Effect of an essential oil mouth rinse (Listerine®) on interproximal plaque regrowth compared to chlorhexidine and sterile water : A randomized controlled, three periods cross-over, clinical trial

Mechanical plaque control is the most effective way in preventing periodontal diseases. However, due to some drawbacks in the mechanical methods, chemical plaque control methods have been recommended. The aim of this study was to examine the efficacy of an Essential Oil mouth rinse (Listerine®) on plaque formation in interproximal areas as compared to Chlorhexidine and Sterile water. The study was an observer-blind, 4-day plaque regrowth, cross over study. The study was conducted at the faculty of dentistry, University of Western Cape. 60 dental students aged 16-34 years with a minimum of 20 natural teeth participated voluntarily in the study. Exclusion criteria were established. An informed consent was taken prior to the start of the study. The students used one mouth rinse for 4 days as the only oral hygiene method and then plaque was scored using Silness & Löe plaque index. The same technique was used for the 2nd and 3rd experimental period with the other two mouth rinses with an identical wash out phase of two weeks. The mean plaque index scores for the Listerine mouth wash were 0.94 ± 0.18, for Chlorhexidine 0.54 ± 0.09 and for sterile water were 1.54 ± 0.08. Mean percentage of full mouth plaque free surfaces for the use of Listerine mouth wash was 25 ± 4.32, 54 ± 5.84 and 13 ± 4.46 for Chlorhexidine and sterile water respectively. Mean percentage for interproximal plaque free surfaces (IPFS) for different mouth rinses were also calculated and were 22±4.84 for Listerine mouth rinse, 42 ± 5.18 for Chlorhexidine and 9 ± 3.78 for sterile water. Analysis of variance and construction of 95% confidence intervals showed that both Chlorhexidine and Essential Oils significantly reduced plaque as compared to sterile water. The findings of this study suggest that although Essential Oils can reduce plaque formation but their effectiveness is lesser than Chlorhexidine.