Page 770 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.1 The upper gastrointestinal tr act 745

VetBooks.ir of the affected apex, which is often surrounded by 4.50
a region of radiopaque sclerotic bone (especially in
chronic cases). More subtle indications of infection
of a dental apex include loss of definition and widen-
ing of the periodontal space and loss of the lamina
dura denta. Occasionally in the presence of chronic
infection, a granular radiopacity is observed (termed
‘coral pattern’ or dental rhinitis) in the nasal cav-
ity, resulting from dystrophic mineralisation in the
nasal conchae. Dorsoventral projections are also
useful for imaging periodontal remodelling on the
buccal aspects of the maxillary cheek teeth or the
lingual aspects of the mandibular teeth. Comparison
with the contralateral tooth may facilitate detection Fig. 4.50 Lateral 45° oblique radiograph of the
of subtle dental apical changes. In chronic cases of ventral mandible of a 7-year-old horse showing a
mandibular apical infections with a discharging radiopaque probe placed in a draining mandibular
tract, additional radiographs should be taken after tract, which is demarcating the infected root of the
placing a radiopaque marker into the tract to iden- apex of cheek tooth 208.
tify the tooth and root involved (Fig. 4.50). Apical
infections of the caudal maxillary teeth may be asso-
ciated with sinus empyema, which is seen as fluid Apical curettage and drainage has been reported for
lines on erect lateral radiographs. Radiographs are successful treatment of mandibular apical infections,
neither very sensitive nor specific in detecting early although case numbers are small and the outcome
dental apical disease and additional ancillary tech- has been variable. Endodontic root canal filling
niques such as CT are more sensitive. Scintigraphy for cheek teeth with apical infections has also been
has been shown to be sensitive for detecting dental reported but with limited success, although the
apical infections, due to a focal radionuclide uptake success of these treatments is improving with bet-
over an apical infection. However, the poor specific- ter diagnosis, earlier intervention and imaging and
ity of scintigraphy does not enable such lesions to increased dental technical skill (Figs. 4.51, 4.52).
be confidently distinguished from localised primary Endodontic treatments that have been successful
sinus empyema. CT is much more sensitive due to involve identification of affected pulps, chemical and
the possibility of three-dimensional reconstruction mechanical debridement of necrotic pulp using an
that enables imaging of individual roots, multiple occlusal approach and obturation of the pulp canals
slice examination and the absence of superimposi- followed by occlusal restoration using composites.
tion that limits the sensitivity of radiographs. CT is The salvage of the tooth is attractive as exodontia
practiced routinely in standing horses and is desir- has consequences for occlusion and subsequent den-
able if endodontic treatments are to be considered. tal prophylaxis for the horse’s life. However, in many
cases, the infected tooth will require removal by oral
Management extraction, repulsion or lateral alveolar buccotomy
In young horses with wider apical foraminae, (Figs. 4.53, 4.54).
long-term (2–4 weeks) antibiotic therapy using
broad- spectrum antimicrobials (e.g. trimethoprim- DENTAL CARIES
sulphadiazine and/or metronidazole administered
p/o) can result in clinical remission. In older horses Definition/overview
with narrow apical foramina, it appears that despite Dental caries is the consequence of the action of
antibiotic treatment, a nidus of infected necrotic pulp cariogenic bacteria on mineralised dental tissues in
remains in the pulp cavity, resulting in only a tran- the presence of a carbohydrate substrate. It is collo-
sient clinical improvement in response to antibiotics. quially known as tooth decay in humans.