EVALUATION OF FRACTURE TORQUE RESISTANCE IN MINISCREWS AFTER MULTIPLE REUSE CYCLES

• DOI: 10.22533/at.ed.0462325075

• Palavras-chave: -

• Keywords: Orthodontics. Orthodontic anchoring procedures. Recycling.

• Abstract:

  Orthodontists are increasingly reusing miniscrews used as anchorage devices,
  either when they fail after insertion or when they need to be installed in a new site due to
  changed mechanical needs. The objective of this study was to simulate the reuse of
  miniscrews up to three times and evaluate their resistance to fracture. To achieve this
  objective, 48 miniscrews (Morelli - Sorocaba - SP, Brazil) were used; these were divided
  into the following four groups: C = Control, G1 = one reuse, G2 = two reuses, and G3 =
  three reuses. To simulate the insertion in the patient’s oral cavity, swine iliac bones were
  used. After insertion of the miniscrews into the bone specimens, they were removed,
  cleaned, and sterilized by autoclaving. With a reference in the device, it was possible to
  standardize the insertions. After all groups had undergone the corresponding reuse
  cycles, the miniscrews were submitted to fracture, and the maximum force required for
  fracturing was measured using a digital axial torque wrench. Bovine tibia specimens
  were used for this step because they have higher bone density and cortical thickness.
  The average values ​​of the groups were analyzed using a one-way ANOVA test with the
  Bonferroni post-hoc test. A statistically significant difference in fracture resistance
  between group G3 and the other groups was noted. However, all groups required higher
  mean strengths for fracture than those recommended for miniscrew insertion in patients.