Final answer:
Approximately 20,000 dentinal tubules are contained within 1mm of dentin, which is the layer of a tooth underneath the enamel. The dentin of a tooth contains microscopic tubules. Each dentin tubule has a diameter of about 1-2 micrometers. The number of dentin tubules in 1 mm of dentin can vary depending on factors such as tooth type and individual variations, but it is estimated to be around 20,000 to 45,000 tubules per square millimeter.
Step-by-step explanation:
One millimeter of dentin can contain approximately 20,000 dentinal tubules. These tubules are microscopic channels found within the dentin layer of a tooth, which is the layer that lies underneath the enamel and surrounds the pulp. The number of tubules can vary, but it is dense with these structural features that transmit stimuli from the exterior toward the inner pulp, potentially leading to sensations like pain. The cross-section of a tubule reveals it as a tiny tube that extends from the surface of the dentin down to the nerve in the pulp chamber.