Appearance
When viewed microscopically in cross-section, they appear as concentric rings. In a longitudinal section, they appear as a series of dark bands. The presence of the dark lines is similar to the annual rings on a tree. They are named after Swedish anatomist Anders Retzius.
In the longitudinal section of a tooth. these lines appear near the dentin. They bend obliquely near the cervical region. They curve occlusally near the cuspal regions or the incisal regions.
Produced during the second stage of enamel calcification, also known as the maturation stage, ameloblasts produce matrix and enamel at the rate of 4 micrometers per day; however every fourth day there is a change in development. Brownish lines, the striae of Retzius, develop as a result of a change in the growth process. Macroscopically, these lines can be seen on the labial surface or lip side of anterior or front teeth as horizontal lines on the tooth crown, also known as "imbrication lines" .
Evenly spaced Retzius lines indicate a 6-11 day cycle of enamel formation.
Read more about this topic: Striae Of Retzius
Famous quotes containing the word appearance:
“Hence, the less government we have, the better,—the fewer laws, and the less confided power. The antidote to this abuse of formal Government, is, the influence of private character, the growth of the Individual; the appearance of the principal to supersede the proxy; the appearance of the wise man, of whom the existing government, is, it must be owned, but a shabby imitation.”
—Ralph Waldo Emerson (1803–1882)
“The true, prescriptive artist strives after artistic truth; the lawless artist, following blind instinct, after an appearance of naturalness. The one leads to the highest peaks of art, the other to its lowest depths.”
—Johann Wolfgang Von Goethe (1749–1832)
“When appearance and reality coincide, philosophy and literary criticism find themselves with nothing to say.”
—Mason Cooley (b. 1927)