Morning bad breath (MBB) is often an enduring upset; this double blind, crossover, randomized study aimed to evaluate the bad breath-suppressing of 3 commercially available mouth rinses (Mentadent Professional® 0.05%chlorhexidine (MPc), Meridol® Halitosis (MH) and CB12®) and a placebo on morning halitosis during a washout period of 1 week.

The study was designed as a double-masked, four-group, randomized, crossover clinical trial.

The volunteers were randomly assigned. Randomization was performed using computer generated random numbers. The allocation of active or control solutions was undertaken by a person not directly involved in the research project. No changes to methods after trial commencement (such as eligibility criteria) were performed.

Participants Thirty-six nondental student volunteers (17 women and 15 men; age range 34-22 years old; mean age 27,7) participated in the study. The subjects were recruited through advertisements. All of the candidates were screened for suitability by the research team. The selection criteria were: Good general health condition, dentition with ≥20 evaluable teeth (minimum of five teeth per quadrant), no oral lesions, no severe periodontal problems (no probing depth ≥5 mm or attachment loss >2 mm), and no removable prostheses or orthodontic bands or appliances. Persons allergic to several mouthwash components were excluded from the study. All eligible volunteers were given oral and written information about the products and the purpose of the study and were asked to sign an informed consent form. The study was conducted from 3 September 2018 to 10 December 2019 in the Division of Periodontology, University of L'Aquila.

During the first information meeting, at each participant was given the mouthwash samples to be tested and a sealed envelope in which the sequence to follow was specified. The sequence also included the use of a placebo. The subjects were asked not to change their eating habits, but to refrain from taking halogen substances on the evenings prior the evaluations.

About 12 hours before the analysis, the participants, refraining from oral hygiene practices, performed a 30-second rinse, followed by a gargle. They also committed themselves not to take food or drinks, not to brush their teeth, not to smoke and not to use cosmetics (their fragrances could have disturbed the operator's perception of odours), between this practice and the evaluation.

The following morning the values of hydrogen sulphide, methyl mercaptan and dimethyl sulphide were measured and the values of the Rosenberg scale (0. Absence of odor;1. Barely perceptible odor;2. Slight but clearly perceptible odor;3. Moderate odour; 4. Very annoying smell; 5. Extremely bad smell) and the Winkel index (0. Absence of patina;1. Slight presence of patina; 2. Considerable presence of patina) were assigned. The assessment of morning halitosis was carried out through organoleptic measurement with a lingual patina supervision and with the aid of a dedicated device, the Oral Chroma.

Inclusion Criteria:

• age between 20 and 50 years old

Exclusion Criteria:

• oral lesions
• severe periodontal problems (probing depth ≥5 mm or attachment loss >2 mm)
• removable prostheses or orthodontic bands/ or appliances
• Subjects allergic to several mouthrinse