ISO TS 13498:2011 pdf free download – Dentistry一Torsion test of implant body/connecting part joints of endosseous dental implant systems.
Most dental implant systems currently on the market employ a dental implant body that is inserted within the jaw bone, to which other components can be joined when constructing a prosthetic superstructure.’ The connection between these components and the implant body should be sufficiently rigid to resist masticatory loads, which have a significant torsional component. Implant systems therefore often incorporate features to restrict rotation at the connection. If this is insufficiently strong， then distortion/fracture of the linked components will occur. A standardised torsion test for the joint between the implant body and connecting part facilitates comparative evaluation.
5.2 Torque transducer
The torque transducer shall have a range not exceeding the quintuple of the anticipated minimum torsional yield strength. The maximum inaccuracy of the torque transducer shall be +1 % of the maximum torque to be tested.
5.3 Preparation of test specimen
The connecting part shall be fixed on the implant body using the specified screw at tightening torques stated in the manufacturer’s instructions for use. The ends of the implant body and connecting part shall be fixed in a rigid clamping device. These ends may be modified into shapes larger than the maximum diameter of implant body and/or connecting part and they should be easy to clamp with the holders. An example of a test specimen is ilustrated in Figure 2.
5.4 Test conditions
Carry out the test at room temperature (20士5)。C in air.
5.5 Procedure
5.5.1 The connecting part shall be fixed on the implant body using a specific screw at tightening torques stated in the manufacturer’s instructions for use. Clamp the retaining portions of the implant body and connecting part of a test specimen into the specimen holders of the testing device. Apply torque continuously to the connecting part at a rate of between 1 and 10 degrees per minute and record the torque versus rotation angle curve. Measure the torsional yield strength and the maximum torque of at least six test specimens as described below.
5.5.2
The torsional yield strength is determined by the 2° offset methode (see Figure 3) using the torque versus rotation angle curve produced as described in 5.5.1.
5.5.3
On the torque versus rotation angle curve, locate a point, m, corresponding to 2° of rotation angle and draw a line, mB, parallel to a line, OA. Locate a point S, which is the intersection of mB with the torque versus rotation angle curve. Torque, Mtors, is defined as the torsional yield strength.
5.5.4
The maximum torque, Mmax, is determined by the largest value of torque on the torque versus rotation angle curve.
NOTE It is possible that a sag appears on the torgue versus rotation angle curve depending on the testing configuration. In such cases, the torsional yield strength and the maximum torque are determined according to Figure 3 b).