Role of exogenous TGF-beta in induction of reparative dentinogenesis in vivo.

This study was designed to investigate in vivo i) the role of TGF-beta as an active component of the dentin matrix during induction of reparative dentinogenesis; and ii) the ability of TGF-beta1 isoform to induce dentinogenic events. Dental pulps of dog molars and canines were mechanically exposed, and the following implants were placed intrapulpally for 42 d: i) Demineralized or native autogenous dentin matrix preincubated with a TGF-beta-neutralizing antibody; ii) Millipore filters soaked with solution containing 100 ng/ml of TGF-beta1 from human platelets; iii) biomatrices and filters soaked in control solutions. After incubation of biomatrices with the TGF-beta-neutralizing antibody, demineralized dentin completely lost its inductive activity, while native dentin was only able to stimulate formation of fibrodentin. Millipore filters soaked with TGF-beta1 were consistently surrounded by a thick zone of tubular matrix lined with high columnar polarized cells. The data provide evidence that pulp cells can express their dentinogenic potential in response to an appropriate surface containing exogenous TGF-beta1, and that the dentinogenic activity of dentin matrix may at least partly be ascribed to TGF-beta molecule(s).