Orifice locating with a microscope.

The purpose of this study was to determine whether the use of the dental operating microscope (DOM) could increase the number of root canal orifices located in mandibular molars. Ninety-three first and 111 second extracted mandibular molars were used. With the naked eye, all access cavities were prepared and the number of canals in each root was recorded. Using a DOM with x8-x13 magnification, all teeth had the access cavity preparations again examined. With the naked eye, a total of 641 canals were seen in all teeth. After the DOM examination, 50 more canals could be visualized, representing a 7.8% increase in the total number of located canals. From these canals, 35 were located in the first molars and 15 in the second molars. The use of the DOM increases the number of root canal orifices located.