Responses of pulp vasculature after cavity preparation in rat molars

ObjectivesOur recent study showed that cavity preparation increases the number of proliferative cells in the dental pulp during postoperative days 2–5. This study aimed to clarify pulp vascular changes following cavity preparation.MethodsGroove-shaped cavities were prepared on the medial surfaces of the upper first molars of 100-day-old Wistar rats. The animals were perfusion-fixed and tissues were collected during postoperative days 1–30, with subsequent India ink perfusion, immunohistochemistry for type IV collagen, CD31, and protein gene product (PGP) 9.5 and scanning electron microscopy with KOH digestion. The untreated upper first molars were used as controls.ResultsIn the controls, blood vessels with large diameters were located in the center of the pulp tissue and ramified to make capillary networks and PGP9.5-positive nerves were extensively arborized to form the subodontoblastic nerve plexus beneath the odontoblast layer. Cavity preparation induced disturbance in injured odontoblasts and subodontoblastic capillaries and nerves. Blood vessel density and thickness subsequently increased in the center and periphery of the pulp tissues with the exception of the subodontoblastic capillary network during postoperative days 3–5. PGP9.5-positive nerves overlapped with CD31-positive blood vessels in the mesial coronal pulp. Until day 30, when the tertiary dentin formation was completed, the pulp blood vasculature showed the same distribution and morphological features as that of the controls.ConclusionsThese results suggest that increased vascular flow under neuronal regulation plays an important role in cell proliferation in the dental pulp following cavity preparation.