Differences in apical vapor lock formation after sodium hypochlorite irrigation with and without surfactant using two needle types

Background: Endodontic irrigation with 5.25% sodium hypochlorite (NaOCl) solution using single side-vented and double side-vented needles is commonly used. Surfactant is added to reduce high surface tension of the NaOCl solution. Apical vapor lock, or air entrapment inside closed-end root canal system, lowers the efficacy of irrigants. Thus, the irrigants are hindered in penetrating the root canal system and can lead to risk of reinfection. Objective: The objective is to analyze the difference of 5.25% NaOCl solution with and without surfactant using two types of irrigation needle in the formation of apical vapor lock. Methods: Forty lower premolars were prepared and randomly divided into four groups (n = 10 per group) then irrigated with 5.25% NaOCl solution with and without surfactant using a single side-vented or double side-vented needle. Contrast medium was added so that the measurement of the apical vapor lock could be performed using a digital radiograph. Analysis was done with two-way analysis of variance and the Tukey method. Results: 5.25% NaOCl solution with a single side-vented needle showed a significant difference from 5.25% NaOCl solution with a double side-vented needle. 5.25% NaOCl solution with a surfactant using a single side-vented needle showed a significant difference from 5.25% NaOCl solution using a double side-vented needle, likewise NaOCl 5.25% using double side-vented needle group from NaOCl 5.25% with surfactant using single side-vented needle group. Conclusion: Minimal formation of an apical vapor lock resulted from the use of 5.25% NaOCl solution with a surfactant using a single side-vented needle.