Oil pulling is a method based on Ayurvedic medicine which aims to obtain local and systemic benefits by swirling oils in the oral cavity for a period of 15 minutes, before spitting it out.12 Although the exact mechanism of action is not clear, there are some proposed theories. One proposed theory is the saponification or "soap making" process which occurs as a result of alkali hydrolysis of fat.9 Second theory speculates the inhibition of plaque formation and adhesion of bacteria due to the viscous nature of the oil. 13 According to the third theory, presence of antioxidants in oil prevent lipid peroxidation and thus help to the destruction of microorganisms and potentiating the action of Vitamin E in the oral cavity.14 The effect of oil pulling on halitosis and the use of oil pulling in addition to conventional oral hygiene practices was investigated in some studies13,15,16 but to the best knowledge of the authors, no study has evaluated the plaque-inhibiting effects of oil pulling. Therefore this study was conducted to evaluate the plaque-inhibiting effects of oil pulling using 4- day plaque regrowth study model17,18 compared to 0.2% CHX-containing mouthrinse. The tested hypothesis was that oil pulling would perform plaque regrowth inhibition as well as the CHX-containing mouthrinse.

The study was a single-center, observer masked, cross-over design with subjects randomly allocated to treatment sequences. During a 2-week preparatory period, participants rendered plaque, calculus and stain free by a thorough scaling and polishing of the teeth by both hand and ultrasonic instruments and were instructed in self-performed plaque control. At the end of the preparatory period, all subjects had clinically healthy gingiva.

Participants were randomly allocated to two groups by closed envelop system (BM) and masked to the mouthrinse received. The tested products and regimens of use are shown in Table 1. Mouthrinses were filled in identical but coded bottles. Instructions for usage was written on the bottles. On day 1 (Monday) of each study periods, after disclosing the teeth with erythrosine all subjects received scaling and polishing to remove plaque and extrinsic stain and disclosing of the teeth was repeated. By this way it was confirmed that all participants had a plaque score of 0 at baseline. Subjects were then asked to refrain from all forms of tooth cleaning and to apply the rinsing regimen. The tested agents included the following: 1) 0.2 % chlorhexidine mouthrinse ( 10 mL, twice daily for 30 seconds) 2) Coconut oil (10 Ml, twice daily 15-20 minute) All agents were to be used after breakfast and dinner and the subjects should be avoided rinsing, eating and drinking during the first hour after rinsing. During the 4- day period, the use of any other rinse, chewing gum or toothpaste was not allowed. The mouthrinses were in identical bottles but total subject blindness cannot be possible due to the taste, color, consistency, rinsing time differences.

On day 5 (Friday), subjects received an oral soft tissue examination and were asked to complete a standardized questionnaire to evaluate their attitudes with regard to the product used. The patients were asked about the flavor of the mouthrinse, the alteration in the taste of food and drinks, the perception of the plaque reduction, the staining that the mouthrinse created, the feeling to create nausea. After the completion of the questionnaire, each subject was scored for staining using Lobene stain index.19 After that, disclosing was performed with erythrosine and plaque scoring was performed using the Turesky et al. 20 modification of the Quigley and Hein index.21 Stain and plaque indices were recorded from the buccal and lingual surfaces of all fully erupted permanent teeth, with the exception of the third molars. In addition, Gingival Index (GI) and bleeding on probing (bop) were recorded from six sites of each teeth. All clinical examinations were performed by a single clinician (YS) who was masked to the study.

After recording the clinical parameters, subjects received a polishing to remove all plaque and tooth stain if present and 14 days of washout periods were allowed after 4- day period. 22 During the wash out period, the subjects returned to normal oral hygiene methods with a standard toothbrush* and a fluoride containing tooth paste**. These procedures were repeated until each participant used each of the rinses.

Inclusion Criteria:

• no systemic disease
• having ≥ 22 natural teeth,
• having no removable or fixed prostheses or fixed and removable orthodontic appliances.

Exclusion criteria:

• use of antibiotics and anti-inflammatory drugs in previous 6 months;
• allergy to any ingredient used in the study;
• smokers;
• pregnant of lactating females;
• history of mouthrinses, gels or chewing gums use that contains antimicrobial agents in the preceding 3 months
• having teeth with probing depth ≥4mm and signs of gingival inflammation.