PERIODONTAL DISEASE

General Information on Disease Mechanism

Periodontal disease is the most common chronic, destructive, infectious and inflammatory syndrome in dogs and cats. Approximately 80% of dogs and 70% of cats over 2 years of age are affected by this condition. Destruction of the periodontal tissues (alveolar bone, periodontal ligament, and cementum) results from the effects of long term bacterial colonization (plaque) on the tooth surface. Plaque accumulation irritates gingiva and allows bacteria to survive under the gum. Endotoxins released by these bacteria cause a local immune response which gradually destroys the supportive tissues of the tooth. Unless plaque is removed from tooth surface and below the gum, continuous interaction between host immune system and bacteria results in progression of this destructive event. In time, developing calculus (tartar)  keeps bacteria in close contact with gingiva, thus allowing deep tissue invasion of bacteria resulting in loss of periodontal ligament and alveolar bone. Maintenance of crestal bone height with the loss of periodontal ligament and alveolar bone around the tooth root (vertical bone loss) results in severe pocket formation. With the loss of the bone parallel to the cementoenamel junction of several adjacent teeth and crestal bone (horizontal bone loss) minimal pocket formation takes place.

Stages of Periodontal Disease

Periodontal disease is generally classified in four stages. Gingivitis is the inflammation of the gum. Periodontitis is inflammation and destruction of the periodontal tissues.

Stage 1 (Gingivitis): Gingival inflammation and edema is present at the margin of attached gingiva. Probing causes gingival bleeding. There is no tooth mobility, furcation exposure or attachment loss.

Stage 2 (Early Periodontitis): Gingival recession begins. There is up to 25% attachment loss.

Stage 3 (Established Periodontitis): Gingival recession continues. There is 25% to 50% attachment loss (greater than 3 mm). Slight tooth mobility occurs in single-rooted teeth. Beginning furcation involvement is seen.

	Stage 3 established periodontitis in the maxillary fourth premolar. Gingival recession (yellow arrow)

Stage 4 (Advanced Periodontitis): Severe gingival recession occurs. There is greater than 50% bone loss resulting in complete furcation involvement. Apical abscess formation, tooth mobility and deep pockets are present.

Severe tartar built-up on the upper premolars and molars.	Same teeth after the tartar is cleaned. The first molar tooth (left) has significant root exposure.
Periodontal pocket >12 mm depth indicates significant periodontal disease.	Radiographs of the area confirms 100% bone loss around the caudal root of upper fourth premolar.

Diagnosis of Periodontal Disease

Periodontal examination is done with a periodontal probe. Periodontal probe is gently inserted into the gingival sulcus to determine the attachment point of the gingiva to the tooth. In a healthy tooth the probe stops at less than 2 mm depth and no bleeding occurs during probing. If periodontal disease is present pocket depth measures grater than 2 mm and bleeding usually takes place during probing. This indicates an inflammatory process in the connective tissue adjacent to the junctional epithelium.

Each tooth is probed on a minimum of four sides. Abnormal probing depths are recorded on the dental chart and treatment options are discussed with the client.

Infrabony pocket on the palatal aspect of maxillary canine tooth	Palatal infrabony pocket (yellow arrows). Normal crestal bone height (white dotted line)

Treatment of Periodontal Disease

Treatment of periodontal disease starts with an oral examination on an awake animal.

Treatment of stage 1 disease includes a thorough dental cleaning. The animal is anesthetized for a detailed oral examination, charting and dental radiography of the affected areas. Calculus accumulated above the gumline is removed with an ultrasonic scaler (supragingival cleaning). Calculus accumulated below the gumline is removed with a curette (subgingival cleaning). Cleaned teeth are polished with a prophy paste and rinsed with chlorhexidine solution. Fluoride is applied on the teeth. Homecare instructions are given to the client during the discharge. A recheck appointment is scheduled in 6 months. Gingivitis usually resolves within a couple of weeks of the dental cleaning.

Stage 2 disease is treated similarly to stage 1 disease. Additionally, pockets between 4 to 10 mm deep are treated with root planing and administration of a long acting antibiotic (Doxirobe® Gel). Prior to administration of Doxirobe® Gel, thorough root planing and subgingival curettage is performed to remove calculus and necrotic tissue below the gumline. The contents of the antibiotic gel is then properly mixed and instilled into the periodontal pockets. A drop of water is applied on the visible surface of antibiotic at the gingival margin to harden the gel. If necessary, the hardened gel is packed into the pocket using an appropriate instrument such as plastic spatula. The application of Doxirobe® Gel allows sustained release of antibiotic for several weeks at the site of application. The antibiotic is bacteriostatic against the bacteria associated with periodontal disease, inhibits destruction of periodontal tissues, helps rejuvenate periodontal tissues, and decreases edema, inflammation and pocket depth.

Treatment of stage 3 disease depends on the type and degree of attachment loss. With the loss of attachment two types of periodontal pockets form. Suprabony pockets occur when the supportive alveolar bone is lost in a horizontal fashion at a similar rate mesial and distal surfaces of several adjacent teeth. Infra bony pockets occur when the supportive alveolar bone is lost in a vertical fashion extending into a space between the tooth and the alveolar socket. Suprabony pockets <5 mm is treated with supra and subgingival cleaning of plaque and tartar, closed curettage and root planing, and application of antibiotic (Doxirobe® Gel). This treatment provides connective tissue remodeling and reattachment of soft tissues reducing the pocket depth. Slight mobility seen in single-rooted teeth can be treated with periodontal splinting. Homecare with short term oral antibiotics (Clindamycin), chlorhexidine rinses, and CET chews is essential. Patient needs to be rechecked in 3 months. Suprabony pockets >5 mm without gingival recession can be treated with apically repositioned flap surgery. This allows visualization of the roots and facilitates removal of subgingival calculus. Infrabony pockets can be treated with closed curettage and root planing followed by instillation of a local antibiotic (Doxirobe® Gel) when they are not so severe. Severe infrabony pockets can be treated with open curettage and root planing (requires gingival flaps) followed by filling the cleaned infrabony pocket with bioactive glass particles (Consil®) and suturing the gingival flaps back in place. When applied into a pocket, bioactive glass particles attracts fibrin, collagen fiber, and growth protein to the area. Within days new bone production begins at this area. An oral antibiotic (Clindamycin) is used for a short period.

Stage 4 disease is usually hopeless to treat. Severe gingival recession, greater than 75% of bone loss and tooth mobility mostly requires extraction of the affected teeth. Open curettage and root planing, periodontal splinting (to stabilize mobility), guided tissue regeneration, and repositioning flaps can be tried but these are all heroic attempts with little to no success.

It should be remembered that the success of any periodontal treatment is based on the cooperation of the animal, owner and the veterinarian. Failure in cooperation in any one of these would result in failure of the treatment.