Fifteen patients will be included in this group. Tongue scraping will be performed by the same operator in all patients. Posterior-anterior movements will be performed with the scraper over the lingual dorsum, followed by cleaning the scraper with a gauze. This procedure will be performed ten times in each patient, in order to standardize the mechanical removal of the tongue coating.

Fifteen patients will be included in this group. One session of aPDT will be performed with the photosensitizer (PS) urucum manipulated at a concentration of 20% (Fórmula e Ação®) in spray, to be applied in sufficient quantity to cover the middle third and back of the tongue (5 sprinkles) for 5 minutes for incubation. The excess will be removed with a sucker in order to keep the surface wet with the PS itself, without using water. Six points with a distance of 1 cm between them will be irradiated, considering the halo of light scattering and effectiveness of aPDT. The apparatus shall be precalibrated at wavelength 440-480nm for 60 seconds per point, irradiance of 450mW/cm and the light shall be irradiated so that a halo of 2cm diameter is formed per point.

Tongue scraping will be performed by the same operator in all patients. Posterior-anterior movements will be performed with the scraper over the lingual dorsum, followed by cleaning the scraper with a gauze. This procedure will be performed ten times in each patient, in order to standardize the mechanical removal of the tongue coating. After, one session of aPDT will be performed with the photosensitizer (PS) urucum manipulated at a concentration of 20% (Fórmula e Ação®) in spray, to be applied in sufficient quantity to cover the middle third and back of the tongue (5 sprinkles) for 5 minutes for incubation. Six points with a distance of 1 cm between them will be irradiated, considering the halo of light scattering and effectiveness of aPDT. The apparatus shall be precalibrated at wavelength 440-480nm for 60 seconds per point, irradiance of 450mW/cm and the light shall be irradiated so that a halo of 2cm diameter is formed per point.

Tongue scraping will be performed by the same operator in all patients. Posterior-anterior movements will be performed with the scraper over the lingual dorsum, followed by cleaning the scraper with a gauze. This procedure will be performed ten times in each patient, in order to standardize the mechanical removal of the tongue coating.

Oral air collection will follow the manufacturer's guidelines (Oral ChromaTM Manual Instruction) where the participant will be instructed to rinse with cysteine (10 mM) for 1 minute, then remain with his/her mouth closed for 1 minute. A syringe from the same manufacturer for collection of mouth air will be introduced into the patient's mouth. During 1 minute the patient will remain closed mouth, breathing through the nose, without touching the syringe with the tongue. The plunger will be pulled out, we will re-empty the syringe air into the patient's mouth and again pull the plunger to fill the syringe with the breath sample. We will wipe the tip of the syringe with gauze to remove moisture from the saliva, place the gas injection needle in the syringe, and adjust the plunger to 0.5 ml. The gases collected at the entrance door of the appliance are injected in a single movement. This procedure will be done before and immediately after treatment.

The microbiological analysis of tongue coating will be performed by collecting biofilm samples from the region of the lingual dorsum with a 1μl inoculation loop. Samples will be transferred into individual vials containing 1.5 ml of reduced transport fluid and vortexed for approximately 30 seconds. After homogenisation, the ten-fold dilution series will be prepared in 180μl sterile PBS solution and 10-2, 10-3, 10-4 and 10-5 aliquots, transferred to BHI agar plates. Considering that the main bacteria responsible for the production of CSV are Gram-negative and anaerobic, plaques will be incubated in an anaerobic jar for 72 h at 370 C, for counting of the colony-forming units (CFU) and comparison of the numbers before and immediately after treatment.