title: In-vitro assessment of torque as a metric for confirming bicortical temporary anchorage device placement
title: a pilot study
titleType: Subtitle
Creators: name: Mueldener, Emma
Publisher: name: University of Iowa
Year: 2023
Subjects: Bicortical
Insertion Torque
Orthodontic Mini-Implant
Temporary Anchorage Devices
public abstract

description: Introduction
description: Temporary anchorage devices (TADs), commonly referred to as orthodontic miniscrews, are utilized in treatment as a source of anchorage to support tooth movement. TADs are capable of engaging one bony cortex, monocortical anchorage, or two bony cortices, bicortical anchorage in the bone of the maxilla or mandible. The purpose of this study is to investigate if detection of bicortical TAD engagement in cadaver specimens utilizing torque as a metric for alternative to patient radiographic exposure.
description: Materials and Methods
description: Within this in vitro study, interradicular maxillary and mandibular sites (n=27) were engaged bicortically within two pairs of donated cadaver maxillae and mandibles. Peak insertion torque per turn was measured until TADs were fully engaged with bicortical placement, and CBCT was utilized in addition to visual reference to confirm perforation of both bony cortices. Values of peak torque per single 360 turn (N * cm/ turn) and differences in torque measured between individual 360 turns were incorporated into a line-graph format. A Wilcoxon rank sum test with continuity correction was used to determine if there was a statistically significant difference in bone characteristics between cadaver specimen1 and 2. Descriptive analysis was utilized for comparison of metered insertional torque patterns amongst all sites.
description: Results
description: Line graph distributions analyzing values of peak torque indicate a sigmoid pattern torque with progressive turns of TAD insertion, with the maximum value of measured torque corresponding to bicortical engagement. Differences in torque measured between individual 360 turns were graphically represented and demonstrated a dual peak distribution, with peaks in difference in torque noted between engagement of the first and second cortices. When turns were delayed by a period of 5 minutes, a steep drop in peak torque value per turn was observed. Statistical analysis indicated that there was a statistically significant difference in the peak insertion torque of TADs placed within the mandible of cadaver specimen 2 and the mandible of cadaver specimen 1, and between the maxilla and mandible of cadaver 2 alone when assessing all sites of insertion (p = 0.000124, W= 6767, and p = 1.248e-07, W= 11630 respectively).
description: Conclusions
description: Data collected in the cadaver jaws within this study indicated that electronic torque metering concurrent with interradicular temporary anchorage device placement via a buccal approach can be utilized as a reasonable metric for assessing whether monocortical or bicortical engagement has been achieved upon placement. Intermittent turning of temporary anchorage devices between individual 360 insertional rotation yielded a unique pattern of peak torque per turn that suggests that tissue relation occurs in interim periods between insertional turns.