Fracture resistances of roots prepared with rotary files with different metal alloys and motion kinetics

T he principle aim of root canal shaping is to chemome- chanically clean the entire root canal system without damaging the integrity of the tooth.However, numerous complications during root canal preparation have been reported and include ledge formation, transportation, perforation [1] and dentinal micro-cracks, which could potentially result in vertical root fractures (VRFs).[2,3] VRFs are a serious clinical problem that can lead to the extraction of teeth.[4,5] Wilcox et al. [6] concluded that preserving the dentin is important for preventing VRFs.The majority of clinicians prefer to use nickel-titanium (Ni-Ti) rotary file systems because they have advantages such as shortening the treatment period and greater cutting efficiency.[7,8] However, the increased stress on the root canal walls that occurs during preparations with these files could result in the development of cracks.Kim et al. [9] reported that there is potentially a relationship between the design of the Ni-Ti instruments and the incidence of vertical root fractures.