2.13. Determination of sample size and statistical analysis
caries lesions
REGRESSION, SECONDARY
It was assumed that the primary endpoint (i.e., no increase in DMFS index, i.e., ΔDMFS = Visit 4 - Visit 1 ≤ 0) will occur in about 60% of study subjects. A sample size of 77 study subjects per arm (two arms) was calculated to be sufficient to reject the null hypothesis that the test toothpaste is inferior to the control toothpaste, using a non-inferiority margin of Δ = 20% for the primary endpoint one-sided chi-square test (α = 5%, power = 80%) as described in a previous study (A non-inferiority testing was performed. The non-inferiority margin Δ was set to 20% between the groups. The primary endpoint was analyzed for the per-protocol (PP) population and, in addition, repeated for sensitivity reasons for the ITT population. The confidence interval approach was used to test non-inferiority (The confidence interval approach was also performed to test non-inferiority of the secondary endpoint's percentage of subjects experiencing no increase in the overall number of caries lesions (as examined using DIAGNOcam) as explorative statistical evaluation. Moreover, a logistic regression analysis was performed for this secondary endpoint as a dependent variable and toothpaste, center, gender, and age as independent variables (covariates).A two-sided independent 