Aim: To determine the amounts of fluoride ion release following using persica chewing gum and sodium fluoride chewing gum. Methods: 44, 20-30 year- old subjects will be selected randomly with regard to inclusion criteria: normal salivary flow rate, using no medications, using no systemic / topical fluoride (except tooth paste), excessive tea drinking habit and persica mouthwash users. The subjects will be asked to sign an informed consent. For one week, they will refrain from drinking tea and will use toothpaste with similar fluoride concentration (Running Period). All the participants, the practitioner and Lab technician will be blind during all the steps of the trial about the type of chewing gum used and saliva samples, respectively. This triple blind cross over study will be performed twice with ten-day interval (washout phase). Both types of chewing gum have the same amount of fluoride, color, shape and taste and will be synthetized by one chemist. During both phases of trial, saliva samples will be collected under controlled conditions at similar times in the morning within baseline, 5, 10, 20, 45 min. intervals following 5 min. chewing the gums. After labelling each container with code and date, the samples will be weighted and stored at -18℃ until fluoride analysis. Saliva flow rate (ml ⁄min) and mean fluoride concentrations during different periods and using different chewing gums will be compared and results will be disseminated.