Is Hypoxia Related to External Cervical Resorption? A Case Report

The various forms of tooth resorption

Tooth resorption refers to the loss of the organic and inorganic components of tooth structure by clastic cells. The complex and multifaceted nature of its aetiology, along with the several classification schemes published in the area, are likely to create confusion amongst researchers and clinicians, and may lead to compromised treatment decisions. Therefore, this paper will categorise and address tooth resorption based on aetiology in order to help clinicians diagnose and filter treatment options based on the pathophysiology of the resorption at hand. With recent advancements in the literature, the purpose of this paper is to provide clinicians with a current, clinically relevant summary of the various forms of tooth resorption, with a focus on aetiologically driven treatment strategies and suggestions that facilitate their recognition, diagnosis and management.

A clinical dilemma: Performing or avoiding root instrumentation in the treatment of the acute phase of endodontic-periodontal lesions? A case report

BACKGROUND

This study presents the diagnois, management, and tissue response to an acute periodontal lesion with deep pocketing affecting a maxillary central incisor in a young patient devoid of caries or a history of periodontitis.

METHODS

Clinical and radiographic examinations facilitated the diagnosis of the pathology as an endoperiodontal lesion (EPL) with root damage, exhibiting supracrestal invasive root resorption. Orthograde endodontic therapy was employed to decontaminate and seal the endodontic space. The resorptive site was treated through the endodontic access, debrided, and sealed. No periodontal therapy (surgical or nonsurgical) was performed. No mechanical instrumentation was performed within the pocketed root surface.

RESULTS

At 6-month and 1-year follow-ups after endodontic therapy the periodontium displayed a physiologically healthy condition without pus or inflammation, exhibiting a circumferential probing depth of 2 mm, and absence of tooth mobility. These favorable outcomes persisted throughout a 4-year follow-up period.

CONCLUSIONS

The spontaneous healing of pocketing and abscess occurred without mechanical root instrumentation following endodontic therapy and treatment of external invasive root resorption in an EPL.

KEY POINTS

Accurate diagnosis and identification of relevant etiologic factors are pivotal for effectively managing endodontic-periodontal lesions. Once a diagnosis is established, the therapy focuses on eliminating the primary cause, followed by a subsequent diagnostic phase after healing. The definitive understanding of the diagnosis and etiology of endodontic-periodontal lesions often becomes clear in retrospect, based on the outcomes of the therapy. When probing acute periodontal lesions, deep probing depths may occur without permanent loss of periodontal attachment. If the acute lesion was not induced by a periodontal cause and if no periodontal etiology arises secondarily, resolving the primary cause of the endoperiodontal lesion can lead to the spontaneous resolution of the pocketing. This results in spontaneous healing of periodontium without the need for intentional periodontal therapy. A clinical dilemma arises when considering periodontal treatment during the acute inflammatory phase of endo-periodontal pathology. It is advisable to refrain from mechanical root instrumentation particularly if a clear periodontal cause is not apparent, to prevent from iatrogenic damage to periodontal fibers and the potential risk of gingival recessions. However, this does not imply avoiding periodontal therapy entirely for every case. Rather, it is recommended to delay the decision on root instrumentation until a new diagnostic phase is conducted following the healing of the endodontic etiology.

Factors influencing root resorption in retained mandibular second deciduous molars with congenital absence of second premolars: a cross-sectional study

BACKGROUND

There are currently no studies that quantitatively compare the relationship of root resorption to the patient's systemic history or craniofacial and intraoral morphology, especially in relation to possible host factors. Thus, this study aimed to clarify the factors associated with root resorption in retained mandibular second deciduous molars with the congenital absence of second premolars and predict the prognosis of retained mandibular second deciduous molars.

METHODS

A cohort of 5547 patients who visited the orthodontic clinic at Tokyo Medical and Dental University Dental Hospital between 2013 and 2022 was screened. Lateral cephalometric radiographs, panoramic radiographs, upper and lower dental models, and orthodontic treatment questionnaires were used as reference materials to apply the inclusion and exclusion criteria. Ultimately, 111 patients were included in the analyses. The patients were divided into two groups based on the root resorption levels of the retained mandibular second deciduous molars. Those with less root resorption were classified under the good condition (GC) group, whereas those with more root resorption were classified under the poor condition (PC) group. Demographic, clinical, and cephalometric parameters were compared between the groups. A multivariate logistic regression model was used to predict the probability of root resorption.

RESULTS

The prevalence of congenitally missing mandibular second premolars with persistent mandibular second deciduous molars was 2.0%. In a total of 111 patients, eighty-three teeth (53.2%) were classified into the GC group, whereas 73 teeth (46.8%) were classified into the PC group. The Frankfort-mandibular plane angle (FMA) [odds ratio (OR): 0.87], Frankfort-mandibular incisor angle (FMIA) (OR: 0.93), overbite (OR: 1.38), adjacent interdental space (OR: 1.46), distance from occlusal plane (OR: 0.80), and caries treatment (OR: 7.05) were significantly associated with the root resorption of the retained mandibular second deciduous molars.

CONCLUSIONS

Our findings suggest that skeletal morphology, oral morphological patterns, and history contribute to root resorption in retained mandibular second deciduous teeth with congenital absence of subsequent permanent teeth.

Evaluation of rise in pH and oxygen release at the site of simulated external root resorption cavities using different oxygen-releasing biomaterials: An in vitro study

Context

External inflammatory root resorption has rapid onset and progresses aggressively. It leads to cementum loss, which allows communication between the infected pulp and the periodontium through the denuded dentinal tubules. Primary management strategy includes adequate chemomechanical debridement and lesion arrest for which maintaining alkaline pH and aerobic conditions is essential for healing and repair of the resorption defect.

Aims

The aim of this study is to evaluate rise in pH and oxygen release at the site of simulated external root resorption cavities using different oxygen-releasing biomaterials.

Materials and Methods

In 40 extracted single-rooted teeth access opening and chemomechanical debridement were done. Cavities simulating resorption defect are prepared on the roots. The samples are divided into four groups (n = 10) based on the biomaterial used. After placing the biomaterial, the root apices were sealed. Half of the samples from each group were tested for oxygen release using dissolved oxygen meter and the other half for rise in pH using pH meter at 7, 14, 21, and 28 days.

Statistical Analysis

The pH values were analyzed using Friedman 2-way analysis of variance (ANOVA) and Kruskal-Wallis test. Oxygen release was measured using the two-way and repeated-measures ANOVA.

Results

Calcium peroxide group showed the highest mean pH and oxygen release than other groups at any given point of time.

Conclusions

Incorporating oxygen-releasing biomaterials such as calcium peroxide and perfluorodecalin into intracanal medicaments, such as calcium hydroxide, creates an alkaline and oxygen-enriched milieu in the periapical tissues.

Pathogenesis of non-infection related inflammatory root resorption in permanent teeth: A narrative review

BACKGROUND

The mechanism of action of root resorption in a permanent tooth can be classified as infection-related (e.g., microbial infection) or non-infection-related (e.g., sterile damage). Infection induced root resorption occurs due to bacterial invasion. Non-infection-related root resorption stimulates the immune system through a different mechanism.

OBJECTIVES

The aim of this narrative review is to describe the pathophysiologic process of non-infection-related inflammatory processes involved in root resorption of permanent teeth.

METHODS

A literature search on root resorption was conducted using Scopus (PubMed and Medline) and Google Scholar databases to highlight the pathophysiology of bone and root resorption in non-infection-related situations. The search included key words covering the relevant category. It included in vitro and in vivo studies, systematic reviews, case series, reviews, and textbooks in English. Conference proceedings, lectures and letters to the editor were excluded.

RESULTS

Three types of root resorption are related to the non-infection mechanism of action, which includes surface resorption due to either trauma or excessive orthodontic forces, external replacement resorption and external cervical resorption. The triggers are usually damage associated molecular patterns and hypoxia conditions. During this phase macrophages and clastic cells act to eliminate the damaged tissue and bone, eventually enabling root resorption and bone repair as part of wound healing.

DISCUSSION

The resorption of the root occurs during the inflammatory phase of wound healing. In this phase, damaged tissues are recognized by macrophages and neutrophiles that secrete interlaukines such as TNF-α, IL-1, IL-6, IL-8. Together with the hypoxia condition that accelarates the secretion of growth factors, the repair of the damaged perioduntiom, including damaged bone, is initiated. If the precementum and cementoblast are injured, root resorption can occur.

CONCLUSIONS

Wound healing exhibits different patterns of action that involves immune stimulation in a bio-physiological activity, that occurs in the proper sequence, with overlapping phases. Two pathologic conditions, DAMPs and hypoxia, can activate the immune cells including clastic cells, eliminating damaged tissue and bone. Under certain conditions, root resorption occurs as a side effect.

Repair of an Extensive External Cervical Resorption Lesion Using Intentional Replantation with Crown Rotation

Treatment of large external cervical resorption (ECR) lesions may be compromised, rendering the tooth unrestorable. Intentional replantation is a potential treatment option depending on the site and extent of ECR. We present a case of a large ECR successfully managed with intentional replantation with rotation of the tooth. The female patient consulted the hospital clinic, with an extensive palatal ECR on the maxillary lateral incisor. Routine planar radiographs and cone-beam computed tomography demonstrated a larger palatal than the ECR lesion (Heithersay Class III and Patel's Class 2Bp) not amenable to nonsurgical treatment. Intentional replantation after short-term extrusion was planned. The defect was restored, then a palatal ferrule was achieved by rotating the tooth by 180°. At the 18-month follow-up, the periradicular and periodontal tissues remained healthy, and no other symptoms were reported. In conclusion, this successful video-illustrated clinical case highlights the benefits of intentional replantation in saving teeth with advanced ECR.

Root Surface Changes in Endodontically Treated Teeth Following Orthodontic Movement

INTRODUCTION

Orthodontically induced external root resorption (OIERR) has been labeled an unavoidable consequence of orthodontic tooth movement (OTM). The objective of this study was to investigate the change in surface area (mm²) and volume (mm³) of endodontically treated teeth (ETT) compared to contralateral teeth with a vital pulp (VPT) following OTM.

METHODS

Seventy-six teeth were included in this retrospective analysis: ETT (n=38) and VPT (n=38). All teeth were evaluated using CBCT imaging at two time periods: before OTM (T1) and after OTM (T2). Study teeth were segmented to include all areas contained within the lamina dura and then were converted into a mesh model for data calculation. The surface area (mm²) and volume (mm³) of each tooth was calculated at T1 and T2 based on the number of cubic voxels present within the mesh model. Statistical analysis was performed using a linear mixed-effects model.

RESULTS

The average change in surface area following OTM in ETT was 13.01 mm², and 19.95 mm² in VPT (p<0.05). The average percent change in surface area following OTM in ETT was 2.09%, and 3.38% in VPT (p<0.05). The average change in volume following OTM in ETT was 22.48 mm³, and 32.44 mm³ in VPT (p<0.05). The average percent change in volume following OTM in ETT was 2.62%, and 4.10% in VPT (p<0.05).

CONCLUSIONS

The results from this study suggest that ETT are less susceptible to root resorption following OTM than their vital counterparts.

A clinical approach strategy for the diagnosis, treatment and evaluation of external cervical resorption

AIM

To propose a clinical approach strategy on the diagnosis, treatment, and evaluation of external cervical tooth resorption (ECR) cases. To investigate and discuss the outcome of this approach.

METHODOLOGY

A clinical approach strategy on ECR was developed based on a retrospective observation study of 542 teeth. 47 teeth were excluded due to lack of clinical/radiographical information, and 182 were immediately extracted. This approach had three steps: diagnosis, treatment planning, and evaluation. During diagnosis, the medical, dental history and clinical/radiographical characteristics were evaluated. Depending on the resorption extent, ECR cases were categorized into four classes according to Heithersay's classification. During treatment planning, a treatment decision flowchart was prepared based on four main decisive criteria: probing feasibility, pain, location and extent of resorption (class), and existence of bonelike tissue. Three treatment options were applied: a) extraction, b) monitoring, or c) conservative treatment by external, internal, or combination of internal-external treatments. During evaluation, assessment of ECR progression, tooth survival and other factors like esthetics and periodontal attachment were performed. Descriptive statistical analysis of the outcome for up to ten years (for the overall clinical approach and for each individual treatment decision), was carried out with OriginLabs OriginPro 9 and Microsoft Excel 365.

RESULTS

A three-step strategy was developed on how to deal with ECR cases. Indicative examples of each treatment decision were presented and discussed. The overall survival rate of this strategy was 84.6% (3 years), 70.3% (5 years), 42.7% (8 years) and 28.6% (10 years). Higher survival rate was observed for external treatment decision than for internal. The success of each treatment decision depended on the extent of the resorption (class). The success of a treatment decision should be based on the long-term outcome, as a different evolution can be observed with time.

CONCLUSIONS

A clinical approach strategy was introduced on ECR pathosis. This strategy was not solely based on ECR class, as other important decisive criteria were considered. This step-wise approach, has a 70.3% survival rate with a mean of 5 years. This work will hopefully provide an incentive for a broader collaboration, to potentially establish a universally accepted ECR treatment strategy.

Comparison of imaging modalities in the diagnosis of external cervical resorption (ECR): an in-vitro study

External cervical resorption is a pathological condition affecting the cervical margins of teeth. Due to the increased prevalence and the area it affects, it can be easily misdiagnosed. The ability of clinicians to diagnose ECR and subcategorise the lesions using periapical radiographs and cone beam-CT scans has not been investigated in-depth. This study aims to assess if diagnostic ability to detect ECR lesions with the two modalities was different and if there was a change in the diagnosis when CBCT was used. A human skull, including the mandible was used for this study. The teeth were randomly allocated to the different subcategories, then pre and post-preparation radiographs with CBCT were taken. Statistical analysis was done using IBM SPSS version 16.0 (SPSS Inc., Chicago, IL, USA). The study sample was composed of 60 participants, the overall sensitivity of intraoral radiographs was significantly lower than CBCT. When the participants were told the radiograph and the CBCT were of the same tooth 60% said they would change their diagnosis. The use of intraoral radiographs alone might not be enough to identify and correctly diagnose ECR lesions. CBCT can give a better idea about the nature and the extent of the lesion.

External cervical resorption detected via cone-beam computed tomography in a patient with myelin oligodendrocyte glycoprotein antibody-associated disease: A case report

External cervical resorption may occur in patients with MOG antibody-associated disease, which is clearly detected on cone-beam computed tomography. Therefore, dental screening is essential for these patients before initiating bisphosphonate therapy. Larger sample sizes are crucial to determine any possible association between external cervical resorption and MOG antibody-associated disease.

External cervical resorption-a review of pathogenesis and potential predisposing factors

External cervical resorption (ECR) refers to a pathological state in which resorption tissues penetrate into the dentin at the cervical aspect of the root. Despite being latent in its initial phase, ECR could cause severe damage to mineralized dental tissue and even involve the pulp if not given timely diagnosis and treatment. Nevertheless, the etiology of ECR is still poorly understood, which adds to the difficulty in early diagnosis. ECR has received growing attention in recent years due to the increasing number of clinical cases. Several potential predisposing factors have been recognized in cross-sectional studies as well as case reports. In the meantime, studies on histopathology and pathogenesis have shed light on possible mechanisms of ECR. This review aims to summarize the latest findings in the pathogenesis and potential predisposing factors of ECR, so as to provide pragmatic reference for clinical practice.

Pathophysiological mechanisms of root resorption after dental trauma: a systematic scoping review

Background

The objective of this scoping review was to systematically explore the current knowledge of cellular and molecular processes that drive and control trauma-associated root resorption, to identify research gaps and to provide a basis for improved prevention and therapy.

Methods

Four major bibliographic databases were searched according to the research question up to February 2021 and supplemented manually. Reports on physiologic, histologic, anatomic and clinical aspects of root resorption following dental trauma were included. Duplicates were removed, the collected material was screened by title/abstract and assessed for eligibility based on the full text. Relevant aspects were extracted, organized and summarized.

Results

846 papers were identified as relevant for a qualitative summary. Consideration of pathophysiological mechanisms concerning trauma-related root resorption in the literature is sparse. Whereas some forms of resorption have been explored thoroughly, the etiology of others, particularly invasive cervical resorption, is still under debate, resulting in inadequate diagnostics and heterogeneous clinical recommendations. Effective therapies for progressive replacement resorptions have not been established. Whereas the discovery of the RANKL/RANK/OPG system is essential to our understanding of resorptive processes, many questions regarding the functional regulation of osteo-/odontoclasts remain unanswered.

Conclusions

This scoping review provides an overview of existing evidence, but also identifies knowledge gaps that need to be addressed by continued laboratory and clinical research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01510-6.

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.

RANKL/OPG ratio regulates odontoclastogenesis in damaged dental pulp

Bone-resorbing osteoclasts are regulated by the relative ratio of the differentiation factor, receptor activator NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG). Dental tissue-localized-resorbing cells called odontoclasts have regulatory factors considered as identical to those of osteoclasts; however, it is still unclear whether the RANKL/OPG ratio is a key factor for odontoclast regulation in dental pulp. Here, we showed that odontoclast regulators, macrophage colony-stimulating factor-1, RANKL, and OPG were detectable in mouse pulp of molars, but OPG was dominantly expressed. High OPG expression was expected to have a negative regulatory effect on odontoclastogenesis; however, odontoclasts were not detected in the dental pulp of OPG-deficient (KO) mice. In contrast, damage induced odontoclast-like cells were seen in wild-type pulp tissues, with their number significantly increased in OPG-KO mice. Relative ratio of RANKL/OPG in the damaged pulp was significantly higher than in undamaged control pulp. Pulp damages enhanced hypoxia inducible factor-1α and -2α, reported to increase RANKL or decrease OPG. These results reveal that the relative ratio of RANKL/OPG is significant to pulpal odontoclastogenesis, and that OPG expression is not required for maintenance of pulp homeostasis, but protects pulp from odontoclastogenesis caused by damages.

Retrospective evaluation of endodontic case reports published in the International Endodontic Journal and the Journal of Endodontics for their compliance with the PRICE 2020 guidelines

AIM

To evaluate, retrospectively, the quality of previously published case reports in Endodontics according to the PRICE 2020 guidelines.

METHODOLOGY

An electronic literature search was conducted in PubMed database on 12 March 2020, to identify case reports published during the last five years in the International Endodontic Journal and the Journal of Endodontics. For each of the included case reports, information regarding fulfilment of each of the items of the PRICE 2020 guidelines was extracted as '0' (not present in the manuscript), '1' (present in the manuscript) and 'NA' (not applicable) and translated into a score (percentage of items fulfilled). Additionally, the percentage of papers fulfilling each item was calculated.

RESULTS

Overall, 70 endodontic case reports were identified. The scores of the papers ranged between 56.41% and 79.55%, with a mean score of 70.26 ± 4.36% (SD). The percentage of papers fulfilling each item of the applicable PRICE 2020 items ranged widely, between 0% and 100%. The median of the percentage of all the items (n = 47) was 97.01% and mean 73.33 ± 36.28% (SD). The lowest scores were recorded for specific items in the following domains: 'Case Report Information'-Items 6c, 6g-i, 'Patient Perspective'-Item 8a and 'Quality of Images'-Items 12c-d.

CONCLUSIONS

Several areas with low reporting rates were identified in case reports published over the last 5 years in Endodontics. Authors should be encouraged to follow the PRICE 2020 guidelines in order to increase the quality and improve reproducibility of their case reports.

Association of high HIF-1α levels in serous periodontitis with external root resorption by the NFATc1 pathway

Whether external root resorption is associated with hypoxia in the periodontal ligaments of teeth with severe periodontitis remains unclear. Hypoxia inducible factor-1α (HIF-1α) expression and external resorption sites in the periodontal ligaments of these teeth were observed to elaborate upon the relationship between hypoxia and external root resorption in severe periodontitis. Histological analysis was performed to observe external root resorption. The expressions of HIF-1α and Nuclear factor-activated T cells c1 (NFATc1) in the periodontal ligaments were detected by immunofluorescence, western blotting and real-time PCR. Bone marrow macrophages (BMMs) were stimulated by Porphyromonas gingivalis lipopolysaccharide (Pg.LPS) and cultured under hypoxia in vitro. High levels of HIF-1α and NFATc1 were detected in severe periodontitis. HIF-1α positive-cells were observed in the external resorption sites. Hypoxia promoted Pg.LPS-stimulated osteoclastogenesis of BMMs and bone resorption by the NFATc1 pathway. Increased HIF-1α in severe periodontitis are associated with external root resorption by the NFATc1 pathway.

The Disease Process, Diagnosis and Treatment of Invasive Cervical Resorption: A Review

Invasive cervical resorption (ICR) is a localized, subepithelial, supra-osseous resorptive process of the tooth. Although there are several predisposing factors associated with ICR, its etiology and pathogenesis are poorly understood. The damage to the protective layer on the external root surface appears to allow for the attachment of clastic cells and initiate the resorptive process, which is confined by the inner protective pericanalar resorption-resistant sheet surrounding the root canal space. The use of cone-beam computed tomography (CBCT) is recommended for the diagnosis and assessment of a resorptive lesion. Based on the thorough evaluation of the size and location of the ICR lesion using CBCT, surgical or nonsurgical treatment can be chosen to address the source of the resorption. This review discusses the current status of knowledge regarding the biology of ICR lesions as well as their external or internal treatment using hydraulic calcium silicate-based materials. Future clinical outcome studies are necessary to evaluate the impact of hydraulic calcium silicate-based materials on the healing of ICR lesions.