Orthodontic tooth movement depends on the active periodontal ligament remodeling and regeneration. To analyze this mechanism, we utilized odontoma PDL and tried to find the genes specific in odontoma PDL. Human PDL tissue derived from a premolar complex odotoma was excised, which was extracted from orthodontic reasons, and placed onto flexible bottom plate. One month later, the heterogeneous cells reached confluence and they were cloned. Each clone was collected at 6-8 passages and stocked. Cell morphology and growth and differentiation ability of each clone is analyzing.
Total RNA was extracted from the heterogeneous primary culture cells from the odontoma PDL and from normal tooth PDL. To investigate the difference in the expression of Msx-1, Msx-2, which has been reported to control the tooth development, in odontoma PDL and normal tooth PDL, total RNA was reverse transcribed into cDNA, followed by quantitative real-tune PCR, using specific primers. As a result, all RNAs expressed the Msx-1 and Msx-2 mRNAs, though the expression level varied with the cells. The morphology of the cells also differed from each other.
Furthermore, another periodontal ligament tissues from another complex odontoma were used and analyzed the expression of Msx-1 and Msx-2 and the same tendency was observed. These results suggested that the process for the formation of odontoma involves at least Msx-1 and Msx-2, but also other transcriptional factors. We are analyzing cDNA array method and differential display PCR method, to identity the genes that is expressed specific in odotoma PDL. We are also preparing to immortalize the cloned cells, and to identify the clone specific genes.