merk manual what is periodontal disease

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merk manual what is periodontal disease

Postby malernee » Sat Aug 28, 2004 2:38 pm

see ... /20807.htm
for periodontal pictures

Periodontal Disease
Etiology and Pathogenesis

This bacterial infection of the tissue surrounding the teeth causes inflammation of the gingivae, periodontal ligament, cementum, and alveolar bone. Ultimately, teeth are lost due to the loss of their supporting tissues. This is the major reason for tooth loss in dogs.

Etiology and Pathogenesis: Periodontal disease is caused by gross accumulation of many different bacteria at the gingival margin due in part to a lack of proper oral hygiene. Over a period of weeks, the flora changes from nonmotile, gram-positive, coccoid, aerobic bacteria to more motile, gram-negative, rod-shaped, anaerobic bacteria. Important flora are Propityromonas gingivalis , Bacteroides asaccharolyticus , Fusobacterium nucleatum , Actinomyces viscosus , and A odontolyticus .

As the local bacterial flora increases in mass to 10-20 times normal, gingivitis occurs. The accumulation of bacterial metabolic products increases epithelial permeability in crevicular epithelial desmosomes and allows antigens to contact connective tissue. Metabolic products of bacterial metabolism include hydrogen sulfide, ammonia, endotoxin, hyaluronidase, chondroitin sulfatase, mucopeptides, lipoteichoic acids, acetate, butyrate, isovalerate, and propionate. These bacterial products and host defense mechanisms cause tissue necrosis. Polymorphonuclear leukocytes (PMN) migrate through the sulcular epithelium and form a barrier between the subgingival bacteria and the gingiva. With overwhelming bacterial challenge, PMN die in increasing numbers and release breakdown products. The immune system produces lymphokines that participate in tissue destruction, which follows the path of the local vascular supply. Accelerated tissue destruction and inappropriate repair cause loss of periodontal support. Two forms of disease are recognized: gingivitis and periodontitis.

In gingivitis, the inflammation of the marginal gingival tissues is induced by bacterial plaque and does not affect the periodontal ligament or alveolar bone. There is a change from coral-pink to red or purple, swelling of the gingival margin, and a serous or purulent exudate in the sulcus. The gingivae tend to bleed on contact. Fetid breath is common. Gingivitis is reversible with proper tooth cleaning but, if untreated, may lead to periodontitis.

In periodontitis, the destructive inflammatory process of the periodontium is induced and driven by bacterial plaque that contains specific bacteria that destroy the gingiva, periodontal ligament, alveolar bone, and root cementum. It usually occurs after years of plaque, calculus, and gingivitis. It is irreversible and results in permanent loss of tooth support. There is apical migration of the epithelial attachment and resorption of supporting alveolar bone. Affected teeth may show increased mobility, concurrent gingivitis, and subgingival calculus.

Periodontitis is usually characterized by hyperplasia of the gingival margin in dogs and by recession of the gingival attachment in colony animals. Pet animals also show this tendency; however, infrabony pocket formation (deep isolated areas of bone loss) is more common in pets than in colony-raised animals. Dogs on a hard diet develop fewer problems due to the mechanical cleaning effect of the food. Caudal teeth have more problems than rostral teeth. The maxilla is affected more severely than the mandible, and buccal surfaces have more disease than lingual surfaces. Gingivitis often becomes severe at ~2 yr of age but resolves if treated. Periodontitis usually begins at 4-6 yr of age and, if untreated, progresses to tooth loss.

Treatment: The basic principle is that active periodontal disease will not develop around a clean tooth.

Gingivitis usually can be treated by thorough cleaning of the teeth, including below the gingival margin. If gingivitis does not resolve, further examinations should be performed for the presence of plaque and calculus, which should be removed in subsequent cleanings. Refractory cases should be evaluated for immunocompetence, cellular defects (eg, diminished neutrophil chemotaxis), and systemic disease (eg, diabetes mellitus). Gingivitis reestablishes if the teeth are not kept clean and free of bacteria. Therefore, at-home oral hygiene methods and regular cleanings to prevent gingivitis and its progression to periodontitis should be encouraged.

Periodontitis needs to be treated with thorough cleaning above and below the gum line. In areas of increased subgingival depth (>4 mm), surgical means (usually gingivectomy) should be used to gain access to the root surface for cleaning. Teeth can generally be salvaged until they have lost 75% of their bone support from one or more roots. This can be evaluated by radiography of the jaws, which should be performed if periodontal disease is advanced. Infrabony defects (defects below the crest of the alveolar bone) require flap surgery. Defects on the palatal surface of maxillary canine teeth, which are infrabony in character and invade or approximate the nasal cavity, should be treated with infrabony grafting procedures before a decision is made to extract the tooth. Extraction of such teeth frequently leaves oronasal fistulas, which require surgical repair. Animals with periodontitis should be maintained postoperatively on oral hygiene methods at home and chemoprophylaxis for ≥2 wk with 0.1-0.2% chlorhexidine. Frequent (every 3 mo to 1 yr) prophylactic cleanings should be encouraged to avoid relapse and prevent further bone loss.

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