A: In general, Electromagnetic noise, or “EM-noise” should be taken as an indication that the environment contains an alternating magnetic field of some magnitude. However there could be sudden bursts of electromagnetic noise from different electronic equipment, which could sometimes coincide with a measurement. TV-sets are among those devices that create a lot of noise.
If the probe is close to the instrument (a few centimetres), the noise from the instrument itself will cause the warning. If the warning is only visible when the probe is held close to a SmartPeg, it can be due to:

1. If the implant is really rigid, it makes the signal from the SmartPeg very strong, which can cause the warning. Try to distance the probe from the SmartPeg a millimetre or two. Clinically this should happen very seldom, but on a plastic jaw model for instance, it can be necessary to hold the probe several millimetres from the SmartPeg, due to the lack of dampening soft tissue.
2. If the SmartPeg is not mounted properly, it can cause the warning. If this has happened the SmartPeg threads are probably damaged, and it has to be exchanged.
   

Firmware 12 or later together with probe version 2, makes the instrument less sensitive to electromagnetic noise. For an upgrade contact your local dealer or Osstell directly.

The instrument measures constantly when switched on, except when in menu mode. To ensure that the instrument is working properly, use the SmartPeg test block (TestPeg) to take a measurement.

The SmartPeg measures stability in all directions and singles out the most stable and the least stable directions. The two ISQ values represent these values. If they are both found at the same time, and they differ by more than 3 ISQ units, they are presented on the display together. The two values can also be found by measuring from two different directions.

The SmartPegs are single use, but one SmartPeg can be used for several measurements on the same occasion. To avoid damage to the implant, the SmartPeg material is quite soft, which limits the lifetime of the threads. Autoclaving the SmartPeg weakens the magnet, which makes it unreliable for measurements.

The SmartPeg should be tightened with 4-5 Ncm, which means “finger tight”, using the SmartPeg Mount. It is enough with firm contact between the SmartPeg and the implant. The difference in ISQ value will then stay within 2 ISQ units. (If the SmartPeg is tightened too loosely, the ISQ-value will be lower.) If the SmartPeg is over-tightened, there is a risk that the SmartPeg threads will be damaged.

Yes, you can use either the 121°C or the 137°Cprogram. The probe is also autoclavable.

The probe should only be cleaned in an autoclave or by hand using isopropyl alcohol.

Osstell ISQ and Osstell Mentor use a “spreadsheet” to store the ISQ values (rows 1-20, columns A-T). To view the spreadsheet, press the center key to enter the menu, and then the same key again to enter spreadsheet viewing mode (Display data). Use the arrow keys to move around the spreadsheet.

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For a description of the data displayed, please see What does "Display data" show? Press the center key again to return to measurement mode.

The values can be stored in three different ways – enter the menu and select “ISQ save mode” to choose how.

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Next free (no. 1 for Mentor):	The ISQ value is stored in the next available spreadsheet cell. If a column is full, the value is stored in the next column.
Overwrite (no. 3 for Mentor):	The ISQ value overwrites the current cell.
Next row (no. 2 for Mentor):	The ISQ value is stored in the next available spreadsheet cell, but will not move to the next column if the current column is full.

 

The default is “Next free” (no. 1 for Mentor).

The damping effect from the surrounding tissue can vary a great deal from implant to implant. If the damping is extreme, it may be necessary to hold the probe tip close to the magnet on top of the SmartPeg to get a reading. Normally, the probe is held 2-3 mm from the magnet, but if you do not get an ISQ value, try shortening the distance between the magnet and the probe tip. You can also try holding the probe at a slightly different rotational angle. Always make sure the implant platform is clean.  See also the question about “Electromagnetic noise”.

The SmartPeg measures the stability in all directions and singles out the most stable and the least stable direction. Sometimes, there is no difference between them. To make sure to measure both values, the probe should be held perpendicular to the jaw line for one measurement, and in line with the jaw line for the other measurement. The two ISQ’s represent these values. If the instrument finds them both at the same time, and they differ more than 3 ISQ units, they are presented on the display together.

 

Display data shows the data for each measurement. The memory cell position (e.g., A-2) is shown in the upper left. The ISQ value (e.g., ISQ 72-00) is shown in the upper right. The values are separated by a hyphen. If two values have been detected, select the lowest (also see Why do I sometimes get two different ISQ-values from the same implant? (Sometimes they are even shown at the same time on the display)).

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The second row shows the signal strength from the SmartPeg (e.g., Q 100-00). These values have no significance in daily practice, and are provided purely for scientific purposes.  The values range from 1 to 100 and the higher the value, the stronger the signal.

If the implant is obviously mobile it can happen that the instrument presents a value that does not reflect its mobility. Instead a higher value can be shown, which is really coming from the “shaking” SmartPeg and implant together.

If the implant is embedded in homogenous and symmetrical bone, the instruments will produce approximately the same ISQ values. However, since the transducer is direction-dependent, which the SmartPeg is not, the transducer can produce different values in different directions. The SmartPeg, on the other hand, finds the highest and the lowest stability values (corresponding to two perpendicular directions).

The average ISQ is approximately 70. The clinical range that can be seen is from 40-45 up to 85-90. Most implants have between 55 ISQ to 80 ISQ

If the implant stability is symmetrical (same stability in all directions), only one ISQ-value will be found.

Both the highest and the lowest value reflects the stability situation for a particular implant. The high value is normally in the mesio-distal direction, and the low value normally in the bucco-lingual direction. Both give good information about how the implant situation is, and it can be useful to follow the development of both.

It is impossible to base the decision about immediate loading only on the ISQ-value. The literature shows that good primary stability is essential for a successful outcome, but there are of course also other parameters that have to be considered in such a decision. See also above about which ISQ values to expect. Many direct loading studies show good results with immediate loading if the primary stability is good. It seems as the implant stability will not change considerably from implantation to after osseointegration in many such cases.

Osstell Mentor measures the stability of an implant or more exactly the stiffness of the implant in the surrounding bone. If the stability goes up from a lower value between the implant surgery and some time later, it is the effect of osseointegration.

ISQ, or Implant Stability Quotient, is a scale from 1 to 100 and is a measure of the stability of an implant. The ISQ is a close to linear mapping of the resonance frequency of the SmartPeg that is attached to the implant.

Clinically, the lowest number seen is approximately 40 ISQ. If the stability is less than 30, the implant is more or less “loose”. Values below 20 will not be seen, unless on a lab model with artificially low stability.