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emoval Efficiency of Calcium Hydroxide Intracanaledicament With Two Calcium Chelators: Volumetricnalysis Using Spiral CT, An In Vitro Study

uresh Nandini, BDS, Natanasabapathy Velmurugan, MDS, andeivanayagam Kandaswamy, MDS

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bstracthe vehicles used to carry calcium hydroxide intracanaledicament are many and may affect the retrieval.ccess cavities were prepared in 40 single rooted an-

erior teeth, cleaning and shaping was done and filledith either Metapex or pure calcium hydroxide powder

n distilled water. After 7 days the calcium hydroxideas retrieved using either 17% EDTA or 10% citric acid

n combination with ultrasonic agitation. Volume anal-sis was done using spiral computed tomography. Theercentage difference was calculated and statisticallynalyzed using Kruskal-Wallis and Mann-Whitney Uest. 10% citric acid showed better removal efficiencyhan 17% EDTA for Metapex (p � 0.003). The 17%DTA showed excellent removal efficiency of powderorm of calcium hydroxide in distilled water than

etapex (p � 0.001). Ten percent citric acid removedowder form of calcium hydroxide in distilled wateretter than Metapex (p � 0.05). (J Endod 2006;32:097–1101)

ey Wordsalcium chelators, retrieval, spiral computed tomogra-hy, vehicles

From the Department of Conservative Dentistry and En-odontics, Meenakshi Ammal Dental College, TamilNadu, In-ia.

Address requests for reprints to Dr. S. Nandini BDS (PGtudent), Department of Conservative Dentistry and Endodon-ics, Meenakshi Ammal Dental College, Allapakkam mainoad, Maduravoyal, Chennai-95, TamilNadu, India. E-mail ad-ress: nandini_80@hotmail.com.099-2399/$0 - see front matter

Copyright © 2006 by the American Association ofndodontists.oi:10.1016/j.joen.2006.06.005

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ermann’s introduction of calcium hydroxide in 1930 started a new epoch in thefield of dentistry (1). The clinical success with this material is mainly attributed to

ts alkaline pH and depends on its ability to rapidly disassociate into hydroxyl ions andalcium ions. Tronstad et al. demonstrated the diffusion of calcium ions through theentin to the external surface (2). Calcium hydroxide has been used in various clinicalituations and is kept inside the canal for different time periods ranging from 7 days forntracanal medication to 6 to 24 months for apexification (3). Calcium hydroxide as anntracanal medicament has been shown to reduce the pathogenic species associatedith pulp necrosis (4). The antibacterial efficacy of calcium hydroxide may be depen-ent on the vehicle used (5). Calcium hydroxide placed inside the root canal has to beemoved before obturating the canal with permanent obturating materials.

Ricucci and Langeland reported a case of a failed root canal treatment because ofncomplete removal of calcium hydroxide from the root canal that was placed as intra-anal medicament (6). In vitro studies have shown that remnant calcium hydroxide caninder the penetration of sealers into the dentinal tubules (7), hinder the bonding ofesin sealer adhesion to the dentin, markedly increase the apical leakage of root canalreated teeth (8), and potentially interact with zinc oxide eugenol sealers and makehem brittle and granular (9). Thus, complete removal of calcium hydroxide from theoot canal before obturation becomes mandatory.

Very few studies have been done to assess the efficiency of techniques in removal ofalcium hydroxide. Calcium hydroxide removal before final obturation is routinely accom-lished either by irrigating with NaOCl or saline or instrumentation in a reaming motion.argelos et al., has shown that using 15% ethylenediaminetetraacetic acid (EDTA) solution

r NaOCl alone, as irrigants does not remove calcium hydroxide from the root canal, butombining these two irrigants with hand instrumentation improves the removal efficiency9).

Lambrianidis et al. have studied the removal efficiency of calcium hydroxide dress-ng in different vehicles from the root canal using normal saline, 3% NaOCl, 3% NaOCl

17% EDTA as irrigants in combination with hand filing. They concluded that 45%urface area remained covered with calcium hydroxide. They inferred that amount ofalcium hydroxide powder in the paste does not affect the removal but the vehicle usedor making the paste can affect the retrieval (10). In 1982 Anthony et al. demonstratedhat the vehicle used could affect the calcium hydroxide diffusion through the apicaloramen and the consequent pH change (11). Simon in 1995 assessed the pH ofalcium hydroxide and release of Ca2� from various vehicles and found Ca2� release toe more when distilled water was used as vehicle (12).

Theaimof this in vitro studywas toassess theefficiencyof twocalciumchelatorsnamely7% EDTA solution and 10% citric acid combined with ultrasonic agitation, in the removalf calcium hydroxide placed as an intracanal medicament using two different vehicles. The

wo vehicles used in this study were, the commercially available paste in silicone oil andreshly mixed calcium hydroxide powder in distilled water. The volume of calcium hydroxideemoved was analyzed with spiral computed tomography (CT).

Materials and MethodsThe calcium hydroxide formulations were selected on the basis of the vehicles

sed. Metapex is a commercially available product composed of calcium hydrox-

Removal of Calcium Hydroxide Intracanal Medicament 1097

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de, silicone oil, and iodoform (Meta Dental Corp. Ltd., Elmburst,Y). The chemically pure (95%) calcium hydroxide powder (Merck

ndia Ltd., Mumbai, India) was mixed with distilled water in 1:1atio and barium sulfate was added for radiopacity (13).

Forty extracted single rooted anterior teeth were selected. The teethith fractures, cracks, or any other defects were excluded. Teeth were

tored in normal saline solution that was changed daily till sufficient numberf teeth was collected. Access was prepared and the root canals were sub-

ected to chemomechanical preparation with the step-back technique using-files. The master apical file was standardized to three times the size of the

nitial apical file and 5.25% NaOCl was used as an irrigant after each instru-ent. Recapitulation with smaller size files was done during chemome-

igure 1. (A) Group A1, filled with Metapex. (B) Group A2, filled with Metapex2, filled with calcium hydroxide powder � distilled water.

hanical preparation. Before the final rinse a 20-size file was passed 1 mm a

098 Nandini et al.

eyond the apex to remove any dentinal shaving plugs. The teeth were storedn normal saline in airtight bottles in between procedures.

The teeth were divided into two groups of 20 teeth each.etapex was injected into the root canal until the material extruded

hrough the apex (group A). Calcium hydroxide was placed into theanals with lentulo spiral until the material extruded through thepex (group B). The access cavities were temporarily sealed with aotton pellet and IRM. The teeth were stored at 37°C and 100%elative humidity for 7 days (14). Then the teeth were mounted in alastic stand using modeling wax for the purpose of taking spiral CT.fter CT imaging, the volume of the filled material in each tooth werestimated using Siemens Emotion Duo model of Spiral CT with the

roup B1, filled with calcium hydroxide powder � distilled water. (D) Group

. (C) G

id of Syngo software (Fig. 1).

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Then the teeth in each group were further divided into two sub-roups based on the chelators used for removal, thus giving fourroups:

A1 and A2: Metapex retrieved with 1 ml of 17% EDTA solution/1 mlof 10% citric acid � normal saline � ultrasonic agitation for 1minute.

B1 and B2: Calcium hydroxide powder mixed with distilled waterretrieved with 1 ml of 17% EDTA solution/1 ml of 10% citric acid� normal saline � ultrasonic agitation for 1 minute. Eventhough Barium sulfate is not used clinically nowadays, it wasadded to the calcium hydroxide powder because the radiopacityof plain calcium hydroxide powder was not adequate enough todifferentiate it from dentin accurately during CT imaging.

Citric acid (10%) was prepared just before the use. A second spiral

igure 2. (A) Group A1, filled with Metapex � retrieved with 17% EDTA � ultrultrasonic agitation. (C) Group B1, filled with calcium hydroxide powder � d

ith calcium hydroxide powder � distilled water � retrieved with 10% citric

T was done and the volume of remaining material in each tooth was h

OE — Volume 32, Number 11, November 2006

stimated as before (Fig. 2). The removal efficiency was calculated as(a-b)�100/a], where a was the volume of material packed in the rootanal and b was the volume remaining after retrieval. The data wastatistically analyzed using SPSS Version 10.0.5 software.

ResultsThere was significant difference between the groups when tested

sing Kruskal-Wallis (Kruskal-Wallis statistic � 13.73, p � 0.0033).ntergroup comparisons were done using Mann-Whitney U test assum-ng unequal variance. The removal efficiency for various groups was2.8% (A1), 89.8% (A2), 99% (B1), and 96% (B2) (Fig. 3). The 10%itric acid showed better removal efficiency than 17% EDTA for Metapexp � 0.003). Powder form of calcium hydroxide in distilled water wasemoved efficiently by both the methods (p � 0.08). The 17% EDTAhowed much better removal efficiency of powder form of calcium

agitation. (B) Group A2, filled with Metapex � retrieved with 10% citric acidwater � retrieved with 17% EDTA � ultrasonic agitation. (D) Group B2, filledultrasonic agitation.

asonicistilled

ydroxide in distilled water than Metapex (p � 0.001). The 10% citric

Removal of Calcium Hydroxide Intracanal Medicament 1099

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cid removed the powder form of calcium hydroxide in distilled wateretter than Metapex (p � 0.04).

DiscussionIn previous studies the teeth were sectioned longitudinally and

hotos taken, which were analyzed with digital image processing toeasure the surface area covered with calcium hydroxide after removal

9, 10). In our study volume analysis was done with spiral CT. Volumenalysis gives a more accurate measure than surface area measurement.hree-dimensional volume analysis is used in the field of medicine in aariety of applications (e.g. thoracic and abdominal aneurysm, intra-ranial aneurysm etc), which have proved that the accuracy is equal tohat of conventional techniques like angiograms (15). With spiral CT,hree-dimensional volume measurements are possible without section-ng the specimens and thus avoiding the loss of material during section-ng. The amount of calcium hydroxide packed in the canal should be

easured; only then the amount removed can be compared and anccurate value be obtained. This was not done in previous studies.pecimen mounting was done in modeling wax because even a slighthange in the position of the tooth in between the two spiral CT scansill not affect the measurement of volume.

Literature search shows that hand filing with saline or NaOCl irri-ation does not remove calcium hydroxide completely from the canal.hereas, EDTA and hand filing improved the removal efficiency. In our

tudy two commonly used calcium chelators (17% EDTA solution, 10%itric acid) were used with ultrasonic agitation.

Lambrianidis et al. in their study have revealed that the calciumydroxide content does not influence the removal efficiency from theoot canal walls, but methyl cellulose vehicle resisted removal from theoot canal when retrieved with 17% EDTA. This was probably because ofhe interactions between methylcellulose and EDTA (10). The result ofhe present study also emphasizes the fact that vehicle used to mixalcium hydroxide paste is important for complete retrieval. The pow-er form in distilled water was removed by 96% to 99% in comparison

igure 3. Comparison of calcium hydroxide retrieved using both chelators.

o silicone oil, which was removed by 73% to 89%. The particulate form p

100 Nandini et al.

f calcium hydroxide in distilled water was easily removed, but siliconeil resists dissolution in water and hence was retained in the canal. Both

he chelators efficiently removed powder form of calcium hydroxide inistilled water. The 10% citric acid performed better in comparison to7% EDTA solution in removal of Metapex. This probably could beecause of the reason that EDTA chelates calcium ions in water, butitric acid is able to penetrate the silicone oil better in comparison toDTA and chelates the calcium ions.

The remaining calcium hydroxide was found to be packed mainlyn the apical thirds of about 2 to 3 mm. Specimens filled with Metapex,hich was removed with 17% EDTA showed smears of calcium hydrox-

de on the root canal walls also.Failure of root canal treatment of a maxillary central incisor has

een reported and attributed to incomplete removal of a calcium hy-roxide medicament and subsequent resorption of the material from

he apical portion of the root canal. Retreatment and removal of theemnant calcium hydroxide followed by permanent obturation withutta-percha and sealer showed complete periradicular bone healing6). It is also quoted that depending on the smoothness of the canal wallhe removal of calcium hydroxide may be accomplished to varying de-rees (16) Kim and Kim (8) gave a controversial report to that oforkaew et al. (17) and Holland et al. (18) who have reported that

eakage was less in teeth that received calcium hydroxide as intracanaledicament in comparison to that of nonmedicated teeth. They have

ointed out that the residual calcium hydroxide was incorporated intohe sealer during obturation, which caused a decrease in the perme-bility of the sealer itself or that the calcium hydroxide was mechanicallyushed in to the dentinal tubules blocking them off and decreasing theentin permeability. However, it is not likely that a decrease in theentin permeability will lead to decrease in the apical leakage. Leakaget the apex occurs between the root canal wall and the sealer, betweenhe sealer and the gutta-percha, or within the sealer itself. Kim and Kimhowed more leakage when a calcium hydroxide packed tooth was

ermanently obturated with gutta-percha and zinc oxide eugenol sealer.

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inc oxide eugenol becomes more granular and brittle when it interactsith calcium hydroxide, thus the solubility increases (9, 19, 20).

ConclusionThe vehicle used to prepare calcium hydroxide paste is important

or its retrieval. Oil based calcium hydroxide is more difficult to removehan powder form calcium hydroxide mixed with distilled water. Both7% EDTA and 10% citric acid were found to remove the powder formf calcium hydroxide in distilled water efficiently, whereas 10% citriccid was found to perform better than EDTA in removing oil basedalcium hydroxide.

AcknowledgmentsThe authors thank Dr. Senthil, MD (Radiologist), Aarthi Scans,

hennai.

References1. Stanley HR, Pameijer CH. Pulp capping with a new V-L-C curing calcium hydroxide.

Oper Dent 1985;10:156.2. Tronstad L, Andreasen JO, Hasselgren G, Kristenson L, Russ I. PH changes in dental

tissues after root filling with calcium hydroxide. J Endod 1981;17:17–21.3. Kleier DJ, Barr ES. A study of endodontically apexified teeth. Endod Dent Traumatol

1991;7:1124. de Souza CA, Teles RP, Souto R, Chaves MA, Colombo AP. Endodontic therapy asso-

ciate with calcium hydroxide as an intracanal dressing: microbiologic evaluation bythe checkerboard DNA-DNA hybridization technique. J Endod 2005;31:79 – 83.

5. Cwikla SJ, Belanger M, Giguere S, Progulske-Fox A, Vertucci F. Dentinal tubule

disinfection using three calcium hydroxide formulations. J Endod 2005;31:50 –2.

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6. Ricucci D, Langeland K. Incomplete calcium hydroxide removal from the root canal:a case report. Int Endod J 1997;30:418 –21.

7. Calt S, Serper A. Dentinal tubule penetration of root canal sealers after root canaldressing with calcium hydroxide. J Endod 1999;25:431–3.

8. Kim SK, Kim YO. Influence of calcium hydroxide intracanal medication on apical seal.Int Endod J 2002;35:623– 8.

9. Margelos J, Eliades G, Verdalis C, Palaghias G. Interaction of calcium hydroxide withzinc oxide eugenol type sealers: a potential clinical problem. J Endod 1997;23:43– 8.

0. Lambrianidis T, Margelos J, Beltes P. Removal efficiency of calcium hydroxide dress-ing from the root canal. J Endod 1999;25:85– 8.

1. Anthony DR, Gordon TM, del Rio CE. Effect of three vehicles on the pH of calciumhydroxide. Oral Surg 1982;54:560 –5.

2. Simon ST, Bhat KS, Francis R. Effect of four vehicles on the pH of calcium hydroxideand the release of calcium ion. Oral Surg Oral Med Oral Pathol Oral Radiol Endod1995;80:459 – 64.

3. Cohen S, Burns R. Pathways of the pulp, 8th ed. St. Louis, MO: Mosby, 2002:836.4. Law A, Messer H. An evidence-based analysis of the antibacterial effectiveness of

intracanal medicaments. J Endod 2004;30:689 –94.5. Calhoun PS, Kuszyk BS, Heath DG, Carley JC, Fishman EK. Three-dimensional volume

rendering of spiral CT data: theory and method. Radiographics 1999;19:745– 64.6. Langeland K. Tratamiento Farmacologico de la dentina y del conducto radicular. In:

Guldner PHA, Langeland K, eds. Endodoncia. Barcelona, Spain: Springer-VerlagIberica SA, 1995:203–5.

7. Porkaew P, Retief DH, Barfield RD, Lancefield WR, Soong S. Effect of calcium hy-droxide paste as an intracanal medicament on apical seal. J Endod 1990;16:369 –74.

8. Holland R, Alexandre AC, Murata SS, Dos Santos CA, Junior ED. Apical leakagefollowing root canal dressing with calcium hydroxide. Endod Dent Traumatol1995;11:261–3.

9. Park JC, Kwon TK. Properties of calcium hydroxide: eugenol compound. J KoreanAcademy Conservative Dentistry 1999;24:408 –25.

0. Park SH. Chemical investigation on the reaction between calcium hydroxide medi-cament and zinc oxide-eugenol. PhD Thesis Daegu, Korea: Kyungpook National Uni-

versity.

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