EVALUATION OF THE NUMBER OF CANALS MODELED WITH PRODESIGN M FILES UP TO THEIR FRACTURE IN “EX VIVOS” LOWER TEETH” (Atena Editora)

Abstract

This work aimed to evaluate the number of canals modeled with ProDesign M (PDM) files until their fracture in mandibular premolars “ex vivo”. An “ex vivo” experimental study was carried out on 40 extracted lower premolar teeth with similar curvatures, containing a single canal in each tooth. An endodontic opening was made on the occlusal surface of each dental element. The selected teeth were intact and healthy. Elements with endodontic treatment, with calcified canal and with accentuated curvature were excluded from the research. Initially, the dental elements were numbered from 1 to 40, the radiographic image of each canal was obtained and they were identified with the respective numbers. Two sets of PDM file instruments were used, each containing three files: 15/05, 25/01 and 25/06, 25 millimeters long. The preparation sequence was 6/25 up to 3 millimeters below the Apparent Tooth Length (CAD), simulating the Exploration Working Length (CTEx). After that, the sequence of files 25/01, 15/05 and 25/06 continued until the tip of each instrument passed one millimeter beyond the apical foramen. After using each file, it was visually evaluated with a millimeter ruler (Dia Dent Group International, Inc., Vancouver, British Columbia, Canada), and checked for the presence of fracture or deformation of the spirals. When an instrument fractured, it was discarded and replaced with an identical one from set number 2, and instrumentation of the canals continued until all three instruments fractured. During data collection, they were entered, stored and tabulated in a database in the Microsoft Excel 2016 ® program (Microsoft Corporation, Redmond, WA). The total and average number of turns given with the 15/05, 25/01 and 25/06 files until the fracture was analyzed and calculated. Therefore, the PDM files demonstrated a good result in relation to the tested dental elements, since the 15/05 and 25/06 files achieved, respectively, a total of 170 and 985 turns on 27 and 40 teeth and had an average number of turns 6.29 and 24.62 per “ex vivo” single-rooted mandibular premolar tooth modeled in the crown-apex technique without the occurrence of fracture.