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  • This study aimed to compare the in vitro

    2018-10-22

    This study aimed to compare the in vitro supplementary antibacterial effectiveness of EndoActivator (EA) irrigation, passive ultrasonic irrigation (PUI), a final CHX rinse, and a calcium hydroxide Ca(OH)2 dressing after chemomechanical preparation using SAF.
    Materials and methods
    Results None of the negative control samples showed growth. All positive control samples showed growth. Intragroup quantitative analyses evaluating the bacterial fty720 from S1 to S2 in all groups demonstrated that SAF instrumentation promoted a highly significant bacterial reduction (P < 0.001). Analysis of quantitative data revealed that the number of colony forming units (CFUs) in S2 and S3 was significantly lower than that in S1 (P < 0.001). There was no significant difference in quantitative bacterial reduction between the S2 and S3 samples, except in groups I and II (P = 0.017 and 0.046, respectively). Table 1 reveals the mean, median, and range values for the number of CFUs observed in all groups. When the four groups were compared (intergroup analysis), quantitative data (CFU counts) revealed that EA irrigation and PUI were significantly more effective than the CHX final rinse and Ca(OH)2 dressing. There was no significant difference in effectiveness between EA irrigation and PUI (P > 0.05).
    Discussion Several studies have demonstrated the effectiveness of SAF instrumentation in eradicating microorganisms from infected root canals; however, complete eradication of microorganisms using only SAF instrumentation was not possible in most cases [10,12,21–23]. Furthermore, a study demonstrated the inability of SAF to control apical enlargement, thus limiting the ability of the irrigants to achieve effective and predictable disinfection [24]. A clinical study [10] highlighted the need for a supplementary step after chemomechanical preparation using SAF to enhance disinfection on the basis of the finding that almost 50% teeth in that study had detectable bacteria after instrumentation. The quantitative data obtained in our study showed that SAF instrumentation was effective in promoting a significantly high decrease in intracanal bacterial populations (P < 0.001). In total, SAF instrumentation resulted in negative bacterial culture in 46.6% (28/60) teeth. This finding is consistent with those of several previous reports on the antibacterial efficacy of chemomechanical preparation using SAF [10–12,21,22]. No significant difference in quantitative bacterial reduction was observed between the S2 and S3 samples obtained from groups III and IV, wherein the CHX final rinse and Ca(OH)2 dressing were used (P = 0.134 and 0.280), respectively. The ability of Ca(OH)2 as a temporary dressing to decrease the infection burden below the levels achieved by chemomechanical debridement has been the subject of previous studies [25–27]. However, the findings from these studies have been inconsistent, with some studies showing enhanced disinfection [25,26] and others showing limited or decreased effects [27]. In the present study and a previous study, a Ca(OH)2 dressing placed for 7 days did not significantly enhance disinfection after chemomechanical preparation [28]. The results of this study also confirm the findings of Pavia et al. [16], who reported insignificant quantitative bacterial reduction after a final rinse with 2% CHX. This may be explained by the insufficient volume and contact time to expand the area of action for the substance. Despite the frequency differences between sonic (10 KHz) and ultrasonic (35 KHz) irrigation used in this study, both approaches significantly decreased the bacterial counts to a level lower fty720 than that achieved by chemomechanical preparation using SAF. This may be explained by the mode of agitation used in this study, which was proven effective in several previous studies [29–32]. PUI was used to agitate the irrigation solutions by inserting the tip 1 mm short of the complete working length with no further movements; this induced acoustic cavitation, acoustic microstreaming, and heat, which disrupts and kills any bacteria within root canals. The positive effects of EA irrigation may be explained by the increased number of bubbles exiting along the EA file during irrigation. The vertical pumping motion used as part of the protocol promotes the increased formation of microbubbles that gradually increases in diameter until they collapse, provoking very effective small implosions that produce irregular agitation of the irrigant [20,30]. Another important factor was the agitation of EDTA for 30 s before final agitation of NaOCl for another 30 s; this may allow better disinfection by NaOCl because of more effective removal of the smear layer [30,33].