• Periodontium is composed of the gingiva, periodontal ligament, cementum, and alveolar bone.

• Periodontitis is active inflammation of the periodontium.

• Diastema is a space between teeth within the same arcade.

In the equine dentition, this would be abnormal except for the spaces between the third incisor and canine and the canine and first premolar (or second premolar).

An abnormal diastema tends to collect feed material. Periodontal disease may or may not be present. The presence of a diastema does not mean that periodontal disease is present.

• A periodontal pocket is a defect in the attachment apparatus (periodontium) that typically allows food to collect below the gingiva. There are two types of periodontal pockets: suprabony and infrabony. A suprabony pocket refers to attachment loss in which the bottom of the pocket is coronal to the alveolar bone. An infrabony pocket refers to attachment and bone loss in which the bottom of the pocket is apical to the normal level of alveolar bone.

• Periodontal disease is a collective term referring to all stages of periodontal inflammation (Box 1). The stages are determined by the amount of attachment and bone loss. The bone loss can be estimated by radiology. When evaluating alveolar bone with radiology, one must be cognizant of the three-dimensional aspect of bone loss:

A cyclic process with periods of periodontitis that creates stages of progressive attachment loss.

Reported to be as high as 60% in horses older than 15 years.

Progression appears to be related to food stasis. In the brachyodont dentition (dog, cat, human), the build-up of plaque and calculus is correlated with the progression of periodontal disease.

Periodontal disease is staged according to the amount of periodontium attachment loss.

Treatment goals for periodontitis are to prevent further bone and attachment loss and to allow for periodontium healing with reattachment.

The ultimate goal is to prevent premature tooth loss.

• Periodontal disease is classified based on the veterinary periodontal disease index, which evaluates the amount of periodontium attachment loss.

• The amount of loss should be assessed by oral and radiographic examination.

• If the percentage of attachment loss is less than 50% (stages 0 to 3), periodontal treatment is indicated.