At the beginning, specialists tried to diagnose the stage of periodontal disease depending on the relation between the clinical appearances and the presence of some specific cell populations or specific matrix components (Havemose-Poulsen & Holmstrup, 1997; Romanos et al., 1993). Traditional clinical measurements (probing pocket depth, bleeding on probing, clinical attachment loss, plaque index) used for the diagnosis of periodontium health are often of limited usefulness because they are not su