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Year : 2021  |  Volume : 12  |  Issue : 3  |  Page : 122-127

A cone beam computed tomographic evaluation of root canal treatment quality using periapical and endodontic status scale

1 PG Student, Department of Conservative, Dentistry and Endodontics, Terna Dental College, Navi Mumbai, Maharashtra, India
2 Reader, Department of Conservative, Dentistry and Endodontics, Terna Dental College, Navi Mumbai, Maharashtra, India
3 Lecturer, Department of Conservative, Dentistry and Endodontics, Terna Dental College, Navi Mumbai, Maharashtra, India
4 Professor, Department of Conservative, Dentistry and Endodontics, Terna Dental College, Navi Mumbai, Maharashtra, India
5 Professor and Head, Department of Conservative, Dentistry and Endodontics, Terna Dental College, Navi Mumbai, Maharashtra, India

Date of Submission29-Apr-2021
Date of Decision12-Jul-2021
Date of Acceptance12-Jul-2021
Date of Web Publication17-Sep-2021

Correspondence Address:
Dr. Sagar Jatish Shah
Department of Conservative Dentistry and Endodontics, Terna Dental College, Navi Mumbai
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/srmjrds.srmjrds_31_21

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Background: Cone beam computed tomography (CBCT) is a three-dimensional digital imaging which provides an image that can be viewed in multiple planes thus providing a better understanding of the anatomy of the root canal. Aim: This study aimed to evaluate the endodontic treatment quality of root-filled teeth and to determine the relationship between endodontic technical errors and complications. Materials and Methods: One hundred and fifty-two root canals were evaluated by CBCT from December 2017 to January 2019. Three endodontists assessed the root canals for the presence of technical errors and treatment complications using the periapical and endodontic status scale. Chi-square test and descriptive analyses were performed. Results: Sixty-one (40.4%) root canals had periapical radiolucency followed by 45 (29.8%) root canals with short obturations. Sixty-nine root canals (45.7%) and 45 (29.8%) root canals had nonhomogenous root canal filling and coronal seal (CS), respectively. Statistically significant association was seen with the length of the root canal filling, homogeneity, CS, and complications (P < 0.05). Conclusions: There was high prevalence of apical radiolucency in root-filled teeth. The presence of short obturations, poor CS, and nonhomogenous obturation led to higher prevalence of endodontic complications.

Keywords: Cone beam computed tomography, endodontics, evidence-based dentistry, outcome, success

How to cite this article:
Shah SJ, Kulkarni G, Ramachandran N, Chandrasekhar P, Podar RS, Singh S. A cone beam computed tomographic evaluation of root canal treatment quality using periapical and endodontic status scale. SRM J Res Dent Sci 2021;12:122-7

How to cite this URL:
Shah SJ, Kulkarni G, Ramachandran N, Chandrasekhar P, Podar RS, Singh S. A cone beam computed tomographic evaluation of root canal treatment quality using periapical and endodontic status scale. SRM J Res Dent Sci [serial online] 2021 [cited 2023 Jan 29];12:122-7. Available from:

  Introduction Top

Contemporary endodontics has experienced scientific and technological innovations in imaging, root canal preparations, and obturating techniques all of which aim at reversing the pulpal or periapical pathology to a healthy state.[1] Despite advancements, the complex morphology of root canals often poses a significant challenge. Furthermore, intraoperative errors should be minimized in every way possible as they increase the risk of root canal treatment failure.[2] Existing literature suggests that the quality of root canal filling and coronal seal (CS) influences the prevalence of apical periodontitis (AP) and the success of root canal treatment.[3],[4],[5],[6],[7] The quality of root canal filling includes apical termination of root canal filling and homogeneity of root canal filling.

The role of imaging in endodontics cannot be understated. Cone beam computed tomography (CBCT) stands out as a three-dimensional digital imaging which provides an image that can be viewed in multiple planes thus providing a better understanding of the anatomy of the root canal.[8] There have been numerous studies showing the relationship between technical errors and periapical pathology wherein the majority of them have used periapical radiographs or panoramic images which are a two-dimensional representation of a three-dimensional entity.[9],[10] CBCT overcomes the inherent disadvantage of 2D radiographs and delivers high-quality 3D images preventing overlap and distortion.

Numerous epidemiological tools were proposed for periapical evaluation using radiographic examination. Orstavik et al. devised periapical index (PAI). Lesions were classified in five scores based on the histological and radiographic diagnosis.[11] The PAI has been employed for numerous studies using radiographs for their evaluation.[7] Estrela et al.[12] modified the PAI to CBCT-PAI for the evaluation of periapical radiolucency and bony destruction in CBCT. The periapical and endodontic status scale (PESS) is a recently developed scale that not only provides information on periapical lesions but also helps in quantifying the treatment quality.[13]

Thus, the purpose of this retrospective cross-sectional CBCT study was two fold: to assess the endodontic treatment quality by identifying the frequency of technical errors in the endodontic treatment and to determine the relationship between endodontic technical errors and the presence of complications.

  Materials and Methods Top

The study was approved by the Research Ethics Committee TDC/41/2019. The sample consisted of CBCT scans collected from the image database from the Department of Oral Radiology of Dental College from December 2017 to January 2019 of the patients who visited for CBCT scans for reasons other than endodontic evaluation. The inclusion criteria were as follows: patients older than 18 years of age, patients with informed consent, scans with good quality with at least one endodontically treated tooth. Root stumps, teeth associated with endo-perio lesions, intraosseous pathologies other than common periapical lesions were excluded from the study.

One hundred and thirty-eight patients' scans were evaluated and the samples were divided into six dental groups: maxillary anterior, maxillary premolars, maxillary molars, mandibular anterior, mandibular premolars, and mandibular molars. A total of 152 individual root canals were evaluated which included 18 maxillary anterior, 08 mandibular anterior, 24 maxillary premolars, 09 mandibular premolars, 49 maxillary molars, and 43 mandibular molar root canals.

All the images were acquired using New-Tom GiANO (Verona, Italy) operating at 90 kVp, 3–8 mA, with 0.3 mm voxel size, and 18–22 s acquisition time. Three calibrated examiners evaluated the entire CBCT volume using. Three calibrated examiners evaluated the entire CBCT volume using NNT viewer software on a 15.4-in liquid crystal display monitor (1920 × 1080 resolution, Apple, USA) under ideal light conditions. Disagreements between the examiners were explored until a general consensus was reached. The zoom tool, as well as brightness and contrast adjustment, was used according to the examiners' will.

Assessment of endodontic treatment quality

The endodontic treatment quality was evaluated using the PESS develop by Venskutonis et al.[13] as follows:

L (Length of the root canal filling)

  • L1: 0–2 mm from the radiographic apex
  • L2: >2 mm from the radiographic apex
  • L3: Overfilling (extrusion of material through the apex)
  • L4: Filling material visible only in the pulp chamber
  • L5: Filled canal of a surgically treated root.

H (Homogeneity of the root canal fillings)

  • H1: Complete obturation (homogenous appearance of the root canal filling)
  • H2: Incomplete obturation (voids and porous appearance of the root canal filling).

Coronal seal

  • CS1: Adequate (coronal restoration appears intact radiographically)
  • CS2: Inadequate (detectable radiographic signs of overhangs, open margins, recurrent caries, or lost coronal restoration).


  • Complications/failures (CF) 0: No complications
  • CF1: Root perforation
  • CF2: Root canal not treated/missed
  • CF3: Root resorption
  • CF4: Root/tooth fracture
  • CF5: Endodontically treated root with radiolucency.

The complications (root perforation, root canal not treated, root resorption, root/tooth with fracture, and endodontically treated root with radiolucency were assessed in three planes (axial, frontal, and sagittal). If more than 1 root had a lesion, the biggest was considered. All the canals of the tooth were graded separately for l, H and CF, except for the CS for which only one highest score per tooth was assigned.

Thirty days after the initial assessments, 30% of the sample were randomly selected and re-evaluated under the same conditions to verify the method's reproducibility.

Statistical analysis

Statistical analyses were performed with SPSS software (version 17.0, SPSS, Inc., Chicago, IL, USA). Data were expressed by frequencies and percentages. Intra- and the interexaminer agreements were calculated using kappa and weighted kappa tests for cases where there were two or more than two possible choices, respectively (≤0.40, poor agreement; 0.40–0.59, moderate agreement; 0.60–0.74, good agreement; 0.75–1.00, excellent agreement). Chi-square tests were used to compare the frequencies of qualitative variables. The significance level was set to 5% (α =0.05).

  Results Top

Intra- and the inter-examiner agreements were excellent for all the assessments (ranging, respectively, from 0.81 to 0.87 and from 0.79 to 0.81). Of 152 canals evaluated, 72 root canals were associated with complications CF1, CF2, CF3, and CF5.

[Table 1] shows the distribution of parameters of the PESS scale. Length of root canal filling <2 mm from the apex (L2) was the second most common finding in 45 root canal (29.3%) showing maximum prevalence in mandibular molars. Homogenous obturations (H1) were seen in 82 canals (54.3%) while nonhomogenous obturations (H2) were seen in 69 canals (45.7%) indicating poor quality of obturation in about half the samples. Interestingly, mandibular molars had more number of incomplete obturation (H2) rather than complete obturation (H1).
Table 1: Frequency of procedural errors among endodontically treated root canals

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No complications (CF0) were seen in 79 (52.3%) of root canals which were followed by periapical radiolucency (CF5) in 61 (40.4%) of the root canals followed by CF2 in 09 (6.0%) canals and CF1 affecting 1 canal. Missed canal (CF2) was found in two mandibular anterior teeth, one maxillary premolar, four maxillary molars, and two mandibular molar teeth. Mandibular molars showed a higher number of complications, when compared to any other tooth, and had a higher number of root canals with periapical radiolucency than root canals with no complications.

[Table 2] summarizes the association between complications and length, homogeneity, and CS. Length, CS, and homogeneity were significantly associated with complications (P < 0.05). A significantly higher number of periapical radiolucency (F5) was seen with short obturations (L2). Similar findings were seen with homogeneity and CS wherein a higher percentage of complications was associated with nonhomogenous obturations (H2) and improper CS (CS2). Of all the complications, periapical radiolucency was the most common complication.
Table 2: Association between complications and length, homogeneity, and coronal seal of endodontically treated root canals

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  Discussion Top

This study assessed the treatment quality using the PESS scale of a convenience sample of endodontically treated teeth. The relation between technical errors and its complications were explored. With the map reading approach, CBCT scans provide a valuable information while reducing potential misdiagnosis caused by artifacts.[14] Studies have shown greater accuracy of CBCT in detecting AP when compared to conventional radiography.[15],[16],[17] Furthermore, detection of AP in conventional radiography may be visible after 15–30 days of commencement of the disease while with CBCT, AP can be detected as early as 7 days after the disease development.[18]

Studies evaluating the periapical status of root-filled teeth use various scales such as PAI, complex periapical index (COPI), CBCT-PAI for evaluation. PAI and CBCT-PAI quantify periapical rarefactions while the COPI is designed to facilitate the identification and classification of periapical bone lesions in AP. PESS on the other hand evaluates the status of periapical tissues and the endodontic treatment quality.[13],[19] Universal acceptance of this scale will help in comparison of data and help to standardize unit of measure for further evaluation.

In the current study, the prevalence of apical radiolucencies in root canal-treated teeth was 58.1%. This is in conjunction with several studies that reported around 24%–72% of AP in root-filled teeth on periapical and panoramic radiographs.[7],[20],[21],[22] Such a wide range of prevalence of AP can be due to the nature of the study and instrument used for the analysis of periapical tissues. Archana et al. in her study of 30,980 teeth in Indian subcontinent found that periapical radiolucency was seen in 65% of root canals.[20] However, as this study is a cross-sectional study, it provides information on participants at one point in time.

A higher prevalence of periapical radiolucency was associated with short obturations, roots with nonhomogenous obturations, and with an inadequate CS in the present study. These findings are consistent with the studies reported in the past.[21],[23]

Roots with short obturations, <2 mm from apical foramen (L2), showed periapical radiolucency in 49.2% of roots while those with obturation 0–2 mm from the apex showed periapical radiolucency in 28.4% of cases. These results are in consensus with other studies that demonstrate a higher success rate in the resolution of periapical radiolucency of the teeth when the cleaning and shaping procedures terminated at working length and were followed by adequate obturation of cleaned space. This ensured optimum disinfection of the root canal system.[24],[25],[26]

Determining the quality of root canal filling using 2D imaging techniques remains questionable. A study by Liang et al. showed that mesiodistal radiographs reveal significantly more voids than buccolingual radiographs that are clinically available.[27] A study determining endodontic outcome predictors of PAI and CBCT detected the presence of voids in the same root-filled teeth 3 times more when compared to 2D radiographs.[27] Furthermore, as in the present study, the presence of apical radiolucency is found in 53.6% of cases with nonhomogenous obturation when compared to 29.3% with homogenous obturations.

The third part of the PESS scale dealt with coronal restoration. Numerous studies investigated the relation of coronal restoration with periapical status.[3],[10] It is a well-established fact that coronal restorations function as a barrier to the ingress of bacteria and bacterial products preventing endodontic reinfection. In the present study, 60% of teeth with poor coronal restoration showed the presence of apical radiolucency, these findings are consistent with available literature thus further validate the fact that the success of endodontic treatment equally depends on adequate coronal restoration when compared to optimum disinfection and obturation of root canal systems.[10],[28]

In the present study, the highest number of complications was associated with maxillary anterior and mandibular posterior teeth. Mandibular posterior teeth are the most frequently treated teeth and are associated with the highest incidence of procedural errors and complications.[29] These findings are consistent with Yousuf et al.[29] while on the contrary, Gomes et al.[28] found that the number of periapical radiolucencies was significantly higher in maxillary molars due to the complexity and curvature of the mesial system. On the other hand, Liang et al.[27] found no differences among teeth. A recent study showed that mandibular molars were associated with a greater number of failures than other teeth.[30] The reasons may be attributed to higher frequencies of root canal isthmuses (87.9%) and difficulty in the management of mesial root canals systems.[1],[30] In the present study, maxillary molars were associated with the highest percentage of missed canals followed by mandibular anterior and mandibular molars. The present study did not come across any samples of the filled canals of surgical root or root/tooth fracture.

By the nature of a cross-sectional study, it is impossible to determine the course of a periapical lesion. Periapical radiolucency may not necessarily signify a diseased state. It represents a spectrum of rarefactive lesions which ranges from an active disease, healing lesion to a periapical scar. Thorough clinical examination, patient history, clinical signs and symptoms help clinician validate outcome of the endodontic treatment. The mere presence or absence of periapical lesion without understanding the progression of the disease is not enough to determine the treatment success or failure. Data were not available on the operator and treatment settings. CBCT evaluations are associated with many artifacts which make them less than ideal tools for the evaluation of CS. In fact, clinical and 2D radiographs better serve the purpose. More studies with larger sample sizes and acceptance of a universal tool for assessment of endodontic treatment quality are needed to compare treatment quality and complications in various regions of the world.

  Conclusions Top

The most common technical error was nonhomogenous obturation. About half of the endodontically treated root canals had nonhomogenous obturations, and one-fourth root canals had short obturation and inadequate CS. The study showed a higher prevalence of apical radiolucencies which increased with short obturations, poor CS, and nonhomogeneous obturations. Mandibular molars were associated with the highest number of technical errors and complications.

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Conflicts of interest

There are no conflicts of interest.

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  [Table 1], [Table 2]


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