The influence of growth medium on the photodynamic susceptibility of Aggregatibacter actinomycetemcomitans to antimicrobial blue light.

The aim of this study was to investigate whether antimicrobial blue light (aBL) can cause the death of Aggregatibacter actinomycetemcomitans (A.a) and to determine the influence of different culture media, specifically brain heart infusion and blood agar, on bacterial survival fraction. An LED emitting at 403 ± 15 nm, with a radiant power of 1W, irradiance of 588.2 mW/cm2, and an irradiation time of 0 min, 1 min, 5 min, 10 min, 30 min, and 60 min, was used. The plates were incubated in microaerophilic conditions at 37 °C for 48 h, and the colony-forming units were counted. The photosensitizers were investigated using spectroscopy and fluorescence microscopy. There was no significant difference between the culture media (p > 0.05). However, a statistical reduction in both media was observed at 30 min (1058 J/cm2) (p < 0.05). The findings of this study suggest that aBL has the potential to kill bacteria regardless of the culture media used. Light therapy could be a promising and cost-effective strategy for preventing periodontal disease when used in combination with mechanical plaque control.

Photobiomodulation therapy preconditioning modifies nitric oxide pathway and oxidative stress in human-induced pluripotent stem cell-derived ventricular cardiomyocytes treated with doxorubicin.

Doxorubicin (DOX) is an anthracycline antibiotic that exhibits high heart toxicity. Human-induced pluripotent stem cell-derived ventricular cardiomyocytes (hiPSC-vCMs) are important in vitro models for testing drug cardiotoxicity. Photobiomodulation therapy (PBMT) is a non-invasive therapy that stimulates cells growth and self-repair using light irradiation. This study aimed to investigate the in vitro effects of PBMT preconditioning on cardiotoxicity induced by DOX. HiPSC-vCMs were treated with PBMT for 500 s, followed by the addition of 2 µM DOX. LED irradiation preconditioning parameters were at 660 nm with an irradiance of 10 mW/cm2, performing 5 J/cm2, followed by 24-h DOX exposure (2 µM). Human iPSC-vCMs treated with 2 µM DOX or irradiated with PBMT composed the second and third groups, respectively. The control group did neither receive PBMT preconditioning nor DOX and was irradiated with a white standard lamp. Cells from all groups were collected to perform mRNA and miRNA expressions quantification. PBMT, when applied before the DOX challenge, restored the viability of hiPSC-vCMs and reduced ROS levels. Although downregulated by DOX, myocardial UCP2 mRNA expression presented marked upregulation after PBMT preconditioning. Expression of eNOS and UCP2 mRNA and NO production were decreased after DOX exposure, and PBMT preconditioning before the DOX challenge reversed these changes. Moreover, our data indicated that PBMT preconditioning lowered the miR-24 expression. Our data suggested that PBMT preconditioning ameliorated in vitro DOX-induced cardiotoxicity on transcription level, restoring NO levels and reducing oxidative stress.

Effects of photobiomodulation in salivary glands of chronic kidney disease patients on hemodialysis.

This randomized placebo-controlled trial evaluates the impact of photobiomodulation (PBMT) on the salivary flow and biochemistry of patients with chronic kidney disease (CKD) on hemodialysis. Forty-four patients on hemodialysis self-responded two questionnaires for oral health and salivary gland function perception. The subjects were evaluated for function of salivary glands and randomly allocated to two groups: PBMT group (three irradiations at 808 nm, 100 mW, 142 J/cm2, and 4 J per site); and placebo group. Patients were submitted to non-stimulated and stimulated sialometry and after the treatment at baseline and 14 days. Salivary volume and biochemical of the saliva were analyzed. At baseline, most subjects had self-perception of poor oral health (52.6%) and salivary dysfunction (63.1%). Clinical exam revealed that 47.3% of subjects presented dry mucosa. PBMT promoted increase of the non-stimulated (p = 0.027) and stimulated saliva (p = 0.014) and decrease of urea levels in both non-stimulated (p = 0.0001) and stimulated saliva (p = 0.0001). No alteration was detected in total proteins and calcium analysis. Patients with kidney disease can present alteration in flow, concentrations, and composition of saliva, affecting oral health, but our findings suggest that PBMT is effective to improve hyposalivation and urea levels in saliva of patients with CKD.

Photodynamic therapy with Bixa orellana extract and LED for the reduction of halitosis: study protocol for a randomized, microbiological and clinical trial.

BACKGROUND: Halitosis is an unpleasant breath odour that can interfere with the professional life, social life and quality of life of people who suffer from it. A modality of treatment that has been increasing in dentistry is antimicrobial photodynamic therapy (aPDT). Bixa orellana, popularly known as "urucum" is a plant native to Brazil. The seeds are used to produce a dye that is largely used in the food, textile, paint and cosmetic industries. The aim of this study is to verify whether aPDT with Bixa orellana extract and blue light-emitting diodes (LEDs) is effective in reducing halitosis. This method will also be compared with tongue scraping, the most commonly used conventional method for tongue coating removal, and the association of both methods will be evaluated. METHODS/DESIGN: A randomized clinical trial will be conducted at the dental clinic of the Universidade Nove de Julho. Thirty-nine patients will be divided by block randomization into three groups (n = 13) according to the treatment to be performed. In Group 1, tongue scraping will be performed by the same operator in all patients for analysis of the immediate results. Patients will also be instructed on how to use the scraper at home. Group 2 will be treated with aPDT with Bixa orellana extract and the LED light curing device: Valo Cordless Ultradent®. Six points in the tongue dorsum with a distance of 1 cm between them will be irradiated. The apparatus will be pre-calibrated at wavelength 395-480 nm for 20 s and 9.6 J per point. In Group 3, patients will be submitted to the tongue scraping procedure, as well as to the previously explained aPDT. Oral air collection with the Oral Chroma™ and microbiological collections of the tongue coating shall be done before, immediately after and 7 days after treatment for comparison. DISCUSSION: Halitosis treatment is a topic that still needs attention. The results of this trial could support decision-making by clinicians regarding aPDT using blue LEDs for treating halitosis on a daily basis, as most dentists already have this light source in their offices. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03346460 . Registered on 17 November 2017.

The influence of red laser irradiation timeline on burn healing in rats.

Low-level laser therapy (LLLT) promotes biomodulation of wound healing and literature reports that light delivery during the inflammation could play a different role compared with latter phases of the healing process. The objective of this study was to investigate whether single dose of a red laser (λ = 660 nm) is different from fractionated delivery protocol in full thickness burns. Two lesions were inflicted on the back of 36 rats. In the fractionated dose group (FG), the lesions were irradiated with 1 J/cm² on days 1, 3, 8, and 10 post-wounding. In the single dose group (SG), the lesions were irradiated with 4 J/cm² on day 1, immediately after injury. Control lesions (CG) received no light and were left to heal spontaneously. Blood flow was measured on days 1, 3, 8, 10, 15, and 21 using laser Doppler flowmetry. Animals were killed on days 3, 8, 10, 15, and 21. Skin specimens were obtained and routinely processed for hematoxylin and eosin. The specimens were evaluated according to differential leukocyte counting and angiogenesis. Statistical analysis was performed, and significance was accepted at p < 0.05. Irradiated groups showed a peak of new vessels on day 15 while, for CG, the peak was on day 21. On day 21, FG exhibited a significantly greater number of cumulative neutrophils while SG showed a higher number of mononuclear cells. Our results confirm that both protocols used accelerate angiogenesis and stimulate leukocyte chemotaxis on burn treatment. In addition, this work suggests that a single-dose LLLT accelerates the inflammatory phase of skin repair.

Low-level laser therapy in burning mouth syndrome patients: a pilot study.

OBJECTIVE: The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on the treatment of burning mouth syndrome (BMS). In addition, the laser effect was compared on the different affected oral sites. MATERIALS AND METHODS: Eleven subjects with a total of 25 sites (tongue, lower lip, upper lip, and palate) affected by a burning sensation were selected. The affected areas were irradiated once a week for three consecutive weeks with an infrared laser (λ = 790 nm). The probe was kept in contact with the tissue, and the mucosal surface was scanned during the irradiation. The exposure time was calculated based on the fluence of 6 J/cm(2), the output power of 120 mW, and the area to be treated. Burning intensity was recorded through a visual analog scale before and after the treatment and at the 6-week follow-up. The percentage of the improvement in symptoms was also obtained. RESULTS: Burning intensity at the end of the laser therapy was statistically lower than at the beginning (p < 0.01). Patients reported an 80.4% reduction in the intensity of symptoms after laser treatment. There was no statistical difference between the end of the treatment and the 6-week follow-up, except for the tongue site. CONCLUSION: Under the investigated parameters, infrared LLLT proved to be a valuable alternative for BMS treatment, providing a significant and lasting reduction in symptoms.

Clinical study of the gingiva healing after gingivectomy and low-level laser therapy.

OBJECTIVE: The purpose of this study was to investigate gingival healing after gingivectomy and adjunctive use of low-level laser therapy (LLLT). BACKGROUND DATA: LLLT has been used in animal experiments to examine the influence of laser radiation on the wound healing process since the 1960s. However, clinical trials in dentistry are scarce, and most of them refer to treatment after extraction of the third molars, with only a few reports in the area of periodontics. METHODS: Twenty patients with periodontal disease were selected, and treatment was planned for gingivectomy to bilateral maxillary and mandibular premolar teeth. After surgery, one side was submitted to LLLT using a 685-nm wavelength, output power of 50 mW, and energy density of 4 J/cm(2). The other side was used as the control and did not receive laser irradiation. Healing was evaluated, clinically and biometrically, immediately post-surgery and at days 3, 7, 14, 21, 28, and 35. Results were submitted to statistical analysis. RESULTS: Biometrical evaluation indicated a significant improvement in healing for the laser group at 21 and 28 days. Clinical evaluation showed better repair for the laser group, mainly after the third day. CONCLUSION: LLLT was an effective adjunctive treatment that appeared to promote healing following gingivectomy.