Effect Of Root Canal Dimensions, Injection Rate, And Needle Design On The Apical Extrusion Of An Irrigant: An In Vitro Study

Abstract

Aim: The purpose of this study was to determine the effect of root canal dimensions, type of needle, and injection rate on the apical extrusion of an irrigant in a simulated root canal. Methods: Ten students used two types of 28-gauge needles, to deliver 3 mL irrigant solution into artificial canals prepared in acrylic blocks to a standard size of ISO 25, 30, or 40 (0.06 taper; n = 10). Each block was preweighed to the nearest microgram before and after irrigation once the canal was dried with paper points. This was repeated with a syringe pump at a flow rate of 50, 100, 200 or 300 lL/s with the needle inserted to a standard depth. Results: Significant differences were observed between the side-vented and notched-end needles when the rate of irrigation was higher than 100 lL/s, and when the apical size was below ISO 40 (P < 0.001). The amount of extrusion was more variable and significantly higher when irrigation was performed manually, compared with the syringe pump groups. Conclusions: Injection rates above 100 lL/s increased the risk of extrusion, whereas increasing the apical canal size to ISO 40 reduced the amount of extrusion in all groups. The use of a side-vented needle negates the injectionrate effects.