Assessment of oral implant mobility

Most of the implant literature suggests that successful dental implants are immobile and any detected mobility indicates implant failure. This study evaluated the ability of the Periotest instrument to measure implant mobility in a controlled in vitro model with a sample of 56 in vivo implants. In the in vitro portion of the study, implant model mobility was determined by an axial testing machine (0 to 5 N at 0.2 mm/minute) and the Periotest instrument. The comparison showed a high level of correlation (Pearson's r 0.984). The load that the Periotest placed on the implants during mobility measurements was approximately 5 N, depending on the compliance of the test object. The in vivo portion evaluated the range of mobility of 56 clinically successful endosseous implants. The range of mobility as determined by the Periotest instrument was -6 to +2. This range corresponds to an in vitro model displacement (5 N load) of 0.038 mm to 0.113 mm with a mean of 0.066 mm +/- 0.018 mm (SD). These data demonstrate that clinically successful implants are not immobile, but have a range of mobility.