The periodontium is a supportive structure which su rrounds the teeth and supports them. This structure consists of different tissues including gingiva, cementum, peri odontal ligament and alveolar bone. The aim of this study is to analyze the osteogenic stimulatory effect of the co mbination of dexamethasone and L.L.L.I. on the peri odontal stem cell (PDLSc). The PDLSc were obtained from the firs t premolar root of young healthy patients who had t heir teeth extracted for orthodontic treatment purposes. After obtaining the stem cells, the PDLSc were cultured in plates containing α -MEM and 15% FBS. The osteogenic differentiation wa s carried out in three groups, basic medium, Dexamethasone and L.L.L.I. and negative control and then the alizarin red staining test, calcium test and alkaline phosphatase test were performed. The results showed that intracellular calcium and alkaline phosphatas e in the dexamethasone and L.L.L.I. group was significantly higher than the control group (p<0.05). Also the st ain test showed mineralization of cells in the dexamethasone and L.L.L.I. group. The results of this study show ed that the combination of dexamethasone and L.L.L.I. has a sti mulatory osteogenic effect on PDLSc.