The document discusses variations in root and root canal morphology in maxillary molars. It summarizes that the maxillary first molar most commonly has 3 roots but may rarely have 1, 4, or 5 roots. The maxillary second molar commonly has 3 roots and root canals but may have 1, 2, or 4 roots. The maxillary third molar shows considerable variation, with studies finding 56% having a single root, 24% having 2 roots, 13% having 3 roots, and 7% having 4 roots. Root canals in the maxillary third molar were most commonly 3 canals but may range from 1-5 canals. Understanding variations is important for successful root canal treatment and extraction.