Impact of Cone-beam Computed Tomography on Treatment Planning for External Cervical Resorption and a Novel Axial Slice-based Classification System

Introduction

The aim of this study was to compare treatment plans for external cervical resorption (ECR) developed from periapical (PA) radiographs and cone-beam computed tomographic (CBCT) imaging. The secondary aim of this study was to test a new classification system for ECR based on CBCT axial slice analysis.

External Cervical Resorption: A Comparison of the Diagnostic Efficacy Using 2 Different Cone-beam Computed Tomographic Units and Periapical Radiographs

Introduction

The aim of this study was to compare the diagnostic efficacy of 2 cone-beam computed tomographic (CBCT) units with parallax periapical (PA) radiographs for the detection and classification of simulated external cervical resorption (ECR) lesions.

A Review of External Cervical Resorption

External cervical resorption (ECR) is a relatively uncommon yet aggressive form of dental hard tissue destruction. It is initiated at the cervical aspect of the root surface and extends apicocoronally and circumferentially inside the dentin. Despite the large number of case reports and clinical studies that have investigated ECR, its etiology remains unclear. Recent advancements in clinical assessment measures, such as the use of cone-beam computed tomographic imaging, have provided additional insights into the nature of this lesion. This has facilitated the continued development and improvement of treatment methods for this condition. In this article, we provide an overview of the latest research pertaining to the etiology, histopathology, predisposing factors, diagnosis, classification, and treatment of ECR. Furthermore, we provide a summary of the different classification schemes for ECR and highlight the relevant therapeutic principles.     

Denosumab Use as a Predictor Variable for External Cervical Resorption: A Case-Control Study

IntroductionThe objective of this case-control study was to investigate the association between denosumab use and the risk of developing external cervical resorption (ECR).MethodsThirty-three patients ≥45 years old who were diagnosed with ECR were selected. Controls were matched to the cases based on sex and age (±5 years) in a 1:1 ratio. Confounders were classified into systemic factors, including a history of systemic sclerosis, hepatitis B, denosumab use, and bisphosphonate use, or local factors, including a history of traumatic occlusion, periodontal procedures (scaling and root planing and periodontal surgeries), and tooth extraction (excluding third molar extraction). Additionally, the number of remaining teeth in each subject was recorded using panoramic radiographs. The baseline characteristics of the 2 groups, including age, sex, and the number of remaining teeth, were compared using the chi-square and Mann-Whitney U tests. Binary logistic regression was used to determine the possible association between denosumab use and the risk of developing ECR (α < 0.05).ResultsNo significant differences in baseline characteristics were observed between the case and control groups (P > .05). After adjusting for systemic and local cofounders, denosumab use was significantly associated with the occurrence of ECR (odds ratio = 7.317; 95% confidence interval, 1.410–37.966; P < .05).ConclusionsBased on the binary logistic regression model, denosumab use could significantly predict the risk of developing ECR.     

External Cervical Resorption: A Retrospective Case-Control Study

IntroductionThe current retrospective case-control study examined the potential systemic and local risk factors in relationship to external cervical resorption (ECR). The study hypothesis stated that both local and systemic risks are associated with higher ECR rates.MethodsThe ECR group included data about 76 patients (98 teeth) diagnosed with ECR at the university graduate endodontics clinic from 2008–2018. An equivalent comparative control group without ECR was composed of the same pool of patients and matched with cases by sex and age. Information about dental and medical history, including potential local risk factors (bruxism, trauma, eruption disorders, extraction of an adjacent tooth, orthodontics, and restorations) and systemic risk factors (medical conditions, medication, and allergies), was collected for both groups. Data were analyzed at tooth and patient levels. The chi-square test or Fisher exact test compared proportions between the 2 study groups.ResultsThe overall ECR prevalence among endodontic patients during the 10-year follow-up was 2.3%. ECR was most frequent in maxillary anterior teeth (31.6%), and the Heithersay class 2 was the most frequent (38.8%) ECR diagnosis. Diabetes was the only significant systemic risk factor (P < .05). Trauma, as a local risk factor, was significantly (P < .05) more frequently reported in cases than in controls.ConclusionsThe study hypothesis stating that both systemic and local risk factors were associated with higher ECR rates was partly confirmed, as one systemic (diabetes) and one local (trauma) risk factor were associated with higher ECR rates.     

External Cervical Resorption: A Volumetric Analysis on Evolution of Defects over Time

IntroductionThe aim of this study was to assess the temporal evolution of external cervical resorption (ECR) defects using a volumetric quantification method.MethodsCone-beam computed tomographic (CBCT) images of patients diagnosed with ECR who chose not to receive treatment and attended recalls were collected. ECR defects were segmented in CBCT images at baseline and recall, and their volumes were quantified. The volumetric ratio of resorption defects/teeth was calculated. Three-dimensional classification of defects at baseline and recall and the prevalence of root surface perforations ≥1 mm were determined. The Wilcoxon matched pairs signed rank test, chi-square test, and linear regression models were used to analyze the data.ResultsFifteen patients with 20 teeth diagnosed with ECR and an average recall time of 21 months were included. Nine (45%) teeth showed a change in 3-dimensional classification at recall. The volume of resorption defects (P = .0001) and the volumetric ratio of resorption defects/teeth (P = .0001) increased over time. The prevalence of root surface perforations ≥1 mm was higher at recall (n = 17, 85%) compared with baseline (n = 9, 45%) (P = .008). Linear regression models showed significant associations between the resorption defect volume at recall compared with baseline (P < .0001; 95% confidence interval, 0.053–0.081) and the volumetric ratio of resorption defects/teeth at recall compared with baseline (P < .0001; 95% confidence interval, 0.205-0.356). There was no association between the volume of resorption defects at recall with the length of the recall period, sex, or age (P > .05).ConclusionsWhen left untreated, ECR defects can increase in size and develop more root surface perforations. ECR has a dynamic nature, and its volumetric increase over time does not result from uniform/linear expansion of the defects.     

Accuracy of Digital Periapical Radiography and Cone-beam Computed Tomography for Diagnosis of Natural and Simulated External Root Resorption

Introduction

The aim of this study was to compare the sensitivity and specificity of digital periapical radiography and cone-beam computed tomographic (CBCT) imaging in the detection of natural and simulated external root resorptions (ERRs) with micro–computed tomographic (micro-CT) imaging as the reference standard.

The Surgical Management of External Cervical Resorption: A Retrospective Observational Study of Treatment Outcomes and Classifications

IntroductionThe aims of this study were to assess the survival and clinical success of patients with teeth with external cervical resorption (ECR) who underwent surgical repair, to assess the reliability of using 2 different classification systems for ECR (Heithersay 2-dimensional classification and Patel 3-dimensional classification), and to identify if a 3-dimensional classification is a viable alternative.MethodsA retrospective study was performed in a teaching dental hospital in England. The inclusion criteria were limited to patients who underwent surgical management of ECR between 2015 and 2018. Both periapical radiographs and cone-beam computed tomographic scans of 13 patients were assessed by 2 independent dental practitioners using the Heithersay and Patel classifications. The same radiographic assessment of those records was then repeated 3 weeks later by 1 operator. These data were tested using the Cohen kappa analysis to determine inter- and intraobserver agreement.ResultsA total of 14 teeth affected with ECR were identified in 13 patients (6 women and 7 men) with a mean age of 41 years. The mean follow-up was 20 months. At follow-up, survival was noted in all cases; however, clinical success describing endodontic success, comprehensive restorative integrity, and arrest of the resorptive process was only met in 11 cases. Although helpful in describing the lesions, both classification systems displayed considerable limitations in predicting treatment outcome. A measure of Cohen kappa regarding interobserver reliability found the Heithersay classification to provide a moderate level of agreement (0.69), whereas the Patel classification provided a weak level of agreement (0.40).ConclusionsECR is a complex, aggressive, and uncommon form of external resorption. The long-term success of the treatment is predictable but strictly related to careful case selection and operative skill. In reference to ECR classifications, ambiguity still exists between their distinctive categories, leading to moderate and weak levels of interobserver agreement. Further improvement is required to enhance their use in future research.     

Stresses in Teeth with External Cervical Resorption Defects Restored with Different Biomimetic Cements: A Finite Element Analysis

IntroductionThis study compared the stress distributions in teeth with simulated external cervical resorption defects restored with different restorative materials and identified areas of high stress concentration.MethodsA maxillary central incisor created in a scanned model using HyperWorks software (Altair Engineering Inc, Troy, MI) served as the control. External cervical resorption defects based on Shanon Patel’s classification were created (1Bd/2Bd/3Bd) in the scanned model. The defects were restored using mineral trioxide aggregate, Biodentine, glass ionomer cement, and Bioaggregate. On all the models, a force of 100 N was applied on the palatal aspect 2 mm incisal to the cingulum directed at 45° along the long axis of the tooth.ResultsThe stresses generated in dentin and cementum are less, with a restorative material having a high Young’s modulus. For the 1Bd defect, MTA and Bioaggregate showed least stresses in dentin and cementum, respectively, whereas Biodentine had consistently lower stresses in dentin and cementum. Larger defects like 2Bd and 3Bd restored with Bioaggregate exhibited minimum stresses in dentin and cementum.ConclusionsBioaggregate and Biodentine replace dentin with maximum stress and maximum strain. Elastic moduli similar to or higher than dentin are preferred for restoring cervical third resorptive lesions of the tooth.     

External Cervical Resorption: A New Oral Manifestation of Systemic Sclerosis

Systemic sclerosis (SSc) is a complex, chronic, and progressive autoimmune disease. SSc causes bone resorption of mandible and distal phalanges of fingers through a known mechanism, and it has also been pointed out as a possible cause of apical root resorption of teeth, because tooth resorption is regulated by similar mechanisms to those controlling bone resorption. The objective of this article was to report the first case in the literature of external cervical resorption (ECR) as an oral manifestation of SSc. A 66-year-old female patient with a 35-year history of SSc was diagnosed with multiple ECRs through a computerized axial tomography and clinical examination. All known causes of ECR were discarded after a detailed anamnesis and clinical examination. This report details SSc as a possible cause of ECR and discusses the pathogenesis of ECR in relation with SSc. The systemic alterations provoked by SSc can be related to the etiopathogenesis of cervical root resorption. It is extremely relevant that dental care providers be aware that external cervical resorptions could be present in patients suffering from SSc, consciously look for these lesions, treat them early in case they are present, and advise the patient with SSc of the importance of continuous dental controls.     

A Clinical Evaluation of Cone-beam Computed Tomography: Implications for Endodontic Microsurgery

IntroductionCone-beam computed tomographic (CBCT) imaging is a valuable diagnostic tool for endodontics. Some studies report that CBCT images have limitations in representing the true clinical presentation. This prospective, in vivo study compared limited field of view (LFOV) CBCT measurements with clinical measurements made during endodontic surgery.MethodsEighty-seven subjects requiring endodontic surgery and LFOV CBCT acquisition of the surgical site were enrolled. Data collection involved clinicians answering standardized questions during the radiographic and surgical assessment. Intraoperatively, data were collected and photographically documented. Postoperatively, CBCT scans were evaluated by 3 calibrated, board-certified specialists: 2 endodontists and 1 oral and maxillofacial radiologist. The 2 subsets of data were compared through statistical analysis to quantify their relationship.ResultsThe subjects included 65 maxillary and 29 mandibular teeth from 87 subjects: 25 women and 62 men with an average age of 42 years old. The CBCT evaluators correctly identified the presence or absence of buccal plate fenestrations with 91.0% accuracy (95% confidence interval, 83.1–96.0) with 89.4% sensitivity and 92.9% specificity. The area of fenestrations measured clinically (mean = 19.6 ± 33.4 mm²) was generally larger than the area measured by CBCT imaging (mean across CBCT evaluators = 12.2 ± 19.1 mm²). Fenestration size in the maxillary arch was more likely to be underestimated than in the mandibular arch (P < .0001). Vertical bone height was also underestimated when measured on CBCT imaging.ConclusionsBased on the findings of this study, LFOV CBCT imaging accurately identifies the presence or absence of buccal plate fenestrations, yet, when a fenestration is present, underestimates its area.     

Discontinuation of Denosumab as a Potential Cause of Generalized External Cervical Root Resorption: A Case Report

Generalized occurrence of external root resorption in an adult patient is a rare finding. This case report describes external cervical root resorption extensively affecting the dentition that may be associated with the use and subsequent cessation of denosumab for the treatment of osteoporosis.     

A Volumetric Assessment of External Cervical Resorption Cases and Its Correlation to Classification,Treatment Planning,and Expected Prognosis

IntroductionExternal cervical resorption (ECR) is a relatively uncommon type of external resorption; its treatment planning and prognosis are largely dependent on the clinician’s subjective assessment. This study aimed to provide a volumetric assessment of ECR cases while correlating them to the Heithersay classification, treatment decision, and prognosis determined by 3 calibrated, independent evaluators.MethodsA total of 168 ECR cases with corresponding periapical radiographs and cone-beam computed tomographic (CBCT) imaging were included in this study. An oral and maxillofacial radiologist calculated the volume occupied by the resorptive defects in root structures on CBCT imaging using Amira software (Thermo Scientific, Waltham, MA). Also, 3 board-certified endodontists evaluated anonymized and randomized periapical radiographs and corresponding CBCT images in separate sessions. Examiners were asked to provide a Heithersay classification, whether they would surgically repair the ECR lesion, and the expected prognosis of each case.ResultsThe percentage of radicular volume affected by ECR ranged from 0.5%–58% with a median of 12%. The volumetric quantification of ECR best correlated with classification and prognosis assigned by the independent examiners using CBCT evaluation. The greatest variation in agreement was observed on whether to surgically repair the ECR. However, examiners agreed more uniformly on not to treat when the resorptive port of entry was found on either the lingual or proximal surfaces of the tooth.ConclusionsFor the first time, the volumetric quantification of resorptive defects was calculated in vivo and correlated to the Heithersay classification and prognosis. Because the longevity of teeth affected with ECR depends on the integrity of the remaining root, the findings of this study provide important information to help clinicians decide on treatment planning and inform their patients of the expected prognosis. Future studies should focus on automating volumetric assessments of ECR to aid in unbiased chairside treatment planning decisions.     

Multiple Cervical Root Resorption in a Young Adult Female Previously Treated with Chemotherapy: A Case Report

Multiple idiopathic cervical root resorption is an aggressive form of external root resorption that occurs at the cementoenamel junction and can affect multiple teeth (a minimum of 3) throughout the entire dentition. Most of the individuals affected are healthy with noncontributory medical histories. The resorption is usually detected as an incidental finding on radiographs or during dental examination. This case report describes an adult female with multiple cervical root resorptions who had been treated with chemotherapy for ovarian cancer at 16 years old. Nine years later, a total of 12 teeth were diagnosed with cervical root resorption. All of the known causative factors for external cervical resorption were discarded. To our knowledge, this is the first case reported of multiple cervical root resorption related to chemotherapy.     

Guided Tissue Regeneration in Class IV External Cervical Resorption: A Case Report

External cervical resorption (ECR) is a type of dental resorption that originates from the loss of the cementum's protective layer. The direct exposure of dentin to the periodontal ligament may lead to the invasion of clastic cells through an entry point on the external root surface into the dentinal tissue, causing resorption. Depending on the extension of ECR, different treatments are proposed. Although the literature presents distinct materials and methods for restoring ECR areas, an existing gap is related to care in the treatment of the supporting periodontal tissue. Guided tissue regeneration (GTR)/guided bone regeneration includes the stimulation of bone formation in bone defects using different types of membranes (resorbable and nonresorbable), regardless of its association with bone substitutes or grafts. Despite the benefits of guided bone regeneration, the application of this method in cases of ECR is still under-explored in the literature. Thus, the present case report uses GTR with xenogenic material and polydioxanone membrane in a case of class IV ECR. The success of the present case is related to the correct diagnosis and treatment plan. Complete debridement of resorption areas and restoration with biodentine were effective in tooth repair. GTR contributed to the stabilization of supporting periodontal tissues. The association of the xenogeneic bone graft with the polydioxanone membrane proved to be a viable option for restoring the health of the periodontium.     

External Cervical Resorption: Relationships between Classification,Treatment, and 1-Year Outcome with Evaluation of the Heithersay and Patel Classification Systems

IntroductionThe purpose of this study was to identify possible associations between classification, treatment, and 1-year outcome of external cervical resorption (ECR) lesions using the Heithersay and Patel systems. Performance of the Patel 3-dimensional classification system was also evaluated.MethodsA chart review identified 142 cases of ECR over a 12-year period. Information regarding demographics, predisposing factors, lesion classification, treatment, and outcomes were collected and analyzed. Inter- and intraobserver reliability analyses were conducted for both classification systems.ResultsThere were 72 cases with at least 1 year of follow up; 70% of these cases survived. Treatment recommendations were correlated with both Heithersay and Patel classification. There were no correlations found between 1-year outcome and either classification or treatment done. The weighted reliability analysis showed substantial agreement in both classification systems for both inter- and intraobserver agreement. There was a significant association between the 2 systems; however, the Heithersay system tended to underestimate the apical extent of the lesion.ConclusionsPeriodic review of ECR lesions presents as a viable treatment option, at least for 1 year after diagnosis. The Patel 3-dimensional classification system is at least as effective as the Heithersay system and should be used in future ECR prognosis studies. Further long-term outcome assessments are still needed.     

The Effect of Removable Partial Dentures on Alveolar Bone Resorption: A Retrospective Study with Cone‐Beam Computed Tomography

Purpose: The aim of this study was to compare vertical and horizontal mandibular alveolar bone resorption by measuring bone morphological variation in Kennedy Class II removable partial denture (RPD) wearers and non‐wearers using cone‐beam computed tomography (CBCT). Materials and Methods: In total, 124 sites in the CBCT scans of 62 (29 RPD non‐wearers, 33 RPD wearers) Kennedy Class II patients were analyzed retrospectively. Three‐dimensional representations of the mandible with superimposed cross‐sectional slices were developed with the CBCT scans to evaluate the mandibular alveolar height and width by measuring distances between the mandibular canal, mylohyoid ridge, alveolar crest, and lower border of the mandible in four regions (eight sites) of Kennedy Class II non‐wearers and wearers of RPDs. Results: Mandibular alveolar bone height and width were significantly lower in edentulous sites when compared with dentate sites in both Kennedy Class II non‐wearers and wearers of RPDs (p < 0.05). Additionally, mean vertical and horizontal mandibular bone resorption was significantly higher in RPD wearers than in non‐wearers (p < 0.05). Conclusions: Vertical and horizontal alveolar bone resorption was found to be higher in the RPD wearing patients when comparing the dentate and edentulous sites.     

Symmetry of Root and Root Canal Morphology of Maxillary and Mandibular Molars in a White Population: A Cone-beam Computed Tomography Study In Vivo

Introduction

The aim of the present study was to use cone-beam computed tomography (CBCT) to analyze root canal anatomy and symmetry of maxillary and mandibular first and second molar teeth of a white population.

Methods

A total of 201 patients who required CBCT examinations as part of their dental diagnosis and treatment were enrolled in the present study. Overall, 596 healthy, untreated, well-developed maxillary and mandibular molar teeth (161 maxillary first molars, 157 maxillary second molars, 117 mandibular first molars, and 161 mandibular second molars) were examined by CBCT to establish the symmetry in root and canal anatomy between right and left sides in the same patient by evaluating the number of roots and root canals and the root canal configuration.

Results

Three separate roots with 3 separate canals was the normal anatomy of maxillary first and second molars. Most mandibular first and second molars had 2 separate roots, and the majority had 3 canals. In the present study, first molars, both maxillary and mandibular, exhibited greater asymmetry than the second molars. Maxillary first molars were found to be symmetrical in 71.1% of patients, whereas maxillary second molars were symmetrical in 79.6%. The remaining 28.9% and 20.4% of patients, respectively, showed asymmetry. Around 30% of the mandibular first molars and 20% of the mandibular second molars showed asymmetry.

Conclusions

The results of the present study reported a percentage of symmetry that varied from 70%–81%. These variations in symmetry should be taken in high consideration when treating 2 opposite molars in the same patient, because their anatomy may be different in up to 30% of the cases.     

Prevalence and Size of Periapical Radiolucencies Using Cone-beam Computed Tomography in Teeth without Apparent Intraoral Radiographic Lesions: A New Periapical Index with a Clinical Recommendation

Introduction

The purpose of this study was to determine the prevalence and size of periapical radiolucencies using cone-beam computed tomographic (CBCT) imaging in teeth without apparent signs of intraoral radiographic lesions.