Tumors of Dental Origin

Odontomas are benign tumors that arise from dental tissue in an animal's mouth. These tumors can be quite invasive, most commonly affecting the maxilla or cheekbone. They can be surgically removed, but the procedure requires aggressive, extensive resection of bone, tissue, and sometimes teeth. Surgeons from Purdue University School of Veterinary Medicine, including Sabrina Brounts, DVM, resident in large animal surgery, have published a case report detailing the surgical management of two young Quarter Horses diagnosed with a specific form of odontoma not previously reported in horses--compound odontoma, in which tissues resemble misshapen teeth.

The first case was a 9-month-old Quarter Horse colt with a six-month history of a firm, painless mass growing on the right mandible (jawbone). There was no evidence of infection, so the decision was made to surgically remove the mass. One premolar and one molar also had to be removed. In addition, a collection of tooth-like structures, known as "denticles," was found near the mass. Brounts explains, "A denticle is a tooth-like structure, only smaller and distorted--not as we see a tooth in the mouth." Histologic analysis confirmed that the mass was indeed a compound odontoma. The tumor was removed, but the mandible was fractured in the process and had to be repaired using an external fixator. There was also a large defect in the mouth where the tumor once sat that had to be packed with gauze until granulation tissue could fill it in, so the colt had to be fed through an esophageal tube. At six-month and three-year follow-up visits, there was no evidence of tumor regrowth or any problems eating, despite the loss of two teeth.

The second case was an 11-month-old Quarter Horse filly. The differences in this case were that the mass appeared on the left maxilla, and after 7 1/2 months the filly developed a thick, cloudy discharge from the left nostril. Radiographs revealed that the mass was in the left maxillary sinus and had areas consistent with dental tissue. The filly was taken to surgery, and the mass, also a compound odontoma, was removed along with one premolar. The surgical defect left an opening between the mouth and sinus, which was packed with dental wax to keep food out of the sinus. Unfortunately, seven days later it was apparent on radiographs that numerous denticles remained in the sinus, so a second surgery was conducted to remove more tissue and three more teeth. Five months after the first surgery, more abnormal tissue was seen at the surgical site. This tissue was removed by curettage through a hole in the sinus. In addition, a dental bridge was constructed to replace the dental wax and extend healing time in the mouth. Four years later, there was no evidence of tumor regrowth.

Brounts, S.H.; Hawkins, J.F.; Lescun, T.B.; et al. Journal of the American Medical Association, 225 (9): 1423-1427, 2004.

About the Author

Susan Piscopo, DVM, PhD

Susan Piscopo, DVM, PhD, is a free-lance writer in the biomedical sciences. She practiced veterinary medicine in North Carolina before accepting a fellowship to pursue a PhD in physiology at North Carolina State University. She lives in northern New Jersey with her husband and two sons.

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