CONSORT RANDOMIZED CLINICAL TRIAL

Chafic Safi, DMD, MS,

Meetu R. Kohli, BDS, DMD,Samuel I. Kratchman, DMD,Frank C. Setzer, DMD, PhD, MS,

and Bekir Karabucak, DMD, MS

Outcome of EndodonticMicrosurgery Using MineralTrioxide Aggregate or RootRepair Material as Root-endFilling Material: A RandomizedControlled Trial withCone-beam ComputedTomographic Evaluation

SIGNIFICANCE

There is no significantdifference in the outcomes ofendodontic microsurgerywhen MTA and RRM are usedas root-end filling materialsevaluated by radiograph andcone-beam computedtomographic imaging.

From the Department of Endodontics,University of Pennsylvania School ofDental Medicine, Philadelphia,Pennsylvania

Address requests for reprints to Dr BekirKarabucak, Department of Endodontics,University of Pennsylvania, 240 S 40thStreet, Philadelphia, PA 19104.E-mail address: bekirk@mac.com0099-2399/$ - see front matter

Copyright © 2019 Published by ElsevierInc. on behalf of American Association ofEndodontists.https://doi.org/10.1016/j.joen.2019.03.014

ABSTRACT

Introduction: The purpose of this randomized clinical trial was to evaluate healing afterendodontic microsurgery (EMS) using mineral trioxide aggregate (MTA) versusEndoSequence root repair material (RRM; Brasseler, Savannah, GA) as root-end fillingmaterials. Methods: Two hundred forty-three teeth with persistent or recurrent apicalperiodontitis were randomly assigned to either the MTA or RRM group. EMS was performed,and follow-up visits with clinical and radiographic investigation were scheduled at 6, 12, and24 months with follow-up cone-beam computed tomographic (CBCT) imaging after 12months. Results: One hundred twenty teeth with an average follow-up of 15 months wereevaluated. The overall success rate was 93.3% for periapical (PA) evaluation and 85% forCBCT evaluation. The RRM group exhibited 92% and 84% success rates as assessed on PAand CBCT imaging, respectively. The MTA group exhibited 94.7% and 86% success rates asassessed on PA and CBCT imaging, respectively. No significant difference was observedbetween the 2 groups. Microsurgical classification, root canal filling quality, root-endfilling material depth, and root fracture were found to be significant outcome predictors.Conclusions: EMS is a predictable procedure with successful outcome both 2-dimensionaland 3-dimensional radiographic evaluation when RRMorMTAwas used as the root-end fillingmaterial. (J Endod 2019;-:1–9.)

KEY WORDS

Cone-beam computed tomography; endodontic microsurgery; EndoSequence root repairmaterial; mineral trioxide aggregate; outcome; prognostic factors

Persistent and recurrent apical periodontitis can be treated predictably by modern endodontic surgery.Unlike traditional surgery, modern microsurgical techniques incorporate the use of an operatingmicroscope; ultrasonic tips for precise root-end preparation; and biocompatible root-end filling materialssuch as Super EBA (Harry J Bosworth Co, Skokie, IL), mineral trioxide aggregate (MTA), and morerecently other bioceramic-based materials such as Endosequence Root Repair Material (RRM; Brasseler,Savannah, GA) for better seal and apical tissue response1,2. Weighted pooled success rates have beenestablished in a meta-analysis with cumulative outcomes for the traditional approach at 59.0% and forendodontic microsurgery (EMS) at 93.5%2. The significantly higher success of the modern microsurgicalprocedure has been repeatedly concluded in several investigations3–5.

An ideal root-end filling material should be biocompatible, dimensionally stable, bactericidal, orbacteriostatic; easy to handle; and provide an excellent seal6. MTA (ProRootMTA; Dentsply Tulsa

JOE � Volume -, Number -, - 2019 Endodontic Microsurgery Using MTA and RRM 1

Dental, Tulsa, OK) has been the material ofchoice. It contains tricalcium silicate,dicalcium silicate, bismuth oxide, and smallproportions of tricalcium aluminate andcalcium sulfate. The composition is similar tothat of Portland cement with added bismuthoxide for radiopacity7. The superiority of thematerial, sealability, exemplarybiocompatibility, cementogenesis,reconstitution of the periodontal ligament atthe resected root surface, and clinicalprognostic superiority over others has beencorroborated in various studies8–10. Despitethese biological advantages, MTA exhibitsdifficult handling characteristics because ofits granular consistency and long settingtime11. It has also been reported to causediscoloration of the surrounding toothstructure12.

Recently, other calcium silicate–basedmaterials have been introduced inendodontics to overcome these limitations.RRM is a bioceramic-based material that isavailable as a premixed moldable putty.Several in vitro studies have shown RRM tobe similar in characteristics to MTA13,14.RRM and MTA have also been evaluated ina dog model with periapical (PA) film, cone-beam computed tomographic (CBCT)imaging, micro–computed tomographicimaging, and histologically15. Both materialsperformed equally well with a minimal or noinflammatory response noted histologically.It was observed that RRM and MTAdisplayed equivalent healing with PAradiographs; however, on CBCT and micro–computed tomographic images, RRMshowed superior healing tendency at theresected root surface and the PA area. Aclinical retrospective study evaluating RRMas root-end filling material analyzing clinicaland PA radiographic outcome at aminimum of a 1-year follow-up showed asuccess rate of 92% with no prognosticindicators16. A prospective randomizedclinical trial comparing MTA with iRoot BPplus, a material similar to RRM, at a 12-month radiographic follow-up corroboratedsuccess rates of 93% and 94%,respectively, with no significant difference inoutcome17.

The aim of the current investigation wasto evaluate the outcome of MTA and RRM asroot-end filling material clinically with2-dimensional PA radiographs and3-dimensional CBCT imaging in a prospectiverandomized clinical controlled trial. The datawere analyzed to identify prognosticpredictors of the procedure. The nullhypothesis was that there was no significantdifference in the outcome of EMS for MTA orRRM.

2 Safi et al.

MATERIALS AND METHODS

Study Design and EthicsA noninferiority randomized controlled trial wasconducted to compare the surgical outcome ofMTA (the control group) and RRM (the testgroup). Teeth were randomly assigned to thegroups using an online randomization programdeveloped by the information technologydepartment of the University of Pennsylvania,Philadelphia, PA. The study protocol wasapproved by the ethics committee of theInstitutional Review Board of the University ofPennsylvania (institutional review board number:815114). The minimum sample size wasdetermined to be 124 (62 in each group) basedon a 20% mean difference in outcome betweenthe groups and power 5 0.80 (P , .05). Thesubjects were recruited during the planned timeframe for the study at the Department ofEndodontics, University of Pennsylvania DentalSchool from July 2011 to May 2014.

Subject Enrollment and Inclusion/Exclusion CriteriaConsecutive patients presenting to theDepartment of Endodontics for routineplanned root-end surgery were evaluated forinclusion in the study.

The inclusion criteria were as follows:

1. Age 18 years and older consenting tothe surgical procedure as well asagreeing to preoperative and at least 1follow-up CBCT evaluation after 12months

2. Noncontributory medical history(American Society of Anesthesiologistsclass I and II)

3. A history of previous endodontictreatment with radiographic presenceof apical periodontitis

4. A true endodontic lesion: microsurgicalclassification A, B, or C (Fig. 1)1

5. Lesion size less than 10 mm in diameter

The exclusion criteria were defined asfollows:

1. Nonconsenting patients and patientsyounger than 18 years of age

2. Medical history with American Societyof Anesthesiologists class III to V

3. Insufficient coronal restoration4. Nonrestorability or traumatized teeth5. Teeth with microsurgical classification

D, E, or F (Fig. 1)6. Mobility .17. Radiographic presence of nonapical

root resorption8. Resurgery9. Vertical root fracture

10. Lesions �10 mm in diameter

Preoperative ProceduresPatients were informed about the potential risksof and alternatives to EMS. Written and verbalinformed consent were acquired. A PAradiograph (CS 2100; Carestream Dental,Atlanta, GA) and CBCT image of the tooth weretaken. CBCT scans of the patient were acquiredby 1 of the following machines available in theendodontic department at the time of treatment:

1. From July 2011 to February 2013,SUNI3D (Suni Medical Imaging, SanJose, CA): field of view (FOV) 5 5 ! 5cm, voxel size 5 0.08 mm

2. February 2013 to April 2014, CS 90003D (Carestream Dental): FOV 5 7.5 !

3.7 cm, voxel size 5 0.076 mm3. After April 2014, Veraviewepocs 3D

R100 (Morita, Irvine, CA): FOV 5 4 !

4 cm, voxel size 5 0.125 mm

A surgical evaluation form was used toidentify any preoperative prognostic factorsincluding patient sex, presurgical apicaldiagnosis as per American Association ofEndodontists consensus, treatment renderedbefore surgery (primary or secondary root canaltherapy), tooth position (anterior vs posterior,maxilla vs mandible), microsurgical classificationfrom PA radiographs (A, B, or C), presence of abroken instrument in the affected root(s) seenon PA and CBCT imaging, and root canal fillingquality evaluated on PA radiography. Thequality of root canal filling was evaluated by thecriteria established by Chugal et al18. A rootcanal filling was considered adequate when itexhibited a homogeneous radiopaque area withno visible voids or space between the materialand the walls of the canal or within the body ofthe material itself. Root canal fillings that did notshow a uniform radiodensity and/or with canalspace visible laterally and apically wereconsidered inadequate. Root canal filling lengthwas evaluated on PA radiographs. The qualityof root canal filling length was evaluated byevaluation criteria suggested by Sjogren et al19.A root canal filling ending 0–2 mm from theradiographic apex was considered adequate.Any root canal filling not within that range (shortor long) was considered inadequate. Thepresence or absence of fenestration of thecortical buccal plate and the height of thecortical plate (evaluated on CBCT) weredocumented. Lesion diameter (measuredon CBCT imaging) in millimeters in3 dimensions and the largest value wererecorded (Table 1).

Surgical Procedure and MaterialRandomizationAll EMS procedures were performed bypostgraduate residents under the supervision

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FIGURE 1 – Preoperative microsurgical classification of teeth.

of faculty and followed the guidelines andprinciples outlined by Kim and Kratchman1.Except for the randomization of the root-endfilling material, all procedures followed the

TABLE 1 - Demographic Distribution of Cases

T

%Sex

Male 41Female 58

Preoperative signs and symptomsPresent 55Absent 44

Broken instrumentPresentAbsent 9

Previous retreamentYes 1No 9

Preoperative periapical diagnosisSymptomatic apical periodontitis 7Asymptomatic apical periodontitis 2Chronic apical abscess

Tooth positionAnterior 3Posterior 7

JawMaxilla 4Mandible 5

Microsurgical classificationClass A 47Class B 21Class C 30

Root canal filling qualityAdequate 46Inadequate 43

Root canal filling lengthAdequate 51Inadequate 48

Buccal cortical platePresent 44Absent 55

Lesion size�5 mm 68.5 mm 31

BCRRM, bioceramic root repair material; MTA, mineral trioxide

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same standard protocol. At the root-end fillingstage, the supervising faculty used theUniversity of Pennsylvania Web server forrandomization to assign the teeth to either the

otal MTA BCRRM

120 57 63

(n) % (n) % (n)

.7 (51) 40.4 (23) 44.4 (28)

.3 (69) 59.6 (34) 55.6 (35)

.8 (67) 56.1 (32) 55.5 (35)

.2 (53) 43.9 (25) 44.5 (28)

5 (6) 5.3 (3) 4.5 (3)5 (114) 94.7 (54) 95.5 (60)

0 (12) 1.6 (8) 6 (4)0 (108) 98.4 (49) 94 (59)

0 (84) 77.2 (44) 63.5 (40)5 (30) 22.8 (13) 27 (17)5 (6) 0 (0) 9.5 (6)

0 (36) 22.8 (13) 36.5 (23)0 (84) 77.2 (44) 63.5 (40)

5 (54) 47.4 (27) 42.9 (27)5 (66) 52.6 (30) 57.1 (36)

.5 (57) 56 (32) 39.7 (25)

.7 (26) 25 (14) 19 (12)

.8 (37) 19 (11) 41.3 (26)

.7 (56) 63.2 (36) 31.7 (20)

.3 (64) 36.8 (21) 68.3 (43)

.7 (62) 61.4 (35) 42.9 (27)

.3 (58) 38.6 (22) 57.1 (36)

.2 (53) 57.9 (33) 31.7 (20)

.8 (67) 42.1 (24) 68.3 (43)

.3 (82) 68.4 (39) 68.3 (43)

.7 (38) 31.6 (18) 31.7 (20)

aggregate.

E

MTA or RRM group. The informationtechnology department of the university wastasked to develop a Web-based HealthInsurance Portability and Accountability Act of1996–compliant program for randomization.The program is available to all departments viathe university intranet to conductrandomization of a clinical trial. The programcan be accessed only with a username andpassword; the patient’s chart number wasadded to this specific ConsolidatedStandards of Reporting Trials trial within theprogram, and the program randomly pickedthe material to be used. MTA was assigned avalue of 0, whereas RRM was assigned 1.This allowed for allocation concealment. Thesupervising faculty logged into the software,and the computer generated the allocationsequence of 0 or 1 randomly without anyinvolvement of the operator, the patient, orreviewers. The assistant mixed the materialand handed it over to the operator for use.The operator was aware what he or she wasusing only after it was dispensed to him or herduring the procedure. The materials wereused as per manufacturer instructions. Afterroot-end filling, the surgical site was cleanedand the flap repositioned. Primary woundclosure was achieved with interrupted suturesas needed (5.0 Supramid nylon sutures; SJackson Inc, Alexandria, VA). PA radiographswere taken. Patients received postoperativeinstructions and were prescribed an oralanalgesic (ibuprofen 600 mg) and instructedto rinse twice daily with chlorhexidine 0.2%mouth rinse for 1 week. Antibiotics weregenerally not prescribed unless the patient’smedical history warranted it. Sutures wereremoved 3–5 days after surgery.

Follow-up ProceduresAll patients were invited back yearly afterperiapical surgery for follow-up examination. Atthe follow-up visit, a routine clinicalexamination with a PA radiograph wasconducted. The tooth was evaluated forsymptoms, tenderness to percussion,

ndodontic Microsurgery Using MTA and RRM 3

FIGURE 2 – (A) The Molven radiographic criteria for evaluating teeth after EMS. Complete healing categories. (AA) The lamina dura is restored to the original width. (AB) The laminadura is reconstituted but is less than 2 times the width along the resected root surface. (AC) The lamina dura is widened along the root-end filling material. (AD) Complete bone repair;however, the density of bone in the surgical site is not the same as the surrounding bone. No discernible lamina dura or periodontal ligament at the resected root surface suggestingankylosis. (B) The Molven radiographic criteria for evaluating teeth after EMS. Incomplete healing categories. (B-A) The radiolucent area at follow-up has decreased; however, there is adense radiolucency present that is asymmetric to the apex, sometimes disassociated from the apex, that presents often with a sunburst bone pattern. (B-B) A dense radiolucent areanot in continuity with the periodontal ligament within the surgical site. (C) The Molven radiographic criteria for evaluating teeth after EMS. Uncertain healing categories. C-A representsthe radiolucency as seen on an immediate postoperative radiograph and (C-B) represents the follow-up. The area has reduced significantly but is still larger than 2 times the originalperiodontal ligament space. (D) The Molven radiographic criteria for evaluating teeth after EMS. Unsatisfactory healing categories. D-A represents the radiolucency as seen on animmediate postoperative radiograph and D-B represents the follow-up. The area has enlarged in size or remains the same.

4 Safi et al. JOE � Volume -, Number -, - 2019

FIGURE 3 – (A) Penn criteria for evaluating 3-dimensional scans of teeth after EMS. Complete healing categories. (AA) Reformation of the periodontal space of normal width andlamina dura over the entire resected and unresected root surfaces. (AB) A slight increase in the width of the apical periodontal space over the resected root surface but less than twicethe width of noninvolved parts of the root. (AC) A small defect in the lamina dura surrounding the root-end filling. (AD) Complete bone repair with discernible lamina dura; the bonebordering the apical area does not have the same density as surrounding noninvolved bone. Complete bone repair. Hard tissue covering the resected root-end surface completely. (AE)No apical periodontal space can be discerned. (B) Penn criteria for evaluating 3-dimensional scans of teeth after EMS. Limited healing categories. (BA) The continuity of the corticalplate is interrupted by an area of lower density. (BB) A low-density area remains asymmetrically located around the apex or has an angular connection with the periodontal space. (BC)Bone has not fully formed in the area of the former access osteotomy. (BD) The cortical plate is healed, but bone has not fully formed in the site. (C) Penn criteria for evaluating3-dimensional scans of teeth after endodontic microsurgery. Unsatisfactory healing. The volume of the low-density area appears enlarged or unchanged.

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palpation, and periodontal probing. Alimited-volume CBCT scan was acquired atleast 1 of the follow-up visits with patient’sconsent. The patient’s longest follow-up on PAradiography, CBCT imaging, and clinicalexamination was included in the investigation.The minimum follow-up period for all caseswas 12 months. The investigator was blindedto the material used.

The following data from the follow-upvisits were extracted and assessed duringblinded radiographic and CBCT evaluation:

1. The type of root-end filling material:MTA or RRM

2. The depth of material: equal to and,2.5 mm or less measured on CBCTimaging

3. The detection of an apical root fractureintraoperatively that was eliminatedduring root resection: notes

4. The presence of missed unfilled canalsthat were addressed only surgically:from CBCT imaging

5. Whether the tooth serves as a fixedprosthetic bridge abutment

6. The presence or absence ofinterproximal contacts

7. A full-coverage crown or buildup

Outcome AssessmentClinical examination at the follow-up visits wasperformed by 1 operator (C.S.). Threecalibrated examiners reviewed all theradiographic images (B.K., S.K., and M.K.).They are experienced endodontists familiarwith EMS. The examiners were blinded to thematerial used and to the time of follow-up. Aspecific score was assigned for each casewhen all 3 examiners agreed or achieved aconsensus after discussion. The preoperative,postoperative, and follow-up PA radiographswere projected on a big screen in a dark roomand were displayed in a random fashion.Two-dimensional healing on PA radiographywas determined as complete, incomplete,uncertain, or unsatisfactory according to thecriteria established by Rud et al20 and Molvenet al21 (Fig. 2A–C).

Each patient had 1 preoperative CBCTscan and 1 follow-up CBCT scan. Images wereprojected in a dark room, andDigital Imaging andCommunications in Medicine files of the CBCTscans were viewed using OsiriX (Pixmeo,Geneva, Switzerland) in the multiplanarreconstruction mode with high-definitionprojection. The axes were aligned to obtain idealmesiodistal and buccolingual sections; thesagittal plane was parallel to the mesiodistal longaxis of the tooth, the coronal plane was alignedalong with the root canal, and both planespassed through the middle of the resected root-

6 Safi et al.

end surface. The slice thickness was set to0.125 mm. After proper alignment, healing wasevaluatedusing themodifiedPenn3-dimensionalcriteria as described by Schloss et al22 (Fig. 3).

Results obtained were dichotomized intohealed and nonhealed categories. Casesclassified under complete or incomplete healingon PA evaluation, complete healing, and limitedhealing on CBCT evaluation with absence ofclinical signs and/or symptoms were regardedas healed (successful), whereas those classifiedas uncertain or unsatisfactory on PAradiography and unsatisfactory healing onCBCT imaging with or without clinical signs andsymptoms were labeled as nonhealed (failure). Ifsymptoms were noted at the follow-up visit, thecase was considered a failure irrespective of PAor CBCT presentations.

Statistical AnalysisSignificant association between PA and CBCTimaging was assessed using the Cohen kappatest. Significant associations between theoutcome and prognostic factors wereexamined using the Fisher exact test. Allstatistical tests were performed as 2-tailed withthe level of significance set atP, .05. Statisticaltests were performed using the R softwarepackage v3.1.0 (http://www.r-project.org).

RESULTS

From the 243 teeth that were randomized andunderwent a microsurgical procedure, 122teeth were examined at follow-up. A total of 57teeth were examined from the MTA group and65 teeth from the RRM group. One hundredfourteen failed to attend any of the follow-upvisits. Seventeen other patients whencontacted over the phone indicated that thetooth had been extracted. However, thesepatients could not recall nor come to thedepartment for a clinical follow-up in order toassess the reason for extractions. The reasoncould be restorative, surgical, or periodontalfailure. These cases were considered lost tofollow-up, bringing the total number lost tofollow-up to 121. Among the 122 teeth thatwere examined, 2 teeth were eliminatedbecause of procedural errors as seen onfollow-up CBCT imaging but not detected onPA radiographs. The final sample consisted of120 teeth. The mean follow-up time was 15months (Fig. 1).

The overall success rate as per2-dimensional PA radiography was 93.3%witha success rate of 94.7% for MTA and 92% forRRM, which was not statistically significant.The combined success rate on CBCTevaluation was 85% with a success rate of86% for MTA and 84% for RRM, respectively.Overall, there was substantial agreement

(92.5%) between PA scores and CBCT scores(Cohen kappa 5 0.63; 95% confidenceinterval [CI] 5 0.397–0.862; P , .001) whenusing the data for both materials.

Microsurgical classification (A, B, or C)(P 5 .019; odds ratio 5 6.2; 95% CI,1.231–31.346) and the depth of root-end fillingmaterial (�2.5 mm or less measured on CBCTimaging) (odds ratio 5 50; 95% CI,9.363–706.502) had a significant influence onPA outcome. Root canal filling quality(adequate or inadequate) (P5 .035; odds ratio5 9; 95% CI, 1.378–62.091), depth ofroot-end filling material (odds ratio 5 14; 95%CI, 4.234–48.631), and the presence of a rootfracture (P 5 .02; odds ratio 5 23.2; 95% CI,1.778–302.645) detected intraoperatively evenif eliminated during the resection were theprognosis factors with a significant influenceon CBCT outcome. None of the otherprognostic criteria had a statistically significantinfluence on the outcome of EMS whetherassessed on PA or CBCT imaging.

The 2 teeth that were eliminated fromthe data set had incomplete root resection thatwas detected on the follow-up CBCT scan.Both cases had RRM as the root-end fillingmaterial. None of the MTA-treated teeth hadany procedural errors observed on follow-upCBCT imaging.

DISCUSSION

EMS is a predictable procedure with a highsuccess ratewhen eitherMTAor RRMare usedas a root-end filling material15–17. In the currentinvestigation, the outcome was not found to besignificantly different between the 2 materialswhen healing was evaluated with either 2-dimensional PA radiography or 3-dimensionalCBCT imaging. The overall success rates forMTA and RRM cases on 2-dimensional PAradiography were 94.7% and 92%,respectively. These values are comparable withother studies in which successful healing aftersurgery has been reported to be 90.2%–95.6%for MTA and 92%–94.4% for RRM16,17,23. Thestatistical analysis showed no differencebetween the 2 materials similar to the results ofZhou et al clinically17 and Chen et al in theanimal model15.

Two-dimensional imaging with PAradiography lacks sensitivity in detecting apicalperiodontitis and minute changes inperiodontal ligament reformation24,25. Fewstudies have compared PA versus CBCThealing after surgery with a follow-upperiod ranging from 4–12 monthspostoperatively26–28. The results of theseinvestigations concluded that CBCT imagingshows lower healing than PA radiography inthe time investigated. The results of the current

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TABLE

2-TheDistributionofCasesaccordingtoTheirS

coreson

Periapical(PA)Radiography

andCone-beamComputedTomographic(CBC

T)Imagingas

aFunctionofTime

Tee

thMTA

BCRRM

Complete

Inco

mplete

Unc

ertain

Uns

atisfactory

Complete

Inco

mplete

Unc

ertain

Uns

atisfactory

Complete

Inco

mplete

Unc

ertain

Uns

atisfactory

PAscores

(%)

75.8

17.5

1.7

584

.310

.53.5

1.7

71.5

20.6

7.9

0Suc

cess–failure

93.3

6.7

94.8

5.2

92.1

7.9

Tee

thMTA

BCRRM

Complete

Limited

Uns

atisfactory

Complete

Limited

Uns

atisfactory

Complete

Limited

Uns

atisfactory

CBCTscores

(%)

51.7

33.3

1552

.633

.314

.147

.636

.515

.9Suc

cess–failure

8515

85.9

14.1

84.1

15.9

BCRRM,b

ioce

ramicroot

repa

irmaterial;CBCT,

cone

-bea

mco

mpu

tedtomog

raph

ic;M

TA,m

ineraltrioxide

aggreg

ate.

JOE � Volume -, Number -, - 2019

study suggest a similar pattern. Von Arx et al26

showed that nearly a third of cases had lesshealing on CBCT imaging than PA at the1-year follow-up. Similarly, Christiansen et al27

in their evaluation of 58 teeth with a CBCT scan1 week and 1 year after surgery detected 28%more defects on CBCT imaging than PAradiography. In the current evaluation, thedifference in value between the completelyhealed category in PA radiography versusCBCT imaging has a similar discrepancy in therange of 25%. Completely healed teeth onCBCT imaging was 50% compared with 74%on PA radiography (Table 2). Chen et al15

showed superior CBCT and micro–computedtomographic healing with RRM compared withMTA in an animal investigation, whereas ourresults show no difference between the 2materials on CBCT evaluation.

Microsurgical classification was asignificant preoperative prognostic factor.Among classification A, B, and C, there was a6 times greater probability of detecting a failureon PA when the classification was C (P 5

.019). One can speculate that the healing timefor classification C (a large lesion occupying theapical half) is longer than for classification A (nolesion) or B (a small lesion occupying the apicalquarter). In their comparison of 2 materials,Zhou et al17 reported a lower outcome whenthe lesion was larger than 5 mm. Von Arxet al’s29 meta-analysis of outcome ofmicrosurgery concurred with the study byZhou et al. Both question the kinetics of healingof a large lesion and whether histologicallylarger lesions show scar tissue healing andhence a corresponding area of low density onradiographic evaluation.

Another significant preoperativeprognostic factor was root canal filling quality.There was a 9 times greater chance to seefailure on CBCT imaging when the quality ofthe filling was inadequate (P 5 .035). Thissuggests that inadequate root canal fillings canfunction as a microbial reservoir andcompromise the sealing effect of MTA andRRM. When root canal filling was deemedinadequate in length and density, it was aprognostic factor of consequence in otherstudies as well17,29. On the other hand,whether the tooth had been retreated beforesurgery or not was not found to be a significantfactor16.

The depth of the root-end filling materialwas also a significant postoperative prognosticfactor. In general, having an inadequate depthresulted in failure on PA and CBCT imaging.When MTA was at an inadequate depth, therewas a significant association with failure on PAradiography (P5 .001). Cases with aninadequate MTA depth were 18 times morelikely to fail on CBCT imaging (P5 .003). When

E

RRM was at an inadequate depth, there was asignificant association with failure on PAradiography (P5 .04) and CBCT imaging(P5 .007). Because the depth of the root-endfilling correlates with a proper seal, it can bespeculated that for MTA and RRM to seal itshould have aminimal depth of 2.5mmormore.

An interesting intraoperative finding ofthis investigation is the presence of an apicalroot fracture. Even though it was eliminatedduring surgery, teeth with a root fracture were23 times more likely to fail on CBCT imaging atfollow-up. It has been speculated that the useof ultrasonics during retrograde preparationcould induce and propagate microcracks indentin30. The finding of this investigation mightsuggest that despite the microscopicelimination of the crack by further resection ofthe root, microcracks may remain and canpropagate, compromising healing. It wascoincidental that all the roots that had fractureswere chosen by random selection to be filledwith MTA.

Two cases were eliminated forprocedural errors as detected on follow-upCBCT imaging. The obvious failure wascaused by the incorrect execution of EMS andleakage associated with an incorrectly doneprocedure. It was not a true failure of EMS orthe root-end filling material. These casesunderwent resurgery in the clinic to correct thedrawback. As allowed in the ConsolidatedStandards of Reporting Trials guidelines, thesecases were not representative of EMS andhence at the point of CBCT analysis atfollow-up were eliminated from the data set.

Although every attempt was made tohave all patients enrolled in the study followedup, 52% returned. Because of the final samplesize of the investigation, the CI of the resultswas wide. Three different CBCT machineswere used in this study. Whether the use ofdifferent machines led to a difference in theevaluation of prognosis needs further research.The strength of the present study israndomization of root-end filling material,blinded operators and examiners to type ofroot end-filling material, and the time offollow-up. MTA and RRM have similarradiodensity. In our experience, it is notradiographically distinguishable. Theexaminers were not informed which materialwas being evaluated either. The randomizationprocedure ensures that groups had an evendistribution of known and unknownconfounding factors.

CONCLUSION

In this prospective randomized controlledstudy, there was no significant difference in theoutcomes of EMS when MTA and RRM were

ndodontic Microsurgery Using MTA and RRM 7

used as root-end filling materials. RRM is avalid and suitable material for root-end filling.Microsurgical classification, root canal fillingquality, depth of root end-filling material, andthe presence of a root fracture significantlyaffected the outcome.

8 Safi et al.

ACKNOWLEDGMENTS

The authors thank Dr Fouad Al-Malki, Ms AnyaKohli in making the illustrations and figures forthe article, and Christel Chehoud for help withstatistical analysis.

Supported and conductedindependently by the Department ofEndodontics, University of Pennsylvania,Philadelphia, PA.

The authors deny any conflicts ofinterested related to this study.

REFERENCES

1. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review. J Endod2006;32:601–23.

2. Setzer FC, Shah SB, Kohli MR, et al. Outcome of endodontic surgery: a meta-analysis of theliterature–part 1: comparison of traditional root-end surgery and endodontic microsurgery. JEndod 2010;36:1757–65.

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