Role of αENaC in root resorption of adjacent teeth due to entirely impacted mandibular third molars

BACKGROUND

Entirely impacted mandibular third molar (EIM3M) concerns the pathological external root resorption (ERR) of the adjacent mandibular second molar (M2M) and formation of granulation tissue between two molars. The study aimed to clarify the effect of αENaC, a mechano-sensitive molecule, to explore the mechanical mechanism in this scenario.

METHODS

The force EIM3M exerted on M2M was proved by finite element analysis. αENaC expressions were tested by real-time polymerase chain reaction (PCR), immunoblotting and immunofluorescence. Inflammatory and epithelial-mesenchymal transition (EMT)-related molecules expressions were also detected by real-time PCR. The correlation was analyzed by Spearman's correlation analysis, and receiver-operator characteristic (ROC) curve was further exhibited.

RESULTS

The force was concentrated in the ERR area. αENaC was upregulated, positively correlated with ERR degree and localized to the fibroblasts in ERR granulation tissues. Moreover, αENaC was respectively and positively associated with elevated TNF-α and N-cadherin in ERR granulation tissues. More importantly, ROC analysis verified αENaC as a novel indication of the incidence of this disease.

CONCLUSIONS

Our finding revealed the force from EIM3M causing ERR of M2M, and elucidated the expression and localization of αENaC and its positive correlation with inflammation, EMT and disease severity, suggesting a novel indication in this disease.

Application of deep learning and feature selection technique on external root resorption identification on CBCT images

BACKGROUND

Artificial intelligence has been proven to improve the identification of various maxillofacial lesions. The aim of the current study is two-fold: to assess the performance of four deep learning models (DLM) in external root resorption (ERR) identification and to assess the effect of combining feature selection technique (FST) with DLM on their ability in ERR identification.

METHODS

External root resorption was simulated on 88 extracted premolar teeth using tungsten bur in different depths (0.5 mm, 1 mm, and 2 mm). All teeth were scanned using a Cone beam CT (Carestream Dental, Atlanta, GA). Afterward, a training (70%), validation (10%), and test (20%) dataset were established. The performance of four DLMs including Random Forest (RF) + Visual Geometry Group 16 (VGG), RF + EfficienNetB4 (EFNET), Support Vector Machine (SVM) + VGG, and SVM + EFNET) and four hybrid models (DLM + FST: (i) FS + RF + VGG, (ii) FS + RF + EFNET, (iii) FS + SVM + VGG and (iv) FS + SVM + EFNET) was compared. Five performance parameters were assessed: classification accuracy, F1-score, precision, specificity, and error rate. FST algorithms (Boruta and Recursive Feature Selection) were combined with the DLMs to assess their performance.

RESULTS

RF + VGG exhibited the highest performance in identifying ERR, followed by the other tested models. Similarly, FST combined with RF + VGG outperformed other models with classification accuracy, F1-score, precision, and specificity of 81.9%, weighted accuracy of 83%, and area under the curve (AUC) of 96%. Kruskal Wallis test revealed a significant difference (p = 0.008) in the prediction accuracy among the eight DLMs.

CONCLUSION

In general, all DLMs have similar performance on ERR identification. However, the performance can be improved by combining FST with DLMs.

Could the pulp be preserved in tooth with root resorption caused by embedded tooth?

Background/purpose

At present, there are no recognized guidelines or consensus for the treatment strategy of the asymptomatic tooth with external root resorption caused by an embedded tooth (et-ERR). Most clinicians would like prophylactic or concomitant root canal therapy (RCT) along with the extraction of the embedded tooth. The purpose of this study was to report the prognosis of external root resorption (ERR) and investigate the possibility to preserve the vital pulp of ERR tooth.

Materials and methods

The patients who had asymptomatic et-ERR teeth were included. After extraction of the embedded tooth, the clinical process, prognosis, and adverse events were observed, including symptoms, clinical, and radiographic examination throughout the follow-up period.

Results

A total of four cases with special features were reported. Over a follow-up period of up to 12 months, on clinical examination, 3 ERR teeth preserved pulp vitality without additional intervention except for tooth extraction and have kept normal function free from any symptoms. Radiographic examination showed bone regeneration and recovery of periodontal tissue. While one case failed to keep the vital pulp and ended in intentional replantation.

Conclusion

As to et-ERR, if the embedded tooth can be promptly extracted with a minimally invasive technique and effective infection control, the pulp vitality of the et-ERR tooth is likely to be preserved. In this situation, the preferred management of asymptomatic et-ERR tooth is just followed up without prophylactic RCT.

Clinical and Radiographic Outcomes of Regenerative Endodontic Procedures for Traumatized Permanent Necrotic Teeth with Apical Periodontitis and External Root Resorption

AIM

This clinical study was undertaken to assess the effect of treatment with REPs on 20 teeth with pulp necrosis, apical periodontitis and external root resorption. (ERR).

METHODOLOGY

Teeth were treated with REPS utilizing the American Association of Endodontists (AAE) protocol. Quantitative assessment of changes in radiographic root area (RRA) were statistically analyzed to assess changes in root dimensions after an average follow-up period of 3 years.

RESULTS

All 20 teeth survived, 14 teeth (70%) were classified successful, and only1 tooth (5%) failed throughout the study period. Based on the radiographic examination, all 20 teeth showed complete repair of the periapical lesions and arrested ERR. However, 5 teeth (25%) subsequently developed replacement resorption. The RRA between baseline and 3-year follow-up showed a significant difference for the total 20 teeth (p = 0.009). An analysis according to the trauma type and the extra-oral time showed the RRA increase was significantly different in the non-avulsion group (p = 0.015) and for the avulsion group with an extra-oral time less than 60 min (p = 0.029). The RRA increase was not statistically significant in the avulsion group of extra-oral time more than 60 min (p = 0.405). Nine teeth (45%) and 10 teeth (50%) responded to cold and electric pulp testing respectively.

CONCLUSIONS

Within the limitations of this study, the favourable outcomes of REPs were further confirmed for traumatized permanent necrotic teeth with ERR in terms of periapical lesion healed and a significant increase in RRA. The study contributes further evidence of the role of REPs in arresting ERR.

DIAGNOSTIC PERFORMANCE OF CONE-BEAM COMPUTED TOMOGRAPHY TO DIAGNOSE IN VIVO/IN VITRO ROOT RESORPTION: A SYSTEMATIC REVIEW AND META-ANALYSIS

BACKGROUND

This review analyses the diagnostic performance of cone-beam computed tomography (CBCT) for the in vivo/in vitro detection of external root resorption (ERR) and critically analyses current and past methods of measuring or classifying ERR in vivo/in vitro in terms of radiation doses and cumulative radiation risks.

METHODS

A diagnostic test accuracy (DTA) protocol was used for a systematic review of diagnostic methods following PRISMA guidelines. The protocol was registered with PROSPERO (ID: CRD42019120513). A thorough and exhaustive electronic search of 6 core electronic databases was performed, applying the ISSG Search Filter Resource. The eligibility criteria were designed [problem-intervention-comparison-outcomes (PICO) statement: Population, Index test, Comparator, Outcome] and methodological quality was assessed by QUADAS-2.

RESULTS

Seventeen papers were selected from a total of 7841 articles. Six in vivo studies were assessed as having a low risk of bias. The overall sensitivity and specificity of CBCT for diagnosis of ERR was 78.12% and 79.25%, respectively. The highest and lowest sensitivity and specificity of CBCT for diagnosis of external root resorption are 42%-98% and 49.3%-96.3%.

DISCUSSION

Most of the selected studies reported quantitative diagnoses with single linear measurements of ERR even though multislice radiographs were available. The cumulative radiation dose (μS) to radiation-sensitive structures, such as the bone marrow, brain and thyroid, was observed to increase using the 3-dimensional (3D) radiography methods reported.

CONCLUSIONS

The highest and lowest sensitivity and specificity of CBCT for diagnosis of external root resorption are 42%-98% and 49.3%-96.3%. The minimum and maximum effective doses of dental CBCT for external root resorption diagnosis are 34 μSv and 1073 μSv.

Expression of matrix metalloproteinases 2 and 9 in replanted teeth with external root resorption: A cross-sectional study

OBJECTIVE

To evaluate matrix metalloproteinase (MMP) expression in replanted permanent teeth with external root resorption (ERR).

DESIGN

The present cross-sectional study included 42 patients with replanted permanent teeth, presenting with progressive forms of ERR, and referred for extraction according to the rehabilitation treatment plan or due to root fractures. The control group consisted of 12 healthy premolars, from 5 patients with good periodontal health and no radiographic evidence of root resorption, referred for extraction for orthodontic reasons. Root fragments were processed soon after extraction, and the supernatant was collected to measure matrix metalloproteinase 2/tissue inhibitor of metalloproteinase 2 (MMP-2/TIMP-2) and matrix metalloproteinase 9/tissue inhibitor of metalloproteinases 2 (MMP-9/TIMP-2) complexes through a double-ligand enzyme-linked immunosorbent assay (ELISA).

RESULTS

Case groups with external inflammatory root resorption (EIRR) or external replacement root resorption (ERRR) showed significantly higher levels of MMP-2/TIMP-2 and MMP-9/TIMP-2 complexes than the control group. Additionally, comparisons between the case groups demonstrated that the MMP-2/TIMP-2 complex also had significantly higher levels in the ERRR group (p < 0.001).

CONCLUSIONS

Our results suggest that MMP-2 and MMP-9 participate in the pathobiology of both types of ERR. In addition, the higher levels of MMP-2/TIMP-2 complex in the ERRR group support common modulation mechanisms with physiological bone turnover.

Tissue-specific biomarkers in gingival crevicular fluid are correlated with external root resorption caused by constant mechanical load: an in vivo study

OBJECTIVES

This study investigated the association of changes in cementum protein-1 (CEMP-1), dentine phosphoprotein (DPP), and c-terminal cross-linked telopeptide of type I collagen (CTX-I) levels in human gingival crevicular fluid (GCF) under constant load with external root resorption volume and amount of tooth movement.

MATERIALS AND METHODS

In total, 11 healthy adult patients (mean age, 23.5 years [range, 18.3-37.7]; four men and seven women) were enrolled. GCF samples were obtained from premolars at T0, T1 (1 day), T2 (1 week), T3 (2 weeks), T4 (4 weeks), and T5 (8 weeks) under constant 100-gm buccal tipping force. Opposite premolars were used as controls. Teeth were extracted at T5, followed by quantification of external root resorption volume and histological analysis.

RESULTS

In the test group, T5/T0 ratios of CEMP-1 and DPP levels, differential CEMP-1 levels between T5 and T0, and differential DPP levels between T2 and T0 correlated positively with root resorption volume (r = 0.734, 0.730, 0.627, and 0.612, respectively, all p < 0.05). CEMP-1 levels at T0 and T3 correlated negatively with root resorption volume (r = -0.603 and -0.706; all p < 0.05). CTX-I levels at T5 correlated positively with the amount of tooth movement (r = 0.848, p < 0.01).

CONCLUSIONS

Alterations in CEMP-1 and DPP levels in human GCF at specific timepoints during orthodontic treatment may be associated with different degrees of external root resorption.

CLINICAL RELEVANCE

This study demonstrates that changes in the levels of tissue-specific biomarkers in GCF may facilitate early detection of external root resorption during orthodontic tooth movement.

Cone-beam computed tomography versus periapical radiograph for diagnosing external root resorption: A systematic review and meta-analysis

OBJECTIVE

To compare the diagnostic accuracy of cone-beam computed tomography (CBCT) and periapical radiographs (PR) for the detection of external root resorption (ERR).

MATERIAL AND METHODS

An electronic search in databases, including the Cochrane Central Register of Controlled Trials, PubMed, Embase, the China National Knowledge Infrastructure, and System for Information on Grey Literature in Europe (SIGLE), was performed until August 2016. A manual search of relevant journals and reference lists of enrolled studies was conducted. The studies investigating the diagnostic accuracy of CBCT or PR for ERR, with simulated ERR as the reference test, were considered eligible. The diagnostic accuracy of CBCT and PR was statistically pooled using a bivariate model. Meta-regression and subgroup analysis were performed to explore the sources of heterogeneity. Sensitivity analysis was used to test the stability of the overall results in the meta-analysis.

RESULTS

A total of 15 studies were included in this systematic review. The pooled results showed that CBCT had significantly higher sensitivity (0.89; 95% confidence interval [CI]: 0.77-0.96) and area under curve (0.96; 95% CI: 0.77-0.96) than PR (sensitivity: 0.68; 95% CI: 0.56-0.78; area under curve: 0.88; 95% CI: 0.85-0.90). No difference in sensitivity, specificity, and area under the curve between conventional and digital PR was observed.

CONCLUSIONS

Currently available evidence suggests that CBCT could be reliable to detect the presence of ERR in clinical practice and has a higher diagnostic efficacy than PR.

External root resorption of the second molar associated with mesially and horizontally impacted mandibular third molar: evidence from cone beam computed tomography

OBJECTIVES

The aim of the present study was to assess the incidence and risk factors of ERR in second molars with mesially and horizontally impacted mandibular third molars using cone beam computed tomography (CBCT) images from patients in a Chinese tertiary referral hospital.

MATERIALS AND METHODS

A total number of 216 patients with 362 mesially and horizontally impacted mandibular third molars who were treated at our institution from 2014 to 2015 was retrospectively included. The ERR in second molars was identified on CBCT multiplanar images. The associations between incidence of ERR and multiple clinical parameters were statistically analyzed by Chi-square test. Moreover, the risk factors for ERR in second molars were further assessed by multivariate regression analysis.

RESULTS

The overall incidence of ERR in second molars was 20.17 % (73/362) as detected on CBCT images. The presence of ERR significantly associated with patients age and impaction depth of mandibular third molars. However, no significant relationship was found between ERR severity and impaction depth or ERR location. Multivariate regression analyses further revealed age over 35 years and impaction depth as important risk factors affecting the ERR incidence caused by mesial and horizontal impaction of mandibular third molar.

CONCLUSIONS

ERR in second molar resulted from mesially and horizontally impacted mandibular third molar is not very rare and can be reliably identified via CBCT scan.

CLINICAL RELEVANCE

Given the possibility of ERR associated with third molar impaction, the prophylactic removal of these impacted teeth could be considered especially for those patients with over 35 years and mesially and horizontally impacted teeth.

Three-year follow-up results for non-surgical root canal therapy of idiopathic external root resorption on a maxillary canine with MTA: a case report

External root resorption (ERR) is an uncommon and intractable disease. Treatment alternatives are case-dependant and aim for the repair of the resorptive lesion and long-term retention of the tooth. A forty-year-old Asian female was diagnosed with idiopathic ERR on tooth #11 (the left maxillary canine) by CBCT. Non-surgical root canal therapy was completed with the aid of an operating microscope. The apical third of the root canal was filled with warm gutta-percha and the resorption defect was filled with mineral trioxide aggregate (MTA). The periapical radiographs were taken immediately after operation, one-month follow-up, six-month follow-up and three-year follow-up, respectively. Clinically, the canine was asymptomatic, and no evidence of any further resorption was found. The six-month follow-up radiograph showed initial healing of the bony lesion, while the three-year follow-up radiograph manifested almost complete healing. MTA can be a superior material to be successfully used in the non-surgical treatment of ERR. CBCT is very useful for evaluating the true nature and severity of absorption lesions in root resorption. It is the first complete case report from China about non-surgical treatment of severe ERR along with a relatively long term follow-up.

Multiple idiopathic cervical root resorptions: report of one case with 8 teeth involved successively

Multiple idiopathic cervical root resorptions is a rare condition which is usually detected as an incidental radiographic finding. It involves more than 3 teeth in the same patient and the etiology remains elusive. Diagnosis and treatment of the defect is still challenging. The present report describes a case with progressive multiple external cervical resorption involving 8 teeth, including the history, clinical and radiographic findings. Treatment included surgical intervention and restoration of the defect. A 3-month reevaluation of the case confirmed a stable, uneventful clinical recovery.