At which of the following locations are perikymata usually found?

 # At which of the following locations are perikymata usually found?

a. Cervix of the crown.

b. Apex of the root.

c. Cusp tips.

d. Deposited throughout the crown.

The correct answer is A. Cervix of the crown.

Perikymata are transverse, wave-like grooves, believed to be the external manifestations of the striae of Retzius. They are continuous around a tooth and usually lie parallel to each other and to the cementoenamel junction. Ordinarily there are about 30 perikymata per millimeter in the region of the cementoenamel junction, and their concentration gradually decreases to about 10 per millimeter near the occlusal or incisal edge of a surface. Their course usually is fairly regular, but in the cervical region it may be quite irregular. The terms perikymata and imbrication lines are used without distinction to the surface structures of ridges or grooves. To avoid confusion in the usage of these terms it has been suggested that the terms perikymata or imbrication lines be suffixed by the words ridge or crest to denote elevations and the terms groove or furrow to denote depressions, as for example, perikymata ridge.

Reference: Orban's 13th Edition Page no 58