This study addressed three factors that may affect the penetration of medicaments into periodontal pockets: calculus, ejection site pressure, and irrigator tip design. Ejection site pressure for the Max-I-Probe, the Viadent and Water-Pik tips were determined with a variant of Bernoullis' equation. Depth of irrigant penetration was determined by delivering disclosing solution supragingivally and subgingivally. Following irrigation, assessed teeth were extracted and the percentage of pocket penetration by the dye was calculated. The Max-I-Probe and Viadent tips had significantly greater penetration than did the Water-Pik tip. Furthermore, calculus deposits reduced irrigation penetration in deep pockets (7 to 10 mm). Ejection site pressures of the three tips ranged from 0.10 to 4.80 psi. The ejection site pressure of the Max-I-Probe side-port delivery system was lower than that of the other two systems. Results indicated that subgingival calculus, irrigator tip design, and placement of the tip affect the depth to which drugs can be delivered subgingivally.