Erosive substance loss (in µm) according to different groups as measured using the four different methods.

Obtained values differed significantly between groups regardless of the measurement method Different superscript letters indicate significant differences between measurement method, with uppercase letters indicating significant differences between groups, i.e. in columns (p<0.05, t-test/Bonferroni), and lowercase letters between methods, i.e. in rows. Samples were immersed in solutions with 0% (group 0), 0.07% (group 1), 0.25% (group 2) or 1.0% (group 4) citric acid. Number of analysed samples per group is given in parentheses. Erosive substance loss (in µm) according to different groups as measured using the four different methods.