Ridges are any linear, flat elevations on teeth,  and they are named according to their location. The lower left teeth begin with the number, "3".
The upper left teeth begin with the number, "2". The staging of tooth development is an attempt to categorize changes that take place along a continuum; frequently it is difficult to decide what stage should be assigned to a particular developing tooth.
Lingual surfaces can also be described as palatal when found on maxillary teeth beside the hard palate. The maxillary first molar is the tooth located laterally from both the maxillary second premolars of the mouth but mesially from both maxillary second molars. Maxillary molars usually have three roots.
The function of this premolar is similar to that of canines in regard to tearing being the principal action during mastication. Dentin composes most of the root, which normally has pulp canals. The labial ridge is one that runs cervico-incisally in approximately the center of the labial surface of canines.