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Dead Tracts
Note the enamel layer (A) on the tip of the cusp has been worn down close to the dentin. The dentinal tubules under this region of trauma appear black . Trauma will cause the odontoblastic processes within the dentinal tubules to "die back" toward the cell body. In severe cases the cells themselves may die. Such regions of dentin (with empty dentinal tubules) are called dead tracts (B) and appear dark in ground sections. They are difficult to detect in demineralized sections. The odontoblasts whose processes had occupied the dentinal tubules have responded by forming a protective layer of secondary (or reactive) dentin (C).
Legend
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A - enamel |
C - secondary dentin |
