Guided Endodontics Modified for Treating Molars by Using an Intracoronal Guide Technique.

The aim of this case report was to show the concept of guided endodontics in a maxillary first molar with limited interocclusal space. Guided endodontics involves merging cone-beam computed tomographic imaging and a surface scan of the tooth in order to create a guide to perform a drill path into the seemingly obliterated root canal. In the molar region, the interocclusal space is often too small to accommodate the guide, bur, and handpiece at once, and, therefore, a modified approach is presented. A 52-year-old man was referred because the dentist had failed to localize the distobuccal root canal of a maxillary molar (#3) associated with apical pathosis. After reopening and rubber dam placement, a glide path was established for both the palatal first mesiobuccal root canal and the second mesiobuccal using a size 10 hand file and coronal flaring. Further instrumentation to the working length was achieved by reciprocating file size 25. All 3 canals were temporarily filled with calcium hydroxide. For the distobuccal root canal, guided endodontics was chosen in order to avoid further impairment of the tooth because negotiation of the canal failed even with the use of the operating microscope. Following the merged data obtained from the cone-beam computed tomographic and surface scans, a translucent SICAT Optiguide (SICAT, Bonn, Germany) was constructed containing a sleeve representing the proper direction of a drill path in order to reach the distobuccal root canal. The access cavity was temporarily filled with a composite material made for light-curing. Before light curing, the Optiguide was replaced on the teeth, and a steel pin was pressed through the sleeve and the composite whereby the proper drill path direction was transferred into the composite. After polymerization and removal of the Optiguide and pin from the composite base sleeve, the guided drilling could be performed. This case report is the first on guided access preparation in a molar with pulp canal obliteration and limited interocclusal space. The demand for more interocclusal space was solved by transforming the virtual drill path into a composite-based intracoronal guide. The use of digital technology was essential.