(Root surface strain during canal shaping with single or multi file systems and its influence on apical crack development (An in vitro study)

Abstract

The aim of this study was to determine the root surface strain generated during root canal shaping and its effects on apical microcrack development. Fifteen fully erupted, mandibular first molar were collected and then stored in distilled water. Proximal radiographic views were taken to select teeth with mesial roots that have two separate canals from the orifice to the apex, along the entire root length. The crowns of the teeth were sectioned (2 mm) coronal to the CEJ, leaving it flattened.The distance between the coronal end and apical foramen AF of each root was determined by inserting a # 10 stainless steel k-file into the canal until the tip of the file was just visible at the AF, with a mean length of 18.5 mm. The tooth roots were wrapped with a single sheet of aluminum foil, and embedded centrally in putty addition silicon impression material that was surrounded by an acrylic tube (12 mm high and 20 mm in diameter). Then, the roots were removed after the impression material had set, and the aluminum foil peeled off. A hydrophilic vinyl polysiloxane impression material was placed in the socket and the teeth were immediately replaced, the polysiloxane filled the space created by the foil sheet representing a stimulated periodontal ligament. The apical end of the acrylic tube were cut