The relationship between resonance frequency analysis (RFA) and lateral displacement of dental implants: an in vitro study


  • [Correction added on 28 January 2013, after first online publication: the flex constants N μm−1 have been corrected to lm N−1 throughout the article.]

Correspondence: Lars Sennerby, Department of Oral & Maxillofacial Surgery, Instituite of Odontology, PO Box 450, SE 405 30 Gothenburg, Sweden. E-mail:


This in vitro investigation was conducted to study the relationship between resonance frequency analysis (RFA) and lateral displacement measurements of dental implants. A total of 30 implant sites were prepared in nine fresh bovine bone specimens. The bone density around each preparation was determined by using cone beam computerized tomography (CBCT) and imaging software. Dental implants were then inserted during continuous registration of insertion torque. RFA measurements were performed in perpendicular and parallel to the long axis of the specimens. The bone blocks were embedded in plaster and fixated in a specially designed rig for displacement measurements. A lateral force of 25 N was applied via an abutment perpendicular and parallel to each implant and the displacement measured in μm. In addition, a flex constant (μm N−1) was calculated for each measurement. There was a significant inverse correlation between RFA and lateral implant displacement (μm) measurements and between RFA measurements and the flex constant in both perpendicular and parallel directions in bone (P ≤ 0·001). Moreover, both RFA and displacement measurements correlated with bone density (P ≤ 0·001). It is concluded that RFA measurements reflect the micromobility of dental implants, which in turn is determined by the bone density at the implant site.