AMTN is predominantly expressed by ameloblasts during the maturation stage of amelogenesis and present at lower levels in the junctional epithelium of erupted teeth. (sciencedaily.com)
The two rings have different textured surfaces for baby to choose from according to his or her age and needs: 1) ridged surface for erupting teeth, and 2) raised bump surface (becomingmothers.com)
Generally, babies will erupt teeth between 4 to 7 months. (easybabylife.com)