The purpose of this study was to develop a protocol which allows for improved access cavity preparation in all clinical circumstances. From radiographic and clinical evaluation a systematic organization of 10 burs was found to be optimal for all cases encountered. This standard arrangement makes burs available for use in situations with varying loss of coronal tooth structure and provides an orderly approach to endodontic therapy. A complete protocol accompanies the standardization of instruments making the techniques widely available. The standardization of this phase of endodontic therapy permits foreseeable and reproducible results. The use of a rational protocol in the form of systematically organized burs results in improved root canal therapy because of better patient and instrument management.