The Bio-Molecular Dynamics of Dental Pulp in Different Clinical Scenarios

Dental pulp (DP) is a very dynamic tissue both in health and in disease. When exposed to stressors and pathological conditions. It undergoes a complex series of biological reactions whereby alterations affect the pulp tissue at tissue cellular and molecular levels. The aim of this review is to update the reader on the various bio-molecular alterations in the dental pulp under different clinical conditions: orthodontic treatment (OT), caries, pulpitis and others. The morphological changes in the composition of the DP rang from the reversible remodeling to apoptosis and sometimes necrosis. Many apoptotic factors are involved like Bcl2, Bax and the significant increase in Caspases 9 and 3, as well as, Hsp60, its possible role and its mitochodrial localization. The inflammatory responses in dental pulp and the role of diffusible and cellular factors as well as DP stem cells were highlighted, in particular, where caries was involved in the pulpitis.Recent data report changes in tissue metabolism and homeostasis inside the DP caused by OT leading to increased levels of iNOS reactivity in the nerve fibers of the pulp. Moreover, remodeling of the extra cellular matrix(ECM) is an important feature in clinical scenarios like OT and caries whereby alterations in MMP-2 and MMP-9 expression patterns are reported leading to degradation of type IV and V collagens in the ECM. Furthermore, neurogenic factors are also modified after injuries and OT. Neuropeptides play a significant role not onlyin pain perception but also in vascular responses. Substance P increases in DP and enhances pain perception and so is the increase in CGRP which is correlated with concomitant gain in bone morphogenetic protein expression resulting in more dentin formation. The role of stem cells and the possible molecular mechanisms of dentin genesis are presented in this review. They focus on important signaling proteins and the possible role of various scaffolds in this regeneration process. In conclusion, most alterations inpulpal structure are reversible unless the pulp has a history of caries, restorations, trauma or prolonged heavy orthodontic forces. Pulpal symptoms arising from these clinical conditions should be treated appropriately and swiftly.Otherwise, exacerpation of pulpitis and the interplay of the various bio-molecular factors will lead to inhibition of repair and regeneration.