Preparation of severely curved S-shaped double-curved root canals can be technically challenging. A novel root canal instrumentation technique is proposed, which modifies two techniques, the McSpadden crown-down technique and the Tactile Controlled Activation technique. In the McSpadden crown-down technique, the root canal is divided into two portions, the coronal zone, and the apical zone. However, rather than focusing on the length of file engagement, a formula is proposed to calculate the maximum insertion depths of higher tapered instruments to prevent over-flaring of the canal and preserve pericervical dentin. Tactile Controlled Activation involves activating martensitic nickel-titanium rotary files upon engagement and then immediately withdrawing the files. The proposed technique recommends three apical strokes after initial engagement prior to withdrawal to minimize instrumentation time. This novel technique is described in a case report involving the management of an S-shaped double-curved maxillary lateral incisor. The technique presents a new method of crown-down instrumentation that prevents over-flaring and avoids instrument separation.
Copyright © 2020. Published by Elsevier Inc.

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