Journal article
Effect of miniscrew angulation on anchorage resistance
American journal of orthodontics and dentofacial orthopedics, Vol.139(2), pp.e147-e152
2011
DOI: 10.1016/j.ajodo.2010.08.017
PMID: 21300225
Abstract
Even though the use of titanium miniscrews to provide orthodontic anchorage has become increasingly popular, there is no universally accepted screw-placement protocol. Variables include the presence or absence of a pilot hole, placement through attached or unattached soft tissue, and angle of placement. The purpose of this in-vitro study was to test the hypothesis that screw angulation affects screw-anchorage resistance.
Three-dimensional finite element models were created to represent screw-placement orientations of 30°, 60°, and 90°, while the screw was displaced to 0.6 mm at a distance of 2.0 mm from the bone surface. In a parallel cadaver study, 96 titanium alloy screws were placed into 24 hemi-sected maxillary and 24 hemi-sected mandibular specimens between the first and second premolars. The specimens were randomly and evenly divided into 3 groups according to screw angulation (relative to the bone surface): 90° vs 30° screw pairs, 90° vs 60° screw pairs, and 30° vs 60° screw pairs. All screws were subjected to increasing forces parallel to the occlusal plane, pulling mesially until the miniscrews were displaced by 0.6 mm. A paired-samples
t test was used to assess the significance of differences between 2 samples consisting of matched pairs of subjects, with matched pairs of subjects including 2 measurements taken on the same subject. One-way analysis of variance (ANOVA) with the post-hoc Tukey studentized range test was conducted to determine whether there were significant differences, and the order of those differences, in anchorage resistance values among the 3 screw angulations at maxillary and mandibular sites.
The finite element analysis showed that 90° screw placement provided greater anchorage resistance than 60° and 30° placements. In the cadaver study, although the maximum anchorage resistance provided by screws placed at 90° to the cadaver bone surface exceeded, on average, the anchorage resistance of the screws placed at 60°, which likewise exceeded the anchorage resistance of screws placed at 30°, these differences were not statistically significant.
Placing orthodontic miniscrews at angles less than 90° to the alveolar process bone surface does not offer force anchorage resistance advantages.
Details
- Title: Subtitle
- Effect of miniscrew angulation on anchorage resistance
- Creators
- Niles Woodall - Private practice, Villa Rica, GaSrinivas C Tadepalli - Senior fellow, Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WashFang Qian - Associate research scientist, Department of Preventive and Community Dentistry, University of Iowa, Iowa City, IowaNicole M Grosland - Associate professor, Department of Biomedical Engineering and Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IowaSteve D Marshall - Adjunct associate professor, Department of Orthodontics, University of Iowa, Iowa City, IowaThomas E Southard - Professor and head, Department of Orthodontics, University of Iowa, Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- American journal of orthodontics and dentofacial orthopedics, Vol.139(2), pp.e147-e152
- DOI
- 10.1016/j.ajodo.2010.08.017
- PMID
- 21300225
- 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
- 9984040454902771
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