Scanning electron microscopic description of cellular activity and mineral changes in feline odontoclastic resorptive lesions

The cellular activity and changes in mineral composition of dental tissues involved in feline odontoclastic resorptive lesions were investigated. Teeth with at least 1 lesion (n = 10) were extracted from 10 different cats that were presented primarily for chronic gingivostomatitis and/or severe periodontal disease. Scanning electron microscopic methods were used to determine the presence of resorptive cells in 8 teeth while 2 teeth were evaluated for pathologic changes in dental mineral composition. Observations were complicated by the presence of organic wear on the dental surfaces, however resorptive cells could be clearly identified in feline odontoclastic resorptive lesions. Resorptive cells had morphologic features indicative of "osteoclast-like" cells or odontoclasts. Resorptive cell activity created a resorption area of darker dentin continuous with physiologic dentin. The darker dentin area seemed poorly mineralized and showed a significantly lower calcium/phosphorous ratio compared with adjacent physiologic denting in 1 tooth. A significantly higher level of magnesium combined with available carbonate ions may have increased the solubility in areas of darker dentin.     

Mapping of the radiographic central point of feline dental resorptive lesions

Intraoral dental radiographs of 217 cats presented for dental treatment were examined. Radiographic signs of dental resorptive lesions were identified in 107 cats, and the apparent central point of each lesion was mapped on a diagram of the tooth. Mapping was only possible on maxillary and mandibular canine teeth and on mandibular third premolar, fourth premolar, and first molar teeth. Resorptive lesions were most common on the molar teeth (n = 103) and maxillary canine teeth (n = 96), and least common on fourth premolar teeth (n = 56). Resorptive lesions on premolar and molar teeth were widely scattered, noted more commonly in the coronal portions of the root. Resorptive lesions in canine teeth had a tendency to be located more apically on the roots.     

Multiple tooth resorption in an Italian greyhound

An Italian greyhound was presented three times during a two-year period for dental prophylaxis due to periodontal disease. Clinical examination revealed lesions on several teeth. Radiographs revealed extensive resorptive root lesions. On histological examination, the presence of odontoclasts and signs of boney remodeling of the roots confirmed the resorptive nature of the lesions. Given the extent of the lesions, and poor prognosis with conservative treatment alone, teeth affected by the most severe resorption were extracted at each visit using a flap technique combined with alveolar vestibular osteotomy. Dental resorptive lesions are rarely detected in the dog but may be more frequent than previously thought. The routine use of dental radiographs can be used to reveal these lesions in the dog.     

Congenital oligodontia of the deciduous teeth and anodontia of the permanent teeth in a cat

This report describes a rare case of congenital oligodontia of the deciduous teeth and anodontia of the permanent teeth in a cat. According to cat's veterinarian, the patient had only two deciduous upper canines and no permanent teeth had ever erupted. Post-mortem evaluation showed a complete absence of teeth in the oral cavity and inflammatory lesions were not found on the gums. Histopathological analysis of serial sections of maxilla and mandible revealed absence of odontogenic epithelium, inflammatory cells and odontoclastic resorptive lesions. Diagnosis was confirmed after both the establishment that there were no remaining dental structures and the exclusion of other relevant diseases that lead to tooth loss, such as periodontal disease, renal fibrous osteodystrophy, odontoclastic resorptive lesions, ectodermal dysplasia and trauma.     

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.     

Furcation canals of the maxillary fourth premolar and the mandibular first molar teeth in cats

The furcation region morphology was evaluated in 103 mature feline carnassial teeth (54 maxillary fourth premolar and 49 mandibular first molar teeth). Patent furcation canals were present in 27.2% of teeth. No significant difference (p = 0.88) in distribution of this anatomical variation was found between maxillary fourth premolar and mandibular first molar teeth. The mean width of these furcation canals was 104.0 microns with two-thirds of the canals having a buccal orientation. The presence of furcation canals could be a factor in the etiopathogenesis of feline dental resorptive lesions, as well as a characteristic to be considered in the diagnosis, prognosis, and treatment of endodontic or periodontic-endodontic lesions in cat teeth.     

Subgingival odontoclastic resorptive lesions. Classification, treatment, and results in 58 cats.

A commonly recognized dental problem in cats is the resorption of tooth structure and subsequent loss of the tooth. These tooth defects are often very painful, because the sensitive dentin layer is exposed. The destruction of the tooth through odontoclastic resorption is considered a consequence of inflammatory resorption, probably secondary to periodontal inflammation. Because these resorptive lesions are progressive in nature, it is best to stage this progression of resorption in order to address treatment planning. The purpose of this study was to evaluate a group of 58 cats with resorptive lesions to determine the outcome of treatment 6 months or longer after restoration. In 81% of the cats, there was loss of the tooth, evidence of further resorption, or loss of the restoration at one or more resorption sites. Of the 154 teeth restored, only 33% showed no further evidence of loss of tooth structure.     

Radiographic evaluation and treatment of feline dental resorptive lesions.

Many feline resorptive lesions are easily diagnosed by clinical oral examination, whereas others require dental radiographs. Radiographs can reveal the presence of resorption, and often the nature of the resorptive process as well. Removal of affected teeth when they cause discomfort, or of the portion of the tooth causing the discomfort, remains the only treatment that provides long-term resolution. Until we understand the etiology of the inciting causes and of the factors contributing to the progression of resorptive lesions, reliable prevention cannot be offered.     

Resorptive tooth root lesions in the Malayan tapir (Tapirus indicus)

Facial abscessation and osteomyelitis due to dental disease is commonly seen in the Malayan tapir (Tapirus indicus), but little is known about the prevalence or etiology of these lesions. To determine the prevalence of dental ailments, 56 skulls and mandibles of deceased Malayan tapirs were visually and radiographically evaluated. Dental lesions were scored according to severity, and individuals were classified according to their age (juvenile/ young adult/adult) and origin (captive/free ranging). All of the lesions identified were of a resorptive nature. seemingly originating at the cementoenamel junction and burrowing towards the center of the tooth. Overall, 27% of the investigated skulls presented radiolucent dental lesions. The prevalence among captive animals was 52% (13/25), while only 6% (2/31) of the free-ranging tapirs had dental lesions. The second, third, and fourth premolars and first molar were the teeth most commonly affected, and the mandibular teeth were more often involved than the maxillary dentition. This study demonstrates a high prevalence of resorptive dental lesions in captive Malayan tapirs and provides a strong indication that age and captivity are significant risk factors in the development of these lesions. Dental disease, Malayan tapir, radiology, resorptive lesions, Tapirus indicus.     

Feline odontoclastic resorptive lesions: unveiling the early lesion

The purpose of this study was to increase understanding of the factors initiating feline odontoclastic resorptive lesions (FORLs). Fifty-six teeth (clinically and radiographically unaffected by ORLs) were harvested. Of these, 43 were from cats that had ORLs in other teeth (group A) and 13 were from cats with no clinical or radiographic evidence of ORLs in any teeth (group B). Twenty-six teeth in group A and one tooth in group B showed histological evidence of external root resorption (surface resorption and replacement resorption resulting in ankylosis). Some teeth in group B showed healed cementum resorption. It has previously been assumed that FORLs were similar to lesions associated with peripheral inflammatory root resorption, and were associated with periodontal disease. These histological findings suggest instead that a FORL is a non-inflammatory replacement resorption, resulting in ankylosis. The periodontal ligament of resorbing teeth lacked normal fibrous architecture, but was not inflamed. Resorption was not identified in cervical cementum. However, the histological appearance of the cervical cementum differed between the two groups. Several aetiopathogenetic explanatory models which arise from these observations are discussed.     

The effect of three types of rasps on the occlusal surface of equine cheek teeth: a scanning electron microscopic study

Two hand rasps (tungsten chip blade, solid carbide blade) and an electrically-driven solid carbide axial bur were used to treat the cheek teeth of 2 horses immediately postmortem. All teeth were normal and were rasped to a standard considered satisfactory in practice. Six teeth from each horse served as untreated controls. Following treatment, the teeth were extracted and the clinical crown removed and prepared for scanning electron microscopy. Teeth were also extracted and examined from a horse that had excessive dental treatment previously. Dental debris created by the procedures was collected and examined. All three rasp techniques resulted in amputation of odontoblast processes. The solid carbide blade cut deep gouges and grooves into the surface of the dentin, chipping the enamel and peripheral cement. No smear layer was created. Rasping with a tungsten chip blade created a partial smear layer and a smoother surface than the solid carbide blade. The electrically-driven bur produced a complete smear layer and removed all dental tissues to a smooth layer. The enamel had also been damaged by the electric bur. Crown particles collected after the procedures were larger following hand rasping compared with particles produced by the electric bur. The extent of damage to sensitive and vital dentin tissue was of concern. Further studies are required to establish the optimum technique for rasping equine cheek teeth.     

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.     

Efficacy of enamel matrix proteins on apical periodontal regeneration after experimental apicoectomy in dogs

Adult dogs have a complex apical delta structure in all root apexes of teeth. This complex structure may affect the formation of apical lesions in the teeth such as apical abscesses. The purpose of this study was to evaluate the efficacy of enamel matrix protein (EMP) which was used for periodontal regeneration therapy after an experimental apicoectomy for an assumed apical lesions of the teeth in dogs. The maxillar canine roots and maxillar fourth premolar buccal mesial roots in five beagles were experimentally apicoectomized under general inhalation anesthesia. After the root apex was exposed and excised, EMP was applied on the surface of the exposed dentin. After 12 weeks, dogs were euthanized. and the experimental teeth together with the surrounding soft and hard periodontal tissues were collected for histological evaluation under a light microscope. In the EMP group, the size of the defect where the root apex was removed was smaller than that of the control group. New cementum was dominantly achieved in the EMP group compared to the control group. Furthermore, new collagen fibers that bridged area between the new cementum and new alveolar bone were detected only in the EMP group. The present results demonstrated marked apical periodontal regeneration after apicoectomy in the EMP group. These results, therefore, suggest that the application of EMP can effectively induce the regeneration of periodontal strUctures in apicoectomized dogs.     

Prevalence of dental resorptive lesions in Swedish cats

Ninety-six, randomly selected Swedish cats were evaluated for the presence of dental resorptive lesions. All cats were examined while receiving general anesthesia. Diagnosis was based on oral examination and full-mouth, intraoral dental radiographs. Information concerning age, sex, vaccination status, eating habits, food type, environment (indoor or outdoor housing), oral, discomfort, dental care, and medical treatment was recorded. Hematologic samples included analysis for FeLV, FIV, and calcivirus. Of the cats examined in this study, 32% had gross or radiographic signs of dental resorptive lesions. There was a positive relationship between the occurrence of dental resorptive lesions and increasing age.     

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.     

Scanning electron microscopic studies of the odontoblasts and the pulpodentinal border in domestic sheep (O. ammon aries Linnaeus, 1758)]

In order to investigate odontoblasts and predentin surfaces using SEM techniques, teeth of sheep with one or several roots were subjected to critical point drying. The odontoblasts of the root pulp are distinguished in their shape and arrangement pattern from those in the crown pulp. They regularly are detaching only one process of Tomes, which is extending up to the border between dentin and enamel and which shows a dendritic ramification in the dentin next to the enamel. The distal cell portions of the odontoblasts are joined together by a system of terminal bars. The collagen structures observed between the odontoblasts and predentin are considered to be von Korff's fibres as found in man.     

Feline dental disease

Periodontal disease and chronic gingivitis/stomatitis are the most common feline dental diseases. With routine dental care and increased emphasis on home oral hygiene, these diseases can be controlled. Cats can be seen with a number of other dental disorders, and improved treatment methods such as restorations of early subgingival resorptive lesions, endodontic therapy, and orthodontic therapy can be performed successfully. More study and research are necessary about the gingivitis/stomatitis syndrome and subgingival resorptive lesions so that improved prevention and treatment recommendations can be made.     

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.     

Development, growth and eruption of permanent incisor teeth in Romney sheep

The development of permanent incisor teeth of sheep was followed from the age of six weeks to 116 weeks. The teeth were observed through the bud, cap and bell stages, and the development of enamel and dentine. At the same time that amelogenesis started, the papillary layer developed from the intermediate layer and the outer dental epithelium began to form the cell rests of Malassez. The ameloblasts went through secretory, transitional and maturational phases, and in due course disappeared, after which cementum was laid down over the enamel surface. Initially the connective tissue of the follicle surrounding the growing tooth was very loose, but was replaced from the crown end as the tooth developed, by more dense connective tissue. Around the time of eruption, melanocytes were found on the lingual surface of the coronal end of the follicle. The root was formed under the influence of Hertwig's epithelium, and the cell rests of Malassez appeared to continue to develop from the outer enamel epithelium. Odontoblasts, which arose from the pulp connective tissue, were initially cuboidal but became fusiform as the tooth matured. At the time of eruption, amelogenesis was almost complete and cementum covered the majority of the tooth surface. The cell rests and melanocytes of the tootth follicle appeared to migrate with the tooth as it erupted. The deciduous tooth was resorbed from the lingual surface. The junctional epithelium of the erupted permanent tooth may have arisen from the cell rests, remnants of the dental lamina or gingival epithelium, depending on the presence or absence of inflammation.