Dental Radiography in Relation to Sinus Disease

CHAPTER 50 Dental Radiography in Relation to Sinus Disease

In evaluating a horse with sinus disease, consideration of a dental origin is of paramount importance, and diagnosis necessitates quality radiographic and clinical examination. Survey films narrow the possible field of diagnosis. Intraoral radiographs reveal detailed information that can lead to more specific diagnosis. Understanding and appreciation of disease processes and early recognition and early intervention can arrest or reverse the disease process, thus resolving the problem while maintaining dental longevity.



Common dental lesions resulting in sinusitis include pulpitis of the dental apices of young horses, fractures or dental decay in any age horse, and periodontal disease especially in older horses. Not all root tips (dental apices) are in the sinuses. As a general rule, the apices of the first two cheek teeth, the 6’s and 7’s of the Triadan system, are not located in the sinus; the next two cheek teeth, the 8’s and 9’s, are almost always located in the rostral maxillary sinus; and the last two cheek teeth, the 10’s and 11’s, are located in the caudal maxillary sinus. The rule of thumb, therefore, is “2, 2, and 2,” meaning that the root tips of the first two are not in the sinus, the root tips of the next two are usually in the rostral maxillary sinus, and the root tips of the last two are in the caudal maxillary sinus.

In young horses, apical pulpitis develops most commonly in the 4th premolar, or 08 in the Triadan system, as it erupts between two previously erupted adult teeth. The so-called tooth bumps seen in young horses are a result of the eruption process. The apices may or may not be inflamed. When inflamed, they produce chemotactic agents that attract blood-borne infectious organisms, a process known as anachoresis. These organisms occasionally cause pulpitis, which occurs in varying degrees of severity. Some cases resolve spontaneously; others develop sufficient pulp response to wall off or otherwise resolve infection, and horses with more severe cases develop disease that results in pulp death. Any of these processes can result in sinusitis, diagnosis of which requires quality intraoral radiographs. Treatment varies with the condition.

Infundibular Disease

Dental decay occurs most commonly as infundibular disease. Indirect pulp exposure can ensue as decay breaks down enamel and dentin. Infectious agents thereby gain access to the pulp via dentinal tubules, and this can be followed by apical disease and sinusitis. Although unusual, this disease process generally results in tooth loss. Early recognition of infundibular disease and appropriate treatment can prevent this sequence of events.

An understanding of dental anatomy facilitates recognition and appropriate treatment of infundibular cavities. The occlusal surface of the equine tooth is composed of cementum, dentin, and enamel. The peripheral enamel is coated by cementum. Each upper cheek tooth has a pair of crescent-shaped infundibula variably filled by cementum. During development, the cementum fills the enamel-lined infundibulum from the occlusal surface apically. It is common for the infundibulum to be incompletely filled with cementum during the process of embryologic development. In many horses the apical portion of the infundibulum remains void of cementum throughout the horse’s life.

Infundibular disease begins when there is cemental hypoplasia. Decay begins within the cementum and progresses peripherally (apically) as cemental canaliculi fill with food residue and microorganisms. Continual decay involves the surrounding enamel and later the dentin.

Infundibular disease can be staged. In stage I teeth, the decay process, if present, is confined to the cementum and is restricted from expansion by the enamel border. In the vast majority of teeth, the disease remains limited to this stage. Few of these cases progress to stage II, which is defined as involving enamel. In some cases (stage III) the lesions extend to involve both the enamel and the dentin surrounding the infundibulum. In such cases, the dentin and enamel separating the two infundibula may be lost either by fracture or by further decay. The resulting coalescence of the two infundibula creates a large defect in the occlusal surface. As the grinding process of mastication occurs, the lower arcade moves across the upper arcade with both shearing and crushing forces. If any defects are present in the occlusal surface of either arcade, there is an increased risk of tooth fracture and an increased rate of attrition.

Degradation progresses peripherally from the infundibulum. It may progress apically but not necessarily. No measurement of the depth of involvement is used in this system of classification because it is complicated by the uneven nature of cemental hypoplasia and decay within the infundibulum and the variable depth of the enamel lining. Intraoral radiographs most effectively demonstrate the extent of decay. The general recommendation is to perform restorations on stage II and III cavities, but not stage I problems. Other decay processes can be restored to protect the pulp and prevent further decay and potential tooth fracture, all of which may result in premature tooth loss.

May 28, 2016 | Posted by in EQUINE MEDICINE | Comments Off on Dental Radiography in Relation to Sinus Disease
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