Persistent Inflammatory Response in Periodontal Tissues After Walking Bleach: A Clinical Biomarker-Based Study

This study evaluated the long-term inflammatory response in periodontal tissues following intra-coronal bleaching of non-vital anterior teeth using two peroxide-based agents. Fifty participants were randomised to receive either 35% hydrogen peroxide or 37% carbamide peroxide via the walking bleach technique. Gingival crevicular fluid was collected at five time points over 12 months, and inflammatory biomarkers were analysed. Both bleaching protocols resulted in significant and sustained increases in interleukin-1 beta and receptor activator of nuclear factor kappa-B ligand concentrations, without significant differences between agents. Tooth whitening was effective and stable over time. The strong correlation between both biomarkers suggests a persistent low-grade inflammatory state induced by bleaching. These findings highlight the biological impact of intra-coronal bleaching on periodontal tissues, even in the absence of clinical symptoms, and underscore the need for individualised risk assessment when planning aesthetic treatment in endodontically treated teeth. Trial Registration: ClinicalTrials.gov identifier: NCT02718183.