Morphological and apoptotic changes in the dental pulp associated with Orthodontic stress

Objectives: The dental pulp is a special type of loose connective tissue. It has structural and protective functions (synthesis of dentine), trophic function (provides nutrients through blood and lymphatic vessels) and sensory function (through innervation). The cellular part is characterized by the presence of odontoblasts, fibroblasts, mesenchymal cells, endoteliocytes and immunocytes. Investigations using molecular biology and immunohistochemistry of Caspases, BCL-2, Tunel and PCNA, HSP60 and MMPs were performed to assess the degree of structural-functional modification and cell death of the dental pulp.
Methods: Human dental pulps were extracted from male and female patients (N=20; age 10-14years). Some patients were subjected to a premolar extraction after 3, 6 and 18 months of orthodontic treatment There was an increase of caspases -3,-9 expression. It occurred proportionally to the time of orthodontic treatment. In control pulps samples, pulps which have not undergone any orthodontic traction, positivity was detected mainly at the odontoblasts level. HSP60 was not expressed in control specimens and was very weak in 3 month orthodontic treatment samples. However, it was strongly detected in 6 and 18 months O.T. samples. The expression of Tunnel was evident in all samples, it increased after 3 months of orthodontic traction.
Results: Results showed that orthodontic traction may inhibit the expression of several proteins and induce modification of the normal dental pulp structure. It may increase apoptosis and proliferation in pulp tissue. These results suggest the need for further studies about the effects of long term orthodontic treatment on dental pulp. Apoptosis increased after orthodontic fraction.
Conclusions: There was an expression of caspases-3,-9, HSP60 and Tunnel after 3, 6 and 18 months of orthodontic traction revealing a time-dependent relationship.