In this study, we tested the hypothesis that the inclusion of an oxidizer and
oxygen carrier in the
photosensitization formulation would facilitate comprehensive disinfection of matured endodontic biofilm by light-activated disinfection (LAD). Photosensitizing formulations containing
methylene blue (MB) and an
oxygen carrier alone (perfluorodecahydronaphthalene) (PF1) or in combination with oxidizer (H(2)O(2)) (PF2) or their
emulsions formed with triton-X100 (Bio-Rad Laboratories, Hercules, CA) in different proportions (PF3 and PF4) were tested for photochemical properties and damage to the biofilm structure using confocal
laser scanning microscopy. Conventional chemomechanical preparation, LAD using MB in water, and LAD using MB in
emulsion (PF4) were also conducted on 10-week-old Enterococcus faecalis biofilm within root canals. MB in
emulsion (PF4) was overall the most effective
photosensitizer formulation for photooxidation, generation of
singlet oxygen (p = 0.001), and in disinfecting biofilm bacteria. Advanced noninvasive LAD using a
photosensitizer formulation containing oxidizer and
oxygen carrier disrupted the biofilm matrix and facilitated comprehensive inactivation of biofilm bacteria. This modified
photosensitizer formulation will have potential advantages in endodontic disinfection.