Artificial Teeth: Hardness. In a study by J. Zeng et al., three materials for making artificial teeth—Endura, Duradent, and Duracross—were tested for hardness. Their results were published as the paper “In Vitro Wear Resistance of Three Types of Composite Resin Denture Teeth” (Journal of Prosthetic Dentistry, Vol. 94, Issue 5, pp. 453–457). The Vickers microhardness (VHN) of the occlusal surfaces was measured with a load of 50 grams and a loading time of 30 seconds. Six pairs of teeth were tested for each material. The data on the WeissStats site are based on the results obtained by the researchers. At the 5% significance level, do the data provide sufficient evidence to conclude that there is a difference in mean hardness among the three materials?

In Exercises 16.60–16.63, refer to the discussion of using summary statistics in one-way ANOVA on page 735. Note: We have provided values of Fα not given in Table VIII.