madibular first molar normally have 3 root canals

A mandibular primate space is usually found in the primary dentition between canine and first molar

The primary teeth begin to form in utero at about six weeks. Hard tissue formation occurs in all primary teeth by the 18th week in utero. 3. The permanent teeth begin to develop at approximately four months of age in utero. Maxillary and mandibular first molars begin to calcify at birth.

A permanent tooth erupting in the mouth of an 11 years old child is most likely mandibular second bicuspid

The largest and longest root canal of the maxillary second molar is the lingual