In vivo effects of Orthocryl on acid-softened enamel are investigated. Demineralized enamel slabs are mountened in appliances and after control and treatment periods of one week the enamel specimens removed from the appliances and evaluated for microhardness and acid resistance. A microhardness tester with an elliptical diamond indenter and a 500 gr. load is used to determine the hardness of enamel surface. The depth of the indenter and Knoop Hardness Number (KHN) is measured after abrasion and polishing and acid softening of treatment and control slabs. However there is significant difference between the measurements of intraoral exposure and acid-resistance test.

Keywords: Orthocryl, continous fluoride release, microhardness test