Antibacterial action of laser radiation is an important aspect of its multifactorial influences upon biological systems. One of the main etiological factors of inflammatory of periodontal diseases is plaque, which consists of the numerous microorganisms that possess high pathogenicity and adhesiveness on the surface of teeth and invasiveness to tissue structures. The aim of our study was a comparative study of the sensitivity of E. coli to low level laser radiation of blue and red spectrums in experiments in vitro.

During the research, oral microflora was examined in 35 patients aged 46-58 years who reported to the clinical diagnosis. The material for microbiological examination was dental plaque and the content of caries cavity.

10 strains of E.coli were allocated from patients with dental caries and parodontitis, which were identified on the basic biochemical activity. Pure cultures isolated from patient and reference strain E.coli АТСС N 25922 were used for further studies on effects of red and blue spectra.

Laser light source was a laser diode module of the blue spectrum with a wavelength of 445 nm. Red laser diode module with a wavelength of 635 nm was used as red light source (exposure: 5, 10, 15, 20 and 30 min) in continuously uninterrupted static regime. After the irradiation the entire volume of the culture (0,1 ml) was passaged with a spatula and incubated at 37 °C. After 24 hours the number of colonies was counted and the results were compared with the E.coli of the control group that was not subjected to the exposure.

According to the results, at irradiation with a 635 nm wavelength laser beam increase of quantitative properties was observed with the preservation of characteristics in E. coli isolated from the oral cavity of patients with dental caries and parodontitis. The application of red laser spectrum was during 5 min influence on the bacteria growth. The measurement finding was 42.4 ± 1.2×103 CFU/ml for bacteria isolated from patients with dental caries, while in material from patients with parodontitis it was 44.9 ± 1.4×103 CFU/ml (p < 0.001), for reference strain E.coli it was 41.6±1.1×103 CFU/ml. During the irradiation for 30 min the number of E.coli isolated from patients with dental caries made 34.7 ± 0.8×103 CFU/ml (p ˃ 0.05), whereas in the material taken from patients with periodontitis the number of the specified bacteria made 32.5 ± 1.2×103 CFU/ml (p < 0,05). In the control group the number of E.coli was 35,9 ± 1.4×103 CFU/ml for caries and 35.1 ± 1.4×103 CFU/ml (p < 0.05).

According to the data it was established that upon irradiation with a laser beam with a wavelength of 445 nm, an increase of quantitative indicators was achieved during the irradiation for 5 min, the intensity of microorganisms growth constituted 62.8 ± 1.3×103 CFU/ml isolated from patients with dental caries, and material from patients with parodontitis was made 52.9 ± 1.2×103 CFU/ml (p < 0,001). Differences among mean survival for the group were quite low for 30 min influence. During the irradiation the intensity of E. coli growth made 15.1 ± 1.0×103 CFU/ml (caries) and 25.7 ± 1.3×103 CFU/ml (parodontitis), respectively. The intensity of reference strain E.coli growth was 17.4 ±1.6×103 CFU/ml (p < 0.001).

The results of our study demonstrated that growth of E.coli isolated from carious cavities and parodontal pockets upon exposure to low-level laser radiation with a red and blue spectra. It was found that low-level laser radiation can cause both depression and stimulating influence on the growth of the bacterial isolated from patients with caries and parodontits during the beam power of 700 mW.

Ключові слова: low-level laser radiation, caries, parodontitis, Ecsherichia coli

Повний текст: PDF (Ukr)

1. 1. Junqueira J, Ribeiro M, Rossoni R, Barbosa J, Querido S, Jorge A. Antimicrobial Photodynamic Therapy: Photodynamic Antimicrobial Effects of Malachite Green on Staphylococcus, Enterobacteriaceae, and Candida. Photomed. Laser Surg. 2010;28(1):67-72.
2. 2. Bayramov G. Research of periodontal pathogenic and its etiological importance in the formation of different clinical forms of inflammatory periodontal diseases.Clinical dentistry. 2010;2(54):84-86.
3. 3. Chereda V. Microflora as a factor of inflammatory of periodontal diseases. Ukrainian dental Almanac. 2007;1:77-79.
4. 4. Convissar R. The biologic rationale for the use of lasers in dentistry. Dent. Clin. N. Amer. 2004;48(4):771-794.
5. 5. Makhlouf M, Dahaba M, Tunér J, Eissa S, Harhash T. Effect of Adjunctive Low Level Laser Therapy (LLLT) on Nonsurgical Treatment of Chronic Periodontitis. Photomed. Laser Surg. 2012;30(3):160-166. doi.org/10.1089/pho.2011.3069
6. 6. Sezer U, Eltas A, Ustun K, Aras M. Effects of Low-Level Laser Therapy as an Adjunct to Standard Therapy in Acute Pericoronitis, and its Impact on Oral Health-Related Quality of Life. Photomedicine and Laser Surgery. 2012;30(10):592-597. doi.org/10.1089/pho.2012.3274
7. 7. Kucharska O, Korol M. The microbiological balance of the oral cavity in patients with periodontitis.Ukrainian dental Almanac. 2007;1:58-61.
8. 8. O'Neill J, Hope C, Wilson M. Oral Bacteria in Multi-Species Biofilms Can be Killed by Red Light in the Presence of Toluidine Blue. Lasers Surg. Med. 2002;31(2):86-90.
9. 9. Panas М. Efficiency of applying low-level laser radiation against Streptococcus salivarius in case of hard dental tissue lesions. The new Armenian Medical Journal. 2014;8(3):68-73.
10. 10. Raffetto N. Lasers for initial periodontal therapy. Dent. Clin. N. Amer. 2004;48(4):923-936.
11. 11. Redinova T, Ivanova L, Martyusheva O, Cherednikova L, Cherednikova A. Microbiological and clinical characteristics of oral cavity disbioticststus. Stomatologiia (Mosk). 2009;6:12-18.
12. 12. Soukos N, Goodson J. Photodynamic therapy in the control of oral biofilms. Periodontology. 2011;55(1):143-166. doi.org/10.1111/j.1600-0757.2010.00346.x