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Modified Photo-activated Disinfection Technique for Eliminating Root Canal Bacteria Using Multiple-wavelength Lasers
Kaushik Haridas1, Madhu Hariharan2, Anju Varughese3
1Department of Conservative Dentistry and Endodontics, Amrita School of Dentistry, Amrita Institute of Medical Sciences and Research Centre, Amrita Vishwa Vidyapeetham, AIMS, Kochi, Kerala, India,
Aim And Background:
To evaluate the antimicrobial efficacy of photosensitizers (PS) absorbing blue light (450 nm), red laser (650 nm), and infrared laser (808 nm) activated using radial firing tip in root canal disinfection.
Materials And Methods:
Eighty mandibular premolars extracted for orthodontic purposes were stored in the saline solution until use. The extracted teeth were instrumented per protocol using the WaveOne Gold file system in reciprocating motion. Enterococcus faecalis was inoculated, and the samples were incubated for 5 days. They were randomly divided into four groups: Group I - photodynamic therapy (PDT) with toluidine blue (TBO) and 650 nm [200mW power, continuous wave (CW)], group II - indocyanine green (ICG) and 808 nm (300 mW, CW), group III - curcumin irrigant and 450 nm (300mW, CW), and group IV (control group) - 5.25% sodium hypochlorite (NaOCl) ultrasonically activated with EndoActivator (Dentsply Maillefer, Switzerland). The irradiation was done using a 200-µm radial firing tip. After irrigation with saline, the root canal content was diluted and plated on brain heart infusion agar. The colony forming units (CFU) were counted after 24 hours. The data was recorded and statistically analyzed.
Results:
Group I showed the highest CFU (5.40 log 10 ± 0.34), and group IV showed the least CFU (4.32 log 10 ± 0.67); however, group II when compared with group III was not statistically significant (p-value 0.446), and group I and group III when compared with group IV had significantly (p-value of 0.001, < 0.02, and 0.021, respectively) higher CFU. However, group II, when compared with group III, was not statistically significant (p-value 0.446).
Conclusion:
The present study showed that NaOCl, along with ultrasonic activation (group IV) have shown to be effective, followed by PDT using 450 nm with curcumin (group III) and 808 nm with ICG (group II), and least effective was 650 nm with TBO (group I). The application of a diode laser with a radial firing tip of 200 µm can be an adjunct to the disinfection protocols currently followed.
Clinical Significance:
For successful endodontic treatment, the complete disinfection of the root canal system is inevitable. Sodium hypochlorite irrigant with ultrasonic activation has been shown to have a significantly reduced bacterial count, yet it may not achieve complete disinfection of the root canal system. For effective healing of the periradicular tissues and to obtain sterile root canals for endodontic therapy, adjuvant irrigants and irrigation devices can be used, as the cytotoxicity of PS like curcumin is less compared with NaOCl. Hence, PS (curcumin and ICG) and laser devices with 200-µm radial firing tips can be a novel irrigation protocol for effective endodontic management of infected teeth. How to cite this article: Haridas K, Hariharan M, Varughese A, et al. Modified Photo-activated Disinfection Technique for Eliminating Root Canal Bacteria Using Multiple-wavelength Lasers with Radial Firing Tip: An Ex Vivo Study. J Contemp Dent Pract 2025;26(5):453-457.
