BACKGROUND The aim of this research is to outline a procedure able to promote specific cellular differentiation and proliferation with consequent periodontal regeneration. To achieve this goal, use was made of various compounds supposed to have the capacity of aiding periodontal regeneration. METHODS The cells utilised for this study were obtained from explants of human periodontal ligaments. Their proliferation and differentiation capacity was examined in the presence of: coral granules (350, 500 mu), collagene type 1, growth factors (Platelet derived growth factor, PDGF and Transforming growth factor beta 1, TGF beta 1), both on their own and in different combination with one another. The differentiation activity was evaluated by ultrastructural morphological method (Transmission electron microscope-TEM) and by spectrophotometric investigation of the alkaline phosphatasis (ALP). RESULTS The data show that the coral granules and among the growth factors used only TGF beta 1 stimulate the differentiation activity of the periodontal ligament cells valued on the basis of their capacity of producing ALP. These data are supported by the observation with TEM. CONCLUSIONS From these results it is suggested that there may be therapeutic efficiency in the periodontal field of substances promoting cellular proliferation and differentiation.