Porous chitosan bilayer membrane containing TGF-β1 loaded microspheres for pulp capping and reparative dentin formation in a dog model.

OBJECTIVES

The objectives of this study were to develop a chitosan bilayer membrane containing microspheres with sustained TGF-β1 release to enhance odontoblast-like cell function in vitro, and to investigate pulp-capping in a dog model to promote reparative dentin formation in vivo for the first time.

METHODS

A chitosan bilayer membrane was synthesized consisting of a dense film on one side and a macroporous sponge on the other side. The rationale was to use the dense film to block the perforated pulp from bacterial invasion, and the porous sponge to be loaded with microspheres containing TGF-β1 (MS-TGF) for sustained release. Pulp capping in 48 teeth of six beagle dogs was performed to test four groups: Control with no pulp capping material, commercial Dycal, chitosan membrane without MS-TGF, and chitosan membrane with MS-TGF. The dog teeth were harvested for histological analysis at two time points (10 and 60 d).

RESULTS

The spongy side of the membrane had macropores with a mean size of 151 μm. The porosity of the membrane was 83%. Chitosan microspheres containing TGF-β1 showed sustained release, gradually releasing 42% of the TGF-β1 in 7 d. The proliferation of odontoblast-like cells on membrane with MS-TGF was much greater than that without TGF (p<0.05). At 10d, H&E staining revealed mild to moderate pulp inflammation in all four groups, with no dentin bridge formation. At 60 d, pulp inflammation disappeared, but there was no reparative dentin bridge in the group with no pulp-capping material. Chitosan membranes with MS-TGF generated reparative dentin with a thickness of (142±29) μm, 3-6 times thicker than that with Dycal or chitosan bilayer membrane without TGF (p<0.05).

SIGNIFICANCE

A novel chitosan bilayer-microsphere construct containing TGF-β1 for pulp-capping generated 3-6 times more reparative dentin than the controls in a dog model for the first time. The chitosan bilayer-microsphere construct with growth factor delivery may be useful for a wide range of dental and regenerative medicine applications.