CASTABILITY QUANTIFICATION BY IMAGE ANALYSIS

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Excellent castability characteristics in dental alloys are critical for the consistent production of sound, well fitting cast restorations without the necessity of frequent costly and time consuming remakes. The use of mesh monitors to evaluate castability has become increasingly popular. However, they are usually evaluated by manual counting, a method with could be improved upon. The objective of this proposal is to combine newly developed image analysis techniques with the well established mesh casting monitor to produce a "state of the art" evaluation system and to then use this system to quantify castability variations in 8 popular commercial PFM alloys. The study will focus on the following alloys: Will-Ceram Y-2, Cameo, Olympia, Will-Ceram W-1, Naturelle, Rexillium III, Lifecast and Noravex. All manufacturers' recommended burnout and casting techniques will be strictly adhered to except that besides using only the recommended burnout-and casting temperatures, variations of + 100oF will also be used in the study. The cast monitors will be evaluated by area fraction imaging techniques developed with other instrumentation (PIAS System) in a previous investigation. In addition, all samples will be evaluated by ordinary manual counting (with magnification) and the results of two methods compared statistically. The proposed experimental layout is a three factor factorial design: 8 (alloys) x 3 (casting temperatures) x 3 (burnout temperatures) = 72 sets. A sample size of N=10 will be used for each condition. ANOVA and pairwise multiple comparison statistical analyses will be performed on the Arc Sin transformed data obtained by image analysis as well as by manual counting.