Macrophotograph of a milk tooth. Milk teeth, also known as deciduous or primary teeth, are the first set of teeth in the growth and development of humans and other diphyodonts. They develop in the embryo and erupt during infancy. They are gradually replaced by permanent teeth from the age of 6. The picture was created as part of a cooperation with Quintessenz Publishing. Magnification: x30 when printed at 15cm wide.