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Deciduous and permanent teeth from swine, monkeys, and humans, with dentin exposed by attrition, were studied histologically. Bacteria were present in exposed dentinal tubules, in cracks in dentin, and in necrotic pulp tissue. Remaining primary dentin and secondarily formed irritation dentin did not seem to protect the pulp entirely from exogenous irritants, and microscopic changes were observed in the pulp.
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Tronstad et al. (1971) studied this question.
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