Reliability and validity of the instrumental assessment of implant stability in dry human mandibles

Abstract

The aim of this study was to determine the intra- and interobserver reliability and validity of the instrumental assessment of primary dental implant stability, using resonance frequency analysis (RFA). Sixteen tapered implants and 16 cylindrical implants were installed in eight unfixed dry human mandibles (Cawood classification IV/V). Implant stability quotients (ISQ; the outcome variable of RFA) and peak removal torque were determined. Both the intra-observer reliability and the interobserver reliability of the RFA measurements were fair-to-good, while no significant correlations between the ISQ values and removal torque were found. The removal torque of the cylindrical implants was higher than that of the tapered implants. The smallest detectable difference was almost nine ISQ units. Within the limitations of the present dry cadaver study, it was concluded that (i) primary dental implant stability can be assessed reliably with RFA measurements, (ii) the concurrent validity between RFA measurements and removal torque is poor, (iii) cylindrical implants may be more stable than tapered ones and (iv) two subsequent readings of RFA measurements need to differ at least nine ISQ units before the difference between the two measurements can be considered statistically significant. More research is needed to see whether these conclusions can be extrapolated to the clinical situation, including the assessment of implants during function (secondary stability).

Surface treatment of implants: primary stability

“…This analysis, presented as an implant stability quotient (ISQ, with a value between 0 and 100), in which a higher value indicates increased stability 2,6,13 ; is influenced by the bone adjacent to the implant and the rigidity of the bone-implant interface [2][3][4]9,13 . This statement corroborates this study's results, in which higher resonance frequency values were found in implants inserted in wood and 40 PCF Nacional ® polyurethane, the materials with the greatest rigidity amongst those chosen as bone substitutes; it also corroborates studies that show that the resonance frequency of implants is proportional to the rigidity of the surrounding material.…”

“…The Periotest is an instrument that assesses tooth or implant mobility 8 , however its applicability for this purpose is poor due to its low senitivity 2,4,8 . Insertion torque is equal to the implant's final seating torque in the receiving bone site 6 , but this can only be assessed per operandum 2,8 .…”

“…Resonance frequency analysis can be used to to determine primary stability at any moment during the bone healing process, after the implant is inserted [2][3]8,12 . This consists of a clinical assessment of the implant's vibratory oscillations by way of a transducer connected to it.…”

“…The use of endosseous implants in oral rehabilitation has witnessed a significant increase in recent years due to studies showing high success rates [1][2][3][4][5] and scientific and industrial developments that have broadened the application of these implants. To achieve osseointegration, it is crucial that during surgery the implant is stabilized in the receiving bone site 6 , attaining primary stability 2,[6][7][8][9][10] .…”

“…To achieve osseointegration, it is crucial that during surgery the implant is stabilized in the receiving bone site 6 , attaining primary stability 2,[6][7][8][9][10] . This initial fixation depends on surgical technique, implant design and on patient-related factors such as bone density 1,[10][11] .…”