Resonance Frequency Reading of Different Peri-implant Bony Conditions

Objectives: ISQ readings from Osstell machine (Resonance frequency analysis) have been used widely to represent the stiffness of peri-implant supporting bone and implant stability. ISQ has been related to bone height and bone quality. However, it is not clear how the cortical layer or trabecular bone contributes to ISQ and whether a bony defect closed to the implant affects ISQ. This study's aim was to answer the above questions. Methods: Sawbones with 15PCF and 50PCF densities were cut into 40x10x20mm (M-D length x B-L width x height) and 40x10x3mm blocks, respectively, to represent the trabecular bone block and cortical layer. Five different samples were tested: sample 1, trabecular bone block only; sample 2, trabecular bone block with a 3 mm diameter tunnel buccolingually through the block centered at the middle portion of the implant; sample 3: a cortical layer bonded above the trabecular bone block; sample 4: cortical layer only; sample 5: cortical layer with a 1mm crescent defect buccal to implant site. An implant (Branemark MK III 3.75x10mm) was screwed at the center of 40x10 mm surface of each bone block after a 3mm drilling site preparation. An L-shaped transducer was attached to the implant and each sample was tested 3 times with the transducer in M-D or B-L direction. Nonparametric test was performed to detect significant difference. Results: The preliminary results showed significant differences between samples 1 & 2, samples 1, 3 & 4, and samples 4 & 5. The transducer direction affected ISQ if defects appear neighbor to an implant (p< 0.05). Conclusion: The findings suggest that cortical bone and trabecular bone contribute differently to ISQ and defects in supporting bone may affect ISQ. Further experiments are necessary to understand ISQ.