Identifying early osteoclastic resorptive lesions in feline teeth: a model for understanding the origin of multiple idiopathic root resorption

A large case-control study indicates a breed-specific predisposition to feline tooth resorption

Tooth resorption (TR) is one of the most common dental diseases of cats. It is a painful condition leading to tooth loss. The etiology of TR remains unclear, but old age, breed, other oral and dental diseases, and environmental factors are suspected predisposing factors. In our study, we used part of the data from the extensive feline health online survey of 8115 Finnish cats. As TR is difficult to detect and as the feline health survey included diagnoses defined by both veterinarians and the owners, we limited our study to a subpopulation of cats diagnosed with oral or dental disease by a veterinarian and had dental examination or surgery under sedation (n=944). We utilized case-control study analysed by multivariable logistic regression to determine the risk factors and breed variation of feline TR. The 202 cats diagnosed with TR were defined as TR cases and the remaining 742 cats as controls. The frequency of veterinarian-diagnosed TR was 3.9% in the health survey data (316/8115) and 21% in the subpopulation (202/944). The risk of TR increased with age (14.7% in youngest and 25.3% in oldest age group). Our finding that TR was significantly associated with gingivitis or periodontitis in cats that had also calculus (OR: 2.49 and 3.70, respectively) suggests that inflammatory changes caused by calculus increase the risk of TR. We found that Cornish Rex, European, and Ragdoll are at higher risk for TR (OR: 2.44, 2.98 and 2.90, respectively). Exotic-Persians breed group had lower risk (OR: 0.28). TR was not observed in Turkish van or Devon Rex. The differences between breeds highlight a genetic contribution. In addition, female cats that had food available constantly had significantly less TR than female cats that had feeding times (OR: 0.44). The underlying reasons for this remain unexplained in our study.

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.

Evaluation of Feline Permanent Canine Tooth Mineral Density Using Micro-Computed Tomography

The tooth is made up of three mineralized tissues, enamel, dentin, and cementum, which surround a non-mineralized tissue called the dental pulp. Micro-computed tomography (mCT) is an imaging technology based on X-rays that allows non-invasive visualization of objects at a microscopic scale, according to their radiopacity and in three dimensions (3D). Likewise, it allows the subsequent execution of morphological and quantitative analysis of the objects, such as, for example, the determination of the relative mineral density (MD). The present work aimed to describe the MD of feline teeth using mCT. The studied sample consisted of four European Shorthair cats, from which nine canine teeth were extracted per medical indication. These teeth were evaluated through dental radiography before and after their extraction. Using mCT and the CTAn software, the values of the relative mineral density of the root of each tooth and of specific segments corresponding to the coronal, middle, and apical thirds of the root were determined. Mean MD of root tissues was 1.374 ± 0040 g·cm−3, and of hard root, tissues was 1.402 ± 0.035 g·cm−3. Through mCT, it was possible to determine the mean MD values of feline canine teeth. The study of MD could become an ancillary method for the diagnosis and characterization of dental pathology.

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.

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

The goal of this perspective article is to use multiple idiopathic cervical root resorption (MICRR) as a model to demonstrate the need for transdisciplinary collaborations, from basic science to treatment planning, to improve the quality of health care for all. This is not a review of the literature on the current state of MICRR. Tooth root resorption is a normal physiological process required for resorption and exfoliation of primary teeth; however, root resorption of adult teeth is largely pathological. MICRR is an aggressive form of external root resorption, which occurs near the cemento-enamel junction (CEJ). The cause of MICRR remains elusive, however, it is mediated primarily by osteoclasts/odontoclasts. Accumulating case studies and experiments in animal models have provided insights into defining the etiologies and pathophysiological mechanisms for MICRR, which include: systemic conditions and syndromes, inherited genetic variants affecting osteoclast/odontoclast activity, altered periodontal structures, drug-induced root resorption and rebound effects after cessation of anti-resorptive treatment, chemotherapy, exposure to pets or viral infections, and other factors such as inflammatory conditions or trauma. To determine the causative factors for MICRR, as well as other oral-dental conditions, at minimum, a comprehensive health history should be collected for all patients by dental care providers, discussed with other health care providers and appropriate collaborations established. The examples highlighted in this perspective emphasize the need for transdisciplinary research collaborations coupled with integrated management strategies between medicine and dentistry in order to identify cause(s) early and improve clinical outcomes.

Transcriptomic profiling of feline teeth highlights the role of matrix metalloproteinase 9 (MMP9) in tooth resorption

Tooth resorption (TR) in domestic cats is a common and painful disease characterised by the loss of mineralised tissues from the tooth. Due to its progressive nature and unclear aetiology the only treatment currently available is to extract affected teeth. To gain insight into TR pathogenesis, we characterised the transcriptomic changes involved in feline TR by sequencing RNA extracted from 14 teeth (7 with and 7 without signs of resorption) collected from 11 cats. A paired comparison of teeth from the same cat with and without signs of resorption identified 1,732 differentially expressed genes, many of which were characteristic of osteoclast activity and differentiation, in particular matrix metalloproteinase 9 (MMP9). MMP9 expression was confirmed by qPCR and immunocytochemistry of odontoclasts located in TR lesions. A hydroxamate-based MMP9 inhibitor reduced both osteoclast formation and resorption activity while siRNA targeting MMP9 also inhibited osteoclast differentiation although had little effect on resorption activity. Overall, these results suggest that increased MMP9 expression is involved in the progress of TR pathogenesis and that MMP9 may be a potential therapeutic target in feline TR.

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.

Dental Pathology of the Iberian Lynx (Lynx pardinus), Part II: Periodontal Disease, Tooth Resorption, and Oral Neoplasia

The Iberian lynx is an endangered felid that has been subject to an intensive, ongoing conservation program to save it from extinction. Identification of dental pathologies could play an important role in the survival of this endangered species. The prevalence of periodontal bone loss, tooth resorption, and oral neoplasia was evaluated in this species. Skulls of 88 adult specimens of the Iberian lynx ( Lynx pardinus) from the Doñana Biological Station (EBD-CSIC), Seville, Spain, were examined macroscopically and full-mouth dental radiographs of all specimens were performed. Different stages of periodontal disease were identified in 81.3% of teeth. Approximately two-thirds (64.8%) of the specimens examined had at least 1 tooth affected by stage 3 or 4 periodontal disease. Maxillary and mandibular incisor teeth accounted for a majority (59.4%) of teeth affected by stage 3 or 4 periodontal disease. Tooth resorption affected 12 teeth (0.63% of evaluated teeth) in 6 skull specimens (6.8% of skulls evaluated). Five of the teeth with resorptive lesions were detected on 1 skull specimen. Six teeth (50%) of those affected by tooth resorption were incisor teeth. Only 1 (1.1%) adult specimen showed signs of oral neoplasia. Our study concluded that there is a high prevalence of periodontal disease that could lead to impaired hunting ability, as well as may represent a threat to overall health and subsequent survival of this endangered species. The extremely low prevalence of tooth resorption in L pardinus could open new pathways in the discovery on the pathogenesis of tooth resorption in felids.

A Familial Pattern of Multiple Idiopathic Cervical Root Resorption With a 30-Year Follow-Up

BACKGROUND

Multiple idiopathic cervical root resorption (MICRR) is a rare entity distinct from pathologic root resorption that occurs as a result of several local and systemic factors.

METHODS

This report describes a familial pattern of MICRR, including a recently identified case and a 30-year follow-up on previously described cases.

RESULTS

The previously reported father (aged 95 years) and son (aged 64 years), and the recently affected daughter (aged 61 years) recounted non-contributory medical history. The resorptive lesions were asymptomatic, unassociated with any predisposing factors, and first identified during the fourth to sixth decades of life. All tooth types were affected, with posterior teeth being affected earlier and with greater frequency; however, distal root surfaces were never affected. The resorptive lesions were progressive in nature, with additional teeth becoming involved as the condition was followed over time. In many instances, surrounding alveolar bone extended into the existing resorptive defects, but without clinical evidence of ankylosis. Gingival tissues, periodontal probing, and tooth mobility were within normal limits. Microcomputed tomography of extracted teeth demonstrated that the lesions were more extensive than clinically evident and rarely invaded the pulp chamber. Histologically, many resorptive lesions were noted along the cementum surface, with evidence of isolated cemental repair. Management of MICRR focused on restoring damaged root surfaces and extracting teeth with extensive root resorption.

CONCLUSIONS

MICRR is a challenging entity with unknown etiology and a lack of well-established preventive and management strategies. The familial pattern noted in this report necessitates future studies to investigate the role of genetic components in MICRR development.

Multiple idiopathic cervical root resorption: a case report

AIM

To report a severe and rare case of multiple idiopathic cervical root resorption (MICRR) in an adult female.

SUMMARY

A healthy 27-year-old Chinese female, with no significant associated factors, presented with MICRR. Resorption progressed quickly and lesions varied in severity, involving 29 teeth and leading to the loss of 23 teeth over a period of only 3 years. The inner surface of the crown showed extensive areas with worm-eaten lacunar resorption, and the resorptive lesions had abundant lysosomes throughout their cytoplasm. Further, heavy deposits of reaction products were shown in variously sized lysosomes.

Risk assessment of feline tooth resorption: a Portuguese clinical case control study

Tooth resorption (TR) is one of the most common dental diseases in cats. Determination of risk factors has not yet been fully assessed and, to the best knowledge of the authors, this disease has never been studied in Portuguese cats. The objective of this case-control study was to determine type and distribution of TR lesions, evaluate risk factors, and establish relationships between variables in this disease. The study included data from 71 cats admitted for general anesthesia for various reasons. The cats were randomly selected. The inclusion criteria were availability of clinical history and owner permission. Cats with known oral disease were not excluded from the study. All cats received ultrasonic scaling and polishing of the teeth, a thorough oral examination, and full-mouth radiographs. A strong statistical relation was found between age and TR. The age group of 10 to 15-years showed an increased risk of 6.56 times for TR occurrence compared with the group 0 to 4-years of age. Presence of gingivitis in all index levels was related to an increased risk for TR. No relation was found between age or gingivitis index and lesion type. Mandibular third premolar and molar teeth were most commonly affected by TR, especially for type 1 lesions. Canine teeth were statistically more likely to have type 2 lesions. The trend for the canine teeth to be more affected with type 2 lesions needs further verification.

Tooth Resorption in the Swedish Eurasion Lynx (Lynx Lynx)

The etiology of tooth resorption in the domestic cat remains unknown. The high prevalence and progressive nature of the disease complicates defining healthy control groups. In order to evaluate the possible influence of various life style changes on the prevalence of tooth resorption, healthy control groups are a prerequisite. This paper presents a prevalence study for tooth resorption in a free-ranging wild felidae population. Skulls from 46 free-ranging Eurasian lynx (Lynx lynx) were examined. The age of the animals had previously been estimated based on cementum annuli in the maxillary right canine tooth. The dental examination included both dental probing and radiographic imaging. Complicated fractures of the canine teeth were found in 9/46 (19.5 %) skulls. In one fractured canine, apical root resorption and periapical lucency was detected. The root resorption was attributed to inflammatory resorption as a consequence of the initial dental trauma and necrotic pulp. No signs of tooth resorption were found in the remaining teeth. Supernumerary roots were detected in 18/46 skulls (39.1 %). Supernumerary “peg” teeth caudal to the mandibular first molar tooth were detected in 6/46 (13.0 %) skulls. Although further studies on dental ultra-structure are needed, the Swedish Eurasian lynx may, in the future, be useful as a healthy comparative model for studies on the etiopathogenesis of tooth resorption in the domestic cat.

Multiple idiopathic cervical resorption: case report and discussion of management options

AIM

To present a case of cervical root resorption affecting all teeth and resulting in multiple tooth loss.

SUMMARY

A healthy 33-year-old Chinese male, with no contributory medical or family/social history, presented with generalized cervical root resorption. Lesions varied in severity amongst teeth and even involved an impacted third molar. All cervical root surfaces were affected and lesions often extended coronally, undermining enamel. CBCT demonstrated that the lesions were more extensive and more widely distributed than was seen using conventional radiography. Bone extended into many resorptive defects but without clinical evidence of ankylosis. Periodontal probing, pulp testing, percussion sound and mobility were within normal limits. Key learning points  • Aetiology of the generalized idiopathic cervical root resorption is uncertain. • Management is complex, and options have included surgical exposure and restoration of affected sites, extraction and submergence of affected roots. • A staged approach involving early intervention with restoration of resorptive defects, followed by progressive extraction and replacement with implant-supported prostheses is recommended.

Radiographic evaluation of the types of tooth resorption in dogs

OBJECTIVE

To determine the prevalence of tooth resorption in dogs and to evaluate whether a classification system for tooth resorption in humans is applicable in this species.

ANIMALS

224 dogs > 1 year old admitted for periodontal treatment or other dental procedures in 2007.

PROCEDURES

Full-mouth radiographs of all dogs were reviewed for evidence of tooth resorption. Tooth resorption was classified in accordance with radiographic criteria described for use in humans. Patient signals and concurrent dental conditions were recorded and tabulated.

RESULTS

Tooth resorption was detected in 120 of 224 (53.6%) dogs and 943 of 8,478 (11.1%) teeth. The classification system for use in humans was applicable in 908 of 943 (96.3%) affected teeth. Tooth resorption was more frequent among older and large-breed dogs; no significant differences were found among sex categories. The 2 most common types of tooth resorption were external replacement resorption (77/224 [34.4%] dogs and 736/8,478 [8.7%] teeth) and external inflammatory resorption (58/224 [25.9%] dogs and 121/8,478 [1.4%] teeth). External cervical root surface resorption was detected in 13 of 224 (5.8%) dogs; external surface resorption was detected in 10 of 224 (4.5%) dogs, and internal inflammatory resorption and internal surface resorption were detected in 9 of 224 (4.0%) and 1 of 224 (0.4%) dogs, respectively. Internal replacement resorption was not detected.

CONCLUSIONS AND CLINICAL RELEVANCE

The classification of tooth resorption in humans was applicable to tooth resorption in dogs. Resorption lesions, in general, and external replacement and external inflammatory resorption, in particular, were frequently detected in dogs.