Treatment of Odontogenic Cysts in Dogs

Introduction
Odontogenic cysts are cysts in the lower or upper jaw originating from dental structures. In dogs, odontogenic cysts are infrequently diagnosed and they are exceedingly rare in cats. Odontogenic cysts are characterized as expansive fluid filled lesions in the mandible, premaxilla, or maxilla with a partial or complete epithelial lining. Due to their slowly expansive growth the cysts deform the jaw bones and displace adjacent teeth. Malocclusion and mobility of adjacent teeth can be part of the clinical presentation. Clinically the cysts present as a swelling of the jaw bone often in combination with a swelling in the oral cavity. If odontogenic cysts are located in the premaxilla or maxilla compression and displacement of nasal structures can occur. In severe cases unilateral but also bilateral obliteration of the nasal airways can be found. In the majority of cases odontogenic cyst formation can be linked to retained teeth in the jaw bone. The inability of these retained teeth to erupt spontaneously is supposed to be the origin of the cyst formation. The embedded dental epithelium which is responsible for the enamel production during odontogenesis is held responsible for fluid accumulation. Odontogenic cysts in combination with retained teeth are also known as dentigerous cysts. Odontogenic cysts can also be encounterd is case of supernumerary teeth with an abnormal eruption pattern. Nevertheless, odontogenic cyst can also occur without the presence of retained teeth. In these cases cyst formation is again thought to originate from remnants of dental epithelium and the presentation is similar to that of dentigerous cysts. If the cyst is closely related to dental roots it is called a radicular cyst in analogy with human dentistry. Radicular cysts usually are small and present as an incidental finding during dental radiography performed for other reasons. An interesting group are the odontogenic cysts in combination with an ameloblastic odontoma. An odontoma is a benign tumor comprised of dental structures, including enamel, dentine, and cementum. The odontoma can differ in the degree of differentiation of the dental structures. In ameloblastic odontoma there also is a prominent presence of dental epithelium in combination with the aberrant dental structures. Although plain radiography is effective in showing the lytic bone lesions, computed tomography imaging is preferred to fully comprehend the extension of the cyst. Especially when the cysts are located in the premaxilla of maxilla CT imaging is essential. In addition 3-D reconstructive imaging can be advantageous in preoperative planning.  [...]