Growth factors found in human cementum and dentin

Objective:Since demineralized mammal dentin shows osteoinductive activity, it is noted that the activity induced odontogenesis and/or cementogenesis also resides in the cementum. The aim is to search for periodontal ligament regeneration promoting factors in the cementum and dentin. Methods:After the root of an extracted human tooth was cut into 1mm thickness round slices and demineralized with 0.1M HCl solution, the cementum and dentin were prepared by dissecting with a sharp spatula under a microscope. These samples were extracted using a 4M guanidine solution as the cementum extract or dentin extract. It was determined that these extracts induced the alkaline phosphatase (ALP) activity of HPDL and C2C12 cells in a cell culture system, and the residences of TGF-b and BMP-2 were analyzed by Luciferase Reporter Assay (LRA) in them. Noggin, the inhibitor of BMP-2, and SB431542, the TGF-b1 inhibitor, were used for ALP activity detection induced by the TGF- band BMP-2. Results:The ALP activity of HPDL cells was enhanced by adding authentic TGF-b1, but was reduced by authentic BMP-2. On the contrary, the ALP activities of the MC3T3 and C2C12 cells, osteoblast-like cells, were enhanced by BMP-2, but reduced by TGF-b1. The cementum and dentin extracts induced ALP activity in the HPDL cells and reduced that in the MC3T3 and C2C12 cells. Both extracts contained TGF-b1 and BMP-2, detected by the LRA. When Noggin and SB431542 were separately added to the culture system, respective ALP activity enhanced by the TGF-b1 and BMP-2 was increased. These results indicated that these growth factors counteracted the ALP inducing activity of each other. The cementum and dentin were almost the same in TGF-b1 quantity, but the cementum was lower than the dentin in BMP-2 quantity. Conclusion:Cementum and dentin may be involved in periodontal regeneration by releasing growth factors during periodontal therapy.