[Inflammation and infection: cellular and biochemical processes]

The terms inflammation and infection are often used interchangeably. Technically this is incorrect. Inflammation is defined as the body's response to a potentially damaging stimulus. Infection involves tissue invasion by microorganisms. An inflammatory reaction will be provoked when infection occurs in an otherwise healthy patient. Inflammation can be recognized clinically by 5 cardinal signs: rubor (redness), calor (warmth), tumor (swelling), dolor (pain), and functio laesa (loss of function). These clinical signs can be explained by the biochemical and cellular processes activated during the inflammatory response. Rubor and calor are the result of local vasodilation. Tumor, dolor and functio laesa result from extravasation of blood plasma, white blood cells, and inflammatory mediators. Pulpitis is an example of inflammation; a periapical abscess is an example of infection.