Control of Dental Plaque and Gingival Inflammation by Natural Ingredients-Based Mouthwash

<b>Background/Objectives</b>: This study aimed to investigate the effects of a new alcohol-free marine mouthwash containing an algae extract, a coastal plant extract, and seawater on plaque reduction, gingivitis, and oral microbiota balance. <b>Methods</b>: In a single-center, prospective, randomized comparative study, 50 subjects with gingivitis were assigned to either a marine mouthwash group (Test, <i>n</i> = 26) or a marketed mouthwash group (Comparator, <i>n</i> = 24). Clinical assessments included plaque, gingivitis, halitosis, and volunteer self-evaluation at baseline (T0) and after 7 days (T7). Gingival microbiota was sampled using swabs at baseline (T0) and after 7 days (T7). <b>Conclusions</b>: Both groups demonstrated reductions in dental plaque, gingivitis, and halitosis at T7 compared to baseline. Improvements in halitosis were observed in both groups but did not reach statistical significance. Microbiota analysis revealed that the Test group experienced the enrichment of health-associated bacterial taxa and a reduction in disease-associated species, notably <i>Porphyromonas endodontalis</i>, while the Comparator group showed an increase in pathogenic taxa. The marine mouthwash was well tolerated and positively rated by participants. Combining an algae extract, a coastal plant extract, and seawater, it effectively reduces plaque and gingivitis and may contribute to oral microbiota balance. It represents a promising alternative to conventional chemical oral care products.