Page 768 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.1 The upper gastrointestinal tr act 743

VetBooks.ir 4.45 4.46

Fig. 4.45 This section of an extracted tooth shows
four vital pulp horns with one single necrotic pulp
(arrows).

cheek teeth. Mandibular teeth 307, 308, 407 and
408 are most frequently affected in the lower jaw
and maxillary teeth 108, 109, 208 and 209 are most
commonly involved in the upper jaw.
The aetiology of dental apical infections is unclear.
It is possible that the mechanisms for apical infection
are slightly different in maxillary and mandibular
teeth. It is probable that anachoretic (blood borne)
inoculation of the pulp via the apical vasculature Fig. 4.46 A unilateral maxillary swelling typical of
is the most likely mechanism. It has also been sug- apical pulpitis of the maxillary premolars (arrows).
gested that infundibular cemental hypoplasia, which
has been identified in ultrastructural examination of
maxillary teeth, may predispose to apical infection, rostral maxillary teeth are infected), sinusitis and
although this does not appear to be the mechanism discharging tracts (Fig. 4.46). It is probably painful
in all cases. However, the mandibular teeth lack initially, although many cases present chronically,
infundibula and are recorded with apical infections when the pulp innervation is necrosed and the con-
with a similar frequency to maxillary teeth. Bacterial dition apparently non-painful. Occlusal exploration
contamination of the pulp, after penetration of the with a probe will reveal dentinal occlusal fissures in
porous dentine on the occlusal surface, or subse- over 50% of cases and these should be considered
quent to fissure fractures as occurs in humans, may significant, especially in conjunction with diagnostic
be an initiating event. It has also been suggested that imaging changes (Fig. 4.47).
congenital enamel defects predispose to structural
weakness in the tooth, which when exposed to the Clinical presentation
forces of mastication result in fractures that create Unilateral maxillary and mandibular swellings, with
physical communication between the occlusal sur- ipsilateral submandibular lymphadenopathy are
faces and pulp cavities of a tooth, resulting in pulp typical. Eventually, the apical infections can absces-
infection. The pathological fracture of teeth along sate and discharge through tracts in the thin ventral
such fault lines is commonly observed in maxillary mandible for affected lower teeth. Maxillary apical
cheek teeth but rarely in mandibular teeth. infections rarely discharge through the maxillary
Pulpitis presents as clinically detectable unilat- bone, except after aspiration or trephination over
eral swellings on the mandible and maxilla (when the swelling is attempted. Caudal (Triadan 08–11)