Relationship Between Primary/Mechanical and Secondary/Biological Implant Stability

Purpose: This systematic review was prepared as part of the Academy of Osseointegration (AO) 2018 Summit, held August 8-10 in Oak Brook Hills, Illinois, to assess the relationship between the primary (mechanical) and secondary (biological) implant stability. Materials and Methods: Electronic and manual searches were conducted by two independent examiners in order to address the following issues. Meta-regression analyses explored the relationship between primary stability, as measured by insertion torque (IT) and implant stability quotient (ISQ), and secondary stability, by means of survival and pert-implant marginal bone loss (MBL). Results: Overall, 37 articles were included for quantitative assessment. Of these, 17 reported on implant stability using only resonance frequncy analysis (RFA), 11 used only IT data, 7 used a combination of RFA and IT, and 2 used only the Periotest. The following findings were reached: Relationship between primary and secondary implant stability: Strong positive statistically significant relationship (P < .001). Relationship between primary stability by means of ISQ and implant survival: No statistically significant relationship (P = .4). Relationship between IT and implant survival: No statistically significant relationship (P = .2). Relationship between primary stability by means of ISQ unit and MBL: No statistically significant relationship (P = .9). Relationship between IT and MBL: Positive statistically significant relationship (P = .02). Accuracy of methods and devices to assess implant stability: Insufficient data to address this issue. Conclusion: Data suggest that primary/mechanical stability leads to more efficient achievement of secondary/biological stability, but the achievement of high primary stability might be detrimental for bone level stability. While current methods/devices for tracking implant stability over time can be clinically useful, a robust connection between existing stability metrics with implant survival remains inconclusive.