗
Fracture surface analysis of dental ceramics: clinically failed restorations.
Fractography was used to study all-ceramic restorations that had failed clinically. Some basic tenets of fracture mechanics and fractography are reviewed and related to the examination of clinically failed all-ceramic restorations. Dicor and Cerestore restorations that had failed either at trial placement or 17 to 36 months postcementation were evaluated. Failed Dicor restorations were studied to determine the origin of failure and calculate the intraoral stress at failure. Descriptive information regarding crack origin and crack path were obtained from failed restorations constructed of first-generation Cerestore. A majority of the crowns apparently failed from the internal surface, indicating this as the highest tensile surface and/or the location of the largest flaws. Flaws were identified as being related to fabrication or inherent in the ceramic microstructure.
Aluminum Oxide↗
Effect of surface finish on the flexural strength of feldspathic and aluminous dental ceramics.
The effects of surface finish on flexural strength of a feldspathic porcelain, aluminous porcelain, and a computer aided design-computer aided machining porcelain (Vitabloc MKI) were examined. A total of 105 bars of the feldspathic ceramic were made, randomly divided into seven groups, and sintered according to manufacturer's recommendations. The groups consisted of as-fired, self-glazed, overglazed, ground, polished, ground/annealed, and polished/annealed. A total of 45 bars of the aluminous ceramic and Vitabloc MKI were made and randomly divided into three groups: as-fired, ground, and polished. Overglazing, grinding, and polishing all significantly increased (P < .05) the flexural strength (four-point-bend test) of the tested materials (15% to 30%).
Aluminum Oxide↗