By Brent L. Wilson RVT, VTS (dentistry)

Dental radiographs have become common practice even in veterinary clinics that perform only routine teeth cleaning and polishing. Although not an unusual occurrence during professional teeth cleaning, the presence of unerupted adult teeth may often be overlooked during routine oral examinations. As a result, the possibility of tooth impaction may not be adequately conveyed to the pet owner. Granted, an oral examination on a rambunctious young boxer or the space confinements on that 8-lbs. Maltese may inhibit the visualization of this hidden threat. To ensure adequate examination, use the spay or neuter visit, which usually happens at five or six months of age, to perform a dental radiograph. Further, make sure everyone working on a particular patient is adequately trained in the proper dentition of a dog or cat, so they can quickly spot missing teeth—or any other abnormality—and alert the veterinarian and owner.

More times than one may think, missing teeth may actually be impacted, which results in a condition that can be very serious for the patient. Dentigerous cyst formation can deteriorate much of the surrounding bone in which the impacted tooth is embedded. Although these cysts are not malignant, they destroy the surrounding alveolar bone as they expand, resulting in the loss of adjacent teeth. Unfortunately, the patient may never alert the owner to any pain or discomfort. In fact, enough destruction can occur over a short period that it leaves the bone vulnerable to fracture.

Missing teeth is a common occurrence in many breeds and can become something that is overlooked and even thought of as a "normal" finding. However, if you are not radiographing for missing teeth, you may not know they are there. The case described in this article is extremely rare for a general practice. Although any tooth can suffer impaction, it is unusual or "rare" to find a patient's large lower molars to be impacted. In my almost 15 years of radiographing every dental procedure—whether for a simple cleaning or actual conformation of missing teeth—finding the lower large molar impacted is extremely uncommon in my opinion. Fortunately, the diagnosis potentially saved this dog from a painful and debilitating condition.

Why radiographing for missing teeth matters

Presenting for castration in May 2018, Thor, a boxer-mix rescue approximately 10 months of age, had a routine oral exam whereby several missing teeth, along with abnormal crowns, were observed (Figure 1). His preliminary examination, including a full chemistry panel and complete blood count (CBC), revealed nothing to contraindicate general anesthesia. The castration was completed and at discharge, the owner was advised of the dental findings, along with the recommendation for further dental evaluation, possible extractions, and dental radiographs to confirm missing teeth.

In August 2018, Thor presented again for his scheduled professional dental cleaning. His preanesthetic examination again revealed nothing of concern and he was cleared for general anesthesia. A thorough cleaning and periodontal evaluation was performed whereby numerous teeth were observed suffering from enamel hypoplasia and deformed crowns. Several teeth were extracted due to their deformity and clinical findings. Full-mouth radiographs were performed, especially of the missing lower premolar #408 where discovery of its impaction was confirmed (Figure 2). Thor recovered well from this event and the owner was informed of the findings and potential danger regarding dentigerous cysts.

Two months later, Thor presented again for his scheduled dental therapy, which consisted of removal of the impacted lower premolar #408.

Given the deep location of the tooth, the patient was placed in dorsal recumbency and the area on his lower-right mandible below tooth #408 was surgically prepared. A hypodermic needle was placed and further radiographs were performed to help determine the exact location of the impacted premolar within the mandible (Figure 3). A surgical incision was created and the underlying mandibular bone was exposed (Figure 4). Using a #8 round bur and copious lavage with sterile saline, the mandibular bone was slowly removed until tooth structure was visualized (Figures 5 and 6).

With the location of the tooth structure determined, a winged elevator was used to begin elevation (Figure 7). Even with an impacted tooth, the periodontal ligament can be intact and produce as strong a hold as any tooth that erupts normally. With proper elevation technique using a winged elevator and exercising patience, the impacted tooth was elevated and removed completely (Figures 8 and 9). The entire alveolus in which the tooth was embedded was debrided to remove potential remnants of a cyst lining the alveolus. It is extremely important to debride the alveolus well, since any retained cyst material can continue to progress and destroy bone. Post-extraction radiographs confirmed complete removal. A follow-up dental radiograph three months later showed adequate healing and supportive bone growth.

As stated earlier, if you are not radiographing for missing teeth, you may not know they are there. Being familiar with dog and cat adult dentition and their dental formula is important. With practice, both the veterinarian and technician can quickly and easily make an observation, exposing a hidden threat that may otherwise be overlooked.

Brent L. Wilson, RVT, VTS (dentistry) has been a registered veterinary technician in North Carolina for the past 28 years and has held his VTS in dentistry credentials since 2008. He has been employed by All Animals Veterinary Hospital in Sanford, N.C., since 1990 and enjoys the challenge of oral health issues facing the majority of patients seen from simple cleanings to more extensive procedures, such as the ones described in this article.