Grouping for the clinical trial
swelling
Thirty applicants who met the inclusion criteria were recruited. They were scaled and their group (MCOI vs. control group) was determined by randomization. In the first phase, 2 weeks later, all participants in the MCOI and control groups collected unstimulated whole saliva for a volume of 2–3 mL before the clinical measurements (the PI, SBI, BOP, and existence of swelling). All participants (from both groups) rinsed their mouths with one cup of tap water before the clinical examination and then held their saliva in their mouths until it flowed naturally into a 10 mL tube (Axygen Scientific, Union City, CA, US). They were told to keep spitting and collecting approximately 2–3 mL of saliva in a tube, which was immediately stored at − 80 °C.Next, for 3 days, in the MCOI group, participants used the new oral irrigator device twice a day (in the morning and before bed) for 3 min at medium intensity. In the control group, the participants did not brush their teeth for 3 days, even after meals, before the second phase. The standard method was explained to the MCOI group participants as follows: 1. You can eat normally, with the exception of gum. 2. You should refrain from brushing your teeth. 3. Other than the MCOI provided, no other cleaning products may be used.Participants in the control group were also strictly instructed to adhere to the following: 1. Except for gum, you can eat normally. 2. You should refrain from brushing your teeth. 3. No other cleaning products are permitted. 4. Gargle lightly with tap water three times before going to bed.All participants were instructed as above, and in the second phase, saliva collection and clinical examinations were repeated as in the first phase.