ERaC

ATeapsMBrhaWaeiDTrm

KM

A

2c0

d

Basic Research—Technology

J

x Vivo Study of the Efficiency of Two Techniques for theemoval of Mineral Trioxide Aggregate Useds a Root Canal Filling Materialhristos Boutsioukis, DDS, MSc, Giovana Noula, DDS, and Theodor Lambrianidis, DDS, PhD

Naimods

wfeirMscA(

i

Cofepw7i(m

tgm

Gcwgr

bstracthe purpose of this study was to evaluate the removalfficiency of mineral trioxide aggregate (MTA) used asroot filling material. Ninety-three human teeth pre-

ared with a step-back technique were randomly as-igned to 2 groups and filled with vertically compactedTA (group A) or MTA and a gutta-percha cone (group

). Fillings were removed by using ultrasonics and/orotary nickel-titanium instruments. Roots were split intoalves, and a 1 to 4 scoring system was used to assess themount of residue. Data were analyzed with Kruskal-allis and Mann-Whitney tests. Remnants were found in

ll specimens. Rotary instruments were unable to pen-trate canals in group A. The combination of rotarynstruments and ultrasonics was superior in group B.ark discoloration of most MTA fillings was evident.he results suggest that MTA cannot be completelyemoved from the root canal system by any of theethods examined. (J Endod 2008;34:1239–1242)

ey WordsTA, retreatment, rotary Ni-Ti instruments, ultrasonics

From the Department of Endodontology, Dental School,ristotle University of Thessaloniki, Thessaloniki, Greece.

Address requests for reprints to Dr Christos Boutsioukis,9, Kimis Street, 551 33 Thessaloniki, Greece. E-mail address:hb@dent.auth.gr.099-2399/$0 - see front matter

Copyright © 2008 American Association of Endodontists.oi:10.1016/j.joen.2008.07.018

m

OE — Volume 34, Number 10, October 2008

onsurgical retreatment should be considered as the treatment of choice for mostcases of failed endodontically treated teeth (1, 2). Its main objective is to regain

ccess to the apical foramen by complete removal of the filling material, thereby facil-tating sufficient cleaning and shaping of the root canal system (3, 4). Obturating

aterials must be effectively removed without altering the shape of the root canal systemr extruding debris into the periradicular tissues. Numerous techniques have beenescribed, including use of hand or rotary instruments, heat, ultrasonics, or chemicalolvents in different combinations (5– 8).

Mineral trioxide aggregate (MTA) (ProRoot; Dentsply Tulsa Dental, Tulsa, OK) isidely recommended for use as a root-end filling material, for direct pulp capping, and

or repair of root perforations (9 –11). Applications for this material have been rapidlyxpanding. MTA has been used for obturation of root canals in apexification (12, 13),n permanent teeth with open apices (14, 15), in reimplanted teeth (16), and inetained primary teeth without permanent successors (17). The possibility of usingTA as a root canal filling material in fully developed permanent teeth has also been

uggested (14, 18) and investigated (19 –23). However, the presence of MTA in the rootanal might pose significant procedural problems to the clinician in case of retreatment.lthough the need to investigate the ability to remove MTA root fillings has been stressed23), no such reports have been published yet.

The aim of this study was to evaluate ex vivo the efficiency of ultrasonics and rotarynstrumentation for the removal of MTA root canal filling material.

Materials and MethodsNinety-three freshly extracted human single-rooted teeth were used in this study.

riteria for tooth selection included a single root canal, no visible root caries, fractures,r cracks, no signs of internal or external resorption or calcification, a completely

ormed apex, and curvature of �5 degrees according to Schneider (24) with no lateralxit of the apical foramen, in accordance with a previous study (25). Root canalreparation was also performed according to a previous study (25). Instrumentationas standardized with an ISO size 40 H-file reaching full working length, to an ISO size0 H-file 4 mm coronally and a final coronal flaring with a rotary-driven nickel-titanium

nstrument size 40 .06 taper (Profile; Dentsply Tulsa Dental, Tulsa, OK). Rocanal-R1Rocanal SA, Krysna, South Africa) was used as a lubricant. No specific attempts wereade to remove the smear layer.

The root canals of all teeth were dried with paper points. One tooth was excludedo serve as a negative control. The remaining 92 teeth were randomly divided into 2roups, A and B, of 46 teeth each. White MTA (ProRoot; Dentsply Tulsa Dental) wasixed according to the manufacturer’s recommendations (26) and used as follows.

In group A, MTA was applied with a lentulo spiral (Antaeos; Vereinigte DentlwerkembH & Co, Munich, Germany), then incrementally packed into the root canal, andondensed with preselected pluggers (Antaeos) up to the canal orifice. In group B, MTAas applied in the root canal by using a lentulo spiral (Antaeos). An ISO size 40 .02utta-percha cone was introduced to within 2 mm of the working length to facilitateetreatment.

A wet cotton pellet was placed in the access cavity, which was sealed with inter-

ediate restorative material. The quality of the filling was evaluated in standarized

Evaluation of Removal Efficiency of MTA Used as a Root Filling Material 1239

mw

doovea

sopd

lA(mau

im(u

i

aaumet

fpejbhrSI

lit

iipc

wswsrie

tv

dgoM

nNhgrctpw

mpsatppmt

r

Fnic

Basic Research—Technology

1

esiodistal and buccolingual x-rays and was considered satisfactoryhen no voids could be detected.

Teeth were stored at 37°C � 1°C and 100% relative humidity for 10ays. All teeth were reexamined with a 4�magnifying glass to verify absencef fractures or cracks. Incomplete vertical root fractures were detected in 5f 46 specimens in group A after the storage period. No specimens withertical fractures could be identified in group B. These specimens werexcluded from the study and replaced by additional specimens preparedccording to the same protocol.

The coronal filling was removed with a carbide bur on a high-peed handpiece. Setting of the material was confirmed with an end-dontic probe. One tooth from each group was excluded to serve as aositive control. The remaining teeth from each group were furtherivided into 3 subgroups of 15 teeth each.

In subgroup 1, filling materials were removed by using a spreader-ike tip long enough to reach working length in all specimens (EN-11;mdent AB, Nynäshamn, Sweden) on a portable ultrasonic deviceUS30m; Amdent) under constant water irrigation at a flow rate of 30L/min. The ultrasonic device was set to 10% of maximum power,

ccording to manufacturer’s recommendations. A size 10 K-file wassed to check for patency.

In subgroup 2, filling materials were removed by using GT rotarynstruments size 40, .04 and .06 taper operated on an X-SMART electric

otor (Dentsply Maillefer, Ballaigues, Switzerland) with constant speed250 rpm) and torque (1 N/cm) control. Rocanal-R1 (Rocanal SA) wassed as a lubricant. A size 10 K-file was used to check for patency.

In subgroup 3, filling materials were initially removed as describedn subgroup 2 and subsequently as described in subgroup 1.

The crowns were removed, and roots were split and examinedccording to a previous study (25). A scoring system was defined tossess the quantity of the residue on the canal walls. Evaluation scalessed were (1) no visible remnants, (2) scattered remnants, (3) distinctasses, and (4) densely packed remnants (Fig. 1). Remnants were

valuated in each third (apical, middle, and cervical) of all sections, andhe highest score observed on the 2 sections of each tooth was recorded

igure 1. Root canal after removal of MTA filling (subgroup A1). Patency couldot be regained. Note characteristic patterns of material remnants correspond-ng to the 4 evaluation scales (arrows). This specimen was used for observer

calibration.

240 Boutsioukis et al.

or each third. After calibration with selected specimens, evaluation waserformed by 2 investigators who were blinded to the method applied inach specimen. In cases of disagreement, sections were re-evaluatedointly by the observers. Data were subjected to statistical interpretationy using Kruskal-Wallis and Mann-Whitney tests (P � .05). The nullypothesis was that there is no significant difference between examinedemoval methods regarding the amount of residual filling materials.tatistical analysis was performed with SPSS 15.0 (SPSS Inc, Chicago,L).

ResultsRemnants of filling materials were found in all specimens regard-

ess of the placement and removal methods used. Positive control teethn both groups showed densely packed material in all thirds as opposedo the negative control.

Rotary instruments were unable to penetrate any of the root canalsn group A. Therefore, subgroups A2 and A3 were excluded from scor-ng, whereas specimens in subgroup A1 were subjected to the scoringrocedure (Fig. 2). In 7 of 15 specimens in subgroup A1, patency of theanal could not be regained.

When examining the efficacy of material removal in group B, thereere significantly fewer remnants in the middle third of the teeth in

ubgroup B3 than in B1 (P � .001) or B2 (P � .011). Moreover, thereere significantly fewer remnants in the coronal third of the teeth in

ubgroup B3 than in subgroup B2 (P � .004). Patency could not beegained in 5 of 15 specimens in subgroup B1, whereas it was regainedn all specimens in subgroups B2 and B3. No further significant differ-nces were detected.

Another finding regardless of group was the dark discoloration ofhe MTA in most of the specimens (Fig. 3). The discoloration was ob-ious in depth and not just on the surface of the material.

DiscussionIt is important to remove as much obturating materials as possible

uring retreatment to uncover remnants of necrotic tissue or microor-anisms that might be responsible for endodontic failure (27, 28). Nonef the methods used in this study was effective in completely removingTA from the root canal system.

Indications for use of MTA, as stated by the manufacturer (26), doot include orthograde obturation of fully developed permanent teeth.evertheless, various techniques have been proposed. Previous studiesave considered MTA as a primary filling material (21, 22). Singleutta-percha cones have been used in addition to MTA to facilitateetreatment (20). MTA has also been used as a sealer with laterallyondensed gutta-percha cones (19, 23). However, its physical proper-ies might have to be modified to facilitate use as a sealer (19). In theresent study, 2 different filling techniques were used, in accordanceith previous studies (20 –22).

It seems that removal efficiency is highly dependent on the fillingethod used. Canals filled completely with MTA were impossible to

enetrate with rotary instruments and thus were excluded from thetudy (subgroups A2 and A3). It appeared that set MTA did not presentny significant voids that would allow rotary instruments to advance inhe canal. Conversely, hand files have been reported to successfullyenetrate simulated canals filled with MTA (22). H-files tested during ailot study failed to advance within MTA-filled canals. Differences inaterial attachment to acrylic resin or dentin along with different filling

echniques might account for these diverse findings.The use of rotary instruments appeared to be more efficient in

emoving filling materials in group B (MTA and a single gutta-percha

one). The presence of the gutta-percha cone might have enhanced

JOE — Volume 34, Number 10, October 2008

isBt

o(csc

tsamgs

d(ma

uBdct

ojcpd

a

F A3 ar

Fd

Basic Research—Technology

J

nstrument advance within the canal. However, because specimens inubgroup B3 presented significantly fewer remnants than either B1 or2, it seems that additional use of ultrasonics is required to remove

hick MTA remnants.Ultrasonics has been shown to be quite successful in the removal

f hard pastes, although great patience and persistence were necessary29). Moreover, the ultrasonic tip must reach full working length, aondition not always met during the study, even though only teeth withtraight root canals were included. Patency could not be regained in aonsiderable number of specimens in subgroups A1 and B1 in contrast

igure 2. Bar charts summarizing scores in each subgroup. Subgroups A2 and

igure 3. Root canal after removal of MTA filling (subgroup B2). Note evident

ark discoloration of MTA remnants.

OE — Volume 34, Number 10, October 2008

o subgroup B3. The presence of a dense filling to the working length inubgroups A1 and B1 along with narrow apical canal diameter mightccount for a reduction in oscillation amplitude and limited perfor-ance of the tip (30), whereas the space provided by prior removal of

utta-percha might have enhanced the effectiveness of ultrasonics inubgroup B3.

No rotary instrument separation was noted during removal proce-ures. Conversely, the risk of ultrasonic tip separation should be noted31). Two tips were separated during use and were successfully re-oved. Marked length decrease was observed in another tip, possibly asresult of gradual attrition.

The use of solvents to dissolve hard pastes is usually considerednsuccessful (29). There are no known efficient solvents for MTA.ioPure MTAD (Dentsply Tulsa Dental) has been shown to partiallyissolve set MTA (32). Yet, direct contact of the MTA remnants with aontinuously replenishing MTAD for an extended period of time solu-ion would be required (32), which is clinically unfeasible.

The discoloration of white MTA has been previously reported in an-ther study (33). In both studies the material was affected in depth, which

ustifies assumptions of a possible chemical reaction. This discolorationould compromise the aesthetics of a tooth, even if MTA is used for directulp capping or repair of a root perforation. Further research is required toetermine the chemical process leading to color alteration.

ConclusionsMTA cannot be completely removed from the root canal system by

ny of the methods examined in this study.

References1. Taintor J, Ingle J, Fahid A. Retreatment versus further treatment. Clin Prevent Dent

1983;5:8 –14.2. Friedman S, Stabholz A. Endodontic retreatment: case selection and technique—part

1: criteria for case selection. J Endod 1986;12:28 –33.3. Stabholz A, Friedman S. Endodontic retreatment: case selection and technique—part

2: treatment planning for retreatment. J Endod 1988;14:607–14.4. Mandel E, Friedman S. Endodontic retreatment: a rational approach to root canal

e not presented because they were excluded from the scoring procedure.

reinstrumentation. J Endod 1992;18:565–9.

Evaluation of Removal Efficiency of MTA Used as a Root Filling Material 1241

1

1

1

1

1

1

1

1

1

1

2

2

2

2

2

2

2

2

2

2

3

3

3

3

Basic Research—Technology

1

5. Friedman S, Stabholz A, Tamse A. Endodontic retreatment: case selection andtechnique—part 3: retreatment techniques. J Endod 1990;16:543–9.

6. Hülsmann M, Stotz S. Efficacy, cleaning ability and safety of different devices forgutta-percha removal in root canal retreatment. Int Endod J 1997;30:227–33.

7. Pitt Ford TR, Rhodes JS. Root canal retreatment: 2—practical solutions. Dent Update2004;31:97–102.

8. Masiero AV, Barletta FB. Effectiveness of different techniques for removing gutta-percha during retreatment. Int Endod J 2005;38:2–7.

9. Lee SJ, Monsef M, Torabinejad M. Sealing ability of a mineral trioxide aggregate forrepair of lateral root perforations. J Endod 1993;19:541– 4.

0. Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregatewhen used as a root-end filling material. J Endod 1993;19:591–5.

1. Pitt Ford TR, Torabinejad M, McKendry DJ, Hong CU, Kariyawasam SP. Use of MTAaggregate for the repair of furcal perforations. Oral Surg Oral Med Oral Pathol OralRadiol Endod 1995;79:756 – 63.

2. Bortoluzzi EA, Souza EM, Reis JMSN, Esberard RM, Tanomaru-Filho M. Fracturestrength of bovine incisors after intra-radicular treatment with MTA in an experimen-tal immature tooth model. Int Endod J 2007;40:684 –91.

3. Martin RL, Monticelli F, Brackett WW, et al. Sealing properties of mineral trioxideaggregate orthograde apical plugs and root fillings in an in vitro apexification model.J Endod 2007;33:272–5.

4. Hayashi M, Shimizu A, Ebisu S. MTA for obturation of mandibular central incisorswith open apices: case report. J Endod 2004;30:120 –2.

5. D’Arcangelo C, D’Amario M. Use of MTA for orthograde obturation of nonvital teethwith open apices: report of two cases. Oral Surg Oral Med Oral Pathol Oral RadiolEndod 2007;104:e98 –101.

6. Panzarini SR, Holland R, de Souza V, Poi WR, Sonoda CK, Pedrini D. Mineral trioxideaggregate as a root canal filling material in reimplanted teeth: microscopic analysisin monkeys. Dent Traumatol 2007;23:265–72.

7. O’Sullivan S, Hartwell G. Obturation of a retained primary mandibular second molarusing mineral trioxide aggregate: a case report. J Endod 2001;27:703–5.

8. Andelin WA, Browning DF, Hsu GHR, Roland DD, Torabinejad M. Microleakage ofresected MTA. J Endod 2002;28:573– 4.

9. Holland R, de Souza V, Nery MJ, Filho JAO, Bernabe PFS, Dezan E Jr. Reaction of dog’steeth to root canal filling with mineral trioxide aggregate or a glass ionomer sealer.

J Endod 1999;25:728 –30.

242 Boutsioukis et al.

0. Vizgirda P, Liewehr F, Patton W, McPherson J, Buxton TB. A comparison of laterallycondensed gutta-percha, thermoplasticized gutta-percha, and a mineral trioxide ag-gregate as a root canal filling material. J Endod 2004;30:103– 6.

1. Al-Hezaimi K, Naghshbandi J, Oglesby S, Simon J, Rotstein I. Human saliva penetra-tion of root canals obturated with two types of mineral trioxide aggregate cements. JEndod 2005;31:453– 6.

2. Yeung P, Liewehr F, Moon P. A quantitative comparison of the fill density of MTAproduced by two placement techniques. J Endod 2006;32:456 –9.

3. Holland R, Mazuqueli L, de Souza V, Murata SS, Dezan EJ, Suzuki P. Influence of thetype of vehicle and limit of obturation on apical and Periapical tissue response indog’s teeth after root canal filling with mineral trioxide aggregate. J Endod2007;33:693–7.

4. Schneider SW. A comparison of canal preparation in straight and curved root canals.Oral Surg Oral Med Oral Pathol 1971;32:271–5.

5. Lambrianidis T, Kosti E, Boutsioukis C, Mazinis M. Removal efficacy of various cal-cium hydroxide / chlorhexidine medicaments from the root canal. Int Endod J2006;39:55– 61.

6. Dentsply Tulsa Dental. ProRoot MTA (mineral trioxide aggregate) root canal repairmaterial: directions for use. 2003 [cited 2008 Mar 15]. Available at: http://store.tulsadental.com/lit/productsearch.aspx?categoryid�TDP_REPAIR.

7. Bergenholtz G, Lekholm U, Milthon R, Heden G, Odesjo B, Engstrom B. Retreatmentof endodontic fillings. Scand J Dent Res 1979;87:217–24.

8. Sjögren U, Hagglund B, Sundqvist G, Wing K. Factors affecting the long-term results ofendodontic treatment. J Endod 1990;16:498 –504.

9. Jeng HW, ElDeeb ME. Removal of hard paste fillings from the root canal by ultrasonicinstrumentation. J Endod 1987;13:295– 8.

0. Van der Sluis LWM, Versluis M, Wu MK, Wesselink PR. Passive ultrasonic irrigation ofthe root canal: a review of the literature. Int Endod J 2007;40:415–26.

1. Plotino G, Pameijer CH, Grande NM, Somma F. Ultrasonics in endodontics: a reviewof the literature. J Endod 2007;33:81–95.

2. Smith JB, Loushine RJ, Weller RN, et al. Metrologic evaluation of the surface of whiteMTA after the use of two endodontic irrigants. J Endod 2007;33:463–7.

3. Watts DJ, Holt DM, Beeson TJ, Kirkpatrick TC, Rutledge RE. Effects of pH and mixingagents on the temporal setting of tooth-colored and gray mineral trioxide aggregate.

J Endod 2007;33:970 – 6.

JOE — Volume 34, Number 10, October 2008