Impact of Three Radiographic Methods in the Outcome of Nonsurgical Endodontic Treatment: A Five-Year...

Clinical Research

Impact of Three Radiographic Methods in the Outcome ofNonsurgical Endodontic Treatment: A Five-Year Follow-upRafael Fern�andez, DDS,* Diego Cadavid, DDS,* Sandra M. Zapata, DDS,*Luis G. �Alvarez, BSc, MSc,† and Felipe A. Restrepo, DDS*

Abstract
Introduction: The periapical film radiograph (PFR) anddigital periapical radiograph (DPR) techniques havesome limitations in the visualization of small periapicallesions (PLs) when compared with cone-beam computedtomography (CBCT). However, the evidence supportingtheir effectiveness is very limited. This retrospectivelongitudinal cohort study evaluated the outcome ofendodontic treatments measured/monitored by PFR,DPR, and CBCT during a 5-year follow-up and also deter-mined the prognostic factors that influenced treatmentsuccess. Methods: A total of 132 teeth (208 roots)with vital pulps received endodontic treatment. Theperiapical indexes with scores $2 for PFR and DPRand $1 for CBCT indicated the presence of PLs. Prog-nostic factors were determined by bivariate and multi-variate analyses. Statistical significance was defined ata P level <.05. Results: CBCT detected a higher numberof PLs (18.7%, n = 39 roots), followed by DPR (7.7%, n= 16 roots) and PFR (5.7%, n = 12 roots). Likewise,CBCT was more sensitive than PFR and DPR in detectingdeficiencies in extension and density of the root canalfilling (P # .001). Of the 17 prognostic factors evalu-ated, 4 were significantly associated with poor outcometo the treatment (P< .05): root canal curvature, disinfec-tion of gutta-percha, presence of missed canals, and thequality of definitive coronal restoration. Conclusions:The success outcome of endodontic treatment after 5years in teeth with vital pulps varied with each radio-graphic method: 94.3%/PFR, 92.3%/DPR, and 81.3%/CBCT. (J Endod 2013;39:1097–1103)
Key WordsCone-beam computed tomography, outcome of nonsur-gical endodontic treatment, periapical radiography,retrospective study

From the *Department of Endodontics and Group of Basicand Clinical Sciences on Dentistry (CBO), CES University;†Department of Operative Dentistry and Research Committee,School of Dentistry, CES University and University of Antioquia,Medell�ın, Colombia.

Supported by Knowledge Management Division (2011 DI-01) and School of Dentistry, CES University.

Address requests for reprints to Dr Rafael Fern�andez, Facul-tad de Odontolog�ıa, Departamento de Endodoncia, UniversidadCES, Calle 10 A No. 22–04, Medell�ın, Colombia. E-mail address:[email protected]/$ - see front matter

Copyright ª 2013 American Association of Endodontists.http://dx.doi.org/10.1016/j.joen.2013.04.002

JOE — Volume 39, Number 9, September 2013

Clinical evaluation and periapical radiographs (PAs) have been methodstraditionally validated by randomized clinical trials and systematic reviews

to confirm the absence of both pain and a periapical lesion (PL) as criteriafor success of endodontic treatment (1, 2). In addition, the presence orabsence of a preoperative PL, the complete isolation of the operative field,the density and extension of the root canal filling, and the quality of coronalseal have been identified as factors that influence the prognosis of thetreatment (3–6). However, the PA, which projects 2-dimensional (2D) imagesof tridimensional structures such as teeth and maxillary bones, provides a limitedevaluation of the PL that could lead to overestimation of the success rate of thetreatment (2, 7). Cone-beam computed tomography (CBCT) is a radiographicmethod that builds images in a tridimensional way (axial, coronal, and sagittalplanes), providing a number of advantages in the diagnosis, planning, andfollow-up of cases. Its ability to detect PLs more frequently as compared withthe PA has been reported (8, 9). However, several authors have suggestedthe need to reevaluate the success of endodontic treatment with longitudinalstudies and long-term follow-up by using CBCT as strict evaluation criteria(2, 10).

A recent systematic review of the diagnostic accuracy of periapical bone tissuelesions that used periapical film radiographs (PFR), digital periapical radiographs(DPR), and CBCT in endodontics concluded that there is insufficient scientific evidenceto support the superiority of these last 2 radiographic methods when compared with thePFR (11). Therefore, the purposes of this study were (1) to determine whether theradiographic method used to evaluate endodontic treatments impacts outcomes and(2) to determine which prognostic factors played a significant role in the outcomeof the endodontic treatment.

Materials and MethodsThe ethics institutional committee at CES University, Medell�ın, Colombia

approved this retrospective study. A total of 102 patients referred from the oral reha-bilitation postgraduate program received treatment at the CES University EndodonticPostgraduate Program between January and September 2006. The endodontic treat-ment was performed in teeth with vital pulps and without PLs, as determined bypreoperative clinical and radiographic evaluation with DPR. All the cases were peri-odically evaluated for a period of 4 years by both postgraduate programs. All patientswere contacted by phone or e-mail and invited to follow-up between January andSeptember 2011.

Sixty patients (32 female and 28male) without any prior important medical historyand an average age of 52 years were included in the 5-year follow-up after theendodontic treatment. The purpose of the study and the level of radiation exposurewere known to all patients before they signed the informed consent.

The sample included a total of 208 roots from 132 teeth (incisors, canines,premolars, and molars) The indications for endodontic treatment were as follows:

1. Proximity to the pulp chamber after the prosthetic preparation2. Insufficient tooth structures for a permanent crown3. The need to generate a more parallel path of insertion of the prosthetic restoration in

teeth that had a moderate buccolingual or mesiodistal inclination

Outcome of Nonsurgical Endodontic Treatment 1097

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http://dx.doi.org/10.1016/j.joen.2013.04.002

Clinical Research

Nonsurgical Endodontic ProcedureAll procedures were performed by 3 dentists during their last year

of the endodontic postgraduate program. They were supervised bya qualified and experienced endodontist. All the preoperative, intrao-perative, and postoperative information was properly compiled fromthe clinical and radiographic patients’ records.

After coronal access, the patency of all root canals was verifiedwithfiles #10 K-Flexofile (Dentsply Maillefer, Ballaigues, Switzerland). Twotreatment techniques were performed, modified step-back techniquewith K-Flexofile hand files (Dentsply Maillefer) and lateral compactionof gutta-percha (SBLC) in 77 teeth/104 roots and crown-down tech-nique with ProTaper rotary files (Dentsply Maillefer) and verticalcompaction of warm gutta-percha (CDVC) in 55 teeth/104 roots.

Once the coronal preparation of the canals was carried out withGates-Glidden #1-3 burs or SX file for SBLC and CDVC techniques,respectively, the working length was determined by using Root ZX (J.Morita Mfg Corp, Kyoto, Japan) and verified with DPR. Depending onthe morphology of each canal, the apical enlargement was done upto files #40 or 45 and F2 or F3. In both techniques, the irrigationprotocol included 10 mL 5.25% sodium hypochlorite (NaOCl) duringthe entire root canal preparation. Syringes and 30-gauge needles (Na-viTip; Ultradent, South Jordan, UT) were used. The smear layer wasremoved with 10 mL 17% EDTA for 1 minute, followed by a finalwashout with 5 mL 5.25% NaOCl. When the treatment could not becompleted in a single visit, calcium hydroxide (Calcifar-P; EUFAR,Bogot�a, Colombia) was placed inside the root canal. The canals werelater dried with sterile paper points. Depending on the technique,they were filled with gutta-percha and Topseal root canal sealer (Dents-ply Maillefer) by using cold lateral compaction technique withendodontic finger spreaders size A and B (Dentsply Maillefer) orvertical compaction of warm gutta-percha with the System B device(SybronEndo, Orange, CA) in the apical third and back-filling in therest of the canal with the Obtura II system (Obtura Spartan, Fenton,MO). The temporary coronal seal between visits and until the definitivecoronal restoration was done with Coltosol-F (Colt�ene/Whaledent,Altst€atten, Switzerland) or IRM (Caulk/Dentsply, Milford, DE). Theuse of isolation with rubber dam, microscope, and a protocol of disin-fection of gutta-percha before use with 5.25% NaOCl were alsorecorded.

Clinical and Radiographic Evaluation at Follow-upThe clinical and radiographic evaluation (PFR, DPR, and CBCT)

was carried out 5 years after the nonsurgical endodontic treatment.Each patient was asked for any symptoms or spontaneous pain afterthe endodontic treatment. The periodontal tissues were evaluated forsigns of infection and inflammation. Percussion test, periodontalprobing, and quality of definitive coronal restoration were recorded.The presence of provoked or spontaneous pain and sinus tracts wereconsidered as failure criteria, independent of the radiographic findings.

A long-cone x-ray unit (Os70-FIAD, Medell�ın, Colombia) that wasoperated at 70 Kv and 8 mA and exposure time of 0.050–0.125 secondswith film E-speed (Kodak Co, Rochester, NY) for PFR and the radiovi-siography (Schick-CDR; Schick Technologies, Long Island, NY)coupled to the same x-ray unit for DPR was used. Both methodsprovided images of all the teeth in 3 projections (orthoradial, mesial,and distal) by using the paralleling technique (Schick Technologies).CBCT images were obtained with a 3D-Accuitomo 80 CBCT scanner(J. Morita Mfg Corp), which was operated at 80 kVp, 4–5 mA, 4 �4-cm of field vision, voxel size 0.125 � 0.125 � 0.125 mm, 12 or8-bits, and 17 seconds of exposure time. The PFR were processedmanually in a darkroom following the recommendation of the manufac-

1098 Fern�andez et al.

turer and were observed in a negatoscope with�3 magnification. Thedigital images produced by DPR and CBCT were stored in the software’sdatabase (CDR-2.5, Schick and i-Dixel, J. Morita Mfg Corp, respec-tively). They were operated in one single desktop workstation withWindows 7 operative system (Microsoft Corp, Redmond, WA).

Three previously calibrated blinded examiners, 2 endodontistsand 1 oral radiologist, evaluated all the images independently. The find-ings were recorded in Microsoft Excel 2010 (Microsoft Corp). Anordinal scale (1–5 scores) of the periapical index (PAI) (12) wasused for the evaluation by PFR and PDR. A score of 1 indicated periap-ical health, and scores$2 were associated with PLs. For the CBCT eval-uation, an ordinal scale (0–6 scores) of the CBCT PAI (13) was used,where a score of$1 indicated PL. The cutting points made in each ofthe scales (PAI and CBCT PAI) became the criteria to determine thepresence or absence of PLs in the dichotomy evaluation of success ineach one of the roots. The interexaminer concordance level was carriedout by means of Cohen kappa statistic. In those cases in which there wasno agreement between the examiners, the case was again analyzed untilan agreement was reached.

A total of 17 prognostic factors (preoperative, intraoperative, andpostoperative) were categorized and evaluated for each root and radio-graphic method (Tables 1–3). The evaluation of the curvature of thecanal was based on the criteria described by Schneider (14). Thequality of the final restoration at follow-up was recorded as adequateor inadequate, depending on the clinical and radiographic evaluationby PFR and DPR. CBCT was not used because of the heterochromaticnature of the x-ray beam projection, which produces beam hardeningand generates distortion artifacts of the metallic structures (8). Finalrestoration was considered inadequate if there was loss of marginaladaptation, recurrent caries, and history of decementation (3).

StatisticsThe treatment success variable was dichotomized in absence

versus presence of PLs, and it was used as a dependent variable.PASW Statistics 18 (SPSS Inc, Chicago, IL) software was used for thestatistical analysis. A univariate description of the data (absolutefrequencies and percentages) was followed by bivariate analysis. Chi-square test and odds ratio (OR) were used to analyze each of the prog-nostic factors and the presence or absence of PLs. Significance wasdefined at a P level < .05. To find the prognostic factors that influencedthe success of the endodontic treatment, a stepwise multivariate logisticregression analysis was performed.

ResultsFive years after the endodontic treatment was performed, 60 of

102 patients (58.8%) were available for evaluation. Of these, 37(61.6%) had at least 1 tooth treated, and 23 (38.4%) had several teethtreated (2–6 roots). The reasons for not including these 42 patientswere the following: 28 could not be contacted because of change of resi-dence, telephone, or absence of e-mail address in the clinical record,13 did not show any interest and decided not to participate, and 1patient died of natural causes. At the end, 208 roots of 132 teethwere evaluated.

The kappa score for interexaminer agreement was K = 0.92, K =0.96, and K = 0.82 for PFR, DPR, and CBCT, respectively. These scoresare consistent with a very good concordance (15).

Regarding the visualization of PLs in at least 2 spatial planes(coronal, sagittal, and axial), a high correlation was found betweenPFR/DPR in 204 roots (98.07%, P > .05), followed by DPR/CBCT in175 roots (84.1%, P < .05) and PFR/CBCT in 172 roots (82.69%,P < .05). CBCT detected a higher number of PLs (n = 39, 18.7%),


TABLE 1. Bivariate Analysis of Associations between Prognostic Factors and Post-treatment PLs on Findings from PFR

Prognostic factor No. of roots Without lesion, n (%) With lesion, n (%) P value OR 95% CI (lower–upper)

PreoperativeGender

Male 75 71 (94.7) 4 (5.3) 1.000 1.14 0.33–3.91Female 133 125 (94.0) 8 (6.0)

Tooth typeAnterior teeth 38 35 (92.1) 3 (7.9)Premolars 51 49 (96.1) 2 (3.9) .727 — —Molars 119 112 (94.1) 7 (5.9)

Tooth locationMaxilla 154 143 (92.9) 11 (7.1) .273 0.25 0.03–1.95Mandible 54 53 (98.1) 1 (1.9)

Root canal curvature (�)0–25 195 185 (94.9) 10 (5.1) .357 3.36 0.66–17.26>25 13 11 (84.6) 2 (15.4)

IntraoperativeIsolation with rubber dam

Yes 204 192 (94.1) 12 (5.9) 1.000 — —No 4 4 (100) 0 (0)

MicroscopeYes 129 124 (96.1) 5 (3.9) .234 2.41 0.74–7.88No 79 72 (91.1) 7 (8.9)

Treatment sessions1 113 110 (97.3) 3 (2.7) .071 3.84 1.01–14.61$2 95 86 (90.5) 9 (9.5)

TechniqueSBCL 104 95 (91.3) 9 (8.7) .137 0.31 0.08–1.19CDVC 104 101 (97.1) 3 (2.9)

Disinfection of gutta-perchaYes 170 163 (95.9) 7 (4.1) .076 3.53 1.06–11.80No 38 33 (86.8) 5 (13.2)

Apical extent of root fillingFlush 169 162 (95.9) 7 (4.1) .005* — —Short 21 16 (76.2) 5 (23.8)Long 18 18 (100) 0 (0)

Density of root-filling (voids)Absent 190 180 (94.7) 10 (5.3) .625 2.25 0.45–11.17Present 18 16 (88.9) 2 (11.1)

Material of temporary restorationColtosol 118 110 (93.2) 8 (6.8) .678 0.64 0.19–2.19IRM 90 86 (95.6) 4 (4.4)

Period of time between temporary and definitive coronal restoration (weeks)#1 107 100 (93.5) 7 (6.5) .846 0.74 0.23–2.43>1 101 96 (95.0) 5 (5.0)

ComplicationsAbsent 194 185 (95.4) 9 (4.6) .045* 5.61 1.33–23.69Present 14 11 (78.6) 3 (21.4)

Missed canalsYes 11 8 (72.7) 3 (27.3) .013* 0.13 0.03–0.56No 197 188 (95.4) 9 (4.6)

PostoperativeQuality of definitive coronal restoration at follow-up

Adequate 190 180 (94.7) 10 (5.3) .625 2.25 0.45–11.17Inadequate 18 16 (88.9) 2 (11.1)

PostYes 30 29 (96.7) 1 (3.3) .845 1.91 0.24–15.36No 178 167 (93.8) 11 (6.2)

CDVC, crown-down preparation and vertical compaction of warm gutta-percha; CI, confidence interval; Flush, 0–2 mm short of apex; Long, beyond apex; SBCL, modified step-back preparation and lateral

compaction of gutta-percha; Short, >2 mm short of apex.

*Statistical significance.

Clinical Research

followed by DPR (n = 16, 7.7%) and PFR (n = 12, 5.7%). Three roots(1.4%) revealed PLs by DPR/CBCT but not with PFR, whereas 5 roots(2.4%) showed PLs with PFR and not with CBCT, and 6 roots (2.8%)showed PLs with DPR and not with CBCT.

The prognostic factors that significantly influenced the successof the treatment by using bivariate analysis were different witheach radiographic method (Tables 1–3). They were furtheranalyzed in a multivariate logistic regression model with 90.4%


predictability, 87.2% sensitivity, and 91.1% specificity. Theseprognostic factors were the following: root canal curvature (OR =19.304; confidence interval [CI], 3.638–102.437), disinfection ofgutta-percha (OR = 28.391; CI, 9.108–88.501), missed canals(OR = 72.876; CI, 6.551–810.742), and quality of definitive coronalrestoration (OR = 4.897; CI, 1.102–21.771) (Table 4).

The radiographic evaluation of the extension and density of theroot filling showed correlation in 100% of the cases between the PFR


TABLE 2. Bivariate Analysis of Associations between Prognostic Factors and Post-treatment PLs on Findings from DPR


PreoperativeGender

Male 75 71 (94.7) 4 (5.3) .492 1.76 0.55–5.67Female 133 121 (91.0) 12 (9.0)

Tooth typeAnterior teeth 38 35 (92.1) 3 (7.9)Premolars 51 49 (96.1) 2 (3.9) .490 — —Molars 119 108 (90.8) 11 (9.2)

Tooth locationMaxilla 154 139 (90.3) 15 (9.7) .115 0.18 0.02–1.36Mandible 54 53 (98.1) 1 (1.9)

Root canal curvature (�)0–25 195 183 (93.8) 12 (6.2) .007* 6.78 1.82–25.24>25 13 9 (69.2) 4 (30.8)


Yes 204 188 (92.2) 16 (7.8) 1.000 — —No 4 4 (100) 0 (0)

MicroscopeYes 129 123 (95.3) 6 (4.7) .066 2.97 1.04–8.53No 79 69 (87.3) 10 (12.7)

Treatment sessions1 113 109 (96.5) 4 (3.5) .029* 3.94 1.23–12.66$2 95 83 (87.4) 12 (12.6)


Disinfection of gutta-perchaYes 170 160 (94.1) 10 (5.9) .083 3.00 1.02–8.84No 38 32 (84.2) 6 (15.8)

Apical extent of root fillingFlush 169 161 (95.3) 8 (4.7) .000* — —Short 21 13 (61.9) 8 (38.1)Long 18 18 (100) 0 (0)

Density of root filling (voids)Absent 190 178 (93.7) 12 (6.3) .050* 4.24 1.21–14.88Present 18 14 (77.8) 4 (22.2)


Period of time between temporary and definitive coronal restoration (weeks)#1 107 100 (93.5) 7 (6.5) .704 1.40 0.50–3.91>1 101 92 (91.1) 9 (8.9)


Missed canalsYes 11 8 (72.7) 3 (27.3) .054 0.19 0.04–0.80No 197 184 (93.4) 13 (6.6)


Adequate 190 177 (93.2) 13 (6.8) .302 2.72 0.70–10.63Inadequate 18 15 (83.3) 3 (16.7)

PostYes 30 29 (96.7) 1 (3.3) .550 2.67 0.34–20.99No 178 163 (91.6) 15 (8.4)




Clinical Research

and DPR methods. However, when these methods were compared withCBCT, there were statistically significant differences (P < .001) thatwere only correlated in 143 of 208 roots (68.7%) for the extensionand 100 of 208 roots (48.0%) for density. Regarding extension, 48of 169 flush root fillings (28.4%) by PFR/DPR appeared as long fillingson sagittal and/or coronal CBCT projections. On the other hand,although 6 of 21 appeared as short root fillings (28.5%) by PFR/DPR, they appeared as flush root fillings by CBCT. Regarding density,


PFR/DPR revealed 18 of 208 root fillings with voids (8.6%) comparedwith 120 (57.6%) by CBCT.

DiscussionThis 5-year retrospective longitudinal cohort study evaluated

the success of endodontic treatment in teeth with both vital pulps andindication for prosthetic treatment. Because the patients were internally


TABLE 3. Bivariate Analysis of Associations between Prognostic Factors and Post-treatment PLs on Findings from CBCT


PreoperativeGender

Male 75 67 (89.3) 8 (10.7) .040* 2.55 1.10–5.87Female 133 102 (76.7) 31 (23.3)

Tooth typeAnterior teeth 38 37 (97.4) 1 (2.6)Premolars 51 42 (82.4) 9 (17.6) .011* — —Molars 119 90 (75.6) 29 (24.4)

Tooth locationMaxilla 154 125 (81.2) 29 (18.8) 1.000 0.98 0.44–2.17Mandible 54 44 (81.5) 10 (18.5)

Root canal curvature (�)0–25 195 165 (84.6) 30 (15.4) .000* 12.36 3.58–42.78>25 13 4 (30.8) 9 (69.2)


Yes 204 168 (82.4) 36 (17.6) .024* 14.00 1.42–138.47No 4 1 (25.0) 3 (75.0)

MicroscopeYes 129 105 (81.4) 24 (18.6) 1.000 1.03 0.50–2.10No 79 64 (81.0) 15 (19.0)

Treatment sessions1 113 104 (92.2) 9 (8.0) .000* 5.33 2.38–11.95$2 95 65 (68.4) 30 (31.6)


Disinfection of gutta-perchaYes 170 158 (92.9) 12 (7.1) .000* 32.32 12.95–80.63No 38 11 (28.9) 27 (71.1)

Apical extent of root fillingFlush 119 103 (86.6) 16 (13.4) .000* — —Short 26 13 (50.0) 13 (50.0)Long 63 53 (84.1) 10 (15.9)

Density of root filling (voids)Absent 88 77 (87.5) 11 (12.5) .072* 2.13 0.99–4.56Present 120 92 (76.7) 28 (23.3)


Period of time between temporary and definitive coronal restoration (weeks)#1 107 93 (86.9) 14 (13.1) .048* 2.19 1.06–4.49>1 101 76 (75.2) 25 (24.8)


Missed canalsYes 11 1 (9.1) 10 (90.9) .000* 0.02 0.00–0.14No 197 168 (85.3) 29 (14.7)


Adequate 190 162 (85.3) 28 (14.7) .000* 9.09 3.25–25.44Inadequate 18 7 (38.9) 11 (61.1)

PostYes 30 24 (80.0) 6 (20.0) 1.000 0.91 0.35–2.40No 178 145 (81.5) 33 (18.5)




Clinical Research

referred between the oral rehabilitation and endodontic postgraduateprograms of the College of Dentistry, the sample comprised a specificdental school population. Because our study cohort did not representthe population at large, the results might not be generalized beyond thisspecific cohort.

The 5-year recall rate of 58.8% was lower than those reported byhigh level of evidence-based clinical practice guidelines (16, 17) buthigher than values reported in other studies (4, 10). The low recall


rate in this study was not expected because the post-treatmentmaintenance program in place for oral rehabilitation includes dentalexamination once or twice a year, which is believed to promote optimalfollow-up with patients.

Clinical findings and PA have been suggested as the traditionalmethods to evaluate endodontic treatment success. However,considering the limitations of the 2D view of the PA (3, 8–11),new evaluations that incorporate CBCT and compare its findings


TABLE 4. Multivariate Logistic Regression Model (n = 208)

Prognostic factor B SE Wald df P value Exp(B)

95% CI for Exp(B)

Lower Upper

Disinfection of gutta-percha

3.346 0.580 33.272 1 .000* 28.391 9.108 88.501

Quality of definitivecoronal restoration atfollow-up

1.589 0.761 4.356 1 .037* 4.897 1.102 21.771

Root canal curvature 2.960 0.852 12.086 1 .001* 19.304 3.638 102.437Missed canals 4.289 1.229 12.174 1 .000* 72.876 6.551 810.742

B, coefficient for the constant; CI, confidence interval; df, degrees of freedom for the Wald chi-square test; Exp(B), exponentiation of the B coefficient (odds ratio); SE, standard error; Wald, Wald chi-square test.


Clinical Research

with PFR and DPR, as described in this study, should be included(2, 10, 11). Several authors have also suggested that the traditionalmethods should be used during a follow-up period between 18 and24 months to determine treatment success (18–20). Despite thelimitations of a retrospective study, our data suggest thata follow-up period longer than 24 months may be required tominimize the number of false negatives regarding the diagnosisof PLs.

The sample included anterior and posterior teeth. The roots wereselected as the radiographic analysis evaluation unit because the toothas measurement unit is only relevant for samples with single-rootedteeth (5). The tooth was considered the measurement unit for the clin-ical evaluation only. The clinical success for the treatment was 100%because all the teeth were asymptomatic and functional at the recallappointments. These results are similar to those reported by others(10). In other clinical trials with longer follow-up periods (4–6 years),the clinical success rate was between 88% and 97%, which was slightlylower than those reported in our study (3, 21, 22). When comparingclinical success with radiographic evaluation, the success ratedecreased to 94.3%/PFR and 92.3%/DPR, which are consistent withranges found in similar studies that used 2D radiographic methods(87.4% to 97%) (3, 4, 10, 22, 23). Although our success ratedecreased to 81.3% with the CBCT evaluation, it was still higher than74.1% previously reported by Liang et al (10), taking into accountthe larger sample size and follow-up period of our study. The absenceof statistically significant differences between PFR (E-speed) and DPRand the higher sensitivity of CBCT for the diagnosis of PLs in our studyare also consistent with results from other studies (11, 24).

The PL was visible by DPR/CBCT in 3 maxillary molar roots butnot by PFR, probably because of the superimposition of anatomicstructures such as the zygomatic arch and the maxillary sinus aswell as the contrast obtained with manual processing of the film. Inother 6 roots the PL was visible by PFR/DPR but not by CBCT becausetheir intracoronal post and abundant metallic restorations are knownto produce beam hardening on the CBCT images and distort the visu-alization of PLs (8).

There is scientific evidence that functionality of the teeth is a goodindicator of the success of the nonsurgical endodontic treatment fromthe patient’s perspective. Thus, this information should help patientsdecide among the different treatment modalities (25). In our studyendodontic treatment versus tooth extraction and prosthetic replace-ment was associated with full functionality of the teeth 5 years aftertreatment, which was independent of the radiographic findings. Ourresults were slightly higher than 88%–97% reported by other studies(3, 4, 21, 22).

A multivariate analysis identified root canal curvature, disinfectionof gutta-percha, missed canals, and quality of definitive coronal resto-


ration as predictive factors for treatment success. The quality ofthe definitive coronal restoration has been the only predictive factorof treatment success previously reported by other studies (3–6,10,21–23, 26).

Curvature of the Root CanalAlthough a recent randomized clinical trial suggested that apical

enlargement to 3 sizes larger than the first binding apical file isenough to enhance the flushing action of irrigants in the apicalregion and the success of nonsurgical endodontic treatment (27),in this study, the root canals were enlarged to almost 4–5 sizes largerthan the first binding apical file, regardless of the curvature of thecanal.

Nine of the 13 roots (69.2%) with curvatures >25� had PLs, and 6of them had fractures of the files (5 with Protaper F2 and 1 with K-flex#20) at the working length. These fractures were reported as intraoper-ative complications, and in no case the files could be removed or passedover. It is very possible that the incorrect use or abuse of the instrumentsin these cases with severe curvature increased the risk for fractures.These findings are not consistent with a recent systematic review andmeta-analysis that showed that leaving a fractured instrument insidethe canal was not significantly associated with the prognosis of theendodontic treatment, with the exception of those cases with preoper-ative PLs (28). However, in 5 of 6 cases with fractured instruments andPLs, the non-disinfection of the gutta-percha before obturation and thepresence of missed canals may have influenced the treatment results.We were unable to identify any of the predictive factors for treatmentfailure in the other 4 cases.

Disinfection of Gutta-perchaAlthough the steps performed during nonsurgical root canal

procedures are focused on obtaining success and achieving an environ-ment free of microorganisms inside the root canal system (29), reinfec-tion can occur. Thus, an intraoperative factor to consider is theintroduction of contaminated gutta-percha cones inside the root canalduring the obturation procedure. Several studies have demonstratedthat the cones come sterile from the factory, but their inadequatemanip-ulation and exposure to dental environment can cause contamination bymicroorganisms such as cocci, rods, and yeasts (30, 31). Severaldisinfection protocols with 5.25% NaOCl, 2% chlorhexidine, orMTAD (mixture of doxycycline, citric acid and detergent) have beensuggested to decrease the risk of such contamination (30–32). Inthe present study, 71.1% of the associated cases with PLs in the CBCTevaluation did not have disinfection protocol for gutta-percha(Table 3).


Clinical Research

Missed CanalsThe anatomic variations present in the root canal system can leave

some canals without endodontic treatment and therefore contribute tofailure (33). This is supported by the results of this study, where nearly91% of missed canals were associated with PLs. CBCT evaluation indi-cated that most missed canals (8 of 11, 72.7%) were located in the me-siobuccal root of the maxillary first permanent molar. According toanalysis of 8399 teeth in 32 studies, the incidence of 2 canals in thisroot was 56.8% (34). Its omission during treatment could be due tothe difficulty in locating and negotiating them as a result of the lackof anatomic knowledge and skills of the clinician. The lack of incorpo-ration of the CBCT and the microscope in the endodontic armamen-tarium has also been described as an explanation for missed canals(8, 35). In this study, last year’s postgraduate students performed thetreatments, and a microscope was not used in a large percentage ofmissed canals (63.6%).

Quality of Definitive Coronal RestorationAlthough very few studies have reported the quality of the final

coronal restoration does not affect the success of endodontic treatment(6, 36), a recent systematic review and meta-analysis demonstrated thatit is an important prognostic factor (26). In fact, if these studies onlyhave considered 2D radiographic methods for evaluation of the successof endodontically treated teeth, the results could be overestimated, andrisk factor analysis should be performed again by using CBCT to evaluatethe data from new studies (2). Thus, in our study, CBCT along with PFRand DPR radiographic methods was used for the evaluation of differentfactors previously associated with the prognosis of root canal treatment.Consistent information was obtained that supports the fact that the pres-ence of an adequate coronal restoration had a positive effect on thelong-term outcome of endodontic treatment.

ConclusionThe results reported in this study suggest that CBCT wasmore sensi-

tive than PFR and DPR to visualize PLs in the long-term evaluation of thesuccess of root canal treatment in teeth with vital pulps. The root canalcurvature, the non-disinfection of gutta-percha, the presence of missedcanals, and the inadequate definitive coronal restoration at follow-upwere prognostic factors that negatively influenced treatment outcomes.

AcknowledgmentsThe authors thank Professor Ruben Restrepo Panesso from

University of Texas Health Science Center at San Antonio, andLina Salazar Pel�aez from CES University at Medell�ın, for their valu-able assistance in reviewing this article.

The authors deny any conflicts of interest related to this study.

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