In Vitro Antifungal Efficacy of Blue-Light Photodynamic Therapy with Curcumin and Riboflavin Formulation Activated by 450 nm Diode Laser Against Candida albicans Biofilm on Titanium Implants

<b>Background</b>: <i>Candida albicans</i> is increasingly recognized in peri-implantitis due to its capacity to form resilient biofilms on implant surfaces, limiting treatment success. Antimicrobial photodynamic therapy (aPDT) may offer a non-invasive adjunct by leveraging photosensitizer activation to produce reactive oxygen species that disrupt microbial cells. This in vitro study assessed the antifungal efficacy of QroxB2, a dual-photosensitizer containing riboflavin and curcumin, activated by 450 nm blue light against <i>C. albicans</i> biofilms on titanium implants. <b>Methods</b>: <i>C. albicans</i> biofilms were formed on 63 titanium implants and randomly assigned to nine groups (<i>n</i> = 7): untreated control (GC), chlorhexidine (CHX), riboflavin (RIB), curcumin (CUR), QroxB2 (QBX), laser only (L), and three photodynamic therapy groups combining laser irradiation with each photosensitizer (L + RIB, L + CUR, L + QBX). Treatments were followed by colony-forming unit (CFU) enumeration. <b>Results</b>: The L + QBX group showed the strongest antifungal effect, achieving a 94% reduction in fungal load, with median CFU counts decreasing from 49,000 in the untreated control to 2800 CFU/mL. CHX eradicated all viable cells (0 CFU/mL). Among photosensitizer-only groups, QBX produced a moderate reduction (median 21,800 CFU/mL), whereas laser irradiation alone (L) exhibited no meaningful antifungal activity, with median counts comparable to the untreated control (49,000 CFU/mL). <b>Conclusions</b>: QroxB2-mediated aPDT achieved a significant reduction in <i>Candida albicans</i> colony-forming units on implant surfaces. While not as potent as chlorhexidine, this light-activated, biocompatible approach may serve as a complementary tool in managing peri-implant fungal infections. Clinical validation is warranted.