To determine effectiveness of indirect pulp capping with 5% potassium nitrate in polycarboxylate cement for biological treatment of reversible pulpitis, a clinical study of 232 teeth with active caries lesions from 205 healthy patients aged from 16 to 40 years was performed. They were divided into 2 groups: the study group--140 teeth of 127 persons with 5% potassium nitrate in polycarboxylate cement (Carboxy Adhesor); control group--92 teeth of 78 persons with calcium-hydroxide cement (Dycal). Short-term clinical results showed better desensitizing effect and faster recovery to normal values of electric vitality in teeth treated by potassium nitrate in comparison with Dycal lining (p<0.001). Long-term follow-up (up to 2 years) showed good functional conditions, preserved vitality and x-ray status of the treated teeth.