Dentin-pulp complex's responses to dentin caries

Objective To observe the dentin-pulp complex's responses to dentin caries progression.Methods A total of 65 third molars were collected immediately after extraction,of which 27 teeth with shallow dentin caries including 15 acute caries and 12 chronic caries,28 with deep dentin caries including 16 acute caries and 12 chronic caries,and 10 without caries.The teeth were fixed,demineralized and sectioned at a thickness of 4 μm,which were then subjected to HE staining and cellular reactions to the lesion were measured using computerized histomorphometry to examine:①the number of odontoblast;②the cytoplasm:nucleus ratio of the odontoblast cells;③the adjacent predentine area;④the thickness of tertiary dentin.Results As carious lesion approached the pulp,the number of odontoblast cells significantly reduced,the cell shape changed from columnar to cubic or even flattened,predentin area reduced or even disappeared,inflammatory cells mainly lymphocytes and plasma cells increased with hyperemia.In shallow carious stage,the cytoplasm:nucleus ratio of the odontoblast cells decreased significantly,odontoblast-like cells and collagen fibers were seen in chronic cases.In deep caries,subodontoblastic region was sometimes infiltrated by many inflammatory cells and engorged capillaries were seen there,tertiary dentine often without tubular structure were formed.Conclusion The difference of the dentin-pulp complex's responses to the dentin caries is associated with the depth and activity of carious lesion.