Thesis
In-vitro assessment of torque as a metric for confirming bicortical temporary anchorage device placement: a pilot study
University of Iowa
Master of Science (MS), University of Iowa
Spring 2023
DOI: 10.25820/etd.007088
Abstract
Introduction
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.
Materials and Methods
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.
Results
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).
Conclusions
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.
Details
- Title: Subtitle
- In-vitro assessment of torque as a metric for confirming bicortical temporary anchorage device placement: a pilot study
- Creators
- Emma Mueldener
- Contributors
- Kyungsup Shin (Advisor)Steven D Marshall (Committee Member)Thomas E Southard (Committee Member)Erliang Zeng (Committee Member)Michael A Callan (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Orthodontics
- Date degree season
- Spring 2023
- DOI
- 10.25820/etd.007088
- Publisher
- University of Iowa
- Number of pages
- xv, 92 pages
- Copyright
- Copyright 2023 Emma Mueldener
- Language
- English
- Date submitted
- 04/15/2023
- Date approved
- 05/07/2023
- Description illustrations
- illustrations, tables, graphs
- Description bibliographic
- Includes bibliographical references (pages 46-50).
- Public Abstract (ETD)
- ntroduction: Orthodontic tooth movement and influence of skeletal growth of the upper and lower jaw can be challenging based on such factors as magnitude of tooth movement, patient age, and amount of skeletal correction needed by individual orthodontic patients. Temporary anchorage devices (TADs) are orthodontic mini screw placed within the bone of the upper or lower jaw to help facilitate challenging orthodontic movements. When placed, TADs may engage either one layer or two layers of dense cortical bone, referred to as monocortical or bicortical engagement respectively. The purpose of this study is to devise a method of confirming if bicortical engagement of a TAD can be detected by the strength required to turn a TAD while inserting into bone (insertion torque). Materials and Methods: A total of 27 TADs were placed (n=27) bicortically within two pairs of donated cadaver upper and lower jaws. The highest insertion torque per turn was measured until TADs were fully engaged with bicortical placement, and 3 dimensional radiographs was used in addition to visual reference to confirm perforation of both bony cortices. Values of highest torque per single 360° turn and differences in torque measured between 360° turns were then graphed for comparison. Results: Line graphs analyzing values of highest torque per turn torque demonstrated sigmoid (S-shaped) pattern as the TADs are being inserted. The highest value of measured torque corresponded to bicortical engagement. Differences in torque measured between individual TAD turns resulted in 2 graph peaks, corresponding to when . When turns were delayed by a period of 5 minutes, a different pattern was observed than those that were placed without delays. Conclusions: Data collected in the cadaver jaws within this study indicated that torque, or how hard it is to turn a TAD in the bone, may be an accurate method of determining if a TAD has been placed with bicortical bony engagement.
- Academic Unit
- Orthodontics
- Record Identifier
- 9984428942302771
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