Additional evaluation tips
Evaluate a suspicious periapical lucency, especially in the area of the mandibular premolars, with an additional film exposed
at a slightly different angle (in the horizontal or vertical plane). If the radiolucency is still centered on the apex, it
is likely a periapical lesion. If the lesion moves off the apex or disappears, it may be an artifact, normal radiographic
anatomy (i.e. mental foramen), or some other pathologic process.
Compare any suspect changes in the width of the root canal of a tooth against the surrounding teeth as well as the contralateral
teeth. Evaluate surrounding teeth on the same film as the suspect tooth. The contralateral view should preferably be taken
at the same angle as the original. It is important to note that root canals are not exact cylinders, especially those in canines.
A lateral view may have a much different canal width than a more vertical one (Figures 7A & 7B).9
Figures 7A, 7B, 8, 9, 10, 11
Finally, a thin white line will be seen over the maxillary canines and premolars (Figure 8), which is the confluence of bones between the palate and maxilla.5
Periodontal (alveolar) bone loss results from a combination of a bacterial infection and an inflammatory host response creating
osteoclastic bone resorption.10 Alveolar bone resorption causes the loss of the tooth-supporting structures, which appears radiographically as crestal bone
loss to a level below the cementoenamel junction.1,11,12 This decrease in bone height may also expose the furcation. Horizontal bone loss is the most common pattern in veterinary
patients.10 This pattern appears as generalized bone loss of a similar level across all or part of an arcade (Figure 9).13 The other pattern is vertical (angular) bone loss, which appears as a single area of recession below the surrounding bone
(Figure 10).13 The surrounding bone may be normal or may be undergoing horizontal bone loss. Thus, it is common to have a combination of
the two types in the same arcade.
Bone loss does not become radiographically evident until 30% to 50% of the mineralization is lost.13 Thus, radiographic findings will always underestimate bone loss. In addition, bone loss on only one surface (i.e. lingual, palatal, or facial) may be hidden by the superimposition of bone or tooth, which may result in an undiagnosed bony
pocket. Always interpret radiographs in light of the complete oral examination findings.
Possible differential diagnoses for bone loss due to periodontal disease include neoplasia, trauma, a foreign body, endodontic
disease, bacterial or fungal bone inflammation or infection (osteomyelitis), or a systemic disease such as hyperparathyroidism.
Endodontic disease is defined either as tooth nonvitality or inflammation of the root canal system (root canal, pulp chamber,
and dentinal tubules).1,14,15 Vital teeth rarely have radiographic signs of endodontic disease. The classic radiographic signs are created by pulp death
and secondary infection of the periapical tissues (periodontal ligament and alveolar bone).
On radiographs, an individual tooth with endodontic disease may have one, some, or all of the changes listed below.1,8,16-18 However, only one needs to be present to establish a presumptive diagnosis of endodontic disease. Radiographic changes can
be classified as either changes in the surrounding bone or within the tooth itself.