Fig. (7) Boxplot of roughness values measured for the samples treated with procedure B (a), C (b) and D (c) in the case of polishing included (B2, C2, D2) or excluded (B1, C1, D1). The boxplot that refers to group B2 includes the roughness values obtained for the sub-groups: B2I, B2II and B2III. Analogously, groups C2 and D2 include the sub-groups C2I, C2II, C2III and D2I, D2II, D2III, respectively.