Journal article
Effect of miniscrew placement torque on resistance to miniscrew movement under load
American journal of orthodontics and dentofacial orthopedics, Vol.140(3), pp.e93-e98
2011
DOI: 10.1016/j.ajodo.2011.04.017
PMID: 21889062
Abstract
The primary stability of orthodontic anchorage miniscrews is believed to result from mechanical interlock, with success based upon a number of variables, including screw diameter, angle of placement, monocortical vs bicortical placement, placement through attached or unattached soft tissue, presence or absence of a pilot hole, periscrew inflammation, and maximum placement torque. The purpose of this ex-vivo study was to further explore the relationship between maximum placement torque during miniscrew placement and miniscrew resistance to movement under load.
Ninety-six titanium screws were placed into 24 hemi-maxillae and 24 hemi-mandibles from cadavers between the first and second premolars by using a digital torque screwdriver. All screws were subjected to a force parallel to the occlusal plane, pulling mesially until the miniscrews were displaced by 0.6 mm. The Spearman rank correlation test was used to evaluate whether there was an increasing or a decreasing relationship between maximum placement torque of the screws, miniscrew resistance to movement, and bone thickness. A paired-sample
t test and the nonparametric Wilcoxon signed rank test were used to compare maximum placement torque, bone thickness, and miniscrew resistance to movement between coronally positioned and apically positioned screws in the maxilla and the mandible, and between screws placed in the maxilla vs screws placed in the mandible. Additionally, 1-way analysis of variance (ANOVA) with the post-hoc Tukey-Kramer test was used to determine whether there was a significant difference in miniscrew resistance to movement for screws placed with maximum torque of <5 Ncm, 5 to 10 Ncm, and >10 Ncm.
The mean difference in miniscrew resistance to movement between maximum placement torque groupings, <5 Ncm, 5 to 10 Ncm, and >10 Ncm, increased throughout the deflection range of 0.0 to 0.6 mm. As deflection increased to 0.12 to 0.33 mm, the mean resistance to movement for miniscrews with maximum placement torque of 5 to 10 Ncm was statistically greater than for screws with maximum placement torque <5 Ncm (
P <0.05). As deflection increased to 0.34 to 0.60 mm, the mean resistance to movement for miniscrews with maximum placement torque of 5 to 10 Ncm and >10 Ncm was significantly greater than for screws with maximum placement torque <5 Ncm (
P <0.05). At no deflection was there a significant difference in resistance to movement between the 2 miniscrew groups with higher placement torque values of 5 to 10 Ncm and >10 Ncm.
Ex vivo, the mean resistance to movement of miniscrews with higher maximum placement torque was greater than the resistance to movement of those with lower maximum placement torque.
Details
- Title: Subtitle
- Effect of miniscrew placement torque on resistance to miniscrew movement under load
- Creators
- Michelle Marie McManus - Private practice, Rock Island, IllFang Qian - Associate research scientist, Department of Preventive and Community Dentistry, College of Dentistry, University of Iowa, Iowa City, IowaNicole M Grosland - Associate professor, Departments of Biomedical Engineering and Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IowaSteve D Marshall - Visiting associate professor, Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City, IowaThomas E Southard - Professor and head, Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- American journal of orthodontics and dentofacial orthopedics, Vol.140(3), pp.e93-e98
- DOI
- 10.1016/j.ajodo.2011.04.017
- PMID
- 21889062
- NLM abbreviation
- Am J Orthod Dentofacial Orthop
- ISSN
- 0889-5406
- eISSN
- 1097-6752
- Publisher
- Mosby, Inc
- Grant note
- Dr George Andreasen Memorial Fund
- Language
- English
- Date published
- 2011
- Academic Unit
- Preventive and Community Dentistry; Roy J. Carver Department of Biomedical Engineering; Orthodontics; Orthopedics and Rehabilitation; Injury Prevention Research Center; Dental Research
- Record Identifier
- 9984040572602771
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