Objective. Calcium hydroxide is a common intracanal medicament. The powder can be mixed with different vehicles for placement in canals. This study examines pH changes in dentin with 2 different calcium hydroxide preparations. Study design. The combinations used were calcium hydroxide + distilled water and calcium hydroxide + glycerin (1/7 distilled water). One hundred forty extracted teeth with single canals were used. pH changes in dentin after the intracanal placement of these combinations were evaluated at different dentin thicknesses by measuring the pH of the external environment. Results. For all dentin thicknesses and at all time periods, the calcium hydroxide + glycerin combination showed significantly higher pH values than the calcium hydroxide + distilled water combination. Conclusions. Considering pH elevations, we propose the use of a calcium hydroxide + glycerin combination.