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:
“If the Revolution has the right to destroy bridges and art monuments whenever necessary, it will stop still less from laying its hand on any tendency in art which, no matter how great its achievement in form, threatens to disintegrate the revolutionary environment or to arouse the internal forces of the Revolution, that is, the proletariat, the peasantry and the intelligentsia, to a hostile opposition to one another. Our standard is, clearly, political, imperative and intolerant.”
—Leon Trotsky (1879–1940)
“A positive learning climate in a school for young children is a composite of many things. It is an attitude that respects children. It is a place where children receive guidance and encouragement from the responsible adults around them. It is an environment where children can experiment and try out new ideas without fear of failure. It is an atmosphere that builds children’s self-confidence so they dare to take risks. It is an environment that nurtures a love of learning.”
—Carol B. Hillman (20th century)
“We learn through experience and experiencing, and no one teaches anyone anything. This is as true for the infant moving from kicking to crawling to walking as it is for the scientist with his equations. If the environment permits it, anyone can learn whatever he chooses to learn; and if the individual permits it, the environment will teach him everything it has to teach.”
—Viola Spolin (b. 1911)