A severe infectious or nutritional problem may also result in improper enamel production. In these cases, most or all of the
teeth are affected but only in a small part of the crown, usually a horizontal circumferential strip.6 Canine distemper was a common cause of this condition in the past.2 Improper enamel production may also result from a hereditary decrease in the amount of enamel matrix applied to the teeth
during development.12 This condition is known as amelogenesis imperfecta. In these cases, almost all teeth on almost all surfaces are involved.
Diagnosis
Regardless of cause, the areas of weakened enamel will flake off and expose the underlying dentin. Dentin is a porous material
and becomes stained easily. Consequently, areas of enamel hypocalcification will generally appear tan to dark-brown and pitted
and rough (Figure 20). The tooth surface is hard, however, as opposed to the soft and sticky surface of caries.
The dentinal exposure will result in marked discomfort for the patient.6 Each square millimeter of crown surface contains 45,000 dentinal tubules, each of which communicates with the root canal
system. Dentin exposure will change the fluid dynamics within the dentinal tubules. The change in fluid velocity within the
tubules is translated into electrical signals by the sensory fibers located within the tubules or subjacent odontoblast layer.
These signals result in the sensation of pain (or sensitivity) within the tooth.16 It is rare for veterinary patients to exhibit this discomfort, but occasionally anorexia will result. These exposed dentinal
tubules can also act as a conduit for bacterial infection of the root canal system. The tooth surface roughness results in
increased plaque retention, which speeds the onset of periodontal disease. For all of these reasons, promptly treating these
teeth is critical.
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In cases of widespread hypocalcification, it is common to find malformed roots as well; many times there is little root structure
(Figure 21). While endodontic infection of these roots is rare, the lack of root structure will result in early exfoliation secondary
to trauma or periodontal disease.
Treatment
Treatment is aimed at removing sensitivity and avoiding endodontic infection by occluding the dentinal tubules as well as
smoothing the tooth to decrease plaque accumulation. The most efficient and aesthetic way to accomplish these goals is to
place a bonded composite restoration (Figure 22). This procedure is performed by removing the diseased dentin with a diamond or finishing dental bur or polishing disk. Next,
a commercial bonding agent is applied, and a composite resin is placed and roughly shaped to natural tooth contours and then
light-cured. The restoration is then shaped and smoothed with a diamond bur or sanding disk. Finally, a coat of unfilled resin
is applied for optimum smoothness and shine. In very small teeth, the unfilled resin alone may be sufficient.
If the damage is severe and the client is interested in a permanent correction, crown therapy can be performed. Alternatively,
extraction may be performed, but this is not the recommended course of therapy if the tooth has a normal root structure and
no evidence of endodontic infection.
ORAL PAPILLOMATOSIS
These papillomas are most commonly induced by a papovavirus, but they can be idiopathic.17 They are usually transmitted by direct contact, but indirect contact may also be sufficient. There is generally a two- to
six-month incubation period.18 These papillomas are most commonly seen in young dogs as white, gray, or flesh-colored masses on the oral mucosa (Figure 23). They can be solitary or multiple lesions spread throughout the mouth on the palate, tongue, or oropharynx. The papillomas
are usually pedunculated or cauliflower-shaped. Size may range from a few millimeters to a few centimeters.18
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