Periodontal disease-a primer on recognition and therapy

Periodontal inflammation is the most common syndrome affecting small animals. In no other area of the body can the dedicated veterinarian and dental team make a lifelong difference in patient health and longevity.

The term periodontium describes tissues that surround and support the teeth including the gingiva, alveolar bone, periodontal ligament, and cementum.

Anatomy

In the dog, the healthy free gingival margin of premolars and molars is 1-2 mm coronal (toward the crown) to the cementoenamel junction (CEJ), where root cementum meets the enamel. In the feline, the free gingival margin is 0.5 mm to 1 mm coronal to the CEJ. The attached gingiva is located apical (toward the tooth root) to the marginal gingiva and normally is tightly bound to the alveolar crest and the periosteum of alveolar bone. The width of the attached gingiva varies in different areas of the mouth. Attached gingiva is keratinized to withstand the stress of ripping and tearing. The connection of firm attached gingiva with loose alveolar mucosa is the mucogingival junction (MGJ), also called the mucogingival line (MGL). The mucogingival junction remains stationary throughout life although the gingiva around it may change in height due to hyperplasia, recession or attachment loss.

Within 20 minutes of teeth cleaning, a glycoprotein layer (acquired pellicle) attaches to the exposed crown. Within 6 hours, bacterial colonization (plaque) forms on the glycoprotein layer. In some patients, plaque irritates the gingiva, allowing pathogenic gram-negative bacteria to survive subgingivally. By-products of these bacteria stimulate the host's immune response to release cytokines and prostaglandins that weaken and destroy the tooth's support. The progression of periodontal disease is dependent on the regulatory interaction between bacteria and immune modulators of the host response.

Plaque and calculus

Calculus (tartar) plays a role in maintaining and accelerating periodontal disease by keeping plaque in close contact with gingival tissues, decreasing the potential for repair and new attachment. The therapeutic importance of removing all calculus during the professional oral hygiene visit cannot be overemphasized.

There are numerous grading systems used to classify gingivitis and periodontal disease. Generally, gingivitis is used to describe soft tissue inflammatory changes. Periodontitis is diagnosed when attachment loss has occurred. The patient can be "graded" by the worst tooth (i.e., if there is one stage 4 area, the patient has stage 4 disease). After the disease has been treated, the patient can be upgraded.

Four stages

Photo 1: Stage 1 early gingivitis in the maxillary fourth premolar.

Stage 1 (gingivitis) appears as gingival inflammation at the free gingival margin. As gingivitis progresses, advanced gingivitis appears as gingival inflammation, edema, and bleeding on probing. Advanced gingivitis is limited to the epithelium and gingival connective tissue. There is no tooth mobility or attachment loss. Gingivitis is reversible with proper initial therapy and aftercare at home (Photo 1).

Stage 2 (early periodontitis) occurs when there is apical migration of the junctional epithelium, resulting in a deeper sulcus called a pocket, or gingival recession. In stage 2 disease, up to 25 percent attachment loss occurs (Photo 2 ).

Photo 2: Stage 2 early periodontitis in the maxillary fourth premolar. Note slight gingival recession.

Stage 3 (established periodontitis) is present when 25 percent to 50 percent attachment loss exists around a root. Slight tooth mobility occurs in single-rooted teeth. Early furcation exposure at the trunk of multirooted teeth and/or gingival recession may exist (Photos 3 and 3a).

Stage 4 (advanced periodontitis) presents when marked (greater than 50 percent) attachment loss occurs. Stage 4 periodontal disease can appear as furcation exposure, abscess formation, tooth mobility, deep pockets, and/or gingival recession (Photo 4).

Photo 3: Stage 3 established periodontitis in the maxillary fourth premolar and Photo 3a: Stage 3 furcation exposure in the maxillary fourth premolar.

Abnormal proliferation of the gingiva is termed gingival hyperplasia. The boxer breed is more prone than others to be affected by gingival hyperplasia. Gingival hyperplasia results in increased pocket depths, caused by increased gingival height, not attachment loss. The resultant pseudopocket can accumulate plaque, which, if untreated, may progress to attachment loss. Gingival hyperplasia is treated by gingivectomy and strict home care to help prevent recurrence.

Gingival hyperplasia

Intraoral radiography provides critical information when making periodontal therapy decisions by imaging the supportive bone mesial (rostral) and distal to the affected teeth.

Radiographic appearance

Photo 4: Stage 4 calculus and marked gingival recession in Stage 4 periodontitis.

If clinically and radiographically greater than 50 percent of the bone and tooth support remains, periodontal procedures together with a healthy patient and stringent home care will often result in a saved tooth. A guarded prognosis is given when 50 percent to 75 percent bone loss exists. If greater than 75 percent support is lost, the prognosis for saving the tooth is poor (Photos 5-7).

A periodontal probe is the single most important examination instrument used to evaluate periodontal health. By gently inserting a calibrated periodontal probe just apical to the free gingival margin and tracing the gingival crevice from mesial to distal, a rapid determination of the health of the sulcular tissues can be made.

Periodontal probing

The probe stops where the gingiva attaches to the tooth or at the apex of the alveolus if attachment is lost. Each tooth should be probed on a minimum of four sides. Bleeding on probing is indicative of an inflammatory process in the connective tissue adjacent to the junctional epithelium. If the sulcular lining is intact and healthy, no bleeding will occur. If, however, periodontal disease is present, bleeding will usually take place.

Photo 5: Normal appearing radiograph of the maxillary first molar in a dog with gingivitis, Photo 6: Radiograph of stage 2 disease with 4 mm pocket (periodontal probe inserted), Photo 7: Furcation involvement and exposure in a dog's mandibular third, fourth premolars and first molar.

Normal dogs should have less than 2 mm probing depths, and cats less than 1 mm. Abnormal probing depths are noted on the dental record and discussed with the client, before a treatment plan can be formulated.

The clinical sulcus is the distance from free gingival margin to the most apical point that a probe reaches when gently inserted into the gingival crevice. Pockets that result from attachment loss are called periodontal pockets. The periodontal pocket is a pathologically deepened gingival sulcus. The clinical (absolute) pocket depth is the distance from the free gingival margin edge to the base of a pocket, measured in millimeters.

Pockets

Attachment loss (attachment level) is used to evaluate support loss in cases of gingival recession where little or no pocketing exists. The measurement of attachment loss is the backbone of a periodontal examination. The clinical pocket depth plus recession (measured CEJ to free gingival margin) equals the total periodontal attachment loss.

Periodontal care includes supragingival and subgingival scaling, application of local medication, bone graft implants, periodontal flap surgery, extraction and home care.

Therapy of periodontal disease

Stage 1 gingivitis care includes thorough supra and subgingival teeth cleaning and polishing, followed by daily brushing. Gingivitis will usually resolve within weeks of the oral hygiene visit.

Stage 2 early periodontal disease, where minimal to moderate pockets are diagnosed, can be treated similarly to stage 1 disease +/- root planing, +/- local administration of an antibiotic (LAA). Doxirobeª Gel (Pfizer) contains a flowable biodegradable solution of 8.5% doxycycline hyclate, which is applied subgingivally to cleaned periodontal pockets greater than 3 mm in dogs older than 1 year.

Image 1: Drawing of periodontal pocket before antibiotic insertion.

Upon contact with the gingival crevicular fluid or water, the doxycycline polymer hardens within the periodontal pocket. The application allows sustained release of antibiotic for several weeks at the site of injection. The gel gradually biodegrades to carbon dioxide and water. The antibiotic is not a substitute for scrupulous pocket debridement and other periodontal procedures (Images 1 and 2.)

Image 2: Local antibiotic administered.

Doxirobe allows direct treatment of localized periodontal disease.

Antibiotic at a glance

• Is bacteriostatic against Porphyromonas gingivalis, Prevoltella intermedia, Camphylobacter rectus, and Fusobacterium nucleatum, which are associated with periodontal disease.

• Inhibits collagenase enzymes, which are destructive to the periodontal attachment apparatus.

• Directly binds to dentin and cementum for prolonged release.

• Decreases edema and inflammation, and promotes growth of junctional epithelium resulting in decreased pocket depth.

• Helps rejuvenate tissues of the periodontium (LAA does not regenerate lost tissue).

Established periodontitis (stage 3) and advanced periodontitis (stage 4) therapies are based on dental findings after the patient and radiographs are evaluated. The practitioner should consider:

Percentage of support loss. Greater than 50 percent support loss carries a guarded-to-poor prognosis; greater than 75 percent support loss carries a poor prognosis for long-term success.

Type and extent of attachment loss. Pockets form secondary to the apical migration of the epithelial attachment from the destruction of supporting periodontal tissues. Absolute pockets are classified as either suprabony or infrabony.

Suprabony pockets are present above the crest of alveolar bone. Suprabony pocket bone loss commonly occurs horizontally at similar rates on the mesial and distal surfaces of the teeth.

When the suprabony pocket is less than 5 mm, treatment includes removal of supra and subgingival plaque and calculus, root planing, and, in the dog, installation of local antibiotics. This initial care provides tissue shrinkage, connective tissue remodeling, and gain of soft tissue attachment reducing pocket depth. Home care is essential for maintenance.

If greater than 50 percent of the gingiva and alveolar bone has receded along the root (gingival recession), or if furcation exposures cannot be cleaned at home, extraction is the treatment of choice unless the owner accepts a guarded to poor prognosis.

For suprabony pockets >5 mm without gingival recession, apical repositioned flap surgery can be performed to visualize and clean the roots so that adequate treatment can be accomplished to help eliminate the pocket.

Infrabony (infra-alveolar vertical bone loss) pockets occur when the pocket floor (epithelial attachment) is apical to the alveolar bone. The infrabony pocket extends into a space between the tooth and the alveolar socket. Radiographically, infrabony pockets appear as vertical loss of bone along the root surface.

Future articles will cover specific gingival surgical procedures, home care products and ways to help your client prevent periodontal disease.