Toluidine Blue O (TBO) was used as the photosensitizer (PS) singularly combined with salivary peptides RR14, DR9/RR14, and Hst5 protein, and experiments were conducted to assess its biocompatibility and photodynamic effects on human gingival fibroblasts (FGH) and oral squamous cell carcinoma (SCC-25) cell lines. This evidence concerns the gene HTN3 and oral cavity squamous cell carcinoma.