The maxillary first molar generally has three roots with
three (palatal, mesio and distobuccal) or four root canals.
The fourth root canal is usually located in the mesiobuccal
root. The pulp chamber is quadrilateral in shape, wider
buccopalatally than mesiobuccally, with four pulp horns.
The access cavity preparation is also quadrilateral in
outline with rounded corners and lies on the mesial three
fifths of the crown. The large palatal canal is the most
easily visualized. The distobuccal canal is located 2-3 mm
and palatal to the mesiobuccal canal. Mesiobuccal canal
usually lies beneath the mesiobuccal canal.
