The aim of this study is to compare the effectiveness of two methods of treating bad breath. Patients are enrolled in the study based on an objective test using the Oral Chroma Device, which measures the concentration of volatile sulfur compounds in exhaled air, which are responsible for bad breath. Before the test begins, a sample will also be taken from the tongue to determine the total number of microorganisms. Patients are then randomly assigned to two groups.

Control group: Cleaning the tongue with a tongue scraper and rinsing the mouth with an antiseptic mouthwash.

Intervention group: Cleaning the tongue with a tongue scraper and antibacterial laser therapy on the tongue.

Then, all study participants will undergo a procedure to clean tartar from all their teeth.

Questions to be answered by the study: Will there be a decrease in the concentration of volatile sulfur compounds in exhaled air after treatment? Will the treatment results obtained after laser therapy be better compared to the classic method of treating bad breath? Cleaning procedures within the tongue will be performed at the beginning, then repeated after one week, two weeks, and 3 months from the baseline.

After each stage, the concentration of substances in exhaled air that are responsible for bad breath will be measured. Samples will be taken from the tongue to determine the total number of microorganisms before the first tongue cleaning, and then after 2 weeks from the intervention.

Inclusion Criteria:

• Participants diagnosed with halitosis based on an objective exhaled sulfhydryl (H2S) concentration of ≥ 112 ppb (1.5 ng/10 mL) determined by gas chromatography (Oral Chroma) and who signed an informed consent form previously approved by the Bioethics Committee were included in the study.

Exclusion Criteria:

The study excluded patients with a history of the following diseases:

• otolaryngological, i.e., chronic tonsillitis (presence of tonsil plugs), chronic sinusitis, head and neck cancer
• gastrointestinal, i.e., Helicobacter Pylori infection, esophageal diverticulitis, pyloric sphincter insufficiency, severe gastroesophageal reflux disease
• pulmonary, i.e., bronchitis, bronchiectasis, lung cancer - metabolic, i.e., diabetes, uremia, chronic renal failure, and liver disease as well as individuals taking pharmacotherapies such as antihistamines, steroids, anticholinergics, antispasmodics, alcohol consumers, smokers, and those suffering from severe obesity.
• on antibiotic or antifungals treatment up to 1 month before the survey,
• pregnant Additinaly indyviduals with local abnormalities were excluded: using a removable device, implant and/or prosthesis, with carious lesions, during orthodontic and/or orthopedic treatment, with hypersensitivity to the photosensitizer to be used.