Multiple Idiopathic Cervical Root Resorption: A Challenge for a Transdisciplinary Medical-Dental Team

Unravelling the Oral-Gut Axis: Interconnection Between Periodontitis and Inflammatory Bowel Disease, Current Challenges, and Future Perspective

As the opposite ends of the orodigestive tract, the oral cavity and the intestine share anatomical, microbial, and immunological ties that have bidirectional health implications. A growing body of evidence suggests an interconnection between oral pathologies and inflammatory bowel disease [IBD], implying a shift from the traditional concept of independent diseases to a complex, reciprocal cycle. This review outlines the evidence supporting an 'oral-gut' axis, marked by a higher prevalence of periodontitis and other oral conditions in IBD patients and vice versa. We present an in-depth examination of the interconnection between oral pathologies and IBD, highlighting the shared microbiological and immunological pathways, and proposing a 'multi-hit' hypothesis in the pathogenesis of periodontitis-mediated intestinal inflammation. Furthermore, the review underscores the critical need for a collaborative approach between dentists and gastroenterologists to provide holistic oral-systemic healthcare.

Challenges in differential diagnosis and treatment of cervical root resorption vs. root caries

External cervical root resorption may be occasionally mistaken for root caries and vice versa. Radiographical and clinical differential diagnoses of cervical root resorption and root caries are essential for correct treatment planning and a successful treatment outcome. This article reviews the contemporary literature and summarises the prevailing professional consensus pertaining to external cervical root resorption. Clinical diagnostics which help distinguish cervical root resorption from root caries are outlined and treatment approaches of external cervical root resorption are discussed.

Complete idiopathic resorption of distobuccal root of a maxillary first molar: A case report

Key Clinical Message

This case report provides a rare case of idiopathic root resorption in maxillary first molar and suggests the importance of CBCT in the diagnosis and treatment outcome of complex endodontic diseases. Endodontic surgery is an effective method for treating teeth with persistent apical periodontitis.

Abstract

Idiopathic root resorption is an unexplained root resorption when the patient experiences root resorption without any local or systemic factors. Early diagnosis and appropriate treatment are crucial for long-term outcomes.

Murine IRF8 Mutation Offers New Insight into Osteoclast and Root Resorption

Interferon regulatory factor 8 (IRF8), a transcription factor expressed in immune cells, functions as a negative regulator of osteoclasts and helps maintain dental and skeletal homeostasis. Previously, we reported that a novel mutation in the IRF8 gene increases susceptibility to multiple idiopathic cervical root resorption (MICRR), a form of tooth root resorption mediated by increased osteoclast activity. The IRF8 G388S variant in the highly conserved C-terminal motif is predicted to alter the protein structure, likely impairing IRF8 function. To investigate the molecular basis of MICRR and IRF8 function in osteoclastogenesis, we generated Irf8 knock-in (KI) mice using CRISPR/Cas9 technique modeling the human IRF8G388S mutation. The heterozygous (Het) and homozygous (Homo) Irf8 KI mice showed no gross morphological defects, and the development of hematopoietic cells was unaffected and similar to wild-type (WT) mice. The Irf8 KI Het and Homo mice showed no difference in macrophage gene signatures important for antimicrobial defenses and inflammatory cytokine production. Consistent with the phenotype observed in MICRR patients, Irf8 KI Het and Homo mice demonstrated significantly increased osteoclast formation and resorption activity in vivo and in vitro when compared to WT mice. The oral ligature-inserted Het and Homo mice displayed significantly increased root resorption and osteoclast-mediated alveolar bone loss compared to WT mice. The increased osteoclastogenesis noted in KI mice is due to the inability of IRF8G388S mutation to inhibit NFATc1-dependent transcriptional activation and downstream osteoclast specific transcripts, as well as its impact on autophagy-related pathways of osteoclast differentiation. This translational study delineates the IRF8 domain important for osteoclast function and provides novel insights into the IRF8 mutation associated with MICRR. IRF8G388S mutation mainly affects osteoclastogenesis while sparing immune cell development and function. These insights extend beyond oral health and significantly advance our understanding of skeletal disorders mediated by increased osteoclast activity and IRF8's role in osteoclastogenesis.

Surgical repair of external cervical resorption - Prognosis and prognostic factors

Background/purpose

External cervical resorption (ECR) is an aggressive form of root resorption, which etiology is unclear and its prognosis remains unpredictable. The purpose of this study was to investigate the prognosis and potential prognostic factors of ECR-affected teeth after surgical intervention for external repair with/without root canal treatment.

Materials and methods

Treated ECR cases from 2009 to 2019 were collected retrospectively. The survival of the teeth and the status of root resorption were assessed during the follow-up period. Potential prognostic factors were analyzed with log-rank test and Kaplan-Meier statistics.

Results

A total of 42 treated ECR-affected teeth were enrolled. The two-year survival rate was 71.20% [54.16%, 93.59%]. Persistent root resorption was the main complication after treatment. Patients with multiple ECR-affected teeth had greater recurrent potential than patients with solitary ECR-affected teeth. Prolonged calcium hydroxide dressing may contribute to a more favorable clinical outcome. Gender, age, tooth position and the need for root canal treatment did not show statistically significant effect on the prognosis.

Conclusion

The current surgical method was able to arrest ECR in most cases. However, the case type (the number of ECR-affected teeth per patient) could highly affect the prognosis of the teeth. Clinicians should consider long-term calcium hydroxide dressing in case of pulp involvement to achieve better results.

Invasive Cervical Root Resorption: A Comprehensive Review on Pathogenesis, Diagnosis, and Treatment

Invasive cervical root resorption (ICRR) is a dental pathology, marked by unexpected destruction originating in the cervical region of the tooth. This comprehensive literature review provides a holistic view into the pathogenesis, clinical manifestation, and precise management of ICRR, aiming to guide endodontists and enhance patient care and treatment outcomes. The review delves into the potential etiology of ICRR, covering contributing factors such as trauma, orthodontic treatment, and other pertinent conditions. It outlines the clinical and radiographic indicators, underscoring the crucial role of early detection and precise diagnosis in effectively managing and halting ICRR progression. The exploration of treatment approaches is thorough, ranging from non-surgical methods like vital pulp therapy or root canal treatment to surgical interventions. This review accentuates the essential role of interdisciplinary collaboration among diverse dental specialties in enhancing ICRR management. It highlights the importance of a consolidated strategy in enhancing treatment outcomes and preserving tooth structure and function. Moreover, it investigates prevention methods, risk evaluation, and identifies prospective research pathways to address the existing knowledge gaps.

Identification of Candidate Genes of Familial Multiple Idiopathic Cervical Root Resorption

INTRODUCTION

Multiple idiopathic cervical root resorption (MICRR) is a disease with an unknown etiology that causes invasive cervical root resorption in multiple teeth. Although previous MICRR genomic studies have identified candidate gene variants, the etiology of the condition remains poorly understood. In the present study, we investigated the genetic causality of MICRR to explore candidate variants.

METHODS

Saliva samples from a family containing 2 affected and two unaffected subjects with the dominant transmission of MICRR were subjected to whole-exome sequencing.

RESULTS

As a result, we identified novel candidate variants of 10 genes. Each variant was confirmed by Sanger sequencing. Among them, the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines classified doublecortin domain containing 1 (c.1099 C > T) and β-defensin 114 (c.189 T > G) as "pathogenic," and solute carrier family 45 member 2 (c.152_153del) as "likely pathogenic."

CONCLUSIONS

These results provide new insight to help clarify the pathogenesis of MICRR, and the variants could be applied for further investigation to understand invasive cervical root resorption.

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.

Gingiva-derived Stromal Cells Isolated from Cats Affected with Tooth Resorption Exhibit Increased Apoptosis, Inflammation, and Oxidative Stress while Experiencing Deteriorated Expansion and Anti-Oxidative Defense

Gingiva-derived mesenchymal stromal cells (GMSCs) are multipotent cells characterized by multilineage differentiation potential, proliferative expansion, and unique immunomodulatory ability, making them attractive as a new treatment of periodontal regeneration. In this study, GMSCs obtained from the gingiva of healthy cats (HE) as well as from cats affected by tooth resorption (TR) were isolated and characterized. Feline GMSCs (fGMSCs) from HE patients exhibited fibroblast-like morphology, developed cellular body, specific growth pattern, high expansion, and proliferative potential as well as reduced senescence signature. fGMSCs demonstrated high s-100 and IL-10 positive cells, while simultaneously having low activity of IL-1. Moreover, high activity of ki-67 combined with reduced senescence markers were noted. In comparison, GMSCs from cats with TR exhibited enlarged nuclei and flat, irregular shape along with increased expression of CD44, s-100 and CD45 and downregulation of CD73. GMSCs from TR cats showed lower ability to form colonies, increased incidence of apoptosis, higher number of senescent cells, and reduced cell migration. Upregulation of pro-inflammatory cytokines was also noted in the TR group along with lower expression of mTOR and miR-17 and upregulation of miR-378. Mitochondrial dynamics, biogenesis and antioxidant properties are also negatively impacted in this group. Collectively, our findings suggest that GMSCs isolated from the gingiva of cats affected with TR have deteriorated functionality caused by impaired proliferation and growth and possibly mediated via mitochondrial dysfunction. fGMSCs or their EV's should be further investigated for their role in the pathophysiology of TR in cats.

Inactivation of Sufu in cementoblasts accelerates external tooth root resorption

Cementum has been empirically regarded as an antiresorptive barrier against tooth roots. However, little is known about the factors of homeostasis and resistant mechanisms of tooth roots against resorption. Here, we investigated cementum factors and their interaction against resorption using transgenic mice exhibiting external cervical root resorption (ECRR). Ectopically thickened cervical cementum caused by functional inactivation of ectonucleotide pyrophosphotase/phosphodiesterase 1 (Enpp1) was susceptible to ECRR with aging. In addition, the inactivation of the suppressor of fused (Sufu), a Hedgehog signaling inhibitor, in cementoblasts led to ECRR. Interestingly, concurrent inactivation of Sufu and Enpp1 in cementoblasts remarkably exacerbated ECRR with higher Rankl expression. Cellular and molecular analyses using cementoblasts and bone marrow-derived macrophages indicated that Dickkopf-related protein 1 (Dkk1) induced by the inactivation of Sufu in cementoblasts has roles in the acceleration of ECRR triggered by Enpp1 inactivation. Using compound mutant mice for concurrent Wntless and Enpp1 inactivation, this synergistic cooperation of Dkk1 and Npp1 for resorption found in double mutant Sufu and Enpp1 mice was confirmed by the reproduction of amplified ECRR. On the basis of these findings, we conclude that proper Npp1 function and sustained Wnt activity in the cervical cementum are essential for the homeostasis of tooth roots against resorption in a physiological state.

Personalized Medicine Based on the Pathogenesis and Risk Assessment of Endodontic-Periodontal Lesions

Endodontic-periodontal lesions (EPLs) are chronic inflammatory lesions in the mouth caused by multiple factors. Both periapical and marginal periodontitis are characterized by infection and inflammation around the affected teeth, suggesting that the theory of complex systems might describe the progression of EPL. The diagnosis and treatment of EPLs are complicated by variations of this condition and difficulties distinguishing EPLs from other diseases. Technological advances in diagnostic and treatment methods, including cone beam computed tomography, microscopy, mineral trioxide aggregates, and periodontal regenerative treatment, have improved outcomes, even in untreatable teeth. However, treating EPLs with iatrogenic problems and/or severe periodontitis remains challenging. Assessing the risk of each EPL based on the possible pathogenesis of each EPL is essential for determining individualized treatment and optimizing personalized medicine for individual patients.

Between a rock and a hard place: Regulation of mineralization in the periodontium

The periodontium supports and attaches teeth via mineralized and nonmineralized tissues. It consists of two, unique mineralized tissues, cementum and alveolar bone. In between these tissues, lies an unmineralized, fibrous periodontal ligament (PDL), which distributes occlusal forces, nourishes and invests teeth, and harbors progenitor cells for dentoalveolar repair. Many unanswered questions remain regarding periodontal biology. This review will focus on recent research providing insights into one enduring mystery: the precise regulation of the hard-soft tissue borders in the periodontium which define the interfaces of the cementum-PDL-alveolar bone structure. We will focus on advances in understanding the molecular mechanisms that maintain the unmineralized PDL "between a rock and a hard place" by regulating the mineralization of cementum and alveolar bone.

Sub-clinical Cervical Root Resorption: A Case Report

External cervical resorption (ECR) is a dynamic pathological process characterized by its cervical position on the root and arises below the epithelial attachment and the coronal part of the bone. This report will highlight a case of ECR in an asymptomatic patient. A radiolucent area was noted during a routine dental follow-up examination on the bitewings at the mesial surface of the upper right second premolar. Persistently, the radiolucency had multiple radiographic views indicating a true form of a lesion that could be diagnosed as external cervical resorption. The patient did not report any complaints since dental treatment was completed in 2016. After a series of radiographs and conducting further diagnostic measures, a diagnosis of ECR was confirmed. The best treatment of choice for this case was extraction and restoring the missing tooth with an implant-supported crown. The size and the extent of such a defect could affect the strategy for implant placement. This paper aimed to report that ECR can be asymptomatic for a long time with advanced cervical root resorption in some cases.

The Medical, Clinical, and Radiographic Aspects of Multiple Idiopathic Tooth Resorption: A Systematic Review

Background: Many causes of resorption remain unclear and are thus identified as idiopathic. In such cases, management is difficult, especially when multiple teeth are involved. The aim of the present study was to assess the literature regarding the medical, clinical, and radiographic aspects of multiple idiopathic resorptions (MIR) and to examine the factors associated with the risk of extraction. Methods: The title and protocol were registered a priori in PROSPERO (CRD42020191564), and the study followed the PRISMA methodology. Four electronic databases were searched to include reviews and case reports on MIR in permanent dentition. Results: Among the 1035 articles identified, 31 case reports were included. The mean age of the patients was 32 years (SD = 16.4). MIR were consistently diagnosed after radiographic evaluation and were undetected during intra-oral examination in 62% of cases. The treatment involved extraction in 77% of cases. The risk of extraction increased in the presence of periodontal inflammation. Conclusions: MIR are aggressive forms of resorption requiring routine visits. MIR mostly involve extraction and lead to a challenging prosthetic rehabilitation due to severely damaged abutment teeth. However, the current knowledge on MIR remains fragmental and based on a limited number of case reports.

Multiple idiopathic external cervical root resorption in patient treated continuously with denosumab: a case report

Background

External root resorption is an irreversible loss of dental hard tissue as a result of odontoclastic action. Multiple external cervical root resorptions in permanent teeth are rare. The exact cause of external cervical root resorption is unclear. It is currently well established that RANK/RANKL signaling is essential for osteoclastogenesis and osteoclast-mediated bone resorption. Denosumab is an anti-RANKL antibody used for the treatment of postmenopausal osteoporosis. RANK/RANKL pathway suppression by denosumab is expected to suppress the activity of clastic cells responsible for hard tissue resorption involving both osteoclasts and odontoclasts.

Case presentation

This case report demonstrates aggressive and generalized idiopathic external cervical root resorption that started and advanced during ongoing antiresorptive therapy with the human monoclonal RANKL-blocking antibody denosumab without discontinuation of therapy in a 74-year-old female patient treated for postmenopausal osteoporosis. The extent of resorptive defects was too large and progressively led to fractures of the teeth. The number of teeth involved and the extend of destruction excluded conservative treatment. The affected teeth had to be extracted for functional prosthetic reconstruction.

Conclusions

This finding suggests that treatment with denosumab may be associated with severe and aggressive odontoclastic resorption of multiple dental roots despite an adequate inhibitory effect on osteoclasts in the treatment of osteoporosis. The RANKL-independent pathways of clastic cell formation are likely to be involved in this pathological process.