Dentition mammals the infants have a set of teeth that fall out and are replaced by adult teeth. These are called deciduous teeth, primary teeth, baby teeth or milk teeth. Animals that have two sets of teeth, one followed by the other, are said to be diphyodont. Normally the dental formula for milk teeth is the same as for adult teeth except that the molars are missing. Because mammal teeth are specialised for different functions, many mammal groups have lost teeth not needed in their adaptation. Tooth form has also undergone evolutionary modification as a result of natural selection for specialised
Deciduous teeth This process starts at the midline and then spreads back into the posterior region. By the time the embryo is eight weeks old, there are ten buds on the upper and lower arches that will eventually become the primary (deciduous) dentition. These teeth will continue to form until they erupt in the mouth. In the primary dentition there are a total of twenty teeth: five per quadrant and ten per arch. The eruption of these teeth ("teething") begins at the age of six months and continues until twenty-five to thirty-three months of age during the primary dentition period. Usually, the