Following the completion of a comprehensive periodontal charting, and prior to assigning the patient to one of the two experimental groups, patients will undergo an Oral Hygiene Instruction and Motivation (OHIM) session using a manual toothbrush, individualized interdental brushes, and a commercially available toothpaste containing sodium fluoride. Subsequently, a professional mechanical plaque removal (PMPR) will be performed by the operator, consisting of a conventional dental hygiene session.

In treatment Test 1 patients will receive mouthwash containing 0.12% CHX (Chlorhexidine). Each patient will be instructed to use the assigned mouthwash twice a day (15 ml for 30 s) after common practices of home oral hygiene. Follow-up visits will occur at 1, 2, 3, and 6 months, during which participants will be clinically examined. Microbiological samples will be collected at 1, 2, and 3 months.

After completing a thorough periodontal charting and before allocating patients to one of the two experimental groups, they will receive an Oral Hygiene Instruction and Motivation (OHIM) session using a manual toothbrush, personalized interdental brushes, and a commercially available toothpaste containing sodium fluoride. Following this, an operator will conduct a professional mechanical plaque removal (PMPR), which entails a standard dental hygiene procedure.

In Treatment Test 2 patients will receive mouthwash containing 0.05% CHX (Chlorhexidine) and 0.05% CPC (Cetylpyridinium Chloride) as the main active ingredients in a patented formulation with optimized bioavailability and they will be instructed to use it twice daily (15 ml for 30 s) following their regular home oral hygiene routine.

Follow-up appointments will be scheduled at 1, 2, 3, and 6 months for clinical examinations of participants, with microbiological samples being collected at 1, 2, and 3 months.

Following the execution of a full mouth periodontal chart, the delivery of oral hygiene instructions and motivation and a session of full mouth ultrasonic debridement, patients, according to the allocation group, will receive a 0.2% CHX mouthwash. Patients will be instructed to use the delivered mouthwashes twice a day (15 ml for 30 seconds).

Evaluate the additional effect on bleeding on probing of one month application of 0.12% CHX or 0.05% CHX + 0.05% CPC following a professional mechanical plaque removal (PMPR) session for a clinical evaluation period of 6 months in patients undergoing supportive periodontal therapy (gingivitis with reduced periodontium).

The DNA from subgingival samples will be used to sequence the V3-V4 region of the 16S rRNA gene and will be analyzed using PCR (Polymerase Chain Reaction). The amplicons will be purified and sequenced.