The purpose of this study was to evaluate root canal dressing with calcium hydroxide paste using 5 techniques of placement.After endodontic preparation, each of 50 single-rooted premolars was filled with calcium hydroxide paste through use of one of the following techniques: Gutta-Condensor, MecaShaper, K-type ultrasonic file, Lentulo, and Pastinject. Radiographs of all 3 third root zones were made after cleaning and shaping and obturation. Density measurements (in pixels) were registered by means of an image analyzer and then compared through use of analysis of variance and Newman-Keuls multiple means tests.With respect to average filling density, the techniques ranked as follows, in ascending order: Gutta-Condensor, MecaShaper, K-type ultrasonic file, Lentulo, and Pastinject. There was a significant difference (P <.0009) between the Gutta-Condensor and Pastinject techniques, between the MecaShaper and Pastinject techniques, and between the ultrasonic file and Pastinject techniques; all favored the Pastinject. There were no significant differences between the Gutta-Condensor, MecaShaper, ultrasonic file, and Lentulo techniques or between the Lentulo and Pastinject techniques.The use of a specially designed paste carrier (the Pastinject) improved calcium hydroxide placement in root canals.