GRENZ RAY STUDIES OF ENAMEL MATRIX FORMATION AND CALCIFICATION

¹ School of Dental and Oral Surgery, Columbia University, New York, N. Y.

There are two processes in enamel development as disclosed by the grenz ray: 1, matrix formation (organic phase—radiolucent—acid insoluble), and 2, calcification (inorganic phase—radiopaque—acid soluble). The matrix formation rhythm occurs first as a series of rhythmic bands along the lines of Retzius, and then the calcification rhythm occurs in transverse relation to these bands. The calcification rhythm obscures the formation rhythm in adult enamel but in the decalcification occurring in caries, the original matrix pattern is again disclosed. On the other hand, injuries to the enamel during matrix formation are covered up by the calcification occurring later, in transverse relation to the Retzius lines.