American Journal of Orthodontics and Dentofacial Orthopedics
Original articleEffect of longitudinal flutes on miniscrew implant stability and 3-dimensional bone formation
Section snippets
Material and methods
Eleven skeletally mature female New Zealand white rabbits, 7 to 8 months of age, were used in this study. The Institutional Animal Care and Use Committee at Texas A&M University Baylor College of Dentistry in Dallas approved the care of the animals and the experimental protocol. Each of the 62 miniscrews placed was subjected to a constant force of 100 g.
Two miniscrews were specifically fabricated for this study. They were identical except for the flutes that extended down the entire length of
Results
The overall success rate for the study was 97.0% for the fluted (1 failure out of 31 screws) and 97.0% for the nonfluted (1 failure out of 31) MSIs. Both failures were complete failures; the MSIs were not in bone, and the expansion springs were no longer active. They occurred in different animals and pertained to MSIs loaded anteroposteriorly.
Insertion torque values of the fluted MSIs ranged from 1.5 to 7.0 N.cm, with a mean of 3.98 ± 0.24 N.cm (Fig 5). For the nonfluted MSIs, insertion torque
Discussion
High success rates are attainable with loaded 3-mm-long MSIs. The fluted and nonfluted MSIs were 97% stable over the 6-week experimental period. The success rates were similar to or higher than previously reported for animal models16, 17, 18, 19, 25 and substantially higher than rates reported for humans.7, 8 This suggests that the lower clinical success of MSIs depends on confounding factors, such as root proximity24, 26 and peri-implant infection,26 that are difficult to control. The ability
Conclusions
- 1.
Loaded 3-mm MSIs have high (97%) success rates in rabbit calvaria.
- 2.
Miniscrews remained stable even when placed with maximum insertion torque values below recommended levels.
- 3.
Adding flutes to 3-mm MSIs increased the removal torque by 37% after 6 weeks of healing.
- 4.
There was less bone at 6 to 24 μm from the MSI surface than at 24 to 42 μm and 42 to 60 μm from the implant surface.
- 5.
There was greater bone surrounding nonfluted than fluted MSIs after 2 and 6 weeks of healing.
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Cited by (0)
All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.
Partially funded by the Robert E. Gaylord Endowed Chair in Orthodontics.