Endodontic treatment in primary teeth can be challenging and time-consuming, especially during canal preparation, which is considered one of the most important steps in root canal therapy. The conventional instrumentation technique for primary teeth remains the "gold-standard" overhand instrumentation, which makes procedures much more time-consuming and adversely affects both clinicians and patients. Recently nickel-titanium (Ni-Ti) rotary files have been developed for use in pediatric endodontics. Using rotary instruments for primary tooth pulpectomies is cost-effective and results in fills that are consistently uniform and predictable. This book reviews the use of nickel-titanium rotary files as root canal instrumentation in primary teeth.