Pulp Inflammatory Response Against Bleaching
Bleaching of teeth has been widely used as a teeth whitening procedure. Among the various teeth whitening techniques available today, bleaching is the most effective and conservative technique
Bleaching techniques are also varied, which can be distinguished from the type of bleaching materials and the timing of the application. The most commonly used materials are 10-16% carbamide peroxide, or 25-38% hydrogen peroxide. Oxygen diffusing through enamel and dentine can affect pulp that results in tooth sensibility and toxic effects.1,2
The inflammatory response to bleaching procedures is caused by chemical aggressors involving nonspecific responses including exudative vascular phenomena and inflammatory cell infiltration such as mast cells and macrophages. These cells not only play a significant role in the defense of the pulp, but also play a role in the process of degradation of extracellular matrix, neovascularization, cell growth and repair.1
The results of Vas, et al comparing in vitro between vital teeth performed by bleaching in office, bleaching at home, and those not bleached, showed that macrophage migration was significantly greater in the bleaching in office group using 38% hydrogen peroxide causing a greater inflammation than the other two groups. Nevertheless, the number of blood vessels was the same in all groups and no mast cells were found in the pulp tissue.1 Cintra search, et al also evaluated in vitro on rat vital teeth on hydrogen peroxide concentration (20% and 35%) and bleaching application time ( 15, 30, and 45 minutes) to the pulp tissue. On the second day of observation the results of this study showed that in groups with a 15 minute application time for all concentrations, showed an increasing number of inflammatory cells in a third of corona pulp. While in groups of 30 and 45 minutes for both concentrations of these substances, showed a decrease in the number of inflammatory cells accompanied by necrotic regions. After 30 days, there was observed reduction of the pulp chamber and the extension of the tertiary dentine region in the absence of the inflammatory area detected.3
The study explains that, although the inflammatory process occurs, hydrogen peroxide can also penetrate into the cell membrane, increase the activity of alkaline phosphate, trigger apoptosis in the periodontal ligament and dental pulp, and stimulate mineralization. The alkaline phosphate activity and the mineralization of this extracellular matrix can trigger dentine production.3 Other studies of Cintra et al compared in vitro pulp biological responses to bleaching in office using 20% and 35% hydrogen peroxide. The results showed that inflammation, congestive blood vessels, and pulp disorganization especially in pulp horn occurred in both groups, and the most severe occurred in groups with higher bleaching material concentrations. The study indicated the use of hydrogen peroxide with lower concentrations in bleaching treatment.2
These studies show that the concentration and duration of bleaching application applications are more related to the intensity of the inflammatory response compared with the effectiveness of the teeth whitening process. It is therefore possible for clinicians to consider more about the use of different bleaching care protocols, with similar aesthetic results but less dental tissue damage.