PMC4672169_01
An intraoral photograph of the dog in dorsal recumbency with ORNJ of the left maxilla (Case 5). There is an area of soft tissue necrosis at the level of missing left maxillary first molar tooth with underlying exposed necrotic bone covered partially by debris and hair. Note also the severe abrasion of all remaining teeth.
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F1
Clinically, ONJ lesions were characterized as bone and soft tissue necrosis of variable extent (Figure 1), regardless of evidence of tumor recurrence, and such lesions were detected in 13 cases.
An intraoral photograph of the dog in sternal recumbency with ONJ of the right mandible (Case 9). There is an extensive area of soft tissue necrosis with underlying exposed necrotic bone noted from the distal root of the right mandibular first molar tooth to the level of missing right mandibular third molar tooth. Note an uncomplicated crown fracture of the right mandibular first molar tooth. There is a soft tissue mass noticeable at the buccal aspect of the lesion, suggestive of neoplasia. Biopsy confirmed recurrent SCC.
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F2
Recurrence of neoplasia (Figure 2) was evident on clinical and/or histopathological examination at the time of ONJ diagnosis in five dogs.
Intraoral radiograph, lateral view of the right (A) and left (B) caudal mandible of the dog in Figure 2. (A) There is an extensive area (all bone visible on the radiograph) of bony destruction, dominated by combined moth-eaten and permeative patterns of bone loss on the right mandible. Note also the generalized loss of definition of the mandibular canal, with a solid periosteal reaction, most prominent at the level of the distal root of right mandibular first molar tooth and missing right second and third molar teeth. There is horizontal and vertical bone loss at the distal root of the fractured right mandibular first molar tooth with furcation involvement. (B) Radiograph of the healthy left mandible shows minor horizontal bone loss at the mesial aspect of the left mandibular fourth premolar tooth and second molar tooth. There is a crown fracture of the left mandibular first molar tooth.
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F3
In three dogs where the mandible was involved, increased bone density with generalized loss of definition of the mandibular canal was diagnosed, with a solid periosteal reaction noted in one dog (Figure 3).
Skull CT of the dog (Case 5) showing the section at the level of maxillary molar teeth. There is extensive irregular osteolysis of the right caudal maxilla, palatine bone, and the rostral aspect of the zygomatic arch. There is remodeling of the caudal maxilla, palatine bone, and rostral zygomatic arch on the left side, where previous osteonecrosis was described (Figure 1). There is a missing left maxillary first molar tooth.
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F4
On CT, findings associated with the ONJ/ORNJ lesion were described as extensive and incomplete or irregular osteolysis (Figure 4) in five of six dogs, with one additional case demonstrating diffuse thinning of the mandible with multifocal pitting osteolysis (Figure 5).
Skull CT of the dog (Case 3) showing the section at the level of mandibular first molar teeth. There is a diffuse thinning and multifocal pitting osteolysis of the cortical bone of the right mandibular body, and the changes are most pronounced in the medial cortex.
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F5
On CT, findings associated with the ONJ/ORNJ lesion were described as extensive and incomplete or irregular osteolysis (Figure 4) in five of six dogs, with one additional case demonstrating diffuse thinning of the mandible with multifocal pitting osteolysis (Figure 5).
Regular (A) and polarized (B) histological image of the specimen from the dog with an ORNJ lesion of the mandible (Case 3). (A) The alveolar bone comprises primarily lamellar, osteonal bone with limited interstitial woven bone. The bone is necrotic, as evidenced by diffuse, empty osteocyte lacunae, and attached basophilic to eosinophilic biofilm (top of image). Multifocal, irregularly spaced, and shaped resorption bays are present within the alveolar bone (clear spaces/osteoporosis). Tooth dentin and a thin rim of cementum are evident at the bottom of the image. These eosinophilic matrices are more evident in the polarized image (B). A periodontal ligament is absent between the cementum and adjacent alveolar bone, consistent with ankylosis of the tooth.
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F6
Changes in the bone were described as locally extensive osteonecrosis with bone resorption and osteoporosis (Figure 6).