Changes in the fine structure of the dental pulp in human caries pulpitis

. Electron microscopic investigation of human pulps manifesting caries pulpitis revealed degenerative changes in myelinated and unmyelinated nerves and blood vessels. The degenerative changes noted in nerves were generally less severe and less frequent than those noted in the blood vessels and surrounding pulp tissue. This was attributed to the presence of an abundance of collagen fibers about the nerve bundles and nerve axons. The degenerative changes in the blood vessels ranged from minor changes in endothelial cell morphology to complete necrosis and lysis. These changes were generally accompanied by alterations in the integrity of the basement membrane. Advanced changes in blood vessels of the pulp appeared to result in an increase in vascular permeability causing edema. It was suggested that some of the degenerative changes noted might be related to the humoral phase of the inflammatory response.