We are surrounded and inhabited by an enormous number of microorganisms.
• Whether the organisms cause disease depends on the microorganism and the body’s defenses.
• Traditionally, the microorganisms are divided according to whether they are disease causing (pathogenic) or non–disease causing (nonpathogenic).
• The oral cavity may be the primary site of involvement of an infectious disease, or a systemic infection may have oral manifestations.
• There are different routes of infection:
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- Transferred through the air on dust particles or water droplets
- Some may require intimate and direct contact.
- Some may be transferred by hands or objects.
Microorganisms invading oral tissue can cause local infection, systemic infection, or both.
• Microorganisms in the bloodstream can cause lesions in the oral cavity.
• Microorganisms causing infection in the lungs can be transferred to oral tissue and be present in saliva.
• Oral flora may be affected by changes in salivary flow, administration of antibiotics, and changes in the immune system.
• Opportunistic infection:
When an organism that usually is nonpathogenic causes disease
Assoc. Prof. G. Tomov, PhD