Equine Dentistry Flashcards
How is the equine mouth adapted to constant grinding and high forage diet?
- Interdental diastema
- limited rostrocaudal movement of the TMJ, lots of lateral movement
- TMJ allows occlusional contact of all cheek teeth simluataneously (though usually only 1 side at a time is grinding
- well developed masticatory musculature
- hypsodont (high crowned teeth, enamel extends beyond the gum line)
- irregular enamel ridges -> better grinding surface
What are the 3 strokes of mastication?
Opening, closing, power stroke (major pressure applied to one side at a time)
What may a preference for chewing on one side of the mouth indicate and cause?
May indicate pain/pathology
Will lead to further pathology due to innapropriate wear
What system of dental nomenclature is used for equine teeth?
Triadan
Outline the triadan system of dental nomenclature
First number indicates arcade, second indicates tooth
- Upper R (from horse’s POV) = 1
- Upper L = 2
- Lower L = 3
- Lower R = 4
>Numbered axial -> abaxial starting at central incisor 01->11
> Deciduous teeth labelled 5,6,7,8 -> young horses can look confusing!
What triadan number are the wolf teeth?
05
Which triadan numbers are the incisors?
01-04
Which triadan numbers are the premolars?
106-108
Which triadan numbers are the molars?
09-11
What is formed before a tooth is lost? How may this develop into a pathological state?
Cap - may be retained -> food stuck -> infection etc
What does anisognathism refer to?
Maxillary arcade wider than mandibular
What angle should the occlusional surface of the teeth be at?
10-15 deg
Which cheek teeth are often angled compared to the rest of the arcade?
1st and 6th
What is the upward slope of occlusional surface at caudal aspect of the mouth referred to as?
Curve of Spee
What 4 substances make up a normal cheek tooth? What may also be seen
- cementum (attaches to periodontal ligament and in infundibulum)
- dentine (bulk of tooth, tubular structure)
- enamel (hardest tissue, laminated sheets)
- pulp (blood/n supply to tooth)
> infundibulum (infolding of enamel from occlusional surface)
Where are infundibula found?
2 in each maxillary cheek tooth
NONE in mandibular
1 in each incisor
What pathology may be associated with the cementum?
Hypoplasia -> impaction of food, bacteria, gas bubbles
How thick is the secondary dentine layer?
2mm -> 1cm
Why may dental exams be carried out?
- routine annual checkup
- problems:
> swelling or discharging tracts of the mandible or maxilla
> weight loss
> quidding
> headshaking
> bitting problems
> unilateral nasal discharge
What are the 4 parts of the dental exam?
- Distant observation (esp. eating)
- External exam inc. BCS
- Head exam - symmetry, pain, swelling, LNs, nasal discharge
- Oral exam - incisors to check malocclusion (before speculum)
- interdental spaces for wolf teeth, canines, bitting and tongue injuries
- cheek teeth
How often do dental examinations need to be carried out for a) the healthy horse b) maintainence of a problem horse c) active remodelling of the teeth in a problem horse?
a) 12 months
b) 6 months
c) 3 months
Is sedation for a dental exam advocated?
Yes, though not necessary persay. Allows a more thorough examination
Give 2 common types of gag
Hausmanns gag, wedge gag for incisors (bne careful as may chomp on this -> Fx)
What should cheek teeth be examined for?
- buccal/lingual points, ulceration
- deciduous caps/remnants
- focal overgrowth eg. malerrupted tooth
- molar table angle 10-15deg
- wave/step mouth
- Fx
- excessive transverse ridges
- FBs
- periodontal disease
- Infundibular caries in maxilla arcades, peripheral caries elsewhere
Outline the pathophysiology of “points” - where are they found on mandibular v maxillary arcades?
- Buccal edge of maxilla, lingual edge of mandibular
- Concentrates encourage vertical chewing cf. forage (lateral chewing action) -> uneven attrition, impairs mastication movements -> further overgrowth vicious cycle
What are the effects of enamel overgrowth?
- prevent free movement of jaws
- oral pain -> quidding and weight loss
- bitting problems
- headshaking
- > SHEAR MOUTH (extreme cases)
How may shear mouth be treated?
Bute, diet mod (eg. wet hay), rasp in stages (~3 months) to protect secondary enamel - remember will be even thinner than normal on unworn sections of tooth
What secondary changes may occour with shear mouth?
Remodelling of muscles, ligaments and joints (eg. TMJ)
What are the two most common rasping blades?
Carbide chip blades (cheap, robust, routine work)
Tungsten carbide blades (expensive, brittle, only cut one way[pull], best for hooks etc.)
What 4 types of rasp are required for routine dental work?
- Straight head, long length (lower cheek, 3rd-6th upper cheek)
- Obtuse angled head, long length (caudal upper cheek teeth, curve of Spee) - low thin profile to get into upper buccal space
- Angled offset head, medium length (upper 1st-4th cheek)
- S float (smooth off first cheek teeth and 6th maxillary, bit seat, angle of curve of Spee) - carbide chip only
Are power tools advocated for rasping?
In some situations esp. if whole mouth is bad, removes hooks quickly BUT beware of slipping and causing unplanned damage!
- beware palatine artery - inside upper arcade ~1cm axial to arcade
At what ages should teeth be being shed? How may retained caps affect the horse?
2.5, 3 and 4 years
Retained-> anorexia, poor performance, malocclusion. Food gathers underneath, VFAs produced -> peridontal ligament breakdown
How can retained caps be treated?
Remove with forceps/screwdriver do not damage underlying permenant tooth beneath
Which teeth often overgrow?
106, 206, 311, 411 - rostral displacement of maxillary arcade (parrot mouth) or mandibular brachygnathism
Why may caudal hooks on the mandibular arcade be difficult to assess?
Curve of Spee means caudal teeth are raised anyway. Run finger entirely over last tooth to assess drop off the back.
What may cause focal overgrowths? What can this progress to?
Diastema, displaced teeth, lost teeth, Fx
-> wavemouth
How can focal overgrowths be removed? What care must be taken?
- Rasp
- Care: > do not expose pulp (white enamel on rasp -> pink. Non-occlusional surfaces have v 2dry dentine -> ^ risk of pulp exposure) -> apical tooth infections
> do not create excessive heat (40secs burning -> pulp necrosis)
> frank blood on the rasp more likely nicked a gum/buccal cavity than pulp - dont worry!
How would you prevent over rasping revealing the pulp?
Investigate secondary dentine depth with probe
Give prophylactic ABs if suspected
What may infundibular caries lead to?
Septic pulpitis
Are infundibular caries “normal?” What can they result in?
In horses >15 years normal (~80% horses affected)
- Usually benign
- Can lead to sagittal Fx of tooth
Does the appearance of infundibulea on the occlusal surface correlate with infundibulae in the body of the tooth?
No
Is reduction of traverse ridges advocated?
- Potentially removes usable clincial crown
- If necessary remove larger ridges but leave some normal ridging in places
What is thought to be the most painful oral disease?
Peridontal disease
- Ginvititis
- Periodontal ligament
- Alveolar disease
Is primary peridontal disease common? What are the breed dispositions and
NO - caused by diastemata. Mandibular cheek teeth most frequently affected, draft breeds predisposed . Incidence ^^ with age (60% horses >15%)
How does peridontal disease begin and what may ultimately occour?
- Localised gingivitis with pocket formation
- trapped debris stagnates
- feed compressed during mastication
- osteomyelitis (destruction of alveolar bone)
- bacteria enter pulp cavity through root canals
- usually begins in interproximal spaces (inbetween teeth)
> buccal surface of maxilla
> lingual surface of mandibular
What may be considered a normal finding in dental checks of old horses? How may this cause problems potentially?
Diastemata - due to narrow tooth roots compared to initial occlusal surface (overgrowth/displaced teeth may predispose)
- usually lower cheek teeth
- often clincially silent
- food may get trapped, cause pain and lead to quidding (smaller diastema more problematic than large)
- very rarely causes osteomyelitits
How may diastemata be treated?
- monitoring
- widening or extraction (take care not to cut into tooth)
- removal of impacted food (transient improvement only)
- replace long fibre foods with shorter (eg. alfalfa or grass)
- keep overgrowths opposite in check
What two ways may displacement of cheek teeth occour?
Developmental (overcrowding of arcades during eruption, often bilateral, usually 4/5th cheek teeth) or acquired (more common, usually lower 10/11th in old horses)
- May not require treatment just monitoring
Why may cheek teeth fractures occour? What may result?
- 2ndry to severe infundibular caries
- may lead to septic pulpitis
- can be the cause of aquired overgrowths
What is often the “final common disease pathway” of dental disease?
Apical tooth infection
What age is over represented with mandibular apical tooth infection?
5 year olds (5-7)
What are the clinical signs associated with mandibular apical tooth infections?
- assymmetrical jaw swelling (cf. normal symmetrical swellings in 2-3 year olds)
- ventral discharging tracts
- oral involvement RARE
- quidding (potentially)
- halitosis
- sub mandibular LN enlargement
Why may mandibular bumps be seen on a 2/3 year old? How may this be distinguished from pathological growths?
- dental buds and increased activity in the jaw
- if symetrical probably not pathological!
How are mandibular apical tooth infections diagnosed?
Radiography - halo around tooth root extends to base of jaw
What is the aetiology of maxillary apical tooth infections?
- Infundibular caries
- premature pulp exposure during wear
- pulp exposure after transverse Fx
- peridontal fistulation
- Iatrogenic due to rasping
- Idiopathic common also
Which cheek teeth generally communicate with the maxillary sinus?
caudal 2 communicate with caudal maxillary sinus
mid 2 communicate with rostral maxillary sinus
rostral 2 do not communicate
- can burst into nasal cavity (RARE)
Where are tooth apices situated?
In maxillary sinuses (rostral and caudal)
How would sinusitis present?
Unilateral nasal discharge
What is the best diagnostic for diagnosis of maxillary apical tooth infections (08-11)? What may these infections lead to?
- May lead to sinusitis presenting with unilateral nasal discharge
- Dx which tooth? (Oral exam often insufficient)
- CT best diagnositcs ( radiography sometimes useeful but rarely, scintigraphy too vague, sinoscopy rarely reveals anything specifc)
What imaging technique provides an alternative to mirrors?
Oral endoscopy - enables magnified visualiation of occlusal surfaces, and caudal parts of oral cavity
> difficult to disinfect
What can be visualised in a latero-lateral head radiograph?
- exudate within paranasal sinuses appears as fluid lines
- teeth apices are superimposed preventing visualisation so NOT USEFUL!
What radiographic angle is most useful to visualise apices? Which side should the plate be placed?
Lateral 45deg ventral lateral oblique -> reduced superimposition of mandibular apices
Plate placed on side you want to examine
What is the best way to decide if a latero-lateral radiograph is properly aligned?
Nasal cavities should be perfectly superimposed
Which cheek tooth is most likely to get a root infection?
09 (4th cheek tooth) as is oldest tooth in the mouth
What radiographic signs of dental disease may be noted?
- missing teeth
- malpositioning
- crown deformation
- radicular distortion (ragged appearance)
- loss of lamina dura denta (peridontal region lucency)
- periapical lucency (halo)
- cementoisis
- localised maxillary bone proliferation - osteitis (coarsening and compaction of bone trabeculae)
How is the diagnostic accuracy of scintigraphy described?
High sensitivity, low specificity
What may be detected by sinusitis?
Dental sinusitis
What are CT images composed of? What scale is used to measure these?
Voxels (3D pixels)
Measured in Hounsfield units (HU) - ^ in bone, v in air
What are the advantages of CT v xrays?
- avoids superimposition
- windowing
- view in multiple planes and dimensions
> expensive
What are the pros and cons of standing v GA
Risk of GA v motion blur from standing
What are the radiographic signs of apical tooth root infection?
- Periapical scleroisis
- periapical halo
- Cementoma formation
- Clubbing of tooth roots
What are the CT signs of apical tooth root infection?
- gas within bulging root area
- fragmentation of the root
- ^ pulp volume
- Abnormal pulp morphology
Why may supernumerary teeth cause problems?
Diastema -> food packing, infection etc.
How may older teeth be identified on radiograph?
Shorter tooth root
Other than rasping, how may apical tooth root infections be treated?
- Conservative ABs
- Currettage
- Tooth removal by repulsion, extraction [banged out from top] or lateral buccotomy (
What complications are associated with treatment of apical tooth root infections by repulsion? How many cases are affected by complications?
- 33% mandibular cheek teeth
- 33% maxillary cheek teeth without sinusitis, 66% maxillary with sinusitis
- orosinus fistula causes major problems as food -> sinus (pack with tampons and iodine, change ~24hrs)
> increased need for dental care postoperatively to prevent stepmouth
How does the complication rate for oral extraction v repulsion differ? Are these treatments equally easy?
> 1/3 (nowadays ~5%)
> difficult in caudal cheek teeth of young horses, but possible even in comminuted Fx/no occlusal surface
What tools are used to perform an oral extraction?
Separators to break ligaments
Molar grabbers
Falcrum to use as a lever
Which treatment for apical tooth root infection is minimally invasive?
Lateral buccotomy
What triadan number are the wolf teeth?
05 (1st premolar)
Are there deciduous precursors to wolf teeth? When do they erupt? When may they be lost?
No, erupt at ~1 year, many lost when 1st upper decidous cheek tooth “cap” shed
Are lower wolf teeth common?
No
Why may wolf teeth cause problems?
Bitting problems - advise extraction
What type of nerve block is used for wolf tooth extraction?
Infra orbital nerve block or local infiltration into gum
How are wolf teeth extracted? What vaccine is necessary? What complications may arise?
- Extensive elevation of the tooth
- tetanus
- attempted removal can lead to fracture and development of bitting problem not present previously
Are fractured incisors an emergency?
No
How should fractured incisors be treated? Is the proognosis good?
- starve
- pain relief
- ABs
- lavage wound
- mental foramen n block and cerclage wire to hold together
> good prognosis!
