The tooth located in the primary dentition of the mandible distal to the primary first molar tooth. It is succeeded by the maxillary second premolar. The crown is very similar to although smaller than the permanent maxillary first molar. It does, however, have a more bulbous buccal surface in its cervical region but no tubercle as with the first primary molar. A tubercle of Carabelli may be found on the mesial half of the palatal surface. In some rare occasions the disto-palatal cusp may be reduced or missing. The mesio-palatal cusp is the largest and is connected by an oblique ridge to the disto-buccal cusp to give a large mesial pit (fossa) and a small distal pit. It has three roots, mesio-buccal, disto-buccal, and palatal, which are divergent to make room for the tooth germ of the maxillary second premolar. Sometimes the palatal and disto-buccal roots are fused. Calcification of the tooth begins at about 6 months of foetal life. The tooth erupts at about 24 months after birth and the calcification of the root is complete at about 3 years.