Statistical analyses. Statistical analysis was performed using the "Statistical package for the social sciences (SPSS)" statistical software. The data are presented as mean ± standard error of the mean. The Shapiro-Wilk test, suitable for small populations, showed a non-normal distribution of the variables, for which the non-parametric Friedman test was used. The p value <0.05 was considered normal. The Wilcoxon Signed Rank Test was subsequently used to see which pairwise comparisons resulted statistically different. In addition, as a multiple comparison was done, we applied the Bonferroni correction, thereby setting a p value = 0.05 / 3 = 0.0167. For each of the sampling times 0.120 and 240 minutes, we compared the results and the RRs obtained with the different filters (HFR17, PMMA, F7).