Surgical operating microscope allows a clinician to see in great detail the pulpal floor of a tooth. This in turn facilitates the location of the canals. There are subtle color changes between normal healthy dentin and pathologic reparative dentin. Understanding this will help selectively removing the pathologic dentin to locate canals. Case high lighted here illustrates this phenomenon in an maxillary right third molar. 
Traditional access in a maxillary molar is triangular to rhomboid shape. In this particular tooth, access is modified into a straight line as all canals are located in a straight line. Use of a microscope in this case helped save unnecessary removal of tooth structure.
8 years later the tooth is functioning well as an abutment for a removable partial denture.
