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Table 5 Comparison between placement torque and removal torque according to placement torque range and placement method, and comparison of overall torque values between the self-drilling and pre-drilling methods

From: Long-term evaluation of factors affecting removal torque of microimplants

Placement torque range Self-drilling (N cm) Pre-drilling (N cm)
Placement torque Removal torque Torque ratio n Placement torque Removal torque Torque ratio n
Mean ± SD Mean ± SD   Mean ± SD Mean ± SD  
0–5 N cm 3.07 ± 1.21* 3.49 ± 1.97 1.14 187 3.64 ± 0.96* 4.53 ± 2.98 1.24 54
5–10 N cm 7.17 ± 1.39** 3.66 ± 1.96 0.51 216 7.29 ± 1.47** 4.88 ± 2.65 0.66 79
10–15 N cm 11.83 ± 1.27** 4.04 ± 2.19 0.34 66 11.86 ± 1.44** 5.04 ± 2.63 0.42 58
Total 6.19 ± 3.24 3.64 ± 2.00 0.59 469 7.64 ± 3.43 4.83 ± 2.73 0.63 191
  1. Paired t-test was performed for comparison between placement and removal torque. Independent t-test was performed for comparison between the self-drilling and pre-drilling methods
  2. *Significant difference at p < 0.05 between placement torque and removal torque
  3. **Significant difference at p < 0.001 between placement torque and removal torque
  4. Significant difference at p < 0.001 between the self-drilling and pre-drilling methods