Environment
The ecological factors provided by the environment of the oral cavity are directly proportional to the species richness and species biodiversity of the microorganisms that reside on the teeth. The main ecological factors are pH, saliva, temperature and redox reactions. The majority of microbial organisms prefer neutral pH levels (pH 7). Saliva acts as a buffer, maintaining the pH in the mouth between 6.75 and 7.25. In addition to acting as a buffer, saliva is also a main source of nutrients for the thousands of bacteria (note: gingival crevicular fluid is also a nutrient source but a smaller one ). A two degree (°C) change has been shown to drastically shift the dominant species in the plaque. The normal temperature of the mouth ranges between 35–36°C (Marsh). Redox reactions are carried out by aerobic bacteria. This keeps the oxygen levels in the mouth at a semi-stable homeostatic condition. This allows other bacteria to survive, which will be discussed in the next section.
Read more about this topic: Dental Plaque
Famous quotes containing the word environment:
“The poorest children in a community now find the beneficent kindergarten open to them from the age of two-and-a-half to six years. Too young heretofore to be eligible to any public school, they have acquired in their babyhood the vicious tendencies of their own depraved neighborhoods; and to their environment at that tender age had been due the loss of decency and self-respect that no after example of education has been able to restore to them.”
—Virginia Thrall Smith (1836–1903)
“White males are the most responsible for the destruction of human life and environment on the planet today.”
—Robin Morgan (b. 1941)
“Autonomy means women defining themselves and the values by which they will live, and beginning to think of institutional arrangements which will order their environment in line with their needs.... Autonomy means moving out from a world in which one is born to marginality, to a past without meaning, and a future determined by others—into a world in which one acts and chooses, aware of a meaningful past and free to shape one’s future.”
—Gerda Lerner (b. 1920)