The goal of this clinical trial is to examine the efficacy of mouthwash containing 0.045% cetylpyridinium chloride (CPC) on oral health-related parameters] in [healthy conditions]. The main question[s] it aims to answer are:

• [ Trial 1: effect of immediate-use mouthwash containing CPC vs. non-CPC]
• [Trial 2: effect of concentrated-use mouthwash containing CPC vs. non-CPC] Participants will be treated by mouth wash 3 times a day for 4-weeks If there is a comparison group: Researchers will compare CPC containing mouthwash group and sham mouthwash groups treated with non CPC-containing mouthwash to see the effect of CPC on plaque index, mouth smell, gingival index and tongue coating index.

2.1. Participants In all, 100 subjects were recruited to this clinical study according to the following inclusion criteria: i) Healthy male or female; ii) presence of >20 existing teeth (the number of remaining teeth); iii) no severe pathological soft tissue conditions, periodontitis, or extensive dental plaque; iv) Turesky modification of the Quigley-Hein Plaque Index (PI) of over 1.5 and Loe & Silness Gingival Index (GI) of over 1.5; vi) able to perform oral care/hygiene tasks on his/her own; vii) voluntary participation; and viii) willing to comply with the test protocol. Participants were excluded if they had any kind of visible or known disease requiring prophylactic antibiotic use.

2.2. Study design This was a randomized, controlled, double-blind clinical trial, and the intervention was gargling with the OR twice daily. The participants were randomly divided into four groups: control 1 (C1) (n=19), immediate-use CPC (IUC) (n=16), control 2 (C2) (n=19), and concentrated-use CPC (CUC) groups (n=19). Both C1 and C2 received ORs without CPC, whereas the experimental groups IUC and CUC received CPC ORs of different formulations (Amway Korea Ltd., Seoul, Republic of Korea). Randomized clinical trials (RCTs) are analyzed according to the intention-to-treat (ITT) principle and the per-protocol (PP) approach. ITT aims to assess the experimental design and PP analysis investigates the effect of receiving an assigned treatment. The participants underwent dental scaling before starting the intervention. Ethical approval was granted by the Institutional Research Ethics Review Board, Yonsei University, Wonju Severance Christian Hospital (IRBN CR321058) 2.3. Intervention After obtaining baseline information and randomizing the participants into two groups, dental scaling was performed, followed by clinical treatment. The participants were instructed to gargle twice daily for 7 days. All the participants were instructed not to eat or drink anything for at least 4 hours before the experiment. Oral hygiene, such as gargling and tooth brushing, was prohibited for 8 hours before the visit.

2.4. Measurment of H2S and methyl mercaptan, Quigley-Hein plaque index, Gingival Index,Tongue Coating Index.

Inclusion Criteria:

• Healthy male or female;
• presence of >20 existing teeth (the number of remaining teeth);
• no severe pathological soft tissue conditions, periodontitis, or extensive dental plaque;
• Turesky modification of the Quigley-Hein Plaque Index (PI) of over 1.5 and Loe & Silness Gingival Index (GI) of over 1.5; • able to perform oral care/hygiene tasks on his/her own;
• voluntary participation; and viii) willing to comply with the test protocol.

Exclusion Criteria:

• They excluded if they had any kind of visible or known disease requiring prophylactic antibiotic use.

Mouthwah solution was provided by sponsor who packed experimental and control solution in the bottle. Investigator and participants did not know the contents during treatment period.