Abnormal Wear of Teeth
Introduction
Abnormal wear of teeth in herbivores may result from irregular grinding of molars as well as from periodontal disease. This is especially a problem in horses but occurs in any animal with continuously-growing teeth.
Pathophysiology
The horse's upper cheek teeth extend as much as one-half the width of a tooth outside the lower cheek teeth. Chewing wears the teeth where they contact each other, and if the jaw excursions are not wide enough, sharp edges can form on the lingual aspect of the mandibular teeth and on the buccal aspects of the maxillary molars and may cause quite severe oral lacerations.
A condition sometimes known as “shear mouth” can occur when the grinding surfaces of all cheek teeth are severely sloped with extremely sharp points and an abnormal chewing motion.
Loss of a tooth can also cause problems as the opposing tooth is not worn down and may become too long and hinder chewing.
Malocclusion of teeth may also occur as a result of malformations of the jaws.
Mandibular brachygnathism (parrot mouth) horses tend to have hooks at the front of the first upper cheek teeth and at the back of the last lower cheek teeth.
The opposite occurs in horses with mandibular prognathism (sow mouth).
Treatment
Treatment of wear disorders and overgrowths in horses generally involves rasping or floating of the teeth by hand or using motorised equipment. Molar cutters or burrs may also be used for larger hooks.
Floating or sharp points using hand rasps follows several rules:
- the blades of the rasps should be in solid tungsten carbide as these can be re-sharpened and can last a long time
- different handles with different angulations are needed to reach all parts of the mouth. For the maxillary teeth, open-angled tools are used at the front of the mouth, straight rasps in the middle and closed-angled tools at the back. For the mandibular teeth, straight rasps should be used for the front and then upward-curving rasps for the back.
For larger hooks which require more rasping, several aspects are important:
- a good light source is necessary, usually a head torch
- the tool should only be used for short periods of time in the same place as otherwise excessive heat is created which can damage the tooth
- pulp exposure should be avoided by regularly checking the aspect of the tooth which is being burred.
- teeth occlusal angle should be restored to 10-15°
Rabbits
| Abnormal Wear of Teeth Learning Resources | |
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 Test your knowledge using flashcard type questions |
Veterinary Dentistry Q&A 19 |
References=
Pascoe, R. (2009) Equine Dentistry RVC Student Notes
Lewis, L. D. (1995) Equine Clinical Nutrition: Feeding and Care Wiley-Blackwell