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Break-Open Torque Wrenches Unreliable?

posted in Techniques and Procedures

« Preparing the Implant Abutment | Fosamax and Dental Implant Treatment »

Dr. S. asks:

I use the torque wrenches that break open when you reach the desired torque. I have heard from some colleagues that this kind of torque wrench is unreliable and may break open below, at, or above the desired torque. Is this true? If so, is there any way that I can calibrate or test my break-open torque wrenches? How long do these kinds of torque wrenches stay accurate?

10 Responses to “ Break-Open Torque Wrenches Unreliable? ”

• Dr. Fouda May 22nd, 2007

  
  

  I use Dyna torque wrench and I didn’t face any troubles, however the ratchet wrench of NBC also measures the torque up to 45.

• Dr C May 22nd, 2007

  
  

  I use the DynaTorque-type (Zimmer) wrench and had one single episode when the wrench wouldn’t ‘break’ and resulted in over tightening the abutment screw. The wrench seems to be working now as I compared it to the PTS wrench (with plastic insert that snaps at pre-determined torque) , also from Zimmer. The Straumann type, seems to be very reliable.

• Dr. Arnie F May 22nd, 2007

  
  

  Interesting question about the torque wrench. Ue use Lifecore Prima, and our rep told us that the wrench whould be autoclaved in the “broken” position to prolong its life and to keep the torque it disengages accurate.

• anon May 22nd, 2007

  
  

  I have all my torque wrench calibrated at least once a year.

• T Giorno May 22nd, 2007

  
  

  Most of the torque wrench on the market function on the principle of a metal spring deformation of some kind. (more or less as a roman scale to describe in short!)
  When you expand and relax the spring so many times, you loose calibration, no matter what.
  The most accurate torque wrench to my knowledge is the Torque-Lock by Intra-Lock.
  It works on the principal of metal beam deformation, and reading is direct from 10 to 50Ncm. The gauge movement is relayed by rubis and sapphire gears. (as in a precise swiss watch).
  It doesn not loose calibration as fast as the others. But to be on the safe side, even this one must be caibrated every year or so.

• Dennis May 30th, 2007

  
  

  Torque limiting wrenches have always had problems with reliability due to autoclaving. Regular calibration should be done to make sure that your instrument is functioning properly.

• hersheydmd June 3rd, 2007

  
  

  Interesting.
  How does one go about getting their torque wrenches calibrated?

• Mike Foley October 5th, 2007

  
  

  Anthogyr manufactures the Torque Control, which is a highly reliable system that is unique in its design. It is not a ratchet design which leaves very simple to use, takes less space in the mouth, and is more accurate. Features 7 torque values from 10 to 35 N.cm.

• Paul April 21st, 2009

  
  

  I have 2 DynaTorq 30Ncm wrenches that locked up. I used WD40 on them and they appear to be working just fine now.

• Mike Mallinger October 11th, 2009

  
  

  There is a reliability factor with any of the torque wrenches. The truth is, they should be calibrated the moment they begin to function differently, whether it is the elasticity of a metal or a plastic. In other words, if it is important enough, and I think it is, they should be checked as often as we use them. These instruments just are not manufactured with that kind of reliability.

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