The use of osteoinductive demineralized dentin matrix in the repair of vital pulp exposures was examined. The pulps of the maxillary first molars of adult male Long Evans rats were exposed and capped with either demineralized dentin particles or guanidinium extracted demineralized dentin particles; then covered with a glass ionomer cement restoration. The animals were sacrificed after two weeks and the maxillae were dissected free, fixed in formaldehyde and demineralized. Histologic examination revealed that in those cases where the protective glass ionomer restoration was intact, both groups showed some healing. There was some preliminary indication that the extent of reactive matrix formation was greater in the osteoinductive group. In both groups, odontoblast-like cells appeared to incorporate some of the dentin particles into the reparative dentin bridge. This preliminary work suggests that osteoinductive factors present in demineralized incisor dentin might be used to guide the formation of a dentin bridge in a rat model for vital pulp exposures.