Histomorphometric evaluation of the bone surrounding orthodontic miniscrews according to their adjacent root proximity

Abstract

ObjectiveThis study was conducted to perform histomorphometric evaluations of the bone surrounding orthodontic miniscrews according to their proximity to the adjacent tooth roots in the posterior mandible of beagle dogs.MethodsFour male beagle dogs were used for this study. Six orthodontic miniscrews were placed in the interradicular spaces in the posterior mandible of each dog (n = 24). The implanted miniscrews were classified into no loading, immediate loading, and delayed loading groups according to the loading time. At 6 weeks after screw placement, the animals were sacrificed, and tissue blocks including the miniscrews were harvested for histological examinations. After analysis of the histological sections, the miniscrews were categorized into three additional groups according to the root proximity: high root proximity, low root proximity, and safe distance groups. Differences in the bone–implant contact (BIC, %) among the root proximity groups and loading time groups were determined using statistical analyses.ResultsNo BIC was observed within the bundle bone invaded by the miniscrew threads. Narrowing of the periodontal ligament space was observed in cases where the miniscrew threads touched the bundle bone. BIC (%) was significantly lower in the high root proximity group than in the low root proximity and safe distance groups. However, BIC (%) showed no significant differences among the loading time groups.ConclusionsRegardless of the loading time, the stability of an orthodontic miniscrew is decreased if it is in contact with the bundle bone as well as the adjacent tooth root.

Evaluation of Cephalometric Changes in Treatment of Skeletal Class III Malocclusion Using Miniscrews and Intermaxillary Coil Spring

“…9, No. 3 magnitudes had no effect on osseointegration (19,20) . Because the magnitudes of forces utilized in that investigation were likely within ideal force limitations, the results were unaffected.…”

A novel auxiliary device enhances miniscrew stability under immediate heavy loading simulating orthopedic treatment

“…However, it increases the root proximity and contact risk, and possibly the miniscrew failure risk. 17,18 Additionally, miniscrew stability is improved when it is embedded in a site of thick cortical bone, although the implantation site is restricted. 19 A combination of miniscrews and auxiliary devices can increase miniscrew stability without changing its design, suggesting the possibility of using miniscrews in various locations.…”