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ePaper created 2017-03-17, 12:34:42 | version 1.38.0
| interview “The RFA technique must be accurate and reliable” Resonance Frequency Analysis (RFA) is today a standard method to measure implant stability, but the measurement unit ISQ itself needs to be explained. Prof. Lars Sennerby is one of the developers and re- searchers behind the RFA technique and will sort things out for us below. Prof. Sennerby, what is your experience of the RFA technique? Prof. Neil Meredith showed me a prototype of his invention already in 1992 and we have since then used RFA for implant stability measurements in numerous experimental and clinical studies: first as part of the early development work and Dr Meredith’s Swedish PhD thesis (1997), which I supervised, and then as a clinical routine diagnostic instrument. I find it to give valuable and relevant information about implant sta- bility at any time point during implant treatment and follow-up. What is the background to the ISQ unit? The whole purpose of introducing the ISQ (Implant Stability Quotient) was to give clinicians a unique and easy quantity on a scale from 1–100; the higher the value the better the stabil- ity. ISQ was introduced in 2001 and de- rives from a linear recalculation of the resonance frequencies (RF) in Hertz (Hz) obtained from measurements of dental implants with the first genera- tion of wire-bound transducers. How do you define the ISQ unit? ISQ is calculated from the underlying RF of the transducer peg using a mathemati- cal equation. The ISQ unit has not yet been defined using any other general or specific unit, simply because there is no such unit available. Instead, empirical data from more than 800 scientific publi- cations has guided clinicians how to use the ISQ scale clinically. Fig. 2 How do we then know that implants with the same stability have the same ISQ? It is of course desirable that different pegs for dif- ferent implant designs give the same ISQ value if they have the same implant stability. This is a known prob- lem when calibrating transducer pegs for different implant designs. It has not been so easy to solve, since implant stability per se has not been defined using any other quantity, and a reference had to be created. The reference can then be used when transducers are de- signed and developed. To explain the problem, think of two different implant designs that are placed in identical material and two different ISQ values are obtained. It is impossible to know if the difference depends on the fact that the two pegs are different or if it is because the stability is actually different, or a combination of the two. So a reference is indeed necessary. Fig. 1: The MulTipeg device. Fig. 2: Prof. Lars Sennerby. 36 implants 1 2017