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Changes in the pattern of horseradish peroxidase diffusion into predentin and dentin after cavity preparation in rat molars.

OBJECTIVE
The purpose of this study was to examine the process of reducing dentin permeability in adult rat molars after cavity preparation with horseradish peroxidase as a tracer.


STUDY DESIGN
Class V cavities were prepared on the upper first molars of 18 rats. Horseradish peroxidase was injected into the vascular system at intervals of 3 hours and 3, 5, 7, 10, and 14 days after cavity preparation, and frozen sections were processed by the diaminobenzidine procedure.


RESULTS
Horseradish peroxidase reaction products were noted in the dentinal tubules immediately beneath the cavity up until 14 days after cavity preparation. An abrupt stoppage of reactive products caused by impermeable junctional zone formation at the interface of the primary dentin and reparative dentin was observed at 14 days after cavity preparation.


CONCLUSION
Reparative dentin formation and subsequent impermeable junctional zone formation participate in the reduction of dentin permeability after cavity preparation.