Effect of Apical Preparation Size and Preparation Taper on Irrigant Volume Delivered by Using Negative Pressure Irrigation System

Introduction: The purpose of this investigation was to determine the effect that apical preparation size and preparation taper had on the volume of irrigant delivered to the working length of a root canal preparation in a clinically relevant amount of time. Methods: Forty intact human single-rooted teeth were randomly distributed into 2 separate phases. The first phase aimed to determine the smaller apical size that will allow more volume of irrigant at working length. All samples had the same taper and were sequentially instrumented to sizes of 30.06, 35.06, 40.06, and 45.06. The second phase aimed to determine the taper that will allow more volume of irrigant at working length. Teeth were sequentially instrumented to 40.02, 40.04, 40.06, and 40.08. All samples were irrigated by using the micro-cannula, and the volume of sodium hypochlorite suctioned at working length under negative pressure was measured during a period of 30 seconds by using a custom recovery device. Results: An increase in size from ISO #35 to ISO #40 resulted in a percentage gain of approximately 44% in mean irrigant volume, whereas an increase in size from ISO #40 to ISO #45 resulted in a percentage gain of approximately 4%. An increase in taper from 0.02 through 0.08 resulted in percentage gains of approximately 74%, 5.4%, and 2.4% increase, respectively. Conclusions: The data demonstrated that an increase in apical preparation size and taper resulted in a statistically significant increase in the volume of irrigant. In addition, an apical enlargement to ISO #40 with a 0.04 taper will allow for tooth structure preservation and maximum volume of irrigation at the apical third when using the apical negative pressure irrigation system. (J Endod 2010;36:721-724)