5-FU Weakens Defensive Functions of the Junctional Epithelium.

Aim: To investigate additional factors contributing to the pathophysiology of chemotherapy-induced oral mucositis and periodontitis beyond the systemic immune suppression caused by the chemotherapeutic agent 5-Fluorouracil (5-FU).

Methods: 5-Fluorouracil was topically delivered to the non-keratinized, rapidly proliferating junctional epithelium (JE) surrounding the dentition, and acts as an immunologic and functional barrier to bacterial ingression. Various techniques, including EdU incorporation, quantitative immunohistochemistry (qIHC), histology, enzymatic activity assays, and micro-computed tomographic (μCT) imaging, were employed to analyze the JE at multiple time points following topical 5-FU treatment.