| dc.description.abstract | The purpose of the present study is to evaluate the effects of longitudinal flutes
on mini-screw implant (MSI) bone healing and stability. Using 11 skeletally mature
New Zealand White rabbits, 33 longitudinally fluted and 33 non-fluted MSIs were
placed and immediately loaded with 100g using NiTi coil springs. Insertion torque
values were obtained for each MSI that was placed; removal torque values were obtained
for 28 MSIs that had been in place for 6 weeks and 20 MSIs that had been in place for 2
weeks. The bone volume fraction surrounding the implant 6-to-24 μm, 24-to-42 μm, and
42-60 μm from the MSI surface using micro-computed tomography with an isotropic
resolution of 6 μm. The success rate was 97%, with both the fluted and non-fluted MSIs
each having one failure. Mean insertion torque was slightly higher for fluted MSIs (3.98
N cm ±0.24) compared to non-fluted MSIs (3.95 N cm ±0.24), but the difference was not
statistically significant (p=.930). After 6 weeks, removal torque values were
significantly (p=.008) higher for the fluted (3.42 N cm ±0.26) than non-fluted (2.49 N
cm ±0.20) MSIs. After 2 weeks, removal torque values were higher for fluted (2.87 N
cm ±0.22) than non-fluted MSIs (2.75 N cm ±0.22), but the difference was not
statistically significant (p=.702). After six weeks, bone volumes of the 6-24 μm, 24-to-
42 μm, and 42-to-60 μm layers were significantly (p<.05) greater for the non-fluted than
fluted MSIs. After two weeks, bone volume of three layers were also significantly
(p<.05) greater for the non-fluted than fluted MSIs. Fluted and non-fluted 3 mm long
MSIs can have very high success rates, even with all maximum insertion torque values
being less than 6.2 N cm. Adding longitudinal flutes to 3 mm MSIs increases their
removal torque by 37% after 6 weeks, despite the fact that there was less bone
surrounding the fluted than non-fluted MSIs. | en |
