Abstract: A process of pretreating a lower alkyl cellulose, such as ethyl cellulose, which is to be used in microencapsulation of sodium fluoride for dental purposes. This process comprises dispersing a predetermined quantity of lower alkyl cellulose in an aqueous mineral acid, such as HCl, and stirring and aqueous washing of the cellulose such that the pH of the product is adjusted to 6.0 or less. This product is later dissolved in a BTX (benzene, toluene, xylene) solvent such as toluene. Sodium fluoride is added and process steps such as baffle stirring and drying are utilized to produce microencapsulation of the sodium fluoride with the lower alkyl cellulose. The process produces an encapsulating material of optimum sodium content and gives release time in water of 2.3-7.0 hours for the sodium fluoride.

Abstract: A device for blowing powder onto teeth, the device consisting of a handpiece in the form of a housing connected to a compressed air source and having a discharge nozzle member which can be inserted in a patient's mouth and can be directed towards the patient's teeth. The housing has a powder reservoir with a bottom supply duct. An apertured shuttle bar is reciprocably slidably mounted beneath said duct and has a metering hole registrable with said supply duct and then, by longitudinally moving the bar, with a discharge conduit arranged to receive compressed air from the source so as to discharge a metered amount of powder in said hole into the nozzle member for delivery to the patient's teeth.