The mantle dentin found alon DEJ is: (A) 20 μm, (B) 30 μm, (C) 40 μm, (D) 50 μm
Answer is A. The mantle dentin found along the DEJ is about 20μm thick and it contains larger-diameter argyrophilic (silver stained) collagen fibers arranged perpendicularly to the DEJ. The circumpulpal dentin contains smaller-diameter closely packed collagen fibers. The dentin which forms after root completion is called secondary dentin.