Does the orthodontic treatment induces dental pulp cellular death? Caspase-3 and-9, HSP60 and TUNEL expression

Objective: To evaluate the hypothesis of human dental pulp cell death during orthodontic treatement (O.T) and the degree of apoptosis through the expression level of the proteins Caspase-3,-9, TUNEL and HSP60. Materials and methods: Human dental Pulp were coming from both male and female patients (N=20; age 10-14years). The technique used was the Straight Wire, which involves Nickel-Titanium or Steel archwires. The increase of pressure applied on teeth was gradual. Some patients were subjected to a premolar extraction after 3 months treatment, and others after 6 months. Samples were Bouin-fixed, paraffin-embedded and afterwards processed for immunohistochemistry using anti-caspase-3,-9 antibody, anti-HSP60 and TUNEL. Results: Increasing of caspase-3,-9 expression occurred in 3 and 6 months O.T. samples, while in control pulps positivity was detected mainly at odontoblasts level. HSP60 was not expressed in control samples and very weak in 3 months O.T. samples, it was expressed instead in 6 month O.T. samples, the expression of Tunel is evident in all samples but increased at 3 and 6 months specimens . Conclusion: Our hypothesis is supported by the increasing expression of Caspase-3,-9 , HSP60 and Tunel after 3 and 6 months of orthodontic traction revealing a time-dependent relationship.