Oral hygiene index (OHI)
The mean OHI scores at baseline (OHI-0) in the intervention and placebo groups were 1.88 and 1.66, respectively, and the difference was statistically significant (p = 0.001). The mean OHI at four weeks (OHI-3) were 1.41 and 1.42 in the intervention and placebo groups, respectively, in which this difference was not statistically significant (p = 0.489). According to the results of the Friedman test, during the study time, the changes in OHI scores had a statistically significant decreasing trend in both groups (p = 0.001) (Table 
Comparison of the effect of 