This study gives the understanding of the process ofsmear layer removing ability of all the solution. Removal of smear layer wasmore efficient in coronal and middle third as compared to apical third. Thisfinding is in agreement with results ofAbbott PV, Heijkoop PS et al. study and manystudies which have proved in past that an effective cleaning action in thecoronal and middle third of the canals even with different irrigation solution,time, and volume (15, 16).
In coronal and middle third areas where a largercanal diameter allows better flow of solution and more time to be in contactwith dentine wall which improves the efficiency of solution to remove smearlayer(3,16). Roleof surfactant has been discussed by many authors, in present study SmearClear,SmearOFF and Chloroquick have surfactant in the solution. Abou-Rass and Patonaiconfirmed that reduction of surface tension of endodontic solutions improvedtheir flow into narrow root canals (17). Therefore, addition of surfactants toirrigation solution should improve its penetration into apical narrow part ofroot canal. In present study SmearClear and SmearOFF despite having additionalsurfactant doesn’t shows significant removal of smear layer in apical thirdwhen compared to control group of 17% EDTA, which does not have a any additionsurfactant. This result is in agreement with the findings of Lui et al.
(18). Also,other studies have shown that calcium chelating ability of solution is not improvedby reducing surface tension of solution. Continuous soft chelating irrigation shows significantlybetter removal of smear layer then conventional irrigation protocol when 18%HEBP was used in combination with 5.
25% NaOCl (Chloroquick High). Where 9% HEBPin combination with 3% NaOCl (Chloroquick Low) did not show any significancedifference compared to conventional irrigation protocol groups. In apical thirdof the root canals Chloroquick High shows better removal of smear layer this resultscan be attributed to chelating agent being more time in canal and alsochelating procedure is seen while instrumentation unlike conventionalirrigation protocol where removal of smear layer is done only onceinstrumentation is completed (19). Paque et al. demonstrated that theaccumulated hard tissue debris in root canals irrigated with NaOCl + HEBP wassignificantly less than when irrigation was performed with 2.5% NaOCl alone(20).
Another advantage of this combination is that it keeps the hypochlorite-hypochlorous acid equilibrium towards hypochlorite, which has better tissuedissolution capacity than hypochlorous acid (21). This combination is affectiveon inorganic as well as organic part of smear layer. Resultof this study is in contrast to the recently published study by AbyKuruvilla et al. where 7% malic acidwas more effective in removing smear layer as compared to 17% EDTA and 18%etidronic acid (22). This observation may be seen because 18% etidronic acidwas merely used in a final rinse irrigation protocol.