Microvascular changes after experimental pulpitis in dog 1. formation of a lymph-like vessel incident to the inflammation

Abstract

The dental pulp, which is surrounded by the hard tissue of the tooth, contains the vessels required for circulation in the tooth. Within this closed environment, inflammation progresses very rapidly. Morphologically, the vasculature of dental pulp is being elucidated, but characteristics of lymphatic vessels have not been well established. Therefore, detailed knowledge of the inflammatory defense mechanism in dental pulp is currently lacking. In the present study, vascular changes after pulpitis incident to experimental cavity formation were observed by resin casting and scanning electron microscopy. A standard cylindrical experimental cavity (2-mm diameter x 2-mm depth) was created on the tooth surfaces of the lower premolars of beagle dogs. The synthetic resin was injected 4 h or 1, 3, 7, 30, or 90 days after cavity formation. The blood vessels of the dental pulp exhibited the three-layered structure of main artery and vein in the central layer, arteriole and venule in the intermediate layer, and capillary network (CN) in the surface layer. Four hours after cavity formation, leakage of resin was observed under the CN. One day after cavity formation, resin lumps gathered beneath the CN. After 3 days, a constricted vessel that connects to the venule was observed. After 7 days, a constricted vessel was found to run along the main artery and venule in the axis direction. After 30 and 90 days, the dental pulp was necrotized along the experimental cavity. These results suggest that the newly formed constricted vessel functions similarly to a lymphatic vessel. [MVRC 2 (1) : 13-17, 2008]