Resonance frequency analysis (RFA) is the most extended method for measuring implant stability. The implant stability quotient (ISQ) is the measure obtained by different RFA devices; however, inter- and intra-rater reliability and agreement of these instruments remain unknown. Thirty implants were placed in three different pig mandibles. ISQ was measured parallel and perpendicular (lingual) to the peg axis with Osstell® Beacon, Penguin® and MegaISQ® by two different investigators and furthermore, one performed a test-retest. Intraclass correlation coefficient was calculated to assess the intra- and inter-rater reliability. Pearson correlation coefficient was used to assess the agreement. Intraclass correlation coefficients ranged from 0.20 to 0.65 for the Osstell® Beacon; 0.57 to 0.86 for the Penguin®; and −0.01 to 0.60 for the MegaISQ®. The highest ISQ values were obtained using Penguin® (66.3) in a parallel measurement; the lowest, using the MegaISQ® (60.1) in a parallel measurement. The highest correlation values with the other devices were obtained by MegaISQ® in a parallel measurement. Osstell® Beacon and MegaISQ® showed lower reliability than Penguin®. Osstell® had good agreement for measuring ISQ both in parallel and perpendicular, and MegaISQ® had the best agreement for measuring ISQ in parallel.

Background: Actually, resonance frequency analysis (RFA) is the most extended method for measuring implant stability. The implant stability quotient (ISQ) is the measure obtained by the different RFA devices, however, inter- and intra- rater reliability and validity of some devices remains unknown. Methods: Thirty implants were placed in 3 different pig mandibles. ISQ was measured axial and parallel with Osstell® Beacon, Penguin® and MegaISQ® by 2 different operators and one operator performed a test-retest. Intraclass correlation coefficient was calculated to assess the intra- and inter-rater reliability. Pearson correlation coefficient was used to assess the validity. Results: The higher inter- and intra- rater reliability was obtained by Penguin® when measuring axial. The highest ISQ values were obtained using Penguin® in an axial measurement; the lowest, using the MegaISQ® in an axial measurement. The highest correlation values with the other devices were obtained by MegaISQ® measuring axially. Conclusion: Penguin® had a good reliability for measuring ISQ both inter- and intra- rater. Osstell® had good validity for measuring ISQ both axial and parallel and MegaISQ® had the best validity for measuring ISQ axial.