Análise do torque exercido durante o aperto manual de pilares de implantes

  • André Abreu Trindade Coelho (Student)

Student thesis: Master's Thesis

Abstract

Introduction: In fixed prosthetic oral rehabilitation with dental implants, it is crucial to use the recommended torque values for tightening abutments and prosthetic screws provided by manufacturers. This tightening can be performed using specific screwdrivers and torque wrenches, which allow for more precise control of the tightening torque. Progressive loosening of screws can lead to mechanical and biological complications due to the lack of stability of the dental prosthesis. Although torque wrenches are recommended and commonly used, there are often instances of loosening of prosthetic structures, raising questions about whether the recommended torque value was achieved during the tightening process. This investigation is justified to verify the accuracy of torque wrenches (manual and digital) and compare the manual strength of students and teachers, given the poor existing scientific evidence on this subject. Materials and Methods: This study was divided into 5 preclinical trials. In the first trial, two types of manual torque wrenches with different dynamometric systems, spring-style and friction-style, were used to tighten an abutment to implant analogue embedded in Type III gypsum implant or directly on a torque measurement cell. For each torque wrench, 10 cycles of tightening/loosening were performed for preselected values of 15 and 35 Ncm. The measured value in each cycle was recorded using a torque measurement cell. In the second trial, a third workstation was used, and 10 cycles of tightening were performed using two digital torque wrenches (iChiropro® and iSD900®), with the obtained value recorded on the torque measurement cell. In the third trial, measurements of the maximum torque applied by 5 teachers and 5 students (5th year) from FMD-UCP were conducted using a manual tightening wrench. In the fourth trial, after tightening the screw to 35 Ncm, it was verified whether each teacher/student could loosen it using a manual tightening wrench. The peak torque, measured by the torque measurement cell was recorded. Results: In the first trial, the Spring-Style torque wrench (Straumann®) exerted a higher torque than the Friction-Style torque wrench (Medentika®), and the difference was statistically significant during tightening at 35 Ncm. The average torque values obtained with both torque wrenches were statistically significantly lower, by 25.3-34.3%, compared to the reference values of 15 and 35 Ncm. There were no statistically significant differences regarding the applied torque on the implant analog included in Type III plaster or mounted directly on the benchtop torque gauge. In the second trial, it was observed that digital torque wrenches are more accurate when compared to manual torque wrenches. In the third trial, it was found that the torque applied by the instructors is statistically significantly higher than the torque applied by the students. In the fourth trial, it was verified that manual loosening of prosthetic screws previously tightened to 35 Ncm requires a statistically significantly higher torque than the applied tightening torque. Conclusion: The manual torque wrenches recorded significantly lower values than the reference values. Manual torque wrenches are less accurate than digital torque wrenches. The operator's experience leads to a higher tightening/loosening force. Manual loosening of prosthetic screws previously tightened to 35 Ncm requires a significantly higher torque than the applied tightening torque.
Date of Award25 Jul 2023
Original languagePortuguese
Awarding Institution
  • Universidade Católica Portuguesa
SupervisorAndré Correia (Supervisor) & Luis Mezzomo (Co-Supervisor)

Keywords

  • Torque
  • Prosthodontics
  • Dental abutments
  • Dental implants
  • Implantology

Designation

  • Mestrado em Medicina Dentária

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