ASSESSMENT OF THE EFFECT OF ENDODONTIC … nr1-2011 final.pdfpercent ratios for the samples in which BioPure MTAD had been employed were included in score 2 and 3 cat-egories (45%,

24 volume 1 • issue 1 January / March 2011 • pp 24-30

Abstract

The aim of the present study is to determine the clean-ing level o f the root canal system from organic and min-eral remnants, as well as the extent of smear layer re-moval, and its quantification, by SEM-evaluation of theroot canal surfaces obtained after endodontic irrigationwith different solutions.

Materials and method. 40 human monoradicularteeth, extracted for orthodontic or periodontal reasons,were selected for the study. The teeth were randomlydivided into 4 groups. After creating the access to theendodontic space, endodontic instrumentation followed,by the step back technique, up to the level of the apicalstructure. Endodontic irrigation made use of 10 ml solu-tion, as follows: saline solution for the teeth of group A,5.25%NaOCI for group B, BioPure MTAD (Dentsply)preparation for group C, and SmearClear (Sybron Endo,Orange, CA) preparation for group D. The roots werelongitudinally sectioned, to obtain the inner aspect of thecanal, then subjected to SEM analyses. For the referencezones, the amount of smear layer was quantified, scoresfrom 1 to 4 being given.

Results. When employing a saline solution, 80% ofthe samples received score 5, for expressing the smearlayer removal. The same score was given to other 25% ofthe samples, for which 5.25% sodium hypochlorite wasapplied as an irrigant. Numerous samples (90%) forwhich Smear Clear was employed were included in score1 category, only10% receiving score 2. Relatively closepercent ratios for the samples in which BioPure MTADhad been employed were included in score 2 and 3 cat-egories (45%, respectively 55%)

Conclusions. The increasing order of efficiency, re-garding the total smear layer removal and dentinary sur-face with perfectly open tubules for the irrigants underanalysis, was saline solution, sodium hypochlorite,BioPure MTAD and SmearClear.

Keywords: sodium hypochlorite, BioPure MTAD,SmearClear, smear layer, SEM

INTRODUCTION

Cleaning and shaping of the root canal sys-tem represents an intermediary stage in the en-

ASSESSMENT OF THE EFFECT OF ENDODONTIC IRRIGATIONSOLUTIONS ON THE ROOT DENTIN STATUS

Raluca Mihaela Ro[ca1, Simona Stoleriu2, M\lina Niculi]\1, Maria Vataman3, S. Andrian3

1. PhD student, Dept. Odontology, Faculty of Dent Med, „Gr.T.Popa” U.M.Ph. Iasi2. Assist. Prof. PhD. Dept. Odontology, Faculty of Dent. Med, „Gr.T.Popa” U.M. Ph. Iasi3. Prof. PhD. Dept. Odontology, Faculty of Dent. Med, „Gr.T.Popa” U.M. Ph. IasiCorresponding author: dr. Sorin Andrian: [email protected]

dodontic treatment, the accomplishment ofwhich decisively influences its success. Elimina-tion of the organic debris is especially impor-tant, once known that they may decompose,while the microorganisms may find in the canalthe substrate favourizing their proliferation. Sev-eral studies demonstrated that instrumentationalone cannot satisfactorily disinfect the radicu-lar canal system (SCR), with either steel (1) ornickel-titanium instruments (2). During instru-mentation, the endodontic files release and dis-locate the materials present inside the canals,remove the dentin from its walls, the whole con-tent being eliminated by means of an irrigant.

The irrigant or the ideal combination of sub-stances should remove the big organic debris,wet the canal walls, destroy the bacteria, dissolvethe necrotic tissue, lubricate the canal walls andopen the dentinary tubules through removal ofthe remanent dentinary detritus, thus preparingthe surface for an as good as possible adhesionof the sealers to the dentinary surfaces, for disin-fecting and clearing the zones inaccesible to en-dodontic treatments, without irritating the peri-apical tissues (3).

Considering the anatomical complexity andin spite of the minuteness of the instrumentalmanoevres, of canalary wall host irregularitiesand of the existence of certain areas that cannotbe reached by instruments, chemical agentsshould be applied for tissular removal. SEMstudies demonstrated that 70% of the tissulardebris remain, if their preparation involves noirrigation (4). Along the years, various formulae,in various combinations of substances with vari-ous concentrations, were employed as irrigationsolutions: saline solution, hydrogen peroxide,various anaesthetic solutions, 5.25% sodium

Odontology

International Journal of Medical Dentistry 25

hypoclorite, quaternary ammonium com-pounds, 0.2% chlorhexidine, 50% citric acid,EDTA, MTAD, calcium hydroxide, oxidativepotential water, RC-Prep, Glyde, etc.

The aim of the present study is to appreciatethe SCR cleaning level of organic and mineraldebris, as well as the extent of smear layer re-moval, and its quantification by SEM-evaluationof the root canal surfaces obtained after endo-dontic irrigation with different solutions.

MATERIALS AND METHOD

40 human monoradicular teeth, freshly ex-tracted from either periodontal or orthodonticreasons, were selected, with straight roots andcanals and no radiovisible anatomical aberra-tions and definite apical constrictions, (class IVertucci canals).

The teeth were randomly divided into 4groups. For each of them, coronary access wasperformed, through preparation of a typical ac-cess cavity, followed by endodontic instrumen-tation by the step back technique, up to the levelof the apical structure, previously identified bymeasuring the working length (LI). Endodonticirrigation made use of 10 ml solution, as follows:saline solution for the teeth of group A, 5.25%NaOCI for group B, BioPure MTAD (Dentsply)preparation for group C, and SmearClear(Sybron Endo, Orange, CA) preparation forgroup D.

The irrigant was released in the canal bymeans of a hypodermic syringe and 25 no. nee-dles, with longitudinally sectioned point. Theneedle point was placed 1 mm up of LI, on con-dition of its free movement in the canal, thuspermitting the irrigant to reflow towards thecoronary area and its reaching the previouslyprepared sturcture, concomitantly with prevent-ing its extrusion in the periapical tissues. Wheninstrumentation is over, final irrigation is madein each group, with a corresponding irrigant (5ml for 10 sec).

In a subsequent stage, the canals were driedwith paper cones (VDW, GmbH, Germany). Bymeans of diamond fissure burrs (no. 15 L, Pfingst& Company, Inc, SUA) and a water/air cooling

system, the teeth were sectioned at the level ofenamel-cement junction, the canals being subse-quently sealed here with a temporary material(Citodur, DoriDent).

The roots were longitudinally sectioned in thevicinity of the canal through 2, mezial and distal,ditches, by means of a diamond disc (Gebr.Brasseler GmbH&Co, Germany), under continu-ous cooling, after which they were longitudi-nally cut, by only one strong blow, so that theinner aspect of the canal was obtained. The sam-ples were prefixed in glutaraldehyde for 48 h,then rinsed in a buffer solution and dessicatedwith cu 20% acetone for 12 h.

The samples were fixed with self-polymerizable acrylate, on metallic andmetalized supports, through catodic pulveriza-tion with silver, in a 100 militorres vacuum and6 volts tension, for 3 min and 30 sec. Togetherwith the metallic supports, the samples were in-troduced in the column of the microscope (Tesla320, Czech Rep.), under a 15 kW tension. Thestatus of the parietal dentine surface obtainedwith each irrigant type could be observed, afterwhich the amount of smear layer was quantifiedon reference zones, the following scores beinggiven:

1. open dentinary tubules, smear layer absent.2. low amount of smear layer, a few open

dentinary tubules.3. homogeneous smear layer covering the ca-

nal walls and only a few open tubules.4. canal walls covered by a wholly homoge-

neous smear layer, no open dentinary tu-bules.

5. high amount of non-homogeneous smearlayer, covering completely the walls of thecanal.

For each section, the highest value granted tothe presence of the smear layer resulting fromthe examination of 3 reference zones from thecoronary, mean and apical radicular third, wasselected as a final score.

RESULTS

With reference to the level of SCR cleaning ofdifferent organic and mineral debris and to the

ASSESSMENT OF THE EFFECT OF ENDODONTIC IRRIGATION SOLUTIONS ON THE ROOT DENTIN STATUS

26 volume 1 • issue 1 January / March 2011 •

Raluca Mihaela Ro[ca, Simona Stoleriu, M\lina Niculi]\, Maria Vataman, S. Andrian

pp 24-30

extent of smear layer removal, it was observedthat, in the samples in which saline solution wasemployed as an irrigant, the pulp tissue was ab-sent inside the canals, while abundant amountsof organic and mineral rests occurred. On atransversal canal section close to the apical zone,organic rests in fibrous form, with ”spider web”or network aspect, may be observed (Fig. 1). Themineral agglomerations are either spherical orstellated, occurring either free or adhering to thecanal walls. One may notice the existence of arich smear layer entering the dentinary tubules,blocking them at the surface or sometimes, eveninside them. Some covered, yet identifiabledentinary tubules may be observed in the back-ground (score 5).

Figure 1. Aspect of root canal dentin after irrigationwith a saline solution (SEM X 50)

Figure 2. Aspect of root canal dentin after irrigationwith NaOCl (score 4) (SEM X 1000)

In the samples from group B, no big mineralor organic residues could be observed. The sur-faces thus obtained showed numerousirregularites, occurring as folds, frequently pro-

found, with a “caterpillar trace” aspect. Thedentinary surface was covered by an apparentlycompact layer. On certain sections,a homogene-ous smear layer, with no open dentinary tubuleswas observed (score 4) (Fig. 2). In other zones,the smear layer occurred only in low amounts,as islands (Fig. 3) containing some opendentinary tubules (score 3) (Fig. 4).

Figure 3. Aspect of root canal dentin after irrigationwith NaOCl (score 4) (SEM X 500)

Figure 4. Aspect of root canal dentin after irrigationwith NaOCl (SEM X 1000)

Figure 5. Aspect of root canal dentin after irrigationwith MTAD (score 2) (SEM X 500)


In the samples from group C, dentin gener-ally showed a clean aspect, with some wavy sur-faces created by instrumentation, especially inthe coronary third (Fig 5). A detailed aspect (Fig6) also evidences a very reduced amount ofsmear-layer, blocking some other dentinary tu-bules (score 2 given to the presence of the smearlayer).

Figure 6. Aspect of root canal dentin after irrigationwith MTAD (SEM X 1000)

Figure 7. Aspect of root canal dentin after irrigationwith SmearClear (score 1) (SEM X 500)

Figure 8. Aspect of root canal dentin after irrigationwith SmearClear (SEM X 1000)

In group D, the general aspect of root canaldentine was regular and clear, without anysmear layer, at almost all preparation levels (Fig.7). Most of the dentinary tubules were com-pletely open, highly visible and free of any ma-terial, the smear layer being totally absent (value1) (Fig. 8).

The values of the extent of residues andsmear-layer removal in the 4 groups under in-vestigation are listed in table I.

Table I. Scores for the smear layer aspect whenemploying various endodontic irrigants

Number of samples

SCORE Group

A

(Saline

solution)

Group

B

(NaOCl

5.25%)

Group C

(BioPure

MTAD)

Group D

(SmearClear)

1 - - - 18

2 - - 9 2

3 - - 11 -

4 4 15 - -

5 16 5 - -

Total

number

of

samples

20 20 20 20

When using a saline solution, 80% of the sam-ples received score 5, from the point of view ofsmear layer removal, which is also the case of25% of the samples in which 5.25% sodium hy-pochlorite was used as an irrigant. Most of thesamples for which Smear Clear (90%) had beenused were included in the category with score 1,only10% of them receiving score 2. Relativelyclose percent values from the samples treatedwith BioPure MTAD were recorded in score 2and 3 categories (45%, respectively 55%) (graph1).



Graph 1. Distribution of scores inthe 4 experimental groups

DISCUSSION

Generally speaking, endodontic irrigationacts in essentially two ways, namely: physicalaction, related to the amount and volume of so-lution released in the radicular canal, and chemi-cal action, related to the quality of solution. Irri-gation should facilitate cleaning and removal ofall SCR debris, through its mechanical washingaction. Irrigation avoids sedimentation of thedentinary “mud” (smear-layer) and causes sus-pending of both organic rests and of the dentinlayers detached by the instruments. Removal ofsmear layer is beneficial, as this layer, coveringthe dentinary surface, might contain necrotic tis-sue and bacterial rests, while its presence mightprevent drugs’ penetration into the dentinarytubules. More than that, an adequate surface,permitting an intimate contact and adhesion in-side the root canal system should be created.

Sodium hypochlorite in various concentra-tions has been used as a canal antiseptic for sev-eral decades, due to its efficiency against diffi-cult-to-eradicate microorganisms, such as:Enterococcus, Actynomices and Candida. It dis-solves the endocanalary organic material, hav-ing a minimal action upon both dentine andremanent dentinary detritus; this explains therecommendation for its uasge in association withsome demineralizing agents, for increasing itscapacity of cleaning the difficult-to-instrumentate zones, such as dentinary tubulesand lateral canals (5). Some studies demon-

strated that hypochlorite may remove more than70% of the organic components present in den-tine and more than 50% of the pulpar ones (6).The investigations of Baumgartner and Mader(7) assessed that NaOCI, in concentrations be-tween 1.5:% and 5.25%, is extremely efficient inremoving the vital pulpar tissue from the rootcanal dentin walls, even the non-instrumentedones. The efficiency of NaOCI in this dissolvingaction is generally accepted nowadays, beinginfluenced by the structural integrity of the com-pounds of the conjunctive tissue from the pulparrests. In the present study, the action of sodiumhypochlorite gave better results in the removalof the smear layer, comparatively with the salinesolution, as actually acknowledged in otherstudies, too (8).

Out of some new bioinstrumentation strate-gies here applied, mention should be made ofthe use of canal irrigants and of some antibioticsolutions, such as: erythromycin, chlorampheni-col, tetracyclin and vancomicin. The BioPureMTAD (Dentsply/Tulsa, Tulsa, OK) preparationcontains doxycyclin, citric acid and a surfacetensioactive surfactant. In vitro experimentsshowed that MTAD has some potential for smearlayer removal (9,10), being demonstrated thatMTAD is an efficient solution for smear layerremoval, without significantly modifying thestructure of dentinary tubules, when the canalsare irrigated with sodium hypochlorite, followedby MTAD (11). Some studies showed that theMTAD action was considerably more efficientupon the smear layer, comparatively with so-dium hypochlorite (12), which is actually theconclusion of the present investigation, as well.Association of BioPure with EDTA led to theobtaining of an area of demineralized colagenicmatrix in the eroded dentine, as well as aroundthe dentinary tubules, BioPure being seen, fromthis perspective, as more aggressive than EDTA.The citric acid contained in the product actsupon the smear layer with both its quantity andhomogeneity, having the capacity of formingzones with partially closed tubules, and otherwith open canalicules. However, the presentstudy confirmed the maintenance of smear layerzones, which partially or totally block thedentinary canalicules.



The SmearClear (Sybron Endo, Orange, CA)product is a combination of several surfactantsand a 17% EDTA solution. The surfactants re-duce surface tension and increase the capacity ofendocanalary cleaning of some solutions(EDTA). The main action involves removal ofthe remanent dentinary detritus and opening ofthe dentinary tubes, as confirmed here by thelevel of surface cleaning. EDTA appears as a veryefficient chelating agent which solubilizes cal-cium and dentin (13). The optimum pH forEDTA demineralization on dentin should rangebetween 5 and 6 (14). It was demonstrated thatEDTA increases permeability in the dentinarycanalicules, in the accesory canals and in theapical foramen. EDTA eliminates the smear layerdeposits remaining after instrumentation of thecanal walls (15). Paterson(16) made the observa-tion that this substance has quite a long actiontime, its influence upon dentin being manifestedlong after radicular obturation, if no correctwashings had been made.

Selection of an adequate irrigation solutionhas a decisive influence upon the efficiency andsuccess of the endodontic treatment. The smearlayer, with a mean thickness of 1-2 µm, is at-tached to the dentinary canalicules along 40 nm;once known that these accessory canals have alonger diameter, the material compacted in thesecanals may occur in high amounts during con-ventional canal preparation. As an organolyticsubstance, sodium hypochlorite has no favour-able action upon the mineral fraction of root ca-nal dentin, so that irrigation should begin withchelating solutions.

CONCLUSIONS

1. The saline solution employed as an irriga-tion solution was seen as inefficient in removingboth organic and mineral debris and smear layerfrom the canal walls.

2. NaOCI (5.25%) was efficient in the totaldisolution of organic residues from the innerpart of SCR walls, but had no action on theamount and structure of the smear layer formedafter endodontic instrumentation.

3. Application of BioPure MTAD (Dentsply/Tulsa, Tulsa, OK) was actively working upon thesmear layer, which it partially removed, remain-ing only in some obliterated dentinary tubules.

4. The only viable method for total smearlayer removal and for obtaining a dentinary sur-face with perfectly open tubules is based on theuse of the SmearClear (Sybron Endo, Orange,CA) preparation.

5. Smear layer removal during endodonticirrigation plays a key role in this stage, influenc-ing the realization of an optimum apical sealingduring root canal filling.

References

1. Bystrom A, Sundquist G. Bacteriologic evaluation ofthe efficacy of mecanical root canal instrumenta-tion in endodontic therapy. Scan J Dent Res 1981;89: 321-330

2. Dalton BC, Orstavik D, Phillips C, Pettiette M, TropeM. Bacterial reduction with nickel- titanium ro-tary instrumentation. J Endod 1998; 24: 763-769

3. Hulsman M, Heckendorf M, Lennon A. Chelatingagents in root canal treatment: mode of actionand indications for their use. Int Endod J 2003;36: 810-811

4. Carvalho A S, Camargo C H R, Valera MC, CamargoSE. Smear layer removal by auxiliary chemicalsubstances in biomechanical preparation: a scan-ning electron microscope study. J Endod 2008;11:1396-2008

5. Bystrom A, Sundqvist G. The antibacterial action ofsodium hypochlorit and EDTA în 60 cases of en-dodontic therapy. Int Endod J 1985; 18: 35-45

6. Benz RI, Torabinejad M, Pouresmail M. Quantitativeanalysis of the solubilizing action of MTAD, so-dium hypochlorite, and EDTA on bovine pulpand dentin. J Endod 2003; 29 : 334-337

8. Baumgartner JC, Mader C. A S.E.M. evaluation offour root canal irigation regimens. J. Endod. 2008;13: 147-151

9. O’Hara PC. Antibacterial effect of various endodon-tic irrigants and medicaments on anaerobes. J.ofEndod 2009; 18: 190-200

10. Shabahang S, Pouresmail M, Torabinejad M. In vitroantimicrobial efficacy of MTAD and sodiumhipochlorite. J Endod 2003; 29: 450-459

11. Torabinejad M, Cho Y, Khademi AA, Backland LK.The effect of various concentrations of sodiumhipochlorite on the ability of MTAD to removethe smear-layer. J Endod 2003; 23: 233-244



12. Mancini M, Armelin E, Casaqlia A, Cerroni L,Ciaconi L. A Comparative Study of Smear LayerRemoval and Erosion in Apical IntraradicularDentine With Three Irrigating Solutions: A Scan-ning Electron Microscopy Evaluation. J of Endod2009; 35 : 900-903

13. Tay FR, Pashley DH, Loushine RJ, Doyle MD,Gillespie WT, Weller RN, King NM Ultrastruc-ture of Smear Layer-Covered Intraradicular Den-tin After Irrigation with BioPure MTAD. J ofEndod 2006; 32: 218-221

14. Valdrighi L. The demineralising efficiency ofE.D.T.A. solutions on dentin. Oral.Surg. 2008; 52:446-455

15. Ando F. A study of chemical preparation in endo-dontic therapy. The effect of E.D.T.A on pow-dered dentin and dentinal walls. J.Dent.Sci. 1997;23: 109-122

16. Patterson J. In vivo and in vitro studies of the effectof E.D.T.A. on human dentine and its endodnticimplications. Oral.Surg. 2008; 18: 83-94


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ASSESSMENT OF THE EFFECT OF ENDODONTIC … nr1-2011 final.pdfpercent ratios for the samples in which BioPure MTAD had been employed were included in score 2 and 3 cat-egories (45%,