Dental pulp in mature human teeth: morphological alterations and metalloproteinases-2 and -9, Annexin-5, BCL-2, and iNOS modulation.

Tooth replantation, as a treatment concept, has been subject to controversies regarding the mechanism as well as the various parameters underlying this process. This work aimed to study time-related changes in the pulp of replanted mature human premolars through the changes in the levels of certain factors involved in the underlying mechanisms of pulpal tissue healing after replantation. Eleven experimental mature teeth were extracted, immediately replanted in the original socket and left without any other intervention for 1, 2, 3 and 12 weeks before re-extraction. Three premolars served as control. All specimens were subject to histological analysis and the levels of MMP-2, MMP-9, Annexin V, iNOS and BCL-2 (anti-apoptotic family) were analyzed employing immunohistochemistry. The results showed degradation of the extracellular matrix (ECM), inflammatory cell infiltrate, loss in pulpo-dentine interface and loss of odontoblasts in the dental pulp tissue. This was accompanied by increase over time of MMP-9, Annexin V, iNOS and a decrease of BCL-2 and MMP-2, suggesting that apoptosis increased throughout the experimental period.