Equine Dentistry Flashcards
What the deciduous teeth in a horse?
Incisors and premolars
What the permanent teeth in a horse?
Incisors
Premolars, molars +/- canines
What is the orientation of equine dental anatomy?
What does this mean for their food?
Anisognathous orientation (maxillary and mandibular arches or jaws are of significantly different sizes), with mandibular jaw narrower than mandibular., Allows for effective grinding, but produces sharp edges over time.
Do horse teeth grow?
Tooth does not ‘grow’ so will eventually fall out, usually at 25 years +
Continuously erupt
How many deciduous and permanent incisors do horses have?
What is their function?
Incisors – 3 deciduous, 3 permanent, prehend food in the mouth
What is the iinterdental space and what is often there?
Interdental space containing canines, permanent only, variable number, possible fighting role? Space between incisors and cheek teeth
What is the wolf teeth?
How many is there?
Wolf teeth – vestigial 1st premolar, variable number (0-4), no role – get in the way, no functional role
How many deciduous and permanent premolars do horses have?
Premolars – 3 deciduous, 3 permanent, form one functional unit with molar teeth
How many deciduous and permanent molars do horses have?
Molars – 3 permanent
Horses are hyposodont - what does this mean?
Hypsodont – ‘high crowned teeth’ - Hypsodont dentition, meaning they are characterised by high-crowned teeth and enamel that extends past the gum line. This provides extra material for wear and tear. Enamel continues beyond gum level
What are horses teeth constantly doing?
•Constantly erupting (not growing!) (c.f rabbit teeth)
- 2-5mm eruption/yr
- faster in younger horses vs old horses
- disparity in eruption vs wear –> dental disease
A horse walks into a bar. The barman confuses idioms with jokes and offers him a glass of water, but can’t make him drink
What kind of crown do horse teeth have?
Long reserve crown
Which teeth sit in the maxillary sinus
Upper 08-11
Can vary - but important RE infection
Which parts make up the calcified dental tissue?
Cement
Enamel
Dentine
What is the cement of the tooth?
- Fills infundibulum and upper cheek teeth and surrounds tooth
- Produced by cementoblasts, 65% mineral, 35% organic, covers external surface and infundibulum, subgingival cementum is part of the periodontal ligament complex and living tissue. Cement secreted in response to growth and infection/injury.
- Forms part of periodontal ligament
What is enamel as part of dental anatomy?
What properties does it have and what makes it?
- Hardest substance in the body
- High tensile strength
- Brittle and hard
- Secreted by ameloblasts, 98% hydroxyapatite crystals and 2% keratinous proteins. Inert, cannot repair itself. Brittle, but high tensile strength. Dentine and cementum absorb shock and allows sharp edges to shred roughage. – completely inert, cannot recover if damaged
Which part of dental anatomy cannot repair itself?
Enamel
Inert, cannot repair itself.
Brittle, but high tensile strength
What material protects enamel?
What is it made by?
Dentine
- Elasticity and compressibility protects enamel
- Dentine secreted by odontoblasts, 70% mineral, 30% organic. Elasticity and compressibility allows protection of enamel. Dentine protects pulp during wear and growth.
What is the function of pulp?
What is different about pulp in horse teeth?
Supplies nutrition to the tooth – all teeth
Multiple pulp forms in equine teeth
What does the peridontium comprise of?
What is its function?
-Comprises all structures linking the tooth with
the supporting bone
-The periodontium includes the gingiva, periodontal ligament, alveolar bone, and cementum. The periodontal ligament functions as a “shock absorber” enabling the tooth to be firmly suspended within the alveolus while permitting a slight amount of movement.
What does dentine provide a barrier between?
Why is this important with dental treatment?
- Dentine provides a barrier between the pulp and the occlusal surface
- Important as the BIGGEST risk during dental treatments is indirect or direct pulpal exposure
- Pigments oxidise so superficial layers are brown
- Pigment reduces towards pulp cavity
When do permanent incisors (01-03) erupt in horses?
01: 2-5 years
02: 3-5 years
03: 4-5 years
When do permanent canines (04) erupt?
4-5 years
When do permanent premolars (06 - 08) erupt?
06: 2.5 years
07: 3 years
08: 4 years
When do permanent molars (09, 10, 11) erupt?
09: 1 year
10: 2 years
11: 3-3.5 years
What are some things you can use to age a horse by its dentition?
- Largely inaccurate – especially older horses
- Eruption times most accurate method
- Shape of corner incisor – another more accurate indicator of age
- <10y wider than long
- ~ 10y square
- >10y longer than wide
- Dental star
- Infundibulum/mark disappearance
- Galvaynes groove
- ‘Hook’ on corner incisors
- Shape of occlusal surface – oval à triangular
At what age do you get appearance of dental star on the following teeth:
01 (central)
02 (lateral)
03 (corner)
01 - 5 years
02 - 6 years
03 - 7-8 years
At what age do you get disappearance of cups on the following teeth:
01 (central)
02 (lateral)
03 (corner)
01: 6-7 years
02: 7-11 years
03: 9-15 years
At what age do you get marks worn out on following teeth:
01 (central)
02 (lateral)
03 (corner)
01: 12-15 years
02: 14-15 years
03: 14-15 years
At what age does Galvaynes groove appear on 03 (corner) tooth and when is it at full length?
Appears 10y
Full length of tooth by 20y
At what age does the Hook appear on 03 (corner) tooth?
7 years and 13 years
When doing a dental exam, what do you want to know from the history?
- Dental work history
- Previous dental problems
- Feeding habits – quidding (response to mouth pain in which the horse loses or spits balls of semi-chewed food stuffs out of their mouth), salivation?
- Bitting/riding problems – head shaking?
As part of the dental exam, you should do a full clinical exam - what are you looking for?
What should you observe?
•Full clinical exam
- Body condition – weight loss?
- Concurrent disease
- Visual and manual exam of head
- Asymmetry, swellings, halitosis, nasal discharge
- OBSERVE MASTICATION!!!!
-Should chew in both directions equally when observed
for several chew cycles (20:20)
-Figure of 8 pattern, equally on both sides of mouth
How should you manipulate the jaw when doing a dental exam?
What are you looking for?
- A normal lateral excursion is roughly the width of 1½
teeth (should be even in both directions) - As lateral movement continues and the grinding surfaces
of the cheek teeth come into contact, the incisors should
separate approx. 2–6mm - All dental exams - full mouth speculum with light source and mirror!
- Grasp bridge of the nose with one hand and the ventral mandible with the other, move mandible to the side and listen to cheek teeth. Jaw should move freely without locking to either side.
When do you want to look at the teeth for the first few times?
•Foals
- Birth and weaning
- Congenital – parrot mouth/wry nose/cleft palate
- 1 – 3yo
- May not be necessary – generally just out in the field growing! Depends on their use
- Depends on use/problems
- Retained caps
- Tumours of origin
- Softer enamel?
- Quicker eruption
As the premolars erupt, what does this do the the decisuous roots and crowns?
What if a cap is retained?
As the premolars erupt, they cause resorption of the deciduous root and push the remaining deciduous crown up above the gum line. This premolar cap is usually lost shortly after the molar tooth erupts through the gum. In some instances, this cap can be retained and have sharp spicules of enamel that may penetrate the gum when pressure is applied by the opposing premolar resulting in pain.
What is the treatment for retained caps?
•Removal of retained caps results in almost immediate resolution of oral pain. In addition to retained premolar caps, asynchronous eruption of premolar and molar teeth can result in malocclusions that can affect the horse’s ability to adequately grind feed. This problem is easily recognized and corrected on a routine oral examination.
Why might you do a dental exam prior to bitting (3-4 years old) - what might you be looking for?
- Sharp enamel points
- Might have some loose caps
- Wolf teeth should be checked
- Diastemata
What happens if you leave an enamel point untreated?
If left untreated, these enamel points may continue to lengthen, causing painful ulcers or lacerations of the cheek and tongue
Why do HOOKS develop on adults first premolar and last lower molar?
What does it restrict?
Which are the hardest hooks to treat?
Another common abnormality of the adult horse is the development of hooks on the first upper premolar and last lower molar. These hooks develop as a result of abnormal alignment of the mandibular and maxillary cheek teeth. Hooks may restrict the normal front to back movement of the lower incisors in relation to the upper incisors with change in head position. This is especially important when horses are expected to bend at the neck and poll.
Hooks affecting the last lower molar are more difficult to treat due to the depth of the teeth in the mouth, minimal working space and close proximity of the bone and surrounding soft tissues. Minor oral trauma frequently accompanies reduction of these hooks.
Some malocclusions result in steps or waves - what is a wave?
How can you correct steps or waves?
Other malocclusions result in steps or waves. A wave is a series of overgrown teeth opposed by a corresponding series of over worn teeth. Although there are several techniques for the correction of steps or waves, these abnormalities may not be correctable in a single dental treatment due to the potential for invasion of the pulp chamber if excessive tooth is removed. Therefore, additional treatment at a more frequent interval (often every 4 – 6 months until the malocclusion is corrected) may be necessary.
What is a diastema?
What does this lead to?
(its a long one, soz)
As the cheek teeth erupt, there is a natural tapering of the tooth from the occlusal surface to the root. In young horses, all 6 cheek teeth are packed tightly together with no normal space between the teeth. As the tooth erupts and the occlusal surface is worn, this tapering results in formation of spaces known as diastema between the teeth. Food and other debris can become trapped in these spaces and undergo fermentation. This food packing and bacterial fermentation has a negative effect on the natural defenses in the mouth and infection of the gingiva occurs. With time, this infection migrates along the tooth eventually affecting the surrounding bony and soft tissue attachments of the tooth to the jaw. Periodontal disease may eventually lead to infection of the tooth root, tooth root abscesses and premature tooth loss. Although there are usually no obvious outward clinical signs, this is a painful condition that eventually will lead to difficulty chewing, weight loss and potentially other more serious health problems such as secondary infection of the sinuses and colic.
Why should you never be rude to a jump jockey?
In case he takes offence
Do geriatric horses need annual or more frequent dental exams?
Annually or more frequently?
•Depends on tooth alignment/presence of any disease
- Prevention of periodontal disease essential
- Tooth eruption slows down – so tend to need less rasping and management than younger horses
What is the dental equipment you need with you?
•Selection of dental rasps to reach all teeth
- Sharp tungsten carbide blades
- Open, straight and closed angle – access every tooth
- Curved/gledhill useful for lower cheek teeth (curve of spee)
- Picks and probes
- Elevators (wolf teeth)
- Bucket with antiseptic solution – hibiscrub is fine
- Full mouth speculum
- Lightsource – bright!
- Mirror
- Adjustable headcollar
- Restraint/headrest
- Sedation – better exam, horse more relaxed, more space to work with etc.
- Stocks
- Powertools – essential?
- Thought to be essential – can access a lot more of the mouth and do a lot more with them but need to be used by trained professionals – but be aware of thermal damage, can damage underlying pulp and cause damage in later life
How common are retained deciduous teeth?
How can you treat them?
What happens if a horse has them?
Fairly common
Usually easy to remove, bit of sedation and elevator
Can cause gap between adult incisors – which may or may not close
When trying to remove retained deciduous teeth, what if you can’t tell the difference between adult and deciduous teeth?
May require radiographs if can’t distinguish between adult and deciduous tooth. Usually, the deciduous one is the one on the labial side
What are fractures/displacement of teeth usually from?
What can you do to fix them?
Usually following kick or getting tooth caught – not as well protected as the other teeth
May require extraction, might require restoration to preserve pulp
Often possible to wire back into place and stabilise
X-rays may be necessary – jaw may also be fractured
What is EOTRH?
What does it cause?
- Equine Odontoclastic Tooth Resorption and Hypercementosis
- New, emerging disease – aetiology currently unknown
- Seems to affect older horses
- Causes reabsorption of roots +/-cement deposition, teeth become loose and painful
- Extraction only treatment currently available atm – very successful
- Diagnose by x-ray
Which horses is missing/loose/overgrown teeth most common in?
What can cause it?
Usually older horses
Occasionally abnormal conformation/development
Any realignment should be very gradual – sedation indicated
Loose teeth should be removed to improve comfort
With missing/loose/overgrown teeth - how should you go about fixing them?
Any realignment should be very gradual – sedation indicated
Loose teeth should be removed to improve comfort
Which teeth does slant mouth affect?
What is it?
Any correction?
Secondary to cheek tooth disease
Correction may not be indicated
Which horses is smile/frown mouth normal in?
Correction?
Normal in donkeys (smile)
Correction not normally required
What is wrong with this horse?
Parrot mouth
Undershot jaw
What is shown here?
How can you fix it?
Diastema
Relatively common finding
Gaps develop between teeth
Usually age related
Food usually easily picked out
Can keep clean with old toothbrush!
What is the function of a canine teeth?
What is the problem with them?
- No function in domestic horse
- Traditionally ‘fighting teeth’ in the wild
- Mainly male horses (geldings/stallions)
- Maybe in dominant mares?
- Continually bathed in saliva
- Calculus build up – remove – as they have no use!
- Fractures/EOTRH
What age and breed of horse can wolf teeth be present in?
- Normal finding
- No purpose
- Up to 4/horse – 2 upper, 2 lower. Uppers more common
- Males and females
- Present from young age (6-18mo)
- Variety of sizes, shapes and location!
What are some indications of wolf teeth removal?
- Large
- Unerupted (blind)
- Abnormally positioned
- Lower
- Fractured/loose
- One side only??
- Technically shouldn’t affect bit, but O often wants them removed!
What do sharp enamel points occur due to?
- Anisognathic anatomy
- Continual eruption of teeth
- Eruption rate exceeding wear (diet)
Where do sharp enamel points normally occur?
- Buccal aspect maxillary teeth
- Lingual aspect mandibular teeth
What can sharp enamel points cause if left untreated?
If left untreated can cause painful ulceration – tends to happen further back in the mouth more often than not
What are excessive transverse ridges?
What should you do?
Regular ridging to cheek teeth is normal
-Enables horse to chew effectively
Sometimes ridges are overly large
Can pack food into diastemata
Should be reduced to normal height if necessary
-Never flattened completely!
Teeth come in pairs - what happens if one half of the pair is missing/damaged/displaced?
‘Over eruption’ may be better term!
Teeth normally in pairs – upper and lower oppose each other
If one half of the pair is missing/damaged/displaced then remaining tooth becomes dominant – going to affect ridden work and the way the horses can eat as well
Other than missing/displaced teeth - what else can cause an overgrowth?
- Developmental (asynchronous eruption)
- Post extraction
- Post fracture
- Abnormal jaw alignment (parrot/sow mouth)
How many deciduous teeth do horses shed throughout their life?
Horses shed a total of 12 deciduous teeth throughout their life
- 2.5-4 years old
- Have a full mouth by age 5
What is the most painful dental condition?
Diastema
What can cause diastemas of the cheek teeth?
- Can b developmental due to teeth growing too far apart
- Increasing age – gaps forms
- Displaced/rotated teeth
- Valve (gap wider towards gum) vs Open
- Valve more problematic – food can get trapped and cannot escape again
- Wider at level of gingiva
- Food trapped and can’t escape
What are the 2 different types of diastemas?
Which is more problematic?
Valve - more problematic, food can get trapped and cannot escape again. Wider at level of gingiva
Open
What is the treatment for a diastema?
- Treatment can be challenging – management!
- Balance mouth (remove sharp points/excessive ridges)
- Flush/pick out food
- Pack gaps with putty?
- Widen? Esp valve diastema to allow food to espcape
- Remove tooth/teeth? To prevent food from getting trapped
- Regular visits (often <6 months)
- Sedation – painful!!
- Pain relief/local anaestheti
- Antibiotics??
- May resolve in young horses – due to dental drif
- Symptoms may improve with age in some older horses – become wider, roots are narrowe
- Periodontal disease may lead to early tooth loss/apical infection – important to recognise early and manage
What are caries?
Decay and crumbling of a tooth or bone.
What are the 2 types of caries?
- Peripheral (surrounding edges of teeth) – affect cement around edge of teeth
- Infundibular (centre of upper cheek teeth)
Where are peripheral caries more commonly found?
What is the treatment and management?
- More commonly found towards back of mouth
- Lack of saliva buffer
Treatment:
- Remove sharp enamel points
- Smooth surface to discourage food from sticking
- Flush diastemata (if present) – often associated
Management:
- Diet modification (avoid acids/sugars)
- Regular dental treatment
Where do infundibular caries affect, what is it potentially liked to?
What can it progress to?
What is the treatment?
- Upper cheek teeth affected only – unique structure – extra channels in the middle of them to increase the SA
- Potentially linked to tooth development
- Can lead to tooth fracture if progresses
- Treatment involves filling affected teeth
- Complex, specialist procedure
- Can prevent future fracture
- Remove from occlusion if referral not an option – grind them down a bit so horse isn’t chewing on them
What can cause loose teeth?
- Tend to occur with age
- Teeth shorter overall length
- Reduced periodontal attachment
- Easier to remove? Technically – not always the case!
What is the treatment for loose/displaced teeth?
- Extract if loose
- Extract if displaced?
- Round edges so don’t impinge on soft tissues/cause ulceration
- Flush out packed food (as for diastemata)
- Ongoing management likely
What is the problem with fractures?
- Quite common
- May cause few issues/may be very painful
- May lead to apical (root) infection
- X-rays may be required
- Extraction can be challenging!
- Saggital fractures in upper cheek teeth most likely to cause infection – can cause sinusitis and secondary infections
What is shear mouth and what is it caused by?
- Abnormal angulation of the teeth
- Caused by eating on one side of mouth
- Usually dental pain
- Can be conformation
What is smooth mouth?
What problems does this cause?
How can you manage it?
- Worn out cheek teeth
- Old age
- Overly aggressive dental work?? Possible in younger horses leads to premature smooth mouth
- Can’t chew effectively
- Dietary management required
- Often do very well!
WHat are some congenital/developmental defects of the teeth?
– Parrot mouth – simple hereditary line
- Wry-nose (shown below) – poss hereditary? Maybe due to position in uterus also
- Missing teeth
- Supernumerary teeth
- Neoplasia – rare, classified by tissue type
What can cause wry nose?
Thought to be inherited, but also malposition in utero. Functional and cosmetic results may be achieved with surgery
What are the signs of cleft palate?
What is a possible treatment?
Cleft palate: dribbling milk after suckling, milk at nostrils. Surgical correction possible, but difficult and fraught with complications. Depends on severity.
What do supernumerary, malerupted, missing teeth: result from?
What do they need?
Supernumerary, malerupted, missing teeth: result from inappropriate differentiation of dental germinal tissue during gestational development. Incisors more common than cheek teeth. Supernumerary incisors can be cut or floated if not in wear. Most common excess cheek tooth is a fourth molar, may erupt lingually or bucally if no room in arcade. Need at least annual reduction. Maleruption of 3rd cheek tooth most common, last tooth to erupt, can get stuck => malpositioning in arcade
What is wrong here?
Incisor abnormalities – retained deciduous teeth
What is wrong on this radiograph?
Overgrown teeth
What are some dental treatment techniques that vets often use?
- Reduce sharp enamel points/ETR
- Reduce dominant/overgrown teeth
- Extract wolf teeth
- Radiographs
- Tooth extraction
- Sinus flushing/sinus flaps
- Remove hooks and enamel points, reduce overgrown teeth, re-align incisors, make sure three points of pressure even
- Wolf teeth extraction if necessary, controversial
- Radiographs to identify: caps, diastema, tooth root infections, dental sinusitis, fractures
What is wrong here?
Cheek tooth root abscess
What are some advanced dental techniques?
- Fracture repair
- Wry nose
- Ameloblastoma/tumour removal
- Parrot teeth correction/braces
- And many more…
What is wrong here?
Ossifying fibroma
More common in young horses up to 2 years old
