Long-term durability of orthodontic mini-implants

The current study aimed at examining surface and chemical composition changes of retrieved mini-implants after different periods of service as aids of anchorage for orthodontic patients. This study examined 72 retrieved orthodontic self-tapping and self-drilling mini-implants, 1.7 mm in diameter and 8 mm in length (OrthoEasy system, Forestadent, Pforzheim, Germany) from 36 adult orthodontic patients (18 men and 18 women, mean age = 23 years). The retrieved mini-implants were divided into 3 groups according to service period: 3–6 months (3M–6M) group, 6–12 months (6M–12M) group, and 12–24 months (12M–24M) group, with 24 mini-implants in each group. The control group (As Received) comprised of 24 unused mini-implants of the same type (AR group). All mini-implant heads and threaded bodies were examined for chemical characterization and topographical features by SEM–EDS. The average weight percentages for the following elements Ti, Al, and O2 were obtained and compared among the 4 groups. There was significant decrease in titanium content and deterioration for the surface properties for all parts of the mini-implants after being used inside patients’ oral cavities for more than 6 months p < 0.05. The period of mini-implant service inside patients’ oral cavities should not exceed 6 months.