Blue-Light Disinfection of Removable Dental Prostheses and Appliances: Mitigating the Limitations of Existing Reagents and Techniques
Abstract
Dr. Alka Shukla, Mr. Alshad Seyyadali, Mrs. Sonam Rastogi and Prof. Gopal Nath
Biofilms on removable dental prostheses create reservoirs for opportunistic pathogens, increasing the risk of localized and systemic infections. Effective, biocompatible disinfection strategies are essential to maintain oral health and prosthesis integrity. This study evaluated the antimicrobial efficacy of 450 nanometer blue-light phototherapy against Veillonella parvula, an early colonizer and bridging species in oral biofilms, and assessed its safety on human peripheral blood mononuclear cells. Biofilms were developed on polystyrene microtiter plates and coverslips, while planktonic cultures were prepared from the same inoculum. Samples were exposed to blue light for 10, 15, 20, 25, and 30 minutes. Biofilm biomass was quantified using crystal violet staining, planktonic viability was assessed by colony-forming unit enumeration, and cell cytocompatibility was evaluated through trypan blue staining and cytokine quantification by enzyme-linked immunosorbent assay.
Blue-light phototherapy induced a time-dependent reduction in biofilm biomass, with optical density decreasing from 1.60 ± 0.23 in controls to 0.34 ± 0.07 after 30 minutes, corresponding to approximately 79 percent reduction. Planktonic V. parvula showed fluence-dependent killing, with lethal dose values of 57.9 and 134.2 joules per square centimeter for 37 percent and 90 percent inactivation, respectively. Microscopic analysis confirmed structural disruption of biofilms at prolonged exposure. Human peripheral blood mononuclear cells maintained normal morphology, viability, and proliferation, and displayed no measurable cytokine response.
These findings demonstrate that blue-light phototherapy selectively and effectively targets Veillonella parvula in both biofilm and planktonic states without harming host immune cells. The approach relies on reactive oxygen species generated by endogenous bacterial chromophores, eliminating the need for chemical photosensitizers. Thirty minutes of 450 nanometer exposure represents an optimized therapeutic window, providing a safe, non-chemical, and reproducible strategy for disinfecting removable dental prostheses.