Comparison of the primary stability of orthodontic miniscrews after repeated insertion cycles: An in vitro study

Felipe Nenen, Nicolás Garnica, Víctor Rojas, Rodrigo Oyonarte*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Objectives: To compare the primary stability of miniscrews after repeated cycles of insertion through insertion torque (IT) measurements and resonance frequency analysis (RFA). Materials and Methods: Sixty titanium miniscrews were divided into two groups according to the insertion protocol: one with predrilled sites and the other self-drilled into porcine iliac crest bone specimens. Each group had three cycles of reinsertion. After each insertion, the IT and RFA were measured. The IT was measured by using a torque meter, and the RFA was measured using the Osstell ISQ device. A total of five miniscrews of each group were selected for sequential assessment of the morphology of their tip and threads using scanning electron microscopy after each insertion cycle. Results: No statistically significant differences were found in the IT values of miniscrews reinserted up to three times in the group with predrilled surgical sites. The IT value increased significantly with the number of reinsertions in the self-drilled group. The RFA value decreased as the number of insertions increased in both groups. Conclusions: Under the conditions of this in vitro study, reinserting miniscrews deteriorates the integrity of their tip and thread. Reinsertion should be discouraged particularly when insertion sites are not predrilled. (Angle Orthod. 2021;91:336–342.)

Original languageEnglish
Pages (from-to)336-342
Number of pages7
JournalAngle Orthodontist
Issue number3
StatePublished - 1 May 2021

Bibliographical note

Publisher Copyright:
© 2021 by The EH Angle Education and Research Foundation, Inc.


  • Insertion torque
  • Miniscrews
  • Reinsertion
  • Resonance frequency analysis


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