Acrylic resins used in the fabrication of dentures should not absorb much water, since water sorption reduces strength. The article “Reinforcement of Acrylic Resin for Provisional Fixed Restorations. Part III: Effects of Addition of Titania and Zirconia Mixtures on Some Mechanical and Physical Properties” (W. Panyayong, Y. Oshida, et al., Bio-Medical Materials and Engineering, 2002:353-366) describes a study of the effect on water sorption of adding titanium dioxide (TiO2) and zirconium dioxide (ZrO2) to a standard acrylic resin. Twelve specimens from each of several formulations, containing various amounts of TiO2 and ZrO2, were immersed in water for one week, and the water sorption (in /ng/mm2) was measured in each. The results are presented in the following table.
a.Use the Bonferroni method to determine which of the noncontrol formulations (B through H) differ, at the 5% level, in their mean water sorption from the control formulation A.
b. Repeat part (a) using the Tukey-Kramer method.
c. Which method is more powerful for these comparisons? Why?