Photobiomodulation effects of pulsed and continuous wave near-infrared laser on the proliferation and migration of human gingival fibroblasts: An in vitro study.

There are limited data on comparison of pulsed and continuous wave in photobiomodulation therapy (PBM). This study aimed to investigate the effect of PBM with 980 nm laser in pulsed and continuous wave on the proliferation and migration of human gingival fibroblasts (HGF) cells. Cultured HGF were divided into three main groups: (1) irradiated in pulsed mode (frequencies of 50 and 25 KHz; energy densities of 3 and 5 J/cm2 ), (2) irradiated in continuous mode (energy densities of 3.2 and 5.2 J/cm2 ), and (3) no irradiation as control group. HGF proliferation rate was measured by MTT assay at 24, 48, and 72 h post irradiation. In addition, HGF migration rate was measured by scratch test at 24 h post PBM. At 24 h, the group received continuous irradiation at 5.2 J/cm2 showed significantly higher proliferation compared with the control group (p = 0.012). At 48 and 72 h, the groups received continuous, and 50 Hz pulsed irradiation at energy densities of 5.2 and 5 J/cm2 respectively, had significantly higher HGF proliferation rates compared to the control (p < 0.05). Only the continuous irradiations were effective in significant increase of the cell migration. In conclusion, continuous PBM at energy density of 5.2 J/cm2 showed promising effect on HGF proliferation and migration.

Antibacterial Efficacy of Cold Atmospheric Plasma, Photodynamic Therapy with Two Photosensitizers, and Diode Laser on Primary Mandibular Second Molar Root Canals Infected with Enterococcus faecalis: An In Vitro Study.

Objectives: This study aimed to compare the antibacterial efficacy of cold atmospheric plasma (CAP), photodynamic therapy (PDT) with two photosensitizers (PSs), and diode laser for disinfection of primary mandibular second molar root canals infected with Enterococcus faecalis (E. faecalis). Materials and Methods: In this in vitro experimental study, 50 primary second primary molars underwent chemomechanical preparation of root canals. The root canals were then inoculated with E. faecalis. After 3 weeks of incubation, the teeth were randomly assigned to five groups of CAP, 940 nm diode laser, PDT with 445 nm laser and curcumin PS, PDT with 660 nm laser and methylene blue (MB) PS, and 2.5% sodium hypochlorite (NaOCl). Samples were collected from the vortexed root canals and cultured on agar, and the number of colonies was counted. Data were analyzed by one-way analysis of variance. Results: The percentage of reduction in bacterial count was significantly different among the study groups (P < 0.001). The highest reduction in bacterial count was noted in 2.5% NaOCl and the lowest in 940 nm diode laser group. The difference in bacterial count reduction between 445 nm laser + curcumin and 660 nm laser + MB (P = 0.989), and CAP and NaOCl (P = 1.000) groups was not significant. Conclusion: CAP was found to be more effective than PDT and diode laser as an adjunct to mechanical root canal disinfection of primary molars for elimination of E. faecalis and can serve as an alternative to 2.5% NaOCl irrigation.

In Vitro Effect of 445 nm Blue Laser and 660 nm Low-Level Laser on the Quantity and Quality of Human Gingival Fibroblasts.

Low-level laser therapy (LLLT) has several benefits in dentistry, including anti-inflammatory effects and increased proliferation. This study aimed to investigate the effect of 445 nm blue laser and 660 nm low-power laser on the quantity and quality of human gingival fibroblasts in vitro. In this in vitro experimental study, 445 nm and 660 nm lasers were irradiated on the samples six times. After examining the cells on the 7th and 14th days, the data were analyzed using ANOVA PASS11 and the post hoc Tukey test. The results showed the positive effect of the 660 nm laser on fibroblast proliferation. The viability on the 7th day was the highest in the control group, lowest in the 445 nm laser group and highest in the 660 nm laser group on the 14th day. In the morphological examination, the cells were spherical with narrow appendages in the control group, spindle-shaped with lamellipodia appendages in the 660 nm laser group and spherical with no cytoplasmic appendages in the 445 nm laser group. Evidence of necrosis and granulation phenomenon was observed in the 445 nm laser group. The use of the 660 nm low-power laser, compared with the 445 nm laser, has a positive effect on the quantity and quality of gingival fibroblasts.

In vitro Effect of Photodynamic Therapy with Curcumin and Methylene Blue Photosensitizers on Staphylococcus Aureus.

Statement of the Problem: Staphylococcus aureus (S.A) can colonize in the skin, nasal cavity, and oral cavity. In the oral cavity, it can cause dental caries and periodontal disease. Mouthwashes can be used as an adjunct to mechanical plaque control methods to decrease the load of oral microorganisms. Chlorhexidine (CHX) is a commonly used antimicrobial mouthwash with side effects such as changing the sense of taste, tooth discoloration, oral mucosal burning, allergy, and xerostomia. It also has adverse systemic effects, if swallowed. Purpose: This study aimed to assess the effect of photodynamic therapy (PDT) with curcumin and methylene blue (MB) photosensitizers and different laser parameters on S.A colony count. Materials and Method: In this in vitro experimental study, 99 samples of standard-strain S.A were subjected to PDT with curcumin and MB photosensitizers with/without irradiation of 660 and 445 nm laser with different exposure parameters, and CHX in 9 groups (n=11). The samples were cultured in microplates containing Mueller-Hinton agar, and the number of colony forming units (CFUs) was counted after 24 h of incubation at 37°C. Data were analyzed by the Kruskal-Wallis and Dunn tests. Results: The minimum colony count was noted in CHX group (CFUs=0) followed by MB and 660nm diode laser group irradiated for 100 s (CFUs=147.2727±169.35707). The difference in this respect was significant between MB+660nm diode laser for 100 s and other groups (p< 0.05) except for the MB + 660 nm diode laser for 60 s group. Conclusion: CHX is superior to laser for elimination of S.A. However, PDT with 660 nm diode laser + MB has considerable antimicrobial efficacy against S.A; increasing the duration of laser irradiation enhances the antimicrobial effect.

Effect of low-level laser therapy on postoperative pain after single-visit root canal retreatment of mandibular molars: A randomized controlled clinical trial.

AIM: To compare the effect of low-level laser therapy (LLLT) on postoperative pain after single-visit root canal retreatment on mandibular molars. METHODOLOGY: This randomized controlled clinical trial included 36 patients referred to the Department of Endodontics, Islamic Azad University, Tehran, Iran. Healthy patients who required root canal retreatment on symptomatic first or second mandibular molars, with a PAI index score of 2 or 3, preoperative tooth and percussion pain of <56 mm on a 170-mm visual analogue scale (VAS) were included. After local anaesthesia using inferior alveolar nerve block followed by rubber dam isolation and access cavity preparation, the D RaCe retreatment system was used to remove the existing root filling material, and after canal negotiation and gaining patency, working length was determined with an apex locator. Further canal enlargement was carried out with size 35, 0.04 taper, and size 40, 0.04 taper RaCe rotary instruments and then canals were filled using laterally compacted gutta-percha points and AH Plus sealer. The patients were randomly assigned to treatment groups: In the LLLT group, a 980-nm diode laser set at 6.89 W/cm2 energy density, 0.5 W power, and a tip diameter of 10 mm were activated from the buccal side on the mesial and distal root apices for 15 s. In the sham group, the laser handpiece was placed inside the patient's mouth at the same location, but the laser was not activated. Then patients were instructed to record their postoperative pain levels at 4, 8, 12 and 24 h and 2, 3 and 7 days after treatment on separate VAS scales. For data analysis, the independent sample t and the Mann-Whitney U tests were used. Nominal variables were analysed by using the chi-square test. RESULTS: In the LLLT group, the most intense pain was reported 24 and 48 h post-treatment [mean (SD) = 0.22 (0.54) for both], whereas in the sham group, the most intense pain level was observed 4 h post-treatment [mean (SD) = 0.78 (0.80)]. At the 4-h interval, pain intensity was significantly lower in the LLLT group (p = .016). CONCLUSIONS: Low-level laser therapy reduced postoperative pain after single-visit root canal retreatment of mandibular molars only four hours following the procedure.

Comparison of the effect of photodynamic therapy with curcumin and methylene Blue on streptococcus mutans bacterial colonies.

BACKGROUND AND AIM: Streptococcus mutans (S. mutans) is a bacterium that colonizes in the mouth and is a common cause of dental caries and periodontal diseases. This bacterium comprises 70% of the bacteria in the dental plaque. Although tooth decay is a multifactorial complication, S. mutans biofilms are the main cause of cavitated carious lesions. Considering the importance of this microorganism, we aimed at investigating the effect of photodynamic therapy (PDT) using curcumin (CUR) and methylene blue (MB) photosensitizers on S. mutans. MATERIALS AND METHODS: In this in-vitro experimental study, first, samples of S. mutans were prepared in 110 test tubes and were randomly assigned to 11 groups after colony counting: 1) Positive control group, 2) Negative control group, 3) CUR extract group, 4) 460-nm laser group, 5) 460-nm continuous laser + CUR group, 6) 460-nm discontinues 50% duty cycle (DC) laser + CUR group, 7) 660-nm laser group, 8) 660-nm laser + MB group, 9) MB group, 10) dental light-curing group, and 11) chlorhexidine (CHX) group. After the intervention, cultivation was performed again in blood agar medium, and the bacterial colony-forming units per milliliter (CFU/ml) were counted again. Data were analyzed using analysis of variance (ANOVA) and Tukey's test. RESULTS: CHX and 460-nm low-level continuous laser + CUR had the highest and most significant effect on inhibiting the growth of S. mutans bacterial colonies and showed significant differences with other groups (P < 0.001). CONCLUSION: According to the results, MB- and CUR-mediated PDT can significantly eradicate S. mutans colonies.

In vitro comparison of the effect of photodynamic therapy with curcumin and methylene blue on Candida albicans colonies.

BACKGROUND AND AIM: Candida albicans (C. albicans) causes oral fungal infections. Considering the high prevalence of candidiasis, the toxicity of antifungal drugs, and the fungistatic property which develops drug-resistant species, the present study aimed to assess the effect of photodynamic therapy (PDT) with curcumin (CUR) and methylene blue (MB) photosensitizers and lasers with different exposure parameters on C. albicans colonies. MATERIALS AND METHODS: In this in-vitro experimental study, 150 samples of C. albicans standard strain (ATCC 10231) were examined using different combinations of CUR and MB photosensitizers with and without 460-nm and 660-nm laser irradiation with different exposure parameters in 15 groups of 10 samples each. The samples were cultured in microplates containing Sabouraud Dextrose Agar (SDA) medium, and the colony-forming units (CFU) were counted after 24 h of incubation at 37 °C. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test. RESULTS: The maximum number of colonies was noted in the positive control group (CFU = 201,500 ± 42,093), while the minimum number was detected in the 460-nm laser+10.2% CUR group (CFU = 10,100 ± 2558), followed by the nystatin group (CFU = 22,300 ± 5578). There was a significant statistical difference between the 460-nm laser + CUR group and other studied groups (P < 0.0001). CONCLUSION: The 460-nm laser in combination with CUR has the maximum antifungal efficiency against C. albicans.

In Vitro Effect of Zingiber officinale Extract on Growth of Streptococcus mutans and Streptococcus sanguinis.

Background and Objectives. Tooth decay is an infectious disease of microbial origin. Considering the increasing prevalence of antibiotic resistance due to their overuse and also their side effects, medicinal plants are now considered for use against bacterial infections. This study aimed to assess the effects of different concentrations of Zingiber officinale extract on proliferation of Streptococcus mutans and Streptococcus sanguinis in vitro. Materials and Methods. In this experimental study, serial dilutions of the extract were prepared in two sets of 10 test tubes for each bacterium (total of 20). Standard amounts of bacterial suspension were added; 100ƛ of each tube was cultured on prepared solid agar plates and incubated at 37°C for 24 hours. Serial dilutions of the extract were prepared in another 20 tubes and 100ƛ of each tube was added to blood agar culture medium while being prepared. The mixture was transferred to the plates. The bacteria were inoculated on plates and incubated as described. Results. The minimum inhibitory concentration (MIC) was 0.02 mg/mL for S. mutans and 0.3 mg/mL for S. sanguinis. The minimum bactericidal concentration (MBC) was 0.04 mg for S. mutans and 0.6 mg for S. sanguinis. Conclusion. Zingiber officinale extract has significant antibacterial activity against S. mutans and S. sanguinis cariogenic microorganisms.