**4. Reverse torque**

This type of evaluation of implant stability carries with it a potentially high possibility of a negative outcome. This test uses a torque wrench set at 20-30 N/cm and the implant is then subjected to a rotational force in the counter-clockwise direction. Though, in most integrated situations this should not be an issue, it is possible to break integration in softer bone types such as D4 bone or if done too early in the healing process in other bone types.

## **5. Periotest**

The Periotest device was originally designed to measure the mobility of teeth by using a pneumatic plunger that would read the deflection of the tooth in the natural peridontium. In 1990, Olive et al. used it to test the stability of dental implants [4]. The values reported by the device range from −8 to +50. **Figure 2** shows the values for interpreting implant stability, and **Figure 3** shows the values associate with natural teeth.

Unfortunately, because the Periotest value is strongly related to the excitation direction and position, the reading from the method does not always correspond precisely to a biomechanical parameter [5]. Another possible cause for a false reading is that the clinicians hand, or ability to not move that hand becomes part of the equation. If some of the percussive force is either resisted too much or absorbed too much, the readings will not be true.


#### **Figure 2.**

*Periotest value range.*


**Figure 3.**

*Periodontal mobility classification vs. Periotest values.*
