Equine Dentistry: September 2014

Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH)

This 17-year-old warmblood geldng first presented in 2009 after having fractured the left mandibular 3rd incisor. The photos above reveal mild gingivitisof the left maxillary 3rd incisor and the retained root of the left mandibular 3rd incisor. These are the radiographs obtained at the initial examination:

There is marked tooth resorption of the left maxillary 3rd incisor that has resulted in a pathologic fracture at the junction of the clinical crown and the reserve crown, just apical to the gingival margin. The same process has occurred in the left mandibular 3rd incisor. Note that all the mandibular incisors have small areas of tooth resorption in the middle 1/3.

Treatment at that time consisted of surgical extraction of the left maxillary and mandibular 3rd incisors:

One year later, the patient presented for re-evaluation, with notable mobility of the right mandibular 3rd incisor. As seen in this photograph, there has been progressive gingival recession and feed packing between the left mandibular 2nd and 3rd incisors. The radiographs reveal progression of the tooth resorption in the mandibular incisors, as well as excellent healing of the prior extraction sites.

Treatment consisted of surgical extraction of the right mandibular 2nd and 3rd incisors

The patient was presented again this week (4 years from the last visit) for extraction of the remaining incisors. This photo shows the progression of gingival recession, gingivitis and feed entrapment between the maxillary incisors.

This case is representative of the progression of tooth resorption and periodontal disease associated with EOTRH. The cause of this disease in horses remains elusive. Treatment of this painful condition is extraction of affected teeth. Since this disease often affects the 3rd incisors first, management may initially involve extraction of the maxillary and mandibular 3rd incisors. Once the remaining incisors are more severely affected, extraction of all the incisors is indicated. This is the post-operative photo and the extracted incisors. While is it possible to perform a primary closure with mucoperiosteal flaps, tissue contracture and forces exerted on the flap during eating frequently result in dehiscence. Therefore, absorbable sutures are sued to support the gingiva and the alveolar blood clot, and healing occurs by second intention. Here, #1 chromic catgut was used.

Clients often balk at extraction of all incisors. However, they should be assured that these patients do extremely well post-operatively and are able to graze with out difficulty. This video shows a patient happily grazing 2 weeks after all incisors were extracted:

Side effects of this procedure are limited to occasional slight protrusion of the tongue, as seen in this horse:

This is an imaged captured using an oral endoscope. This instrument gives a very detailed image of the structures within the mouth, which were previously only observed with a large dental mirror. In this photo of the occlusal surface of the right maxillary 1st molar, feed material is present in defects overlying the 5 pulp horns. This occurs with pulp necrosis (death of the pulp); healthy pulp is responsible for production of new dentine overlying the pulp as the tooth material on the occlusal surface wears away (attrition).

In addition to still images, the endoscopy can be recorded in video clips. This type of examination is extremely important in identifying oral pathology and aiding in the formulation of a treatment plan.In this case it supported the radiographic diagnosis of apical (tooth root) abscess of the right maxillary 1st molar. This is the radiograph and the extracted molar::