Pathological studies of cheek teeth apical infections in the horse: 2. Quantitative measurements in normal equine dentine.

Measurements of primary, regular and irregular secondary dentine and pulp dimensions were made on transverse, sub-occlusal and mid-tooth sections, of 40 maxillary and 42 mandibular control equine cheek teeth (CT) of different ages. Maxillary and mandibular CT primary dentine in different age groups had a mean thickness of 922-1,065 microm and 1099-1,179 microm, respectively, on the lateral aspects, and 1,574-2,035 microm and 1155-1,330 microm, respectively, on the medial aspects of pulp horns. Surprisingly, some increase in thickness was found in some mandibular CT primary enamel in the first few years following eruption. Regular secondary dentine thickness increased with age, for example at mid-tooth level in mandibular CT from 124 microm at 3 years dental age to 290 microm at >7 years dental age on the lateral aspect of pulp horns, and from 166 microm to 509 microm on the medial aspects of pulp horns, indicating a deposition rate of 0.5-10 microm/day. This type of dentine was thicker sub-occlusally than in the mid-tooth region. Maxillary dentinal dimensions showed a similar age-related increase in thickness. Maxillary CT dentine was significantly thicker (72% in primary, 43% in regular secondary dentine) on the medial compared to the lateral aspects of pulp horns, but mandibular CT dentine was just 15% and 14% thicker in primary and regular secondary dentine thickness, respectively, on the their medial as compared to their lateral aspects. Dentinal and pulp dimensions varied between individual pulp horns, Triadan tooth position, and dental age, with complex interactions between these variables for some parameters.

Pathological studies of cheek teeth apical infections in the horse: 4. Aetiopathological findings in 41 apically infected mandibular cheek teeth.

Examination of 41 extracted, apically infected mandibular cheek teeth (CT) without obvious causes of infection included radiography, computerised axial tomography and decalcified and undecalcified histology. In CT with recent infections, some pulps remained viable, with proliferative soft and calcified tissue changes confined to the apex. With more advanced CT infections, occlusal pulpar exposure was sometimes present (in 34% of the 41 CT), some infected pulp chambers were filled with necrotic pulp or food, and extensive destructive or proliferative changes were present in the calcified apical tissues. No physical route of infection to the apex was found in 24 CT (59%) that consequently were believed to have anachoretic infections. Fractures involving pulps, including fissure fractures between the clinical crown and infected pulps, were found in eight (20%) CT. Some CT had vertical, full length periodontal destruction between the infected apex and the gingival margin that were believed to be the route of infection in four (19%) CT and dysplastic changes were believed to have caused one (2%) infections.

Pathological studies of cheek teeth apical infections in the horse: 1. Normal endodontic anatomy and dentinal structure of equine cheek teeth.

Morphological examinations were performed on 100 normal equine cheek teeth (CT) of 1-12 years dental age (i.e. time since eruption), using gross examination, dissection microscopy, computerised axial tomography, and decalcified and undecalcified histology. The CT in Triadan 07-10 positions consistently had five pulp horns, but the 06 CT had an additional pulp horn more rostrally. Mandibular and maxillary Triadan 11s had six and seven pulp horns, respectively. Sections of CT taken 2-6mm below the occlusal surface (variation due to normal undulating occlusal surface) showed the presence of pulp in up to 50% of individual maxillary CT pulp horns, and in up to 25% of individual mandibular CT pulp horns. The histological appearances of primary and secondary dentine were described and it is proposed that the type of dentine present most centrally in every pulp chamber examined, currently termed tertiary dentine, should be re-classified as irregular secondary dentine, and that the term tertiary dentine be reserved for the focal areas of dentine laid down following insult to dentine or pulp.

Pathological studies of cheek teeth apical infections in the horse: 3. Quantitative measurements of dentine in apically infected cheek teeth.

Histological measurements of dimensions of primary, regular secondary and irregular secondary dentine, pulp diameter and assessment of the levels of predentine, resting lines and enlarged areas of intertubular dentine were performed in apically infected mandibular and maxillary cheek teeth (CT). These examinations showed significantly reduced regular and irregular secondary dentine thickness in diseased as compared to control CT, with 21/26 infected maxillary CT and 15/18 infected mandibular CT having reduced regular secondary dentine (varying between 27.4% and 89.1% reduced secondary dentine levels compared to age and site matched control CT values). As a result of decreased dentinal deposition, significantly wider pulp horns were present in diseased compared to control CT. No significant differences were found between diseased and control primary dentine thickness in maxillary CT, and minor differences in mandibular CT were not believed to be clinically significant. The significantly reduced presence of predentine and of intertubular dentine and the increased presence of resting lines in diseased compared to control CT confirms that long-term disruption of normal dentine deposition had occurred in many infected CT.

Public attitudes in New Zealand towards the use of animals for research, testing and teaching purposes.

AIM: To investigate the awareness of and interest in the use of animals for research, testing and teaching (RTT) purposes, the levels of support and attitudes towards this use of animals, and the awareness of and opinions on regulations governing it within the public in New Zealand. METHODS: An independent telephone survey was used to collect information including demographics, awareness and interest in the use of animals for RTT, attitudes towards the use of animals for RTT, and awareness of the regulation of the use of animals in RTT and the degree of confidence held in such regulation. RESULTS: Data were obtained from 750 respondents throughout New Zealand. The rim-weighting efficiency figure was 90%, indicating that the sample collected closely matched the population demographics for New Zealand. Overall, 33% of respondents expressed an interest in the issue generally, 39% were interested in the area of animals used for research and testing purposes, and 21% for teaching purposes. A majority of respondents agreed that the use of animals for teaching (72%) and research and testing (68%) purposes was acceptable as long as there was no unnecessary suffering by the animals. Respondents felt animal research was most justified for research into life-threatening and debilitating diseases, and least justified for safety-testing of cosmetics and household chemicals. Only 8% of respondents knew a fair amount (or more) about the legislation pertaining to the use of animals in RTT. CONCLUSIONS: The majority of New Zealanders were neither interested nor concerned about the use of animals in RTT. The largest proportion of respondents fell into a category of accepting this use of animals with conditions such as where there is no unnecessary suffering by the animals or where the research is for a serious disease. However, the responses also indicated that attitudes towards the use of animals in RTT as a general issue may change when that use is given a specific context. CLINICAL RELEVANCE: The understanding of public opinion with regard to the use of animals in RTT is an important tool for New Zealand Veterinary Association nominees on animal ethics committees (AECs), for these veterinarians, as well as acting as assessors of the welfare of the animals involved, are also independent of the institutions using animals, so that, along with the other 'external' members, they provide a societal perspective to the deliberations of AECs.