Risk factors for odontoclastic resorptive lesions in cats

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.

COMPUTED TOMOGRAPHY OF TOOTH RESORPTION IN CATS

Tooth resorption is the most common dental disease in cats and can be a source of oral pain. The current clinical gold standard for diagnosis includes a combination of oral exam and dental radiography, however early lesions are not always detected. Computed tomography (CT) of the skull, including the dental arches, is a commonly performed diagnostic procedure, however the appearance of tooth resorption on CT and the diagnostic ability of CT to detect tooth resorption have not been evaluated. The purpose of this prospective, descriptive, diagnostic accuracy study was to characterize the CT appearance of tooth resorption in a sample of affected cats and to evaluate the sensitivity and specificity of CT for tooth resorption compared to the clinical gold standard of oral exam and intraoral dental radiography. Twenty-eight cat cadaver specimens were recruited for inclusion. Each specimen was evaluated using oral exam, intraoral dental radiography, and computed tomography (four different slice thicknesses). Each tooth was evaluated for the presence or absence of tooth resorption. Teeth with lesions and a subset of normal teeth were evaluated with histopathology. On CT, tooth resorption appeared as irregularly marginated hypoattenuating defects in the mineral attenuating tooth components, most commonly involving the root or cementoenamel junction. Sensitivity for CT detection of tooth resorption was fair to poor (42.2-57.7%) and specificity was good to excellent (92.8-96.3%). Findings from this study indicated that CT has high specificity but low sensitivity for detection of tooth resorption in cats.

Observations of the Periodontal Ligament and Cementum in Cats with Dental Resorptive Lesions

The etiology of feline dental resorptive lesions is unknown, but some evidence suggests that interactions between components of the periodontium may be initiating factors in the development of these lesions. In the present study, 22 clinically normal teeth were harvested from 7 cats. The teeth and periodontium were radiographed and examined histologically. In addition, 14 of the 22 teeth were examined histometrically. Two teeth were histologically normal with an open apical foramen and two were normal with a closed apical foramen. Histological evidence of periodontal ligament degeneration without cementum resorption was observed in 8 teeth, and varying degrees of cementum resorption were observed in 10 teeth. Mandibular molar and premolar teeth had distal drift, and mandibular canine teeth had mesial drift. Alterations in the periodontal ligament may represent a preclinical stage of dental resorption.

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 and vitamin D3 status in cats fed premium dry diets

It has been suggested that tooth resorption (TR) in cats is associated with vitamin D3 status. The purpose of this study was to evaluate any correlation between serum 25-OH-D concentrations and the prevalence of TR. The healthy adult domestic cats (n=64) of this study had been fed similar premium dry-expanded foods throughout their lives. Serum 25-OH-D was measured, and cats received a single, complete periodontal examination, with periodontal probing of each tooth and exploration of the tooth surface using a dental explorer A complete set of 10 dental radiographs was taken for each cat. There were 168 TRs diagnosed in 40 of 64 cats (85 were Type 1 TR and 83 were Type 2). The mean serum 25-OH-D concentration was 187.7 +/- 87.3 nmol/L. The mean serum 25-OH-D in cats with one or more TR was 164.2 +/- 78.8 nmol/L, compared with 226.8 +/- 88.2 nmol/L for those without TR (p = 0.14). The mean serum 25-OH-D in the 13 cats with >5 TR was 131.2 +/- 49.5 nmol/L, which was significantly less than in cats with no TR (p < 0.05). There was no relationship between TR type and serum 25-OH-D. There was no effect of age or sex on serum 25-OH-D. On the contrary, variations in serum 25-OH-D were observed according to the studied breeds. There was no relationship between TR type and serum 25-OH-D. TR prevalence was greater in cats with lower serum 25-OH-D concentrations. In conclusion, the hypothesis that higher serum 25-OH-D concentrations are associated with a higher prevalence of TR is not supported by this study.

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.

Significant association between tooth extrusion and tooth resorption in domestic cats

Abnormal extrusion of canine teeth is often noted in middle-aged and geriatric domestic cats. The same age group of cats also is commonly affected by tooth resorption (TR). This study explored the relationship between these two phenomena of unknown etiology. Using digital radiography, the distance between the alveolar margin (AM) and cementoenamel junction (CEJ), referred to as the AM-CEJ distance, was measured in clinically and radiographically healthy maxillary canine teeth of 24 TR-affected and 29 TR-free cats. The mean AM-CEJ distance of maxillary canine teeth of cats with and cats without TR was 2.68-mm and 2.22-mm, respectively. An analysis of covariance adjusting for age revealed a significant correlation (p = 0.02) between tooth extrusion and TR. Extrusion of the maxillary canine teeth became clinically apparent when an AM-CEJ distance of 2.5-mm or greater was evident in the absence of horizontal or vertical alveolar bone loss. Based on this criterion, 15 of 24 cats with TR (63.0 %) exhibited extrusion of maxillary canine teeth, compared to 9 of 29 cats without TR (31.0 %). Four extruded and five non-extruded maxillary canine teeth were evaluated histologically. Cementum of extruded teeth was significantly thicker compared to that of non-extruded teeth. Four of 4 canine teeth with extrusion (100 %) showed histological evidence of resorption, compared to 1 of 5 canine teeth without extrusion (20.0 %). These results suggest that tooth extrusion is linked to or may be caused by similar factors responsible for the development of TR.

Feline odontoclastic resorptive lesions an unsolved enigma in veterinary dentistry

This article presents a comprehensive review of the literature on feline odontoclastic resorptive lesions (FORLs), including etiopathogenesis, prevalence and predisposition, classification, histopathologic appearance, diagnosis, and treatment. Approximately one-third of all domestic cats may develop FORLs during their life span, and the risk of developing FORLs increases with age. Sophisticated dental treatments promise neither cure nor permanent improvement of affected teeth. Extraction is the current treatment of choice. Research on the etiology of FORLs has not been rewarding in recent years, and the causative factors contributing to the development of FORLs are still unknown.

Comparison of periodontitis and root replacement in cat teeth with resorptive lesions

Cat teeth with resorptive lesions and periodontitis may have a distinctly different clinical and radiographic appearance compared with teeth that have focal, lesion-associated gingivitis. A retrospective, case-controlled study was performed to determine the occurrence of root replacement in cats with resorptive lesions and associated periodontitis. Of 543 teeth evaluated with resorptive lesions, radiographic and/or clinical signs of periodontitis were identified in 236 (43.5%) teeth. Periodontitis was present in 43 of 275 (15.6%) teeth with root replacement and 193 of 268 (72.0%) teeth that had normal radiodensity and maintenance of the periodontal ligament. There was a significantly lower occurrence of root replacement in cat teeth with resorptive lesions and periodontitis.

Elemental composition of teeth with and without odontoclastic resorption lesions in cats

OBJECTIVE

To determine elemental composition of teeth with and without odontoclastic resorption lesions (ORL) in cats.

SAMPLE POPULATION

Normal teeth from 22 cadaver cats and ORLaffected teeth from 21 cats admitted to the veterinary hospital for dental treatment.

PROCEDURE

An electron microprobe was used to analyze weight percentages of calcium, phosphorus, fluorine, sodium, magnesium, sulfur, potassium, and iron in enamel, dentin, and cementum.

RESULTS

Calcium and phosphorus were the most abundant elements. Fluorine, sodium, and magnesium combined were < 5% and sulfur, potassium, and iron combined were < 0.1% of total elemental composition. In enamel of normal teeth, a significant sex-by-jaw location interaction was seen in mean (+/- SD) phosphorus content, which was higher in mandibular teeth of females (1764+/-0.41%) but lower in mandibular teeth of males (16.71+/-0.83%). Mean iron content in dentin of normal teeth was significantly lower in mandibular teeth than maxillary teeth (0.014+/-0.005% vs 0.023+/-0.019%). Mean enamel sodium content was significantly higher (0.77+/-0.046% vs 0.74+/-0.025) and mean enamel iron content was significantly lower (0.017+/-0.008% vs 0.021+/-0.005%) in ORLaffected teeth, compared with normal teeth. In cementum, mean fluorine content was significantly lower (2.98%+/-0.27 vs 2.99+/-0.20%) and mean magnesium content was significantly lower (0.54+/-0.13% vs 0.60+/-0.13%) in ORL affected teeth, compared with normal teeth.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of our study establish baseline mineral content of enamel, dentin, and cementum for normal teeth in cats. Minimal differences in mineral content of enamel and cementum of normal and ORL-affected teeth were detected.