Influence of violet LED associated or not with peroxide gel on inflammation, mineralization, and collagen fiber maturation in dentin and pulp tissue

Objectives: To evaluate the influence of violet LED, associated or not with a 17.5% hydrogen peroxide (HP) bleaching gel, on inflammation, mineralization in pulp tissue, and collagen fiber maturation in dentin and pulp tissue. Materials and methods: The maxillary molars of eighty Wistar rats were distributed into four groups (n = 10): CONT – without treatment; HP – 30 min application of 17.5% HP; LED – 20 min application of violet LED; and HP+LED – application of PH and violet LED. Rats were euthanized and jaws were processed for histologic and immunohistochemical evaluation (IL-17, IL-23, and osteocalcin) and picrosirius red immediately after (T0), and at 7 (T1), 15 (T2), and 30 days (T3) post-treatment, with Wilcoxon, Mann-Whitney, paired T-test, and T-test (α = 0.05). Results: HP and HP+LED presented necrosis and severe inflammatory infiltrate. When compared to CONT group, LED presented severe osteocalcin (OCN) immunostaining in T2 and less immature fibers in T2 and T3. Conclusion: The violet LED caused no severe damage to the pulp tissue, increased IL-17 and IL-23 expression in T0 when associated with HP, and had no influence on pulp tissue mineralization, besides accelerating the maturation of collagen fibers of dentin. Clinical relevance: Violet LED therapy induced no inflammation in the pulp tissue of rats and played no role in pulp tissue fibrosis, besides accelerating the maturation of dentin collagen fibers.