Exploratory investigation of plaque differences was also conducted. The level of significance was set at 5%. Probability values were not corrected for multiplicity. Assuming an average incidence of complications of 0.25, this study, with 40 samples per group, has statistical power of approximately 0.8 to identify a 0.30 difference in the incidence of complications (type I error 0.05, uncorrected chi- squared test).