Diode Laser Irradiation in Endodontic Therapy through Cycles – in vitro Study

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Dijana Trišić1 / Bojana Ćetenović1 / Igor Jovanović2 / Elizabeta Gjorgievska3 / Branka Popović4 / Dejan Marković1

1Clinic for Paediatric and Preventive Dentistry, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia
2Department of Electronics, Faculty of Electronic Engineering, University of Niš, Niš, Serbia
3Faculty of Dentistry, University “Ss Cyril and Methodius” Skopje, Skopje, FYRM, Macedonia
4Institute of Human Genetics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia


Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm), at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

Keywords: Diode Laser; Endodontics; Bactericidal; Temperature Variations; External Root Surface


  1. Nair PN. Pathogenesis of apical periodontitis and the causes of endodontic failures. Crit Rev Oral Biol Med, 2004;15:348-381.[Crossref]
  2. Neelakantan P, Cheng CQ, Mohanraj R, Sriraman P, Subbarao C, Sharma S. Antibiofilm activity of three irrigation protocols activated by ultrasonic, diode laser or Er:YAG laser in vitro. Int Endod J, 2015;48:602-610.[Web of Science][Crossref]
  3. Fedorowicz Z, Nasser M, Sequeira-Byron P, de Souza RF, Carter B, Heft M. Irrigants for non-surgical root canal treatment in mature permanent teeth. Cochrane Database Syst Rev, 2012:Cd008948.[Web of Science]
  4. Bago I, Plecko V, Gabric Panduric D, Schauperl Z, Baraba A et al. Antimicrobial efficacy of a high-power diode laser, photo-activated disinfection, conventional and sonic activated irrigation during root canal treatment. Int Endod J, 2013;46:339-347.[Web of Science][Crossref]
  5. Alfredo E, Marchesan MA, Sousa-Neto MD, Brugnera- Junior A, Silva-Sousa YT. Temperature variation at the external root surface during 980-nm diode laser irradiation in the root canal. J Dent, 2008;36:529-534.[Web of Science]
  6. da Costa Ribeiro A, Nogueira GE, Antoniazzi JH, Moritz A, Zezell DM. Effects of diode laser (810 nm) irradiation on root canal walls: thermographic and morphological studies. J Endod, 2007;33:252-255.[Web of Science]
  7. Machida T, Wilder-Smith P, Arrastia AM, Liaw LH, Berns MW. Root canal preparation using the second harmonic KTP:YAG laser: a thermographic and scanning electron microscopic study. J Endod, 1995;21:88-91.
  8. Nammour S, Kowaly K, Powell GL, Van Reck J, Rocca JP. External temperature during KTP-Nd:YAG laser irradiation in root canals: an in vitro study. Lasers Med Sci, 2004;19:27-32.[Crossref]
  9. Berutti E, Marini R, Angeretti A. Penetration ability of different irrigants into dentinal tubules. J Endod, 1997;23:725-727.
  10. Kouchi Y, Ninomiya J, Yasuda H, Fukui K, Moriyama T, Okamoto H. Location of Streptococcus mutans in the dentinal tubules of open infected root canals. J Dent Res, 1980;59:2038-2046.[Crossref]
  11. Schoop U, Kluger W, Dervisbegovic S, Goharkhay K, Wernisch J, Georgopoulos A et al. Innovative wavelengths in endodontic treatment. Lasers Surg Med, 2006;38:624-630.[Crossref]
  12. Schoop U, Kluger W, Moritz A, Nedjelik N, Georgopoulos A, Sperr W. Bactericidal effect of different laser systems in the deep layers of dentin. Lasers Surg Med, 2004;35:111-116.[Crossref]
  13. Eriksson AR, Albrektsson T. Temperature threshold levels for heat-induced bone tissue injury: a vital-microscopic study in the rabbit. J Prosthet Dent, 1983;50:101-107.[Crossref]
  14. Hmud R, Kahler WA, Walsh LJ. Temperature changes accompanying near infrared diode laser endodontic treatment of wet canals. J Endod, 2010;36:908-911.[Web of Science]
  15. Hmud R, Kahler WA, George R, Walsh LJ. Cavitational effects in aqueous endodontic irrigants generated by nearinfrared lasers. J Endod, 2010;36:275-278.
  16. Beer F, Buchmair A, Wernisch J, Georgopoulos A, Moritz A. Comparison of two diode lasers on bactericidity in root canals–an in vitro study. Lasers Med Sci, 2012;27:361-364.[Crossref][Web of Science]
  17. Kreisler M, Kohnen W, Beck M, Al Haj H, Christoffers AB, Götz H et al. Efficacy of NaOCl/H2O2 irrigation and GaAlAs laser in decontamination of root canals in vitro. Lasers Surg Med, 2003;32:189-196.[Crossref]
Citation Information: Balkan Journal of Dental Medicine, ISSN (Online) 2335-0245, DOI: https://doi.org/10.1515/bjdm-2017-0016. Export Citation