Photo Inactivation of Streptococcus mutans Biofilm by Violet-Blue light.
Among various preventive approaches, non-invasive phototherapy/photodynamic therapy is one of the methods used to control oral biofilm. Studies indicate that light at specific wavelengths has a potent antibacterial effect. The objective of this study was to determine the effectiveness of violet-blue light at 380-440 nm to inhibit biofilm formation of Streptococcus mutans or kill S. mutans. S. mutans UA159 biofilm cells were grown for 12-16 h in 96-well flat-bottom microtiter plates using tryptic soy broth (TSB) or TSB with 1 % sucrose (TSBS). Biofilm was irradiated with violet-blue light for 5 min. After exposure, plates were re-incubated at 37 °C for either 2 or 6 h to allow the bacteria to recover. A crystal violet biofilm assay was used to determine relative densities of the biofilm cells grown in TSB, but not in TSBS, exposed to violet-blue light. The results indicated a statistically significant (P < 0.05) decrease compared to the non-treated groups after the 2 or 6 h recovery period. Growth rates of planktonic and biofilm cells indicated a significant reduction in the growth rate of the violet-blue light-treated groups grown in TSB and TSBS. Biofilm viability assays confirmed a statistically significant difference between violet-blue light-treated and non-treated groups in TSB and TSBS. Visible violet-blue light of the electromagnetic spectrum has the ability to inhibit S. mutans growth and reduce the formation of S. mutans biofilm. This in vitro study demonstrated that violet-blue light has the capacity to inhibit S. mutans biofilm formation. Potential clinical applications of light therapy in the future remain bright in preventing the development and progression of dental caries.
Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, 1121 West Michigan Street, Indianapolis, IN, 46202, USA. gfelixgo@iupui.edu.
Grace F
GF
Gomez
Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, 1121 West Michigan Street, Indianapolis, IN, 46202, USA.|Department of Pediatric Dentistry, West China School of Stomatology, Sichuan University, No. 14, 3rd Section of South Renmin Rd, Chengdu, Sichuan, 610041, China.
Ruijie
R
Huang
Department of Bioengineering, College of Engineering, Temple University, 1947 North 12th Street, Philadelphia, PA, 19122, USA.
Meoghan
M
MacPherson
Department of Operative Dentistry, The University of North Carolina at Chapel Hill - School of Dentistry, 436 Brauer Hall, Room 447, Chapel Hill, NC, 27599-7450, USA.
Andrea G
AG
Ferreira Zandona
Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, 1121 West Michigan Street, Indianapolis, IN, 46202, USA.
Richard L
RL
Gregory
D018441:Biofilms / Q000528:radiation effects*; D008027:Light; D013295:Streptococcus mutans / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*