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.

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

INTRO

The purpose of this study was to identify possible associations between classification, treatment, and one-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.

METHODS

A chart review identified 142 cases of ECR over a twelve-year period. Information regarding demographics, predisposing factors, lesion classification, treatment, and outcomes were collected and analyzed. Inter- and intra-observer reliability analyses were conducted for both classification systems.

RESULTS

There were 72 cases with at least one 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 one-year outcome and either classification or treatment done. The weighted reliability analysis showed substantial agreement in both classification systems for both inter- and intra-observer agreement. There was a significant association between the two systems, however the Heithersay system tended to underestimate the apical extent of the lesion.

CONCLUSIONS

Periodic review of ECR lesions presents as a viable treatment option, at least for one year after diagnosis. The Patel 3-D 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.

Tooth root resorption: A review

Tooth root resorption is multifactorial, leading to progressive destruction and eventual loss of tooth root dentin and cement. There are internal and external types of root resorption, each having its variety. The etiology and pathogenesis of tooth root resorption are poorly understood, and the most significant etiological factors are trauma, pulpal infection, tooth bleaching, and orthodontic treatment. Tooth root resorption is primarily asymptomatic; thus, it is revealed accidentally by radiographic examination. Progressive clinical manifestations are pain, tooth discoloration, tooth mobility, and other conditions. Awareness of the causes and risk factors allowing tooth root resorption, and regular radiographic examination, in case of necessity, make it possible to reveal resorption at an early stage and to prevent its further development. Thus, the aim of this study is to present etiopathogenesis, a clinical course, and diagnostic peculiarities of internal and external types of tooth root resorption, enabling practicing dentists to timely diagnose root resorption and take appropriate measures to avoid further complications. Within the limitation of this review, even though the etiopathogenesis of tooth root resorption is yet not fully understood, it is suggested that the etiological factors fall into two groups (endogenic and exogenic) to enhance further understanding of the possible causes and mechanisms of root resorption and allow practitioners to monitor high-risk patients and make timely diagnoses. Moreover, radiographic examination and CBCT are indispensable for the diagnosis of root resorption.

Survey based assessment of diagnosis through periapical radiograph and CBCT and treatment of root resorption with Brazilian and American dentists and endodontists

Background

This study assesses and compares the knowledge level of endodontists (ENDs) and general dental practitioners (GPs) from Brazil and United States of America (USA) in the diagnosis and treatment of internal and external inflammatory root resorptions through periapical radiographic (PA) and cone beam computed tomography (CBCT) examinations.

Material and Methods

A cross-sectional online questionnaire-based survey was presented to the volunteers containing questions regarding personal and professional profile, as well as three clinical cases of internal and external inflammatory root resorption. A series of multiple-choice questions about the diagnosis and treatment options were surveyed. The data collected was analysed by the Chi-square test with Yates correction with a significance level of 5 %.

Results

Most answers were considered adequate when all three questions about the diagnosis and all two questions relating to the treatment were answered accurately. A total of 374 dentists answered the survey (n: 229 from Brazil vs. 145 from USA) being 41% END and 59% GP. END presented higher level of knowledge than GP regarding to diagnosis and treatment of inflammatory root resorptions both in Brazil and USA (p<0.05); USA presented higher level of adequate responses than Brazil (p<0.05).

Conclusions

END achieved a level of knowledge of the diagnosis and treatment of root resorption superior to the GP. Comparing the results obtained in both countries, it was observed that the USA had a higher correct response rate than Brazil. Key words:Internal root resorption, external root resorption, management, diagnosis, treatment.

Performance of the dentogingival junction with mta and biodentine on the treatment of invasive cervical resorptions. A literature review and case report

Invasive cervical resorption (ICR) is an uncommon phenomenon (0.1%), however, it represents a challenge to the structural and functional integrity of the dentogingival junction, as well as a risk for the survival of the affected tooth. They are characterized by their location and invasive character, being able to appear in any tooth of the permanent dentition. It shows up after the damage to the cervical insertion apparatus, leaving the pulp without participation in the origin of the lesion. They may appear just below the junctional epithelium or at a more apical level. The MTA® (Dentsply, Tulsa dental, Tulsa OK) and the Biodentine® (Septodent, Saint Maur of Fossés, France) are two biomaterials that have demonstrated the ability to promote the neoformation of cement so they are considered an alternative in the treatment of the ICR. This article presents an ICR clinical cases treated with these biomaterials, in which favorable post-operative healing is observed.

Key words:MTA, Biodentine, biomaterials, root resorption, invasive cervical resorption.

Multiple idiopathic cervical root resorption involving all permanent teeth

Multiple idiopathic external cervical root resorption is a rare condition with numerous predisposing factors that have not yet been clearly elucidated. In addition, its diagnosis and treatment pose challenges for clinicians, and thus, the extraction of the involved teeth is commonly performed. Here, we report a 29-year-old pregnant woman with no contributory medical or family/social history who experienced cervical root resorption that progressed aggressively and involved all permanent teeth. This case is unique owing to the involvement of all teeth. Reports of multiple idiopathic external cervical root resorption are rare in the literature, and the pathogenesis of the condition is poorly understood. This report aims to add an additional case to the existing literature, analyse the underlying mechanisms and provide clinicians with some guidance in diagnosing cervical root resorption.

The ins and outs of root resorption

Root resorption is a poorly understood phenomenon and is often misdiagnosed and, as a result, inappropriately treated. The aim of this paper is to provide a practical guide for diagnosis of root resorption lesions using a simple classification, and to describe the principles of management of these resorptive defects in everyday practice.

miR‑494‑3p regulates lipopolysaccharide‑induced inflammatory responses in RAW264.7 cells by targeting PTEN

MicroRNAs (miRNAs/miRs) serve important roles in regulating inflammatory responses at the post-transcriptional level. In the present study, the limma package was used to analyze the GSE43300 array dataset downloaded from the Gene Expression Omnibus database. It was identified that several miRNAs, including miR-494-3p, were upregulated in lipopolysaccharide (LPS)-treated RAW264.7 macrophages compared to control cells. Transfection experiments indicated that overexpressing miR-494-3p inhibited production of LPS-induced proinflammatory cytokines, including interleukin-1β and tumor necrosis factor-α. Conversely, knockdown of miR-494-3p enhanced cytokine expression. Bioinformatics prediction and luciferase assay both revealed that miR-494-3p could directly target phosphatase and tensin homolog (PTEN) and upregulate protein kinase B activity. In addition, miR-494-3p mimics suppressed p65 translocation to the nucleus. Similar effects were observed following PTEN silencing. In conclusion, the results of the present study revealed that miR-494-3p may act as an important immune regulator in LPS-stimulated macrophages, and be an effective therapeutic target for treating infections in the future.

Inflammatory cell expression of Toll-like receptor-2 (TLR2) within refractory periapical granuloma

Background: Toll-like receptor-2 (TLR2) is highly important within the immune system. Characterization of the expression of TLR2 within inflammatory cells in periapical lesions could help in diagnosis and management of refractory cases. The aim of the study is identification of Toll-like receptor (TLR2) through immunohistochemical and immunofluroscence expression in inflammatory cells within refractory periapical granuloma cases. Methods: Eight cases of refractory periapical granuloma were selected out of 772 cases. Histological examination and immunohistochemical staining with polyclonal rabbit antihuman TLR2, monoclonal mouse antihuman CD38, CD68 and CD83 primary antibodies, as well as immunofluorescence staining with goat anti-rabbit TLR2, donkey anti-mouse CD38, CD68 and CD83 primary antibodies was conducted. Positive controls, negative controls and experimental sections with no primary antibody were included in the study. Qualitative analysis and double immunofluorescence technique was used to characterize the TLR + cells. Results: In periapical granuloma, lymphocytes (CD38 cells) expressed the most amount of TLR reactivity followed by macrophages (CD68 cells), and odontogenic epithelial cells. Neutrophils, red blood cells (RBCs) and collagen ground substance were negative to TLR2.  Conclusion: TLR2 was highly expressed by lymphocytes and plasma cells indicative of their major role in the inflammatory process and antigen recognition in refractory periapical granuloma. Dendritic cells expressing TLR2 were low in number suggesting a minor role in sustaining these lesions.

External cervical resorption-part 1: histopathology, distribution and presentation

External cervical resorption (ECR) is the loss of dental hard tissue as a result of odontoclastic action. It is a dynamic process that involves periodontal, dental and in later stages pulpal tissues. Over the last two decades, ECR has attracted increased interest; this is in part due to novel micro-CT and histopathological techniques for its assessment and also improved radiographic detection using CBCT. This literature review will cover the aetiology, potential predisposing factors, histopathology and diagnosis of ECR. Part 2 will cover the management of ECR.

Role of toll-like receptor 2 in inflammation and alveolar bone loss in experimental peri-implantitis versus periodontitis

BACKGROUND AND OBJECTIVE

Peri-implantitis and periodontitis are different entities in immune characteristics even though they share similar features in clinical and radiologic signs. Toll-like receptor 2 (TLR-2), one of the key pathogen-recognition receptors in the innate immune system, plays an important role in the progression of periodontitis. However, the role of TLR-2 in peri-implantitis remains unclear. The objective of this study was to investigate the role of TLR-2 in inflammation and alveolar bone loss in a murine model of ligature-induced peri-implantitis and to compare it with ligature-induced periodontitis.

MATERIAL AND METHODS

Smooth-surface titanium implants were placed in the alveolar bone of the left maxillary molars of wild-type (WT) and Tlr2 knockout (Tlr2-KO) mice 6 weeks after tooth extraction. Silk ligatures were applied to the left implant fixtures and the right maxillary second molars to induce peri-implantitis and periodontitis 4 weeks after implant placement. Two weeks after ligation, bone loss around the implants and maxillary second molars was analysed by micro-computed tomography (micro-CT), and inflammation around the implants and maxillary second molars was assessed at the same time point using histology and TRAP staining, respectively. Expression of mRNA for proinflammatory cytokines (interleukin-1β [Il1β], tumor necrosis factor-α [Tnfα]), an anti-inflammatory cytokine (interleukin-10 [Il10]) and osteoclastogenesis-related cytokines (Rankl, osteoprotegerin [Opg]) were evaluated, in gingival tissue, using real-time quantitative PCR (RT-qPCR).

RESULTS

The success rate of implant osseointegration was significantly higher in Tlr2-KO mice (85.71%) compared with WT mice (53.66%) (P = .0125). Micro-CT revealed significantly decreased bone loss in Tlr2-KO mice compared with WT mice (P = .0094) in peri-implantitis. The levels of mRNA for Il1β (P = .0055), Tnfα (P = .01) and Il10 (P = .0019) in gingiva were significantly elevated in the peri-implantitis tissues of WT mice, but not in Tlr2-KO mice, compared with controls. However, the gingival mRNA ratios of Rankl/Opg in peri-implant tissues were significantly upregulated in both WT (P = .0488) and Tlr2-KO (P = .0314) mice. Ligature-induced periodontitis exhibited similar patterns of bone loss and inflammatory cytokine profile in both groups of mice, except that the level of Il10 was elevated (P = .0114) whereas the Rankl/Opg ratio was not elevated (P = .9755) in Tlr2-KO mice compared with control mice. Histological findings showed increased numbers of TRAP-positive cells and infiltrated inflammatory cells in ligature-induced peri-implantitis in both WT (P < .01) and Tlr2-KO mice (P < .05), and the numbers of both types of cell were significantly higher in WT mice than in Tlr2-KO mice (P < .01).

CONCLUSION

This study suggests that TLR-2 mediates bone loss in both peri-implantitis and periodontitis. However, different molecular features may exist in the pathogenesis of the two diseases.

Descriptive Analysis of Factors Associated with External Cervical Resorption

INTRODUCTION

The aim of this study was to perform a descriptive analysis of the occurrence of external cervical resorption (ECR) in relation to the patients' characteristics (sex, age, and tooth type) and the potentially involved predisposing factors.

METHODS

This study includes data on 284 patients (337 teeth with evidence of ECR) referred to the University Hospital Leuven (Leuven, Belgium) and Endo Rotterdam (Rotterdam, the Netherlands) for diagnosis and treatment from 2010 to 2015. The medical history, existing radiographs, and dental records were available for evaluation. Each patient was then interviewed followed by a thorough clinical and radiographic examination. Intraoral pictures using a dental operating microscope and digital camera were taken during clinical examination. The radiographic examination consisted of digital periapical radiography and/or cone-beam computed tomographic imaging. A review of existing literature provided a potential predisposing factor checklist for ECR. The clinical data were correlated with the dental and medical history of each patient in an attempt to identify some potential predisposing factor(s) that could contribute to ECR. The frequency of the occurrence of ECR was correlated with tooth type, sex and age of the patient, and each 1 of the recorded potential predisposing factor(s).

RESULTS

From the examined teeth (337) with ECR, 175 (54%) were found in male patients and 162 (46%) were found in female patients. In 59% of the cases, more than 1 potential predisposing factor was identified. Most ECR cases were observed on maxillary central incisors (29%) followed by maxillary canines (14%), mandibular molars (14%), and maxillary premolars (11%). In addition, most ECR cases were observed on maxillary teeth (72%). The most frequently appearing factor was orthodontics (45.7%). Other frequently observed factors were trauma (28.5%), parafunctional habits (23.2%), poor oral health (22.9%), malocclusion (17.5%), and extraction of a neighboring tooth (14%).

CONCLUSIONS

The data indicate that ECR is not related to patient sex. ECR occurs most often in the maxillary central incisor. In the majority of the cases, more than 1 potential predisposing factor was identified, indicating that ECR may be mainly multifactorial. The most frequently appearing factors were orthodontics, iatrogenic or accidental trauma, and poor oral health. This information may be helpful in diagnosing ECR at an early stage when screening patients presenting with these predisposing factors.

Effect of bisphosphonates on root resorption after tooth replantation - a systematic review

BACKGROUND/AIM

Replantation of avulsed teeth may lead to root resorption. Bisphosphonates (BPs), a class of drugs of used to treat resorptive diseases of the bone such as osteoporosis and Paget's disease, have been observed to exert an antiresorptive effect on periodontal bone as well. The antiresorptive properties of BPs could prove them useful in preventing root resorption of replanted avulsed teeth. The aim of this systematic review was to analyze and summarize the currently available literature concerning the use of BPs in preventing root resorption of avulsed teeth.

MATERIALS AND METHODS

PubMed/MEDLINE, Google Scholar, ISI Web of Knowledge, and Embase databases were searched using keywords 'bisphosphonate', 'replantation', and 'tooth'. Quality assessment of each study was carried out. In addition, general characteristics and outcomes of each study were summarized.

RESULTS

After exclusion of 116 irrelevant articles, 10 animal studies were included in this review. The majority of the studies suggest that surface application of zoledronate or alendronate reduces root resorption of replanted teeth in animal models. Surface treatment with etidronate had no significant effect on root resorption, and intracanal etidronate accelerated resorption.

CONCLUSION

Surface application of zoledronate and alendronate reduces root resorption of replanted teeth in animal models. However, the efficacy of intracanal usage of BPs is still debatable.

A novel multimodular methodology to investigate external cervical tooth resorption

AIM

To introduce a multimodular combination of techniques as a novel minimal invasive approach to investigate efficiently and accurately external cervical resorption (ECR).

METHODOLOGY

One case of a central incisor with extensive external cervical resorption was selected to demonstrate the potential of a comparative novel study methodology. ECR diagnosis was based on clinical inspection, digital radiography and cone-beam computed tomography (CBCT). After extraction, the tooth was investigated using microfocus computed tomography (micro-CT), nano-CT and hard tissue histology. These techniques were compared for their accuracy and applicability to highlight their advantages and disadvantages.

RESULTS

Nano-CT was more effective than micro-CT and CBCT for detailed ex vivo exploration of ECR. The reparative tissue, pericanalar resorption resistant sheet (PRRS), pulp tissue reactions, resorption channels and their interconnection with the periodontal ligament space were accurately visualized by detailed processing and analysis of the nano-CT data set with Dataviewer and CTAn software. Nano-CT analysis provided better insight in the true extent of the resorption, based on quantitative measurements and 3D visualization of the tooth structure. Nano-CT imaging results were similar to hard tissue histology at the mineralized tissue level. To clarify the dynamic phenomenon of reparative tissue formation and substitution of the resorbed tissues, nano-CT needed to be associated with hard tissue histology.

CONCLUSION

Nano-CT is a fast and minimal invasive technique for the ex vivo analysis and understanding of ECR and is complementary with hard tissue histology. A combined approach of clinical and CBCT examination, with nano-CT and histological mapping measurements, can provide an ideal platform for future ECR imaging and exploration studies.

Cone beam CT assisted re-treatment of class 3 invasive cervical resorption

Invasive cervical root resorption is an uncommon external root resorption which initiates at the cervical aspect of the tooth. This case report involves a case of cervical root resorption which was initially misdiagnosed and managed as cervical root caries. It was later diagnosed with cone beam CT and the lesion microsurgically removed and restored with resin modified glass ionomer cement. The importance of increasing awareness of this uncommon pathology and the role of cone beam CT in mapping the extent of the lesion is emphasised.