Bioactive Molecules Stimulate Tooth Repair and Regeneration

Dentin extracellular matrix proteins display multifunctional properties. Firstly, they participate to the mineralization processes either as promotors or as inhibitors of crystal nucleation or crystal growth. Secondly, they act as signaling molecules implicated in the differentiation of odontoblast progenitors. These molecules may be used to promote the recruitment of odontoblast progenitors, the proliferation and the final differentiation into functional odontoblast-like or osteoblast-like cells implicated in pulp repair. This has been evaluated through a series of experiments carried out in vivo on the rat first maxillary molar and in vitro on odonto/osteo progenitors. Along this line, BMP7 (OP1) induced in the crown a fibrous osteodentin-like structure where unmineralized pulp remnants were seen. In addition, the mesial root canal was totally filled with a homogeneous dentin-like structure. The bone sialoprotein (BSP) stimulated within one month the formation of a reparative dentinal bridge and the complete closure of the coronal pulp with an atubular homogeneous reparative dentin. Dentonin, a peptide from MEPE, implantated into the exposed pulp produced more rapidly than the two previous molecules reparative mineralization in the coronal pulp and also occlusion of the lumen of the root canal. Implanted in the exposed pulp, A+4 and A-4, two spliced amelogenin gene products, induce either the formation of a reparative dentinal bridge (A+4) or a more diffuse mineralization (A-4). The mechanisms of proliferation and differentiation were studied in parallel in an in vivo situation after implantation in the first maxillary molar of the rat, and in vitro on odontoblast progenitor cell lines. These molecules may contribute to pulp repair and promote new strategies in dental therapies.