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Abnormal Wear of Teeth (view source)

Revision as of 13:57, 26 September 2011

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*Abnormal wear of [[:Category:Teeth - Anatomy & Physiology|teeth]] in herbivores may result from irregular grinding of molars as well as from periodontal disease.  
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==Introduction==
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*Sharp edges usually form on the lingual aspect of the mandibular [[:Category:Teeth - Anatomy & Physiology|teeth]] and the buccal aspects of the maxillary molars and may cause quite severe oral lacerations.
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Abnormal wear of [[:Category:Teeth - Anatomy & Physiology|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.
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**The condition is sometimes known as “'''shear mouth'''”.  
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*Malocclusion of [[:Category:Teeth - Anatomy & Physiology|teeth]] may be acquired as a result of trauma and loss or displacement of [[:Category:Teeth - Anatomy & Physiology|teeth]].
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==Pathophysiology==
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*It is particularly important in those teeth which continue to grow excessive growth, interference with prehension of food or even growth of the [[:Category:Teeth - Anatomy & Physiology|tooth]] into adjacent structures.
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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 [[:Category:Teeth - Anatomy & Physiology|teeth]]''' and on the '''buccal aspects of the maxillary molars''' and may cause quite severe oral lacerations.  
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*Malocclusions in dogs and cats may arise from retention of deciduous [[:Category:Teeth - Anatomy & Physiology|teeth]] in the young animal.  
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*Malocclusion of [[:Category:Teeth - Anatomy & Physiology|teeth]] may also occur as a result of malformations of the jaws. The terminology used for these is rather confusing and the following should assist:
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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.
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**'''Prognathism''' is an abnormally long lower jaw.  
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**A similar effect is produced by '''brachygnathia superior''' (ie short maxilla). Both conditions may be referred to as ''undershot jaw''.  
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'''Loss of a tooth''' can also cause problems as the opposing tooth is not worn down and may become too long and hinder chewing.
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***A typical breed affected is the '''Boxer'''.
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**'''Retrognathism''' is an unusually short lower jaw. This may also be called '''brachygnathia inferior''' (i.e. short mandible). The condition is referred to as ''overshot jaw'' or ''parrot mouth''.
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[[Dental Malocclusion|'''Malocclusion of teeth''']] may also occur as a result of malformations of the jaws.  
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***Typical breeds affected are the '''Borzoi''' or '''Rough Collie'''.
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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.
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The opposite occurs in horses with mandibular prognathism (sow mouth).
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==Treatment==
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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.
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Floating or sharp points using hand rasps follows several rules:
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:the blades of the rasps should be in '''solid tungsten carbide''' as these can be re-sharpened and can last a long time
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:'''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.
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For '''larger hooks''' which require more rasping, several aspects are important:
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:a good light source is necessary, usually a head torch
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: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
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:'''pulp exposure''' should be avoided by regularly checking the aspect of the tooth which is being burred.
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:teeth occlusal angle should be restored to '''10-15°'''
    
==Rabbits==
 
==Rabbits==
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[[Cheek Teeth Malocclusion – Rabbit|Cheek Teeth Malocclusion]]
 
[[Cheek Teeth Malocclusion – Rabbit|Cheek Teeth Malocclusion]]
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{{Learning
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|flashcards = [[Veterinary Dentistry Q&A 19]]
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}}
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=References==
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Pascoe, R. (2009) '''Equine Dentistry''' ''RVC Student Notes''
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Lewis, L. D. (1995) '''Equine Clinical Nutrition: Feeding and Care''' ''Wiley-Blackwell''
    
[[Category:Teeth_-_Pathology]]
 
[[Category:Teeth_-_Pathology]]
 
[[Category:To_Do_-_Clinical]]
 
[[Category:To_Do_-_Clinical]]
 
[[Category:Oral Diseases - Horse]]
 
[[Category:Oral Diseases - Horse]]
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[[Category:To Do - Helen]]
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[[Category:To Do - Review]]
HelenD
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