The Effect of Various Concentrations of Sodium Hypochlorite on the Ability of MTAD to Remove the Smear Layer

Abstract

Various organic acids, ultrasonic instruments, and lasers have been used to remove the smear layer from the surface of instrumented root canals. The purpose of this study was to investigate the effect of various concentrations of sodium hypochlorite (NaOCl) as an intracanal irrigant before the use of MTAD (a mixture of a tetracycline isomer, an acid, and a detergent) as a final rise to remove the smear layer. Ten operators, using a combination of passive step-back and rotary 0.04 taper, nickel-titanium files, prepared 80 single- and multirooted human teeth. Distilled water, four different concentrations of NaOCl, or MTAD was used as intracanal irrigant. The canals were then treated for 2 min with 5 ml of one of the following solutions as a final rinse: 5.25% NaOCl, sterile distilled water, 17% EDTA, or MTAD. The presence or absence of smear layer and the amount of erosion on the surface of the root canal walls at the coronal, middle, and apical portion of each canal were examined under a scanning electron microscope. The results show that although MTAD removes most of the smear layer when used as an intracanal irrigant, some remnants of the organic component of the smear layer remain scattered on the surface of the root canal walls. The effectiveness of MTAD to completely remove the smear layer is enhanced when low concentrations of NaOCl are used as an intracanal irrigant before the use of MTAD as a final rinse. This regimen does not seem to significantly change the structure of the dentinal tubules.

The antimicrobial effects of root canal irrigation and medication

“…Subsequent in vitro experiments showed that this material effectively removed the smear layer. 71 When the antimicrobial effects of MTAD were compared with those of NaOCl and EDTA by using standard in vitro microbiological techniques, MTAD was significantly more effective; 46 however, these effects have recently been challenged by different investigators. Ruff et al 72 reported superior antifungal effect of 6% NaOCl and 2% chlorhexidine compared with MTAD, and Clegg et al 73 questioned the ability of MTAD to remove or disrupt bacterial biofilms in root canals.…”

The Effect of Qmix Solution in the Removal of Calcium Hydroxide From Artificially Created Grooves

“…This may be explained by the reduced amount of irrigation solution contained in a smaller canal volume [22][23][24] . Additionally, in the coronal part of the root canal, more chelator molecules are able to bind calcium ions [25][26][27] because of the larger canal volume at this part.…”

The effect of MTAD on the apical leakage of obturated root canals: an electrochemical study

“…They showed that citric acid or a combination of NaOCl and citric acid irrespective of the order in which they were used was more effective than NaOCl alone to remove the smear layer from the surface of instrumented canals. Because high concentrations of NaOCl are more toxic than diluted solutions and there are no significant differences between the ability of 1.3%, 2.6% and 5.25% as root canal irrigants and MTAD as a final rinse to remove the smear layer 22) , 1.3% NaOCl during instrumentation and MTAD as a final rinse was used to remove the smear layer in Group 5.…”