Effect of photoactivated disinfection using a light-emitting diode

Objectives: The aim of the study was to determine the effect of photoactivated disinfection using a light-emitting diode in the red spectrum after application of photosensitizer (PAD-LED) on bacteria involved in the pathogenesis of periodontitis and peri-implantitis. Methods: Fifteen single species (among them 2 Porphyromonas gingivalis and 2 Aggregatibacter actinomycetemcomitans) and a multispecies mixture consisting of 12 species in a final concentration of 10high6 were exposed to PAD-LED for 30 s and 60 s. After that, changes in the viability were determined. Application of each photosensitizer (Ph-S) and 60 s of light emitting (LED) only served as controls. Statistical analysis was made by Student's t-test and ANOVA with Post-Hoc Bonferroni using the log10 values each. Results: Compared to negative controls, the addition of PH-S reduced the cfu counts by 1.11 log stages (p<0.001). This effect was more visible on gram-negative bacteria than on gram-positives (p=0.048). In contrast, exposure to LED did not change the numbers of viable microorganisms. After PAD-LED for 30 s, the cfu counts were 1.42 log stages lower compared to negative control (p<0.001) and 0.31 log stages lower compared to Ph-S (p=0.012) in mean. 60 s PAD-LED reduced further the numbers of viable bacteria, the differences were 1.99 log stages compared to negative control (p<0.001). Focusing on group of microbes (microaerophiles, anaerobes, superinfecting species, multi-species), differences in the sensitivity were visible after 30 s PAD-LED and 60 s PAD-LED (p=0.023 and p=0.004 respectively). The Bonferroni analysis confirmed a higher efficacy against anaerobes after 30 s PAD-LED (p=0.015) as well as microarophiles (p=0.015) and anaerobes (p=0.003) after 60 s PAD-LED compared to superinfecting species each. Conclusion: PAD-LED might be a promising tool in therapy of infections caused by microaerophilic and anaerobic periodontopathogens. The study was supported by CMS Dental, Kopenhagen, Denmark.