ABSTRACT
Double-curved canals, despite their rarity, pose a great challenge to complete endodontic treatment, and the difficulty lies in negotiating these canals and reaching their apex, whereas the greatest difficulty lies in their shaping, disinfection, and obturation. Conventional methods require excessive preflaring to the level of the first curvature to facilitate access and handling of the second one. Modern technologies facilitate dealing with these cases without compromising the dental tissues, metal alloys have become more flexible, and activation techniques have made it possible to deliver irrigants deeper. The triad of minimum shaping with tactile-controlled activation technique, hybrid irrigation, and sealing with bioceramics constitute an integrated and effective method to deal with these cases, and this protocol was used in the following three cases.
ABSTRACT
The preparation of severely curved S-shaped double-curved root canals can be technically challenging. A novel root canal instrumentation technique is proposed, which modifies 2 techniques: the McSpadden crown-down technique and the tactile controlled activation technique. In the McSpadden crown-down technique, the root canal is divided into 2 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 overflaring 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 3 apical strokes after the initial engagement before 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 overflaring and avoids instrument separation.