Eruption
Tooth eruption in humans is a process in tooth development in which the teeth enter the mouth and become visible. Current research indicates that the periodontal ligaments play an important role in tooth eruption. Primary teeth erupt into the mouth from around six months until two years of age. These teeth are the only ones in the mouth until a person is about six years old. At that time, the first permanent tooth erupts. This stage, during which a person has a combination of primary and permanent teeth, is known as the mixed stage. The mixed stage lasts until the last primary tooth is lost and the remaining permanent teeth erupt into the mouth.
There have been many theories about the cause of tooth eruption. One theory proposes that the developing root of a tooth pushes it into the mouth. Another, known as the cushioned hammock theory, resulted from microscopic study of teeth, which was thought to show a ligament around the root. It was later discovered that the "ligament" was merely an artifact created in the process of preparing the slide. Currently, the most widely held belief is that the periodontal ligaments provide the main impetus for the process.
The onset of primary tooth loss has been found to correlate strongly with somatic and psychological criteria of school readiness.
Read more about this topic: Human Tooth
Famous quotes containing the word eruption:
“The eruption of lived pleasure is such that in losing myself I find myself; forgetting that I exist, I realize myself.”
—Raoul Vaneigem (b. 1934)
“Movies are one of the bad habits that corrupted our century. Of their many sins, I offer as the worst their effect on the intellectual side of the nation. It is chiefly from that viewpoint I write of them—as an eruption of trash that has lamed the American mind and retarded Americans from becoming a cultured people.”
—Ben Hecht (1893–1964)
“I have done my fiddling so long under Vesuvius that I have almost forgotten to play, and can only wait for the eruption and think it long of coming. Literally no man has more wholly outlived life than I. And still it’s good fun.”
—Robert Louis Stevenson (1850–1894)