title: Effect of liquid and paste-type lubricants on torque values during simulated rotary root canal instrumentation.
abstract: OBJECTIVE
  To evaluate the effects of lubrication on torque generated during rotary preparation of simulated root canals in dentine using ProFile and ProTaper Nickel-Titanium instruments.
  
  
  METHODS
  Thirty-two 3 mm thick dentine discs were used for this study. Four pilot holes were drilled perpendicularly through each disc. These simulated root canals were filled with water, aqueous 15% ethylenediamine tetraacetic acid (EDTA) or a paste-type lubricant (Glyde). Empty canals served as controls. Peak torque values and apically directed forces of rotary instruments were measured using a specially designed testing platform. Full torsional loads over time were calculated by integration of continuous torque records. Data were compared using analyses of variance with the alpha-type error set at 0.05.
  
  
  RESULTS
  Maximum torque values using ProFile instruments were significantly (P < 0.005) reduced by the EDTA solution, whilst no reduction was observed using Glyde. With ProTaper instruments, no lubricant effects on maximum torque values were observed (P = 0.372). Full torsional loads over time were significantly reduced for both ProFile and ProTaper preparation (P < 0.005) by the use of lubrication. The two fluids performed significantly better than paste-based Glyde. All lubricants reduced force when applied to ProTaper by mean reductions ranging from 12 to 54%, whilst Glyde lead to increased force when applied to ProFile.
  
  
  CONCLUSIONS
  Under the conditions of this laboratory study, lubrication appeared to be advantageous. Aqueous solutions generally performed better than the paste-type product under investigation, which showed untoward effects when used in conjunction with a rotary instrument with a U-shaped cross-section (ProFile).
authors.affiliation: Division of Endodontology, Department of Preventive Dentistry, Periodontology, and Cariology, University of Zürich Center for Dental Medicine, Zürich, Switzerland.
authors.forename: O A
authors.initials: OA
authors.lastname: Peters
authors.forename: C
authors.initials: C
authors.lastname: Boessler
authors.forename: M
authors.initials: M
authors.lastname: Zehnder
mesh_terms: D000704:Analysis of Variance; D003762:Dental Instruments; D003799:Dental Stress Analysis; D004492:Edetic Acid; D006801:Humans; D008153:Lubrication; D008422:Materials Testing; D008963:Molar; D012388:Root Canal Irrigants; D018915:Root Canal Preparation / Q000295:instrumentation*; D019415:Torque
chemical_list: D012388:Root Canal Irrigants; D004492:Edetic Acid