Five most commonly misdiagnosed pathologies

The basis for any accurate diagnosis is a thorough knowledge of the discipline of dental disease. The more one knows how to recognize the pathology and the prognosis for the condition, the more accurate the eventual diagnosis and treatment plan will be.

Radiographs can supplement the ability to evaluate the dentition below the gingival margin.

Arriving at the most definitive dental diagnosis requires a combination of four and often five avenues of approach. These are visual, tactile sense, dental radiography, dental probing, and often sedation or general anesthetic.

Two-thirds of the normal adult dentition is located beneath the gingival margin. An even larger percentage is subgingival prior to the exfoliation of the primary teeth. As a result, evaluation of the complete dental health of our patients often is extrapolated simply from the appearance of the dental crowns and to a much lesser degree, the mobility of the tooth.

A much more accurate evaluation will be obtained by augmenting with other diagnostic modalities. In dentistry, these are the periodontal probe, metal hand explorers and dental radiographs to supplement our ability to more accurately evaluate the dentition located below the gingival margin. It is highly recommended the use of these modalities become as routine and indispensable as the stethoscope and otoscope in the traditional veterinary health examination.

Not every patient must be sedated to evaluate the integrity of the oral cavity. But when probing subgingivally — which often requires accurate measurements within millimeters, dental radiography etc. — a high degree of patient compliance is required. Unfortunately, our veterinary patients aren't as tolerant of these diagnostic procedures as humans. Thus, required compliance can be acquired only by chemical means (anesthesia) in many instances.

As we will see, the inability to visualize the entire dentition and supporting structures leads to four of the five most common misdiagnoses we encounter in veterinary dentistry.

1. Inaccurately evaluating the periodontal state of the dentition.

Simply relying on visualization of the dental crowns to evaluate periodontal health of the patient leads to the most common misdiagnosis in dentistry. This is especially true if one relies on calculus formation as a basis for degree of periodontitis.

When plaque lies relatively undisturbed in the sulcus surrounding the tooth, an inflammatory reaction occurs. The floor of the sulcus with its boney labial plate and supporting alveolar bone all around the tooth recedes and is eventually lost. The soft tissue of the gingiva usually recedes at a much slower rate, obliterating the boney labial plate destruction from view. As result, the degree of disease tends to be under appreciated. (See Photo 1.)

Photo 1: Visually, the periodontal health of this canine tooth appears normal. Periodontal probing reveals the tooth has lost 12 mm of support bone.

Because periodontal disease occurs subgingivally, the primary method to evaluate the degree of destruction accurately is through the use of the periodontal probe, and when indicated, dental radiology. By the use of these instruments, the sulcus depth and loss of support bone (attachment level) can be determined, charted and a specific plan of appropriate therapy initiated. (See related story)

2. Extracting teeth (proclaiming them hopeless prior to accurate evaluation).

Old habits can die hard! The accepted treatment of choice for many years was simply to ignore the problem or extract.

Ask yourself: Would you like to save these teeth if they were yours? Humans primarily need our dentition for chewing food and cosmetics. Our patients, on the other hand, require teeth for mastication and as a substitute for their lack of hands. Consider how important your teeth would be if you had to pick everything up in your mouth instead of your hands! Our patients won't starve to death if they lose their teeth, but their quality of life certainly will suffer.

There are many teeth presented in practice every day that are truly hopeless and should be extracted (see related story). There are many more, however, that can be of service to the patient for years to come. Only by accurate dental diagnosis can we decide the proper therapy choice for each tooth.

3. The number and severity of Feline Resorptive Odontoclastic Lesions (FROL)

FROLs are, due to their nature, extremely hard to evaluate by visualization alone. The lesion, as a small area, usually starts at the junction of the enamel with the root. This location often is hidden by the gingiva, making detection without probing almost impossible. This is especially true due to the tendency for feline gingiva to migrate into the cavities created by the odontoclastic lesions. The lesion then tends to destroy the tooth from inside out by extending both into the root and under the enamel of the crown. Often the crown is affected visually only after the tooth has been destroyed internally.

Due to the hidden nature of this pathology, the evaluation of the entire tooth through radiology and probing plays an extremely important part of the diagnostic approach in the evaluation of these often painful lesions. An early detection, extent of the lesion and determination of treatment options are desirable.

4. Prognosticating teeth without radiographs.

It is common for the practitioner to be called upon to evaluate and handle a myriad of dental situations, such as:

• Extraction of a permanent tooth due to mistaking it for a deciduous tooth,

• Determination of whether all the permanent teeth are present in a puppy prior to their eruption,

• Is there an unerupted permanent tooth below the surface where there is an apparent missing tooth?

• Is an erupted tooth deciduous or permanent?

All of these scenarios can be answered readily with confidence by the use of dental radiography.

5. Endodontically involved teeth.

The endodontic system's integrity of a tooth can be exposed to the oral environment in a number of ways. The most common in veterinary dentistry is a fracture of the tooth's crown deep enough to expose the root chamber and its pulp. Deep carious lesions, FROLs, congenital malformations of the tooth and idiopathic pulpal necrosis also can create endodontic disease. (See related story)

Unlike the four previous misdiagnoses, usually the fact that the tooth's pulp has been exposed to the environment is enough, in itself, to diagnose endodontic disease. Radiographs of the tooth are indicated to demonstrate how advanced the pathology has progressed. But lack of radiographic evidence of endodontic disease does not rule out endodontic involvement, especially if pulpal exposure is evident. It simply means there has not been enough boney change to been seen on the radiograph yet. It often requires about 40-percent bone loss to be detectable upon X-ray.

Occasionally, the opening into the pulp is so small it has to be demonstrated with a small diameter explorer or endodontic file. In the case of malformation of the tooth, it might not be possible to demonstrate the breach into the root system. In these cases of very small outward exposure, there is usually a relatively obvious radiographic evidence of endodontic disease to confirm the suspected diagnosis.

It has been said often but cannot be over emphasized: The recognition of endodontic disease is important because ignoring the problem is not an option. The tooth either should be treated and saved or extracted. Otherwise the infection is progressive and relentless as well as leaving the patient at risk for anachoretic infections.

Dr. Mulligan is a founding diplomate of the American Veterinary Dental College. A frequent lecturer and author, he is retired and based in El Cajon, Calif.