The Effect of Time on Orthodontic Mini-Screw Implants Stability (An experimental study)

Hassan Moyasser Dawood Al-Nuaimy, Hussein Ahmad Jasim Al-Obaidy


Background: Mini-screw implants have become an accepted and reliable method for providing orthodontic anchorage. The present
study aimed to measure the primary and secondary stability of mini-screw implants using the removal torque value as indictor for
the stability and comparing between four different periods of mini-screw implants removal (Immediate, 2 weeks, 4 weeks and 6
Materials and Methods: Forty mini-screw implants, all of the same manufacture, length (7 mm), diameter (1.4 mm) and of cylinder
type, were implanted in the tibia bone of two sheep (ten in each tibia) after anesthesia and flap reflection using drilling burs. The
insertion torque were standardized and equalized for all mini-screws. Mini-screw implants were removed after different periods
of time (immediately, 2 weeks, 4 weeks and 6 weeks) using digital torque screw driver (DID-4). One-way ANOVA test was used to
compare among the groups.
Results: The results showed that mini-screw implants stability significantly decreased during the first two weeks then started to
increase during the four and six weeks.
Conclusions: It was concluded from this study that mini-screw implants stability is affected by the period of implantation, decreased
during the first two weeks and then started to increase.


MSI (Mini-screw implant); DID4 (digital insertion torque screw driver; Stability; Torque


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