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:
“Modern man’s capacity for destruction is quixotic evidence of humanity’s capacity for reconstruction. The powerful technological agents we have unleashed against the environment include many of the agents we require for its reconstruction.”
—George F. Will (b. 1941)
“People between twenty and forty are not sympathetic. The child has the capacity to do but it can’t know. It only knows when it is no longer able to do—after forty. Between twenty and forty the will of the child to do gets stronger, more dangerous, but it has not begun to learn to know yet. Since his capacity to do is forced into channels of evil through environment and pressures, man is strong before he is moral. The world’s anguish is caused by people between twenty and forty.”
—William Faulkner (1897–1962)
“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)