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.     

The pathogenesis of excessive wear in the permanent teeth of sheep

The two central pairs of permanent incisor teeth (l1P, I2P) were compared post mortem in sheep from two flocks, one of which showed excessive wear. Sheep were usually killed in groups of six. Excessive wear occurred during the winter and spring after the eruption of l1P. When l1P erupted at an early age it was also subject to that season;s wear but when it erupted at a later age, it was subject to less wear according to the amount of time it was in apposition with the dental pad during the high wear season. A small amount of compensatory growth at the root of the tooth occurred in some sheep when cementum was deposited on the apex. Apparent eruption of the crown of the tooth was actually due to gum recession. Normal reparative dentine was laid down in the pulp cavity of the crown of the tooth in anticipation of wear, but where wear was excessive unstructured dentine was deposited. In two cases the rate of wear was so great that the reparative dentine could not keep up and infection was able to gain access to the pulp cavity. There was no evidence of difference in the rate of wear of the molar teeth between the two flocks.     

The formation of apical delta of the permanent teeth in dogs

To determine the process of formation of apical delta, a histological study on the permanent teeth was carried out in dogs. A litter of 7 clinically healthy beagle dogs and 33 adult dogs (4- to 15- year-old) of 12 breeds with periodontal disease were used for the experiments. Teeth extracted from 6-,7-,8- and 9-month-old beagles were sectioned and stained with HE solution. Tooth roots obtained from adult dogs with periodontal disease were ground. Each tooth was classified into the following root types under a light microscope: Type I (no apical delta = no apical closure), II (few apical delta), IIIA (low apical delta) and IIIB (high apical delta). In the 6-month-old beagles, more than half the tooth roots were classified as type I. In the 7-month-old beagles, type IIIB apical delta was the most predominant and types I, II and IIIA apical delta were occassionally seen. Apical closure and delta were observed in all beagles at 8 months of age histologically. In the 8- and 9-month-old beagles, all root apexes observed were type IIIB. Most of the 314 tooth roots extracted from 33 adult dogs were type IIIB, but a few were type IIIA.     

Dental radiology: ageing changes in permanent teeth of beagle dogs

Radiographic interpretation of dental or periodontal disease is dependent in part on an understanding of ageing changes, A progressively ageing colony of healthy beagle dogs (120 to 3759 days) was studied by use of high-detail radiographs made following the death of the dog. Morphological features whose radiographic appearance was found to be especially age-dependent were: root canal size, both vertical and horizontal alveolar bone resorption, visualisation of the lamina dura dentis, and detection of hypercementosis. Understanding of these ageing changes is necessary to avoid over-diagnosis of disease.     

Observations on the eruption of the permanent incisor teeth of farmed Javan rusa deer (Cervus timorensis russa) in New Caledonia

The eruption of the permanent incisor teeth of 14 farmed Javan rusa deer (Cervus timorensis russa) of known birth date and their live weights were observed about every 2 weeks from 12 to 30 months of age. The permanent incisor pattern was 11, 14-17 months; 12, 18-23 months; 13, 20-26 months; and 14, 22-27 months. There was no significant relationship between body weight and timing of permanent incisor eruption.     

Variability in the eruption of the permanent incisor teeth in sheep

The incisor teeth of 176 sheep of six breeds were inspected every two to three months for a year to record the shedding of the deciduous teeth and the eruption of the permanent teeth. In all the breeds the permanent central incisors erupted at between 12 and 18 months of age. In 96 per cent of the sheep the permanent middle incisors erupted at between 18 and 26 months; and in 92 per cent the permanent lateral incisors erupted at between 24 and 36 months of age. The permanent corner teeth erupted at between 32 and 44 months in 96 per cent of the sheep. The gingival redness and swelling accompanying the eruption of a permanent tooth disappeared within two months. In 14 cases two pairs of incisors erupted during the year, in 18 cases the incisors erupted asymmetrically, and in 22 cases no incisors erupted. Rotation of one incisor was observed in five sheep and was combined with dental deviation in one.     

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.     

Vital pulp therapy for complicated crown fracture of permanent canine teeth in dogs: a three-year retrospective study

A 36-month retrospective study compared the results of vital pulp therapy based on the duration of pulp exposure for complicated crown fracture of 97 permanent canine teeth in 76 dogs. Postoperative oral and radiographic examinations were performed at 3, 12, and 36-months following treatment. Based on the 36-month postoperative examinations 88.2%, 41.4 %, and 23.5% of teeth were vital when treated within 48-hours, 1-week, and 3-weeks of pulp exposure, respectively. There was a significant difference in the incidence of tooth vitality between groups. The duration of pulp exposure following complicated crown fracture influenced the success of vital pulp therapy. Vital pulp therapy should be performed as soon as possible following traumatic pulp exposure.     

Comparative scanning electron microscope analysis of the enamel of permanent human,bovine and porcine teeth

BackgroundBovine and porcine teeth are often used in in vitro experiments as substitutes of human teeth.ObjectivesThe aim of the present study was to perform a comparative analysis of enamel morphology of permanent human, bovine and porcine teeth under the scanning electron microscope.MethodsAs many as 10 human, 10 bovine, and 10 porcine teeth were studied. All the teeth were sectioned and the halves were randomly divided into 2 groups according to the examined tissue (vestibular enamel at the mid-height of the dental crown and in the cervical area). Human and bovine enamel was etched for 15 sec and porcine enamel for 30 sec. The scanning electron microscope analysis was performed. The length and width of enamel prisms were determined with the “Met-Ilo” 1.1 computer program.ResultsAll enamel samples revealed the same etching pattern—Silverstone''s type 2. Bovine enamel showed a similar porosity and the amount of interprismatic enamel compared to human enamel while the amount and width of interprismatic enamel bands in porcine enamel were evidently greater. The shape of the porcine prisms was visually similar to human prisms, although dimensions were significantly different. However, bovine prisms differed in form and appeared to be distinctly elongated.ConclusionsReported findings indicate that the results of experimental studies carried out on bovine and porcine enamel should not be compared with the results obtained on human enamel.     

Larval cyathostomiasis (immature trichonema-induced enteropathy): a report of 15 clinical cases

Clinical and laboratory findings are recorded from a series of 15 cases (aged one to 16 years) of sudden-onset chronic diarrhoea with weight loss, progressing in many cases to emaciation and death, associated with the emergence of fourth stage cyathostome (trichoneme) larvae in large numbers through the colonic and caecal mucosae. Apart from a single incident in mid-October, disease only occurred in winter and spring (January to May). Characteristic features included hypoalbuminaemia, increased alpha and beta plasma globulin levels and neutrophilia without left shift. Faecal egg counts were frequently negative and eosinophilia and anaemia were not features. Horses treated in the early stages responded well to larvicidal doses of fenbendazole (60 mg/kg bodyweight) but in cases where this therapy was delayed for weeks or months the prognosis was poor.     

Regulation of uterine estrogen receptors (ER) by beta-adrenergic stimulation in immature rats

The effects of a 3-day intramuscular (i.m.) administration of clenbuterol (25 μ.g/ Kg), propranolol (12 mg/kg), clenbuterol (25 μg/kg) plus propranolol (12 mg/ Kg) and estradiol (0.5 μg) upon the female reproductive system were investigated in immature Sprague-Dawley rats. Clenbuterol and estradiol treatments induced a significant increase in uterus weight and in relative uterus weight, whereas in the groups treated with propranolol and clenbuterol plus propranolol no differences were detected versus controls. The uterine estrogen receptor levels were significantly increased by clenbuterol administration. In the rats dosed with propranolol and clenbuterol plus propranolol, no modifications occurred in estrogen receptor concentrations when compared with control values. Uterine progesterone receptors were never significantly affected by any of the considered treatments. Data obtained indicate that clenbuterol treatment induces an increase in uterus weight and in estrogen receptor levels and that these effects are regulated by acute beta-adrenergic stimulation, as the contemporaneous administration of high doses of a beta-blocker inhibit such effects.     

Ultrastructural features of atretic follicles in the sexually immature ostrich (Struthio camelus)

The aim of this study was to describe the ultrastructural features of atresia in follicles of the immature ostrich (12–14 months old); a ratite that displays seasonal, precocious ovarian activity. The early stage of atresia in primordial, pre-vitellogenic and vitellogenic follicles was characterized by the accumulation of lipid droplets in the granulosa cells. Granulosa cells with condensed cytoplasm and nuclei were a prominent feature during the intermediate phase of atresia. The degenerating follicles were then infiltrated by stroma during the terminal stages of atresia. The results of this study provide further information on the morphology of atretic ovarian follicles in the immature ostrich.     

Efficacy of paraherquamide against immature Trichostrongylus colubriformis in the gerbil (Meriones unguiculatus)

Paraherquamide was 98 to 100 per cent effective against six-day-old Trichostrongylus colubriformis infections in gerbils when given as single oral doses of 1.56 mg kg-1 and above. Doses of 0.78 or 0.39 mg kg-1 were 96 and 66 per cent effective, respectively. A single oral dose of 200 mg kg-1 was well tolerated.     

Technique and outcome of nares amputation (Trader's technique) in immature shih tzus

Dogs with brachycephalic conformation frequently suffer from stenotic nares. This study investigated the clinical effects of stenotic nares resection in shih tzu puppies using an amputation technique first described in 1949. The authors hypothesized that surgical correction of the stenotic nares would result in improvement of nasal discharge/noise, breathing difficulty (dyspnea), and exercise limitations (exercise intolerance), and that the technique would provide a cosmetic result. Based on the results of this study, the authors recommend early surgical correction (amputation) of stenotic nares in shih tzu puppies as an effective and cosmetic technique.     

Standing oral extraction of cheek teeth in 100 horses (1998--2003)

REASONS FOR PERFORMING STUDY: Extraction of cheek teeth (CT) by the conventional repulsion technique requires general anaesthesia and carries a high rate of post operative complications. Consequently, an alternative method of extraction, i.e. orally in standing horses, was evaluated. HYPOTHESIS: The need for and risks of general anaesthesia could be avoided and post extraction sequelae reduced by performing extractions orally in standing horses. METHODS: One hundred mainly younger horses (median age 8, range 2-18 years) with firmly attached CT that required extraction because of apical infections, displacements, diastemata, idiopathic fractures and the presence of supernumerary CT had the affected teeth (n = 111) extracted orally under standing sedation. Follow-up information was obtained for all cases, a median of 16 months later. RESULTS: Oral extraction was successful in 89 horses and unsuccessful in 11 due to damage to the CT clinical crown (n = 9) during extraction, for behavioural reasons (n = 1) and because the apex of a partly extracted CT fell back into the alveolus following sectioning (n = 1). Predispositions to extraction-related CT fractures were present in 5 of the 9 cases, i.e. advanced dental caries (n = 2) and pre-existing 'idiopathic' fractures (n = 3). The iatrogenically fractured CT were later repulsed under standing sedation (n = 3) and under general anaesthesia (n = 6). Eighty-one of the remaining 89 horses had successful oral CT extraction with no or minimal intra- or post operative complications occurring. Post operative complications in the other 8 cases included post extraction alveolar sequestration (n = 3), alveolar sequestration and localised osteomyelitis (n = 1), localised osteomyelitis (n = 1), incorporation of alveolar packing material into alveolar granulation tissue (n = 1), and nasal discharge due to continued intranasal presence of purulent food material (n = 1) and to ongoing sinusitis (n = 1). The above sequelae were treated successfully in all cases, with general anaesthesia required in just one case. Following oral extraction, significantly (P<0.001) fewer post operative problems developed in 54 horses with apically infected CT in comparison with 71 previous cases that had repulsion of apically infected CT at our clinic. CONCLUSIONS AND POTENTIAL RELEVANCE: Oral extraction of cheek teeth is a successful technique in the majority of younger horses with firmly attached CT and greatly reduces the post operative sequelae, compared with CT repulsion. Additionally, the costs and risks of general anaesthesia are avoided. Further experience and refinement in the described protocol could potentially increase the success of this procedure and also reduce the incidence of post operative sequelae.