Purpose: The aim of this study was to investigate the effect of Teethmate Desensitizer (TD), an aqueous slurry of calcium phosphates, on the pre- and postcementation sensitivity of contralateral premolars prepared for full-coverage restorations. Materials and Methods: In this clinical study, using a split-mouth design, 20 patients were allocated and two contralateral vital premolars per patient were randomly assigned to treatment with TD and placebo (PLA; distilled water). One day after preparation and temporization, sensitivity (PRE) upon air blast (AB) and probe scratch (PS) was determined using a 10-cm-long visual analog scale (VAS). The trial was double-blinded; neither the patient nor the investigator knew the treatment performed. Sensitivity was assessed immediately after treatment, before seating the final crowns after 1 week, and 1 month after cementation. Statistical data analysis was performed with one-way analysis of variance followed by Tukey post hoc test and two-sided paired t test. Statistical significance was determined at α .05. Results: VAS scores upon stimulation with AB and PS were significantly lower at POST and 1 week, and with AB after 1 month. TD-treated teeth showed significantly less sensitivity than PLA. At the postcementation recall, TD and PLA were not significantly different and the average pain scores were almost 0. Conclusion: Treatment of teeth prepared for full crown restorations with TD can significantly reduce preand postcementation sensitivity.