Concentration-dependent effect of bleaching agents on the immunolabeling of interleukin-6, interleukin-17, and CD5-positive cells in the dental pulp

Abstract

Aim

To evaluate lymphocyte-like cell activation (CD5-positive cells) and the expression of interleukin (IL)-6 and IL-17 in the pulp after dental bleaching with two concentrations of hydrogen peroxide (H₂O₂).

Methodology

The right and left maxillary molars from 40 rats were treated randomly with bleaching gel with 20% H₂O₂ (BLUE group, 1 application of 50 min), 35% H₂O₂ (MAXX group, 3 applications of 15 min), or placebo gel (Control). After 2 and 30 days, the rats were killed (n=10), and the jaws were processed for histological and immunohistochemistry analysis of the pulp tissue. The scores of inflammation and immunolabeling (IL-6/IL-17) were submitted to Mann-Whitney and Kruskal-Wallis followed Dunn tests, respectively; ANOVA tests were used for comparisons of number of CD5-positive cells and pulp chamber area values (P<0.05).

Results

At 2 days, 60% of specimens of the BLUE group were associated with moderate inflammation in pulp horns, and in the MAXX group with necrosis (P<0.05). At 30 days, the pulp was organized, and tertiary dentine was formed. The MAXX group had superior immunolabeling of IL-17 at 2 days differing significantly from other groups (P<0.05). At 2 days, 90% of the specimens of the BLUE group had moderate immunolabeling of IL-6, and 50% of the MAXX group had severe immunolabeling, both significantly different from the control (P<0.05). There was no significant difference between the groups at 30 days (P>0.05). CD5-positive cells were present at 2 and 30 days, particularly in the bleached groups (P<0.05), without significant difference between time periods (P>0.05).

Conclusions

IL-6 and IL-17 participated in inflammation in the pulp tissue of rats after dental bleaching, particularly at 2 days. The immunolabeling was greater with increasing H₂O₂ concentration. This process was accompanied by the prolonged activation of CD5-positive cells.

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