DEFINITION/OVERVIEW
- Inflammation and infection of some or all of the tooth’s support structures (gingiva, cementum, periodontal ligament, and alveolar bone); compared with gingivitis (inflammation of the marginal gingiva), periodontitis indicates some degree of periodontal attachment tissue loss
ETIOLOGY/PATHOPHYSIOLOGY
- An intact epithelial barrier (junctional epithelium at the base of the gingival sulcus) and high rate of epithelial turnover and surface desquamation prevent bacteria from gaining direct access to tissue in a healthy state
- The normal level of the base of the sulcus is at the cementoenamel junction (CEJ)
- Some bacterial products may diffuse through the junctional epithelium to reach the underlying gingival connective tissue; normal host defense mechanisms limit the penetration of these products and their damaging effects
- Fluctuations in the host–parasite/pathogen equilibrium may result in cycles of either diminished or increased intensity of the inflammatory response; it may be possible to think of periodontitis as the outcome of an imperfectly balanced host–parasite interaction
- Caused by bacteria located in the gingival crevice; initially, a pellicle forms on the enamel surface of a clean tooth; the pellicle is composed of proteins and glycoproteins deposited from saliva and gingival crevicular fluid; the pellicle attracts aerobic gram-positive bacteria (initially Actinomyces and Streptococcus spp.); more bacteria soon adhere, forming plaque; within days the plaque thickens, becomes mineralized and transforms into calculus, which is rough and irritating to the gingiva; with deeper accumulations, the oxygen is depleted and anaerobic motile rods and spirochetes begin to populate the subgingival area; more plaque builds on top of the calculus; endotoxins released by anaerobic bacteria cause tissue destruction and bone-loss periodontitis; host response to the bacteria and toxins present can also damage the host tissues
- An association has been established between periodontitis and microscopic hepatic, renal, and central nervous system (CNS) lesions in some animals
- Causes
- Gingivitis: dogs; Streptococcus and Actinomyces spp. (see also Chapter 25)
- Periodontitis: dogs; pigmented and nonpigmented bacteroides (Porphyromonas denticanis, Porphyromonas salivosa, Porphyromonas gulae, Prevotella spp., Bacteroides spp.), Fusobacterium spp.
- Cats: Peptostreptococcus, Actinomyces, and Porphyromonas spp.
- Soft diet promotes periodontal disease through accumulation of plaque
- Lack of self-cleaning mechanism caused by teeth that are crowded or maloccluded
- Gingivitis: dogs; Streptococcus and Actinomyces spp. (see also Chapter 25)
- Risk factors
- Toy breeds with crowded teeth
- Dogs that groom themselves: causes hair to be imbedded in the gingival sulcus
- Other debilitating illnesses
- Poor nutritional state
- Toy breeds with crowded teeth
SIGNALMENT/HISTORY
- Dogs and cats 6 months and older may be affected
CLINICAL FEATURES
- Stage 1 (PD 1): gingivitis only without attachment loss; the height and architecture of the alveolar margin are normal
- Stage 2 (PD 2): early periodontitis implies that there is less than 25% of attachment loss; there are early radiological signs of periodontitis; the loss of attachment of alveolar bone on the root is less than 25% as measured either by clinical attachment level, or radiographically as determined by the distance of the alveolar margin from the CEJ relative to the length of the root; at most, stage 1 furcation involvement (Figs. 26-1 and 26-2)
- Stage 3 (PD 3): moderate periodontitis implies that there is 25–50% loss of attachment of alveolar bone on the root as measured either by clinical attachment level, or radiographically as determined by the distance of the alveolar margin from the CEJ relative to the length of the root; at most, stage 2 furcation involvement (Figs. 26-3 and 26-4)
- Stage 4 (PD 4): advanced periodontitis implies that there is more than >50% loss of attachment of alveolar bone on the root as measured either by clinical attachment level, or radiographically as determined by the distance of the alveolar crest from the CEJ relative to the length of the root; stage 3 furcation involvement will be involved in multirooted teeth (Figs. 26-5 and 26-6)
Figure 26-1 Apparent stage 2 periodontal disease in a dog with plaque, calculus, and gingival recession. Confirmation of extent of attachment loss can be determined radiographically.
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