This study was conducted to evaluate the antimicrobial efficacy of gold nanoparticles (AuNPs) of Pelargonium Graveolens leaves extract for children in comparison with the commonly used chlorhexidine. There are no previously available studies concerning the anti‐microbial activity of Pelargonium Graveolens leaves.

Sixty participants with mild to moderate gingivitis were randomly allocated in a ratio of 1:1 to receive twice‐daily mouthwash for 3 weeks (30 with a novel herbal mouthwash containing Pelargonium Graveolens AuNPs as a study group and 30 children with chlorhexidine as a control group). Clinical parameters (plaque index and gingival index) were assessed at the baseline (before the use of mouthwash), and then they were assessed 3 times at one‐week intervals after the first assessment through the period of the study. On the other hand, microbiological examination was done using supragingival plaque sampling with a curette for those participants at the baseline and three weeks after the use of the mouthwash.

After completing the intervention, although the study group had lower plaque scores compared to the control group, the difference was statistically significant. On the other hand, the study group had a significant reduction in the gingival index scores compared to the control group ( p  = 0.000). The microbiological analysis revealed that the treatment mouthwash significantly depleted the count of S. mutans in the last visit.

The novel Pelargonium Graveolens AuNPs mouthwash was effective in improving (PI) and (GI), which mean improve oral health status. Rinsing with Pelargonium Graveolens AuNPs mouthwash reduced the count of oral Streptococcus mutans significantly in children. Clinical trial registration Number: ClinicalTrials.gov on April 15, 2023, with ClinicalTrials.gov ID: NCT05816512.