Brook A. Niemiec
DVM, DAVDC, DEVDC, FAVD
Dr. Niemiec is chief of staff of Veterinary Dental Specialties & Oral Surgery, with 14 offices throughout the United States. He is a regular speaker on local, national, and international levels and was elected Clinical Instructor of the Year for the 2016 Western Veterinary Conference. He has authored many articles, chapters, and books and founded the veterinary dental telemedicine website vetdentalrad.com. Finally, he coordinates the San Diego Vet Dental Training Center, with 3 to 4 meetings per year covering basic and intermediate veterinary dentistry.Read Articles Written by Brook A. Niemiec
A 7-year-old, neutered male cat presented for a routine dental cleaning. Significant calculus and gingivitis were present throughout the mouth; halitosis and several missing teeth were also noted. The rest of the physical examination was unremarkable and the pre-operative workup was within normal limits.
Based on the level of oral inflammation, dental prophylaxis and examination, with likely extractions, were planned for the patient.
Following induction of anesthesia, a complete oral examination was performed, which confirmed moderate to significant calculus and gingivitis throughout the mouth. Oral examination also revealed a mobile right maxillary fourth premolar (108), with a 12-mm periodontal pocket (Figure 1).
- Calculus and gingivitis
- Missing teeth
- Mobile maxillary premolar with periodontal pocket
Based on this patient’s history and oral examination:
- What is your diagnosis?
- What treatment options would you recommend?
- The most likely diagnosis for a patient with heavy calculus and gingivitis, along with a mobile tooth, is advanced periodontal disease.1
- The best treatment option is extraction of the diseased (mobile) tooth.
However, dental radiography should be performed prior to all extractions, and full-mouth dental radiographs should be taken during every dental procedure, especially in patients with advanced periodontal disease.2-4
Prior to pursuing tooth extraction, a dental radiograph was exposed of the affected area in the patient’s mouth (Figure 2).
Based on this radiograph:
- Is advanced periodontal disease still the most likely diagnosis?
- Would you pursue tooth extraction or choose another treatment option?
The dental radiograph (Figure 3) reveals:
- Significant lysis of bone and a moth-eaten appearance (red arrows) surrounding the right maxillary premolar (108) (rather than bony destruction, which would be seen with advanced periodontal disease)
- Irregular, productive coronal radiation (lower red arrow) of the marginal bone that extends slightly mesial to #108 at the level of 2 tooth roots, most likely those of #106 and/or #107
- Tooth resorption evident on all 3 roots of #108.
- The significant bone lysis is consistent with a more aggressive process, most likely neoplasia.5
- In addition to extraction, treatment should include harvesting a section of bone and soft tissue from the affected area for histopathologic evaluation.
The biopsy revealed high-level squamous cell carcinoma (SCC).
Neoplasia is defined as abnormal growth of cells that is not responsive to normal growth control.6 Neoplasms can be further classified by their biologic behavior as benign or malignant.7,8
- Malignant oral neoplasms typically invade bone early in the course of disease, resulting in irregular bone destruction, which will have a mottled, moth-eaten appearance.
- Late in the course of disease, radiographs reveal a complete loss of bone (teeth will appear to float in space).
- If the cortex is involved, an irregular periosteal reaction may be seen as well as lysis of the cortical bone.
- In my experience, as many as 50% of oral SCCs are not characterized by the presence of a mass lesion and, instead, cause bone destruction (as was the case in this cat).
- Most benign neoplastic growths show no bone involvement on dental radiographs.
- If bone involvement does occur, it is expansive:
- The bone “pulls away” from the advancing tumor.
- This space fills with decalcified soft tissue.
- Tooth movement typically results due to this process.
Both malignant and benign neoplasms may have bone involvement, but benign masses usually have distinct bone margins (Figure 4), while the bone affected by malignant neoplasms has a moth-eaten appearance.
If oral masses or suspicious bone changes are noted on radiographs, histopathologic testing of biopsy samples is always necessary. Accurate diagnosis of oral masses is critical because a variety of benign and malignant tumors appear radiographically similar. SCC can be destructive (no mass) and/or productive (mass is present); as noted earlier, no mass was present in this cat.
In addition, osteomyelitis can create similar radiographic findings to those found in neoplasia. If bone lysis is seen on radiographs, or any other suspicious clinical findings are present, histopathology should be pursued.
To aid the pathologist, the practitioner should:
- Note the type and extent of bony involvement (if any) on the histopathology request form
- Include copies of the radiographs and intraoral pictures with the form.
Histopathology results must be interpreted in light of (and should agree with) the radiographic findings. For example, in this case, the radiographic evidence indicates malignancy; if the biopsy result had indicated a benign process, I would have questioned the result and investigated further.
As stated previously, the most common cause of tooth mobility is advanced periodontal disease. However, neoplasia also causes bone resorption and can create tooth mobility. Additional clues that mobility may be related to neoplasia rather than periodontal disease include:
- One quadrant having several diseased teeth while the remainder of the mouth is relatively healthy.
- The mobile tooth often lacks deep periodontal pockets; however, in this case, a periodontal pocket was present.
- Lack of calculus when the mobile tooth is extracted, indicating a quick loss of bone in the affected area and its lack of exposure to the oral cavity (exposure would result in calculus production).
Early and aggressive therapy is the key to successful management of oral neoplasia in the dog and cat. Unfortunately, treatment of feline oral SCC is very challenging, especially when SCC is advanced:
- The minimum 2-cm margins typically recommended for removal of malignant masses are difficult to achieve in feline patients.
- These tumors in feline patients are poorly responsive to other modalities, such as chemotherapy and radiation therapy.9
Referral to a veterinary dentist, surgeon, or oncologist is recommended for optimal therapy.
AAHA’s Guidelines Highlight Importance of Dental Radiography
The 2013 AAHA Dental Care Guidelines for Dogs and Cats clearly outline the importance of dental radiography in all patients, regardless of whether visible pathology is present, stating that full-mouth radiography is “necessary for accurate evaluation and diagnosis.” It is also essential for proper treatment; the guidelines specify, “It is not until the oral radiographs have been evaluated that a full treatment plan…can be successfully made with any degree of accuracy.” Read the guidelines at aahanet.org/PublicDocuments/Dental_Guidelines.pdf.
AAHA = American Animal Hospital Association; SCC = squamous cell carcinoma
- Niemiec BA. Periodontitis. Veterinary Periodontology. Ames, IA: Wiley Blackwell, 2013.
- Niemiec BA. Dental Extractions Made Easier. San Diego: Practical Veterinary Publishing, 2013.
- Niemiec BA. Case-based dental radiology. Top Companion Anim Med 2008; 24(1):4-19.
- Verstraete FJ, Kass PH, Terpak CH. Diagnostic value of full-mouth radiography in cats. Am J Vet Res 1998; 59(6):692-695.
- Niemiec BA. Veterinary dental radiology. In Niemiec BA (ed): Small Animal Dental Oral and Maxillofacial Pathology: A Color Handbook. London: Manson Publishing, 2013, pp 63-87.
- Ogilvie GK, Moore AS. Managing the Canine Cancer Patient: A Practical Guide to Compassionate Care. Yardley, PA: Veterinary Learning Systems, 2006.
- Niemiec BA. Dental radiographic interpretation. J Vet Dentist 2005; 22(1):53-59.
- Deforge DH, Colmery BH (eds). An Atlas of Veterinary Dental Radiology. Ames, IA: Iowa State University Press, 2000.
- Ogilvie GK, Moore AS. Feline Oncology: A Comprehensive Guide to Compassionate Care. Yardley, PA: Veterinary Learning Systems, 2001.