The effectiveness of topical 2% sodium fluoride applied with and without 10% strontium chloride pretreatment was compared in patients complaining of tooth hypersensitivity. In addition the radiopacity of 2% sodium fluoride and 25% strontium chloride treated dentin was studied in vitro. Reduction of sensitivity to cold and mechanical stimuli was evaluated during a period of 3 months by pain scoring in the exposed cervical dentin of homologous teeth on the two sides of the jaws. There was a significant decrease in the sensitivity of the exposed cervical dentin after treatment with sodium fluoride solution with or without pretreatment with strontium chloride solution. At the end of the experimental period the combined strontium and fluoride treatment was found to be more effective than that of fluoride alone in reducing sensitivity to cold. The increase in radiodensity of dentin samples immersed in strontium chloride was statistically significant, while there was no significant increase in density for the samples immersed in sodium fluoride solutions. A mineralization process is possibly the effective means by which fluoride or strontium diminishes sensitivity of dentin.