title: Influence of manual preflaring and torque on the failure rate of ProTaper rotary instruments.
abstract: We evaluated the influence of manual preflaring and torque on the failure rate of rotary nickel-titanium ProTaper instruments Shaping 1 (S1), Shaping 2 (S2), Finishing 1 (F1), and Finishing 2 (F2). These factors were evaluated using an in vitro method by calculating the mean number of Endo-Training-Blocks shaped before file breakage under different conditions. Group A (S1 on simulators with no preflaring) shaped 10 blocks before failure, group B (S1 on manually preflared simulators) shaped 59 blocks (p<0.01 versus group A), group C (S2 with low torque) shaped 28 blocks, group D (S2 with high torque) shaped 48 blocks (p<0.01 versus group C), group E (F1 with low torque) shaped eight blocks, group F (F1 with high torque) shaped 23 blocks (p<0.01 versus group E), group G (F2 with low torque) shaped four blocks, and group H (F2 with high torque) shaped 11 blocks (p<0.01 versus group G). Manual preflaring creates a glide path for the instrument tip and is a major determinant in reducing the failure rate of these rotary nickel-titanium files. All instruments worked better at high torque.
authors.affiliation: Department of Endodontics, School of Dentistry, Turin University, Turin, Italy.
authors.forename: Elio
authors.initials: E
authors.lastname: Berutti
authors.forename: Alfonso Roberto
authors.initials: AR
authors.lastname: Negro
authors.forename: Mario
authors.initials: M
authors.lastname: Lendini
authors.forename: Damiano
authors.initials: D
authors.lastname: Pasqualini
mesh_terms: D003722:Dental Alloys; D003762:Dental Instruments; D004868:Equipment Failure; D003765:Models, Dental; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods*; D014025:Titanium; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium