Effect of an Essential Oil Mouthrinse on Salivary S.mutans Levels

Objectives: The objective of this study was to determine effect of an essential oil mouthrinse on salivary Streptoccocus mutans levels among orthodontic patients with braces. Methods: A single-blind randomized controlled study with two parallel groups was conducted.  Twelve orthodontic patients were included in the study. Experimental group (EO) included in 6 orthodontic patients rising their mouth with essential oil mouthwash (EO; Listerine with 0.092% eucalyptol, 0.042% menthol, 0.06% methyl salicylate, 0.064% thymol) twice a day, 20 ml per time for 30 seconds after brushing. The control group  (Saline) comprised  6 patients rinsing their mouth with solution of physiologic saline in the same manner with the experimental group. Non-stimulated salivary samples were collected at baseline (T0) and after 4 weeks (T1). Colony-forming units per ml (CFU/ml) of Streptococcus mutans colonies on MSB Agar (Mitis Salivarius Bacitracin) were counted. The Mann-Whitney U test was applied. Results: There was no statistically significant difference in mean of CFU mutans streptococci between the experimental and control group at baseline (p=0.818). The difference of CFU mutans streptococci between baseline and after 4 weeks were -45.83±39.93 (x10⁶ ) and 29.50±64.07 (x10⁶) in the experimental group and the control one, respectively. There was a significant difference for CFU mutans streptococci between baseline and after 4 weeks (p=0.031) in EO. The CFU mutans streptococci at the end of the rinse periods (after 4 weeks) showed statistically significant difference between Saline vs EO (p = 0.035). CFU mutans streptococci reduced 66.8% in the EO compared with increased 111.5% in the Saline groups. Conclusions: Essential oil containing mouthwash was found effectiveness in reducing the amount of Streptococcus mutans in saliva among patients with fixed orthodontic appliances. However, the study should be continued to conduct with larger sample size.