Instrumentation and obturation of the apical third of root canals: addressing the forgotten dimension.

Modern developments in instrument design and obturation techniques have greatly improved the efficiency of conventional endodontic therapy. Nickel titanium rotary instruments allow the practitioner to prepare canals more quickly and predictably. However, apical preparations by such instruments fail to address the anatomical complexity of the root canal system. Morphologic studies consistently show that canals are mostly oval or irregular in shape; therefore, round preparations by instrumentation result in uninstrumented areas of the root canal system. This is of particular importance in the apical third and in cases of preexisting periapical pathology, where residual bacteria may reside and cause persistent infections. How beneficial are these new instrumentation and obturation techniques to the basic purpose of root canal therapy in eradicating bacteria? This article presents the shortcomings of current instrumentation and obturation techniques and offers possible solutions to improve the outcome of endodontic therapy.

Relative frequency of teeth needing conventional and surgical endodontic treatment in patients treated at a graduate endodontic clinic--a Penn Endo database study.

OBJECTIVE: The objective of this study was to identify the most commonly retreated tooth at a postgraduate endodontics program and to compare this result with teeth requiring primary root canal treatment as well as those that required further surgical endodontic treatment. STUDY DESIGN: The study population consisted of 6,894 patients treated between 2000 and 2005 by endodontic postgraduate students at the University of Pennsylvania School of Dental Medicine. Data regarding tooth type and endodontic treatment rendered were obtained from the Penn Endo database. RESULTS: Initial root canal treatment was most commonly done on mandibular molars. Anterior teeth were 1.411 times more likely to undergo NSRT than molars. Maxillary molars were 1.048 times more likely to undergo conventional retreatment than mandibular molars. Maxillary anterior teeth were 3.032 times more likely than mandibular molars to undergo surgical treatment. CONCLUSIONS: Mandibular molars may most commonly receive initial root canal treatment but it is the anterior teeth that are more likely to undergo surgical and nonsurgical retreatment. Maxillary molars are more likely to receive surgical intervention than mandibular molars. These data call for further investigation into the reasons for such discrepancy.