Individual surgical skills may be considered as a potential factor that influences case selection and clinical outcomes [1,2,3]. Cairo et al. [4] reported in their systematic review high heterogeneity in mean root coverage of gingival recessions treated by coronally advanced flap procedures. It may be explained by the possible impact of surgical skills of different operators on the clinical results achieved.

Moreover, the effect of centers has also been found by Cortellini et al. [5] in their multicenter clinical study. In their randomized controlled clinical trial, the coronally advanced flap alone was compared with the coronally advanced flap plus the connective tissue graft for the treatment of localized gingival recession defects. The difference in outcomes achieved in the study may be explained by the difference in individual skills and experience between operators.