6 Pathogenesis of Periodontal Disease
When you have completed this chapter, you will be able to:
• List the factors that contribute to the development of periodontal disease in dogs and cats.
• Define periodontal disease and describe the appearance of the gingival and other supporting tissues when periodontal disease is present.
• Discuss the etiology of periodontal disease and define the terms plaque and calculus.
• Characterize the bacterial colonization present with periodontal disease and explain how the patient’s immune response contributes to damage to periodontal tissues.
• Differentiate between Class 1, Class 2, and Class 3 furcation exposure.
• Describe the staging of periodontal disease using the AVDC classification system.
Clients often ask, “Why does my pet have periodontal disease when all the pets I have had in the past had no dental problems?” Many factors determine the reason one patient develops periodontal disease and another does not (Box 6-1). These factors are as follows: age, species, breed, genetics, chewing behavior, diet, grooming habits (which can cause impaction of hair around the tooth and in the gingival sulcus), orthodontic occlusion, health status, home care, frequency of professional dental care, and bacterial flora of the oral cavity.
Periodontal Disease
Periodontal disease is an inflammation and infection of the tissues surrounding the tooth, collectively called the periodontium (Figure 6-1). Periodontal disease is characterized by movement of the gingival margin toward the apex (exposing more crown and root) and migration of the attached gingiva with associated loss of the periodontal ligament and bone surrounding the tooth. An older term, pyorrhea, which indicates discharge of pus from the periodontium, is no longer used.
Systemic Effects of Periodontal Disease
The systemic effects of periodontal disease are fairly well documented in humans. Research in veterinary medicine is still ongoing. Theoretically, bacteria from infected tissues enter the bloodstream. Organs such as the lungs, kidneys, and liver are most susceptible to infection.
Etiology
A glycoprotein component of saliva, known as the acquired pellicle, attaches to the tooth surface. The pellicle, which takes only 20 minutes to form, helps bacteria attach to the tooth surface. Approximately 6 to 8 hours after pellicle formation, bacteria start to colonize the tooth surface. This bacterial layer is known as plaque. The bacteria that have colonized the tooth surface die. The bacteria that are attached to the tooth absorb calcium from saliva and become calcified. This new substance is known as tartar or calculus.
Types of Bacteria
The healthy gingival flora is made up of mostly gram-positive aerobic bacteria. These bacteria require oxygen to survive. As periodontal disease progresses, gram-negative bacteria begin to colonize the tooth surface. The aerobic bacteria metabolize oxygen, creating an environment in which the anaerobic (those that live without oxygen) bacteria start to develop. As the condition progresses, spirochetes begin to colonize. The bacteria are arranged in what is called a biofilm, which is an aggregate of bacterial colonies protected by a polysaccharide complex. It is the disruption of this biofilm, more than anything else, that is important in the control of periodontal disease.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
