dentistry

Polyodontia in donkeys

Citation

J. B. Rodrigues, F. Sanroman-Llorens, E. Bastos, F. San Roman, C. Viegas. March 2013. Polyodontia in donkeys. Equine Veterinary Education. 25:7. 363-367.

Authors
Publication details
Publication date: 
24 March 2013
Volume: 
25
Issue: 
7
Page numbers: 
363-367
DOI number: 
10.1111/eve.12030  
Abstract

Polyodontia is defined as the presence of teeth in excess of the normal dental formula. In equids, supernumerary teeth are uncommon but, when present, are usually located mainly in the caudal aspects of the cheek teeth rows (distomolars), also being found adjacent to normal cheek teeth or even in an ectopic location. It is believed that this disorder is a result of an inappropriate differentiation of dental germinal tissue during gestational development, with external trauma also acting as an initiating factor, when teeth germs are affected. The presence of these abnormal teeth can lead to axial displacement, dental overgrowths, dental-related soft tissue damage, diastemata formation, periodontal disease and development of secondary sinusitis. A large prospective, cross-sectional study was performed in 800 donkeys, with the aim to investigate the prevalence and aetiopathogenesis of clinically diagnosed oral and dental disorders. Polyodontia was recorded in 2.25% of the donkeys, presenting 36 supernumerary teeth, with 2.80% being incisors and 97.20% cheek teeth, with prevalence increasing with age. The caudal aspects of the maxillary cheek teeth rows were the most common locations for supernumerary teeth development (distomolars). The mandible was far less commonly affected than the maxilla. Although polyodontia is uncommon in donkeys, it should be considered in the differential diagnosis of dental disease. A methodical oral examination and a complete radiographic survey of the entire dental arcades are crucial for a correct early diagnosis and treatment plan implementation. The increasing prevalence of fully erupted supernumerary teeth recorded in older groups suggested a late onset eruption process, and therefore, in donkeys undergoing regular dental prophylaxis, the presence of previously unnoticed supernumerary teeth should always be sought.

Online references

Common dental disorders in the donkey

Citation

Nicole du Toit, Padraic M. Dixon. May 2011. Common dental disorders in the donkey. Equine Veterinary Education.

Authors
Publication details
Publication date: 
1 May 2011
DOI number: 
10.1111/j.2042-3292.2011.00236.x
Abstract

Normal dental anatomy and the range of dental disorders found in donkeys are largely similar to those described in horses. Recent studies have shown dental disease to have a high prevalence in donkeys. Some dental disorders, such as diastemata, displaced teeth and wave mouth can have serious clinical consequences by causing oral pain and weight loss and even predispose to colic. Many of these signs can be prevented by regular dental treatment that can slow down or even prevent the progression of these disorders.

Online references

Comparison of the microhardness of enamel, primary and regular secondary dentine of the incisors of donkeys and horses

Citation

Nicole du Toit, B. Bezensek, Padraic M. Dixon. June 2008. Comparison of the microhardness of enamel, primary and regular secondary dentine of the incisors of donkeys and horses. Veterinary Record. 162:9. 272-275.

Authors
Publication details
Publication date: 
1 June 2008
Journal: 
Veterinary Record
Volume: 
162
Issue: 
9
Page numbers: 
272-275
DOI number: 
10.1136/vr.162.9.272
Abstract

The microhardness of the enamel, primary dentine and regular secondary dentine of seven donkey and six horse incisors was determined with a Knoop indenter at the subocclusal and mid-tooth level. The mean microhardnesses of the donkey incisor enamel, primary dentine and secondary dentine were 264·6 63·00 and 53·6 Knoop Hardness Number, respectively. There was no significant difference between the microhardness of the enamel and primary dentine on the incisors of the donkeys and horses, but the microhardness of the regular secondary dentine of the donkeys' incisors at the mid-tooth level was slightly but significantly less than that of the horses. There was also a difference in the microhardness of the secondary dentine between the subocclusal and mid-tooth levels in both donkey and horse incisors.

Because most donkeys live well beyond 30 years of age (Crane 1997), it has been proposed that their teeth may be harder than the teeth of horses, wear more slowly, and thus remain functional for longer (Misk and Seilem 1999). There have been studies of dental microhardness in human beings (Craig and Peyton 1958, Collys and others 1992), sheep (Suckling 1979), cattle (Attin and others 1997) and horses (Muylle and others 1999b). In horses, there are differences between breeds in the rate of dental wear caused by attrition (Muylle and others 1997, 1998) and in the microhardness of enamel and secondary dentine (Muylle and others 1999b), which could account for these differences. It is proposed that there may be a similar difference between the microhardness of the teeth of donkeys and horses that may contribute to the less rapid attrition of donkey teeth.

The aim of this study was to compare the microhardness of the enamel and primary and secondary dentine of the incisor teeth of donkeys and horses, to determine whether there was a significant difference between them.

Online references

Donkey dental anatomy. Part 2: Histological and scanning electron microscopic examinations

Citation

Nicole du Toit, Susan A. Kempson, Padraic M. Dixon. June 2008. Donkey dental anatomy. Part 2: Histological and scanning electron microscopic examinations. The Veterinary Journal. 176:3. 345-353.

Authors
Publication details
Publication date: 
1 June 2008
Volume: 
176
Issue: 
3
Page numbers: 
345-353
DOI number: 
10.1016/j.tvjl.2008.03.004
Abstract

Ten normal cheek teeth (CT) were extracted at post mortem from donkeys that died or were euthanased for humane reasons. Decalcified histology was performed on three sections (sub-occlusal, mid-tooth and pre-apical) of each tooth, and undecalcified histology undertaken on sub-occlusal sections of the same teeth. The normal histological anatomy of primary, regular and irregular secondary dentine was found to be similar to that of the horse, with no tertiary dentine present. Undecalcified histology demonstrated the normal enamel histology, including the presence of enamel spindles. Scanning electron microscopy was performed on mid-tooth sections of five maxillary CT, five mandibular CT and two incisors. The ultrastructural anatomy of primary and secondary dentine, and equine enamel types-1, -2 and -3 (as described in horses) were identified in donkey teeth. Histological and ultrastructural donkey dental anatomy was found to be very similar to equine dental anatomy with only a few quantitative differences observed.

Donkey dental anatomy. Part 1: Gross and computed axial tomography examinations

Citation

Nicole du Toit, Susan A. Kempson, Padraic M. Dixon. June 2008. Donkey dental anatomy. Part 1: Gross and computed axial tomography examinations. The Veterinary Journal. 176:3. 338-344.

Authors
Publication details
Publication date: 
1 June 2008
Volume: 
176
Issue: 
3
Page numbers: 
338-344
DOI number: 
10.1016/j.tvjl.2008.03.003
Abstract

Post-mortem examination of 19 donkey skulls showed that donkeys have a greater degree of anisognathia (27% width difference between upper and lower jaws) compared to horses (23%). Teeth (n = 108) were collected from 14 skulls and examined grossly and by computed axial tomography (CAT). A greater degree of peripheral enamel infolding was found in mandibular cheek teeth (CT) compared to maxillary CT (P < 0.001). A significant increase in peripheral cementum from the apical region to the clinical crown was demonstrated in all CT (P < 0.0001). All donkey CT had at least five pulp cavities with six pulp cavities present in the 06s and 11s. A new endodontic numbering system for equid CT has been proposed. A greater occlusal depth of secondary dentine (mm) was present in older donkeys (>16 years) than in the younger (<15 years) donkeys studied. Based on gross and CAT examinations, donkey dental anatomy was shown to be largely similar to that described in horses.

Dimensions of diastemata and associated periodontal food pockets in donkey cheek teeth

Citation

Nicole du Toit, Faith A. Burden, Lee Gosden, Padraic M. Dixon. April 2008. Dimensions of diastemata and associated periodontal food pockets in donkey cheek teeth. Journal of Veterinary Dentistry. 26:1.

Authors
Publication details
Publication date: 
1 April 2008
Volume: 
26
Issue: 
1
Abstract

Equine cheek teeth (CT) diastemata often cause deep periodontal food pocketing and are therefore regarded as a painful dental disorder of equidae. However there appears to be no information available on the size or shape of these diastemata. This post mortem study examined 16 donkey skulls (mean age = 32-years) containing 45 CT diastemata to define the anatomical shape and dimensions of these diastemata, and of the associated periodontal food pockets that occur with this disorder. Diastemata were found to more commonly involve mandibular (56.0%) compared with maxillary CT (44.0%), and 71.0% of these diastemata had adjacent intercurrent dental disorders that may have predisposed donkeys to the diastemata. The median widths of all diastemata were 2.0-mm at the occlusal surface and 3.1-mm at the gingival margin, with no diferences in widths between the lateral or medial aspects of diastemata. Diastemata were defined as open (60.00%) or valve (40.00%) based on their gross appearance. This classification was confirmed to be accurate by measurements that showed valve diastemata to have an occlusal to gingival width ratio of 0.4, in contrast to open diastemata where this ratio was 1.07. Food was impacted in 89.0% of diastemata, but all diastemata had adjacent periodontal disease. Periodontal food pocketing was present adjacent to 76.0% of diastemata, more commonly on the lateral aspect (73.0% prevalence; mean pocket depth = 4.1-mm) than the medial aspect (47.0% prevalence; mean pocket depth = 2.4-mm). The depth of periodontal pockets of diastemata was not associated with the height of the erupted crowns of adjacent CT.

Syndicate content