This study gives the understanding of the process ofsmear layer removing ability of conventional irrigation protocol and continuoussoft chelating irrigation protocol.
The main objective of instrumentation is topromote effective irrigation, disinfection, and filling. Smear layer productionis seen while instrumentation procedures of root canal which has to beeliminated with the use of irrigating solution. All the functions required froman irrigant to remove smear layer from root canal wall cannot be achieved byany single irrigating solution. Therefore, combined use of 2 or severalirrigating solutions is required for optimal removal of smear layer (5).WhereasChloroquick solution having HEBP as a soft chelating agent and can be combinedwith NaOCl to become single solution for disinfecting root canals. Highlight ofsuch combination of NaOCl and HEBP is that the NaOCl doesn’t loses itsbiological,antibacterial and tissue dissolving properties (13, 14), whereas the reductionand removalof the inorganic matter is done with HEBP (11, 12). Results of this present study showsremoval of smearlayer was more efficient in coronal and middle third as compared to apicalthird.
This finding is in agreement with results ofAbbott PV, Heijkoop PS et al. study and many studies which have proved in pastthat an effective cleaning action in the coronal and middle third of the canalseven with different irrigation solution, time, and volume (15, 16). In coronaland middle third areas where a larger canal diameter allows better flow ofsolution and more time to be in contact with dentine wall which allows the solutionto remove smear layercomprehensively. (3,16). Roleof surfactant has been discussed by many authors, in present study SmearClear,SmearOFF and Chloroquick have surfactant in the solution.
Abou-Rass andPatonaiconfirmed that reduction of surface tension of endodontic solutionsimproved their flow into narrow root canals (17). Therefore, an addition ofsurfactants to irrigation solution should improve its penetration into apicalnarrow part of root canal. In present study, SmearClear and SmearOFF despitehaving additional surfactant doesn’t show the significant removal of smearlayer in apical third when compared to control group of 17% EDTA, which doesnot have any addition surfactant. This result is in accordance with theobservationsof Lui et al. (18) and also, other studies have shown that calciumchelating ability of solution is not improved by reducing the surface tensionof the solution. Presentstudy results disply that the continuous softchelating irrigation shows thesignificantly better removal of smear layer thanconventional irrigation protocol at apical third level when 18% HEBP was usedin combination with 5.25% NaOCl (Chloroquick High).
Where 9% HEBP incombination with 3% NaOCl (Chloroquick Low) did not show any significancedifference compared to conventional irrigation protocol groups. These resultscanbe attributed to chelating agent being more time in canal and also chelatingprocedure is seen while instrumentation, unlike conventional irrigationprotocol where removal of smear layer is done only once instrumentation iscompleted (19). Paque et al. demonstrated that the accumulation of hard tissuedebris in root canals when irrigated withamalgamation of NaOCl and HEBP was significantly less than irrigationwas performed with 2.5% NaOCl alone (20).Another advantage of this combinationis that it has better tissue dissolution capacity by keeping the hypochlorite-hypochlorous acid equilibrium towards hypochlorite (21). This combination isaffective on inorganic as well as organic part of smear layer at same time.
Resultof this study is in contrast to the recently published study by AbyKuruvilla et al. where 7%malic acid wasmore effective in removing smear layer as compared to 17% EDTA and 18%etidronic acid (22). This observation may be seen because 18% etidronic acid whichis soft chelating agent was merely used in a final rinse irrigation protocol. There arevery few studies available on use of the continuous soft chelating agent forsmear layer removal. In present study, continuous soft chelating irrigationprotocol shows promising results.