The assessment of untreated surface orthodontic mini-implants' osseointegration through three successive methods

Mini-implants (MIs) with untreated surfaces are conventionally retained solely through mechanical forces, without any secondary retention mechanism involved (osseointegration). A previously reported issue is the fracture of untreated surface MIs during removal, after orthodontic treatment. Several factors, including potential osseointegration, may cause these fractures. The current research investigates the possibility of osseointegration of untreated surface MIs using three consecutive techniques: removal torque (Tq) measurement using a customized device, immediately followed by spectroscopy analyses (EDX/EDS-Energy Dispersive X-ray Spectrometry and Scanning electron microscopy-SEM), as well as several histological methods to detect the presence of newly-formed bone-cells, which were seen as an indicator for osseointegration. This observational study involved the analysis of removed untreated surface MIs from patients (with a mean age of 21.58 years and a median value of 17 years) at the end of the MI treatment phase. While the EDS, SEM technique, and analysis of removal Tq suggested the presence of osseointegration on the surface of the MIs, the histological methods disproved these results.