Periodontal disease: What to do about those pesky suprabony pockets

Many mature dogs and cats we see in our practices have periodontal disease, an inflammation and infection of the tooth's support structures (gingiva, cementum, periodontal ligament and alveolar bone). Secondary periodontal pockets form as disease progresses from gingivitis (inflammation of the gingiva caused by plaque) to loss of tooth support (attachment loss). How to best treat this lost area of tooth support makes up a majority of what we do in veterinary dentistry. Can the tooth be saved? If so, is gingival surgery needed? Oral, injectable or locally applied antimicrobials? Bone implant material?

The periodontal pocket is a pathologically deepened gingival sulcus measured in millimeters from the free gingival margin edge to the base of the pocket. Decisions on what to do to eliminate the pocket or lessen the depth should be based on the percentage of support loss, type and extent of attachment loss and the client's ability to provide plaque prevention and ongoing care.

Percentage of support loss

In a normal tooth, the periodontal ligament supports and is attached from the apex to the cementoenamel junction located just apical to the gingival margin. Gingivitis (stage 1 periodontal disease) is inflammation of the gingiva without loss of tooth support. Stage 2 early periodontal disease occurs when less than 25 percent of the gingival attachment has been lost, creating a periodontal pocket or gingival recession.

Greater than 25 percent support loss signifies stage 3 moderate periodontal disease, which carries a guarded-to-poor prognosis. Greater than 50 percent support loss (stage 4 advanced periodontal disease) carries a poor prognosis for long-term tooth survival. Unless the owner can provide—and the patient will readily accept—daily home care, those teeth affected with stages 3 and 4 should be extracted.

Type and extent of attachment loss

Pockets occur as a consequence of apical (toward the root) migration of the epithelial attachment caused by the destruction of supporting periodontal tissues. Pockets can be further classified as either suprabony or infrabony.

The suprabony pocket floor or base exists above the crest of alveolar bone. This bone loss generally occurs horizontally at similar rates on the mesial and distal surfaces of the teeth. When the suprabony pocket occurs with less than 25 percent support loss, treatment considerations include removal of supragingival and subgingival plaque and calculus and root planing. This initial treatment and home care often results in tissue shrinkage, connective tissue remodeling and gain of soft tissue attachment reducing pocket depth.

Suprabony pockets involving between 25 and 50 percent of the root attachment are treated similarly, with the addition of local antimicrobial application. Home care is essential for maintenance.

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

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. Often, gingival recession will accompany the infrabony pocket. Radiographically, infrabony pockets appear as vertical loss of bone along the root surface.

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Locally applied antimicrobials

Currently, two approved products allow direct treatment of localized suprabony pockets—Clindoral (Trilogic Pharma) and Doxirobe Gel (Pfizer). Both products decrease pockets by converting them to healthier environments, allowing an up growth of junctional epithelium.

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Clindoral is a periodontal filler that contains 2 percent clindamycin hydrochloride in a biodegrading gel matrix that releases clindamycin over seven to 10 days from a single application (Photos 1-4). After application, the product warms to body temperature, increasing in viscosity two- to three-fold to form a soft pliable bioadhesive matrix the consistency of a thick jam.

The primary subgingival organisms associated with periodontal disease in both dogs and cats are aerobic gram-positive (Staphylococcus or Streptococcus species) and anaerobic gram-negative bacteria. Clindamycin is approved for use in dental infections because it is active against staphylococcal and many anaerobic (gram-positive and gram-negative) dental infections. Its wide spectrum of activity, excellent tissue and bone penetration and efficacy in purulent environments make it well-suited for use in periodontal disease. One study showed Clindoral applied to stage 2 and 3 periodontal pockets resulted in significantly less pocket depths, less bleeding and less purulent discharge compared with untreated but cleaned controls at 90 days.

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Doxirobe Gel contains a flowable biodegradable solution of 8.5 percent doxycycline hyclate, which can be applied subgingivally to cleaned periodontal pockets greater than 3 mm in dogs older than 1 year. Doxirobe forms a hard matrix held in place by mechanical force. Doxirobe shows bacteriostatic activity against Porphyromonas gingivalis, Prevotella intermedia, Camphylobacter rectus and Fusobacterium nucleatum—pathogens associated with periodontal disease. It also inhibits collagenase enzymes, which are destructive to the periodontal attachment apparatus.

Upon contact with the gingival crevicular fluid or water, the doxycycline polymer hardens within the periodontal pocket and, over several weeks, slowly degrades to carbon dioxide and water, allowing sustained release of therapeutic levels of sensitive medication (Photos 5-7).

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Clindoral appears to be easy to apply, conforms to the pocket topography, lasts longer in the pocket and may have greater efficacy against the common periodontal pathogens we are faced with. Doxirobe's advantage may lie in its ability to exert an anticollagenase effect. Neither Clindoral or Doxirobe should be used in uncleaned pockets or in stage 4 periodontal disease.

In part two of this series, I'll discuss treating infrabony defects with bone implant materials.

Dr. Bellows owns ALL PETS DENTAL in Weston, Fla. He is a diplomate of the American Veterinary Dental College and the American Board of Veterinary Practitioners. He can be reached at (954) 349-5800; e-mail:dentalvet@aol.com.

Suggested Reading

1. Shipp AD, Fahrenkrug P. Periodontics. In: Practitioners' guide to veterinary dentistry. Glendale: Griffin Printing Company, 1992;47-49.

2. Harvey CE, Thornsberry C, Miller BR. Subgingival bacteria—comparison of culture results in dogs and cats with gingivitis. J Vet Dent 1995;12(4):147-150.

3. Zetner K, Thiemann G. The antimicrobial effectiveness of clindamycin in diseases of the oral cavity. J Vet Dent 1993;10(2):6-9.

4. Dow SW, Jones RL. Anaerobic infections, part II: diagnosis and treatment. Compend Contin Educ Pract Vet 1988;9:827-838.

5. Compendium of Veterinary Products. 4th ed. Port Huron: American Compendiums, 1997;161.

6. Zurenko GE, Gorbach SL. Clindamycin: antimicrobial activity. In: Zambrano D, ed. Clindamycin in the treatment of human infections. Kalamazoo: The Upjohn Co, 1992; Chp 1, 1-22.

7. Novak E. Clindamycin: clinical pharmacology. In: Zambrano D, ed. Clindamycin in the treatment of human infections. Kalamazoo: The Upjohn Co, 1992; Chp 2, 1–14.

8. Ehrenfeld M. Clindamycin in the treatment of dental infections. In: Zambrano D, ed. Clindamycin in the treatment of human infections. Kalamazoo: The Upjohn Co, 1992; Chp 11, 1–24.