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Assessment of damping capacity as an index of root proximity in self-drilling orthodontic mini-implants
Mitsuru Motoyoshi1, Yasuki Uchida, Miho Matsuoka
1Department of Orthodontics, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyodaku, Tokyo, 1018310, Japan, motoyoshi.mitsuru@nihon-u.ac.jp.
Objectives:
This study aims to investigate orthodontic mini-implant root proximity, placement torque, and damping capacity and to determine whether placement torque and damping capacity (Periotest value (PTV)) are useful indices for the estimation of mini-implant root proximity.
Materials And Methods:
The root proximity of 143 orthodontic mini-implants (1.6 mm diameter, 8 mm screw thread length) was evaluated in 79 patients (24 males, 55 females; mean age, 22.5 ± 8 years) using cone-beam computed tomography. The placement torque and PTV of each implant were determined using a torque tester and the Periotest, respectively. Variability in these values according to root proximity was evaluated.
Results:
PTVs of mini-implants with multiple (two or more) points of contact between the root and implant were significantly larger than those of mini-implants with no root contact in the self-drilling group. Placement torque did not differ significantly according to root proximity. In the self-drilling group, the odds ratio for root contact was 20.82 (P = 0.000) for a PTV >6.
Conclusions:
Placement torque could not be used to estimate root proximity. The PTV was significantly affected by root proximity in the self-drilling group.
Clinical Relevance:
A threshold of PTV >6 could be applied clinically for the estimation of self-drilling mini-implant root proximity.
