The changes in parameters will be assessed Qui2 and Fisher exact tests for the cross sectional assessment of the six groups treatment groups at baseline, one year and two years. For a paired comparison analysis and to determine differences between treatments with regard to aesthetic, functional and biological parameters between baseline and the two-year follow-up (longitudinal assessment), the McNemar test will be used. To quantify the relative influence of patients' covariates (ie, smoking habits, oral hygiene) on clinical performance of the restorations, Kaplan Meier curves and Cox regression will be used. Differences will be considered to be significant at P<0.05.