Journal article
Bicortical vs monocortical orthodontic skeletal anchorage
American journal of orthodontics and dentofacial orthopedics, Vol.134(5), pp.625-635
2008
DOI: 10.1016/j.ajodo.2007.01.031
PMID: 18984394
Abstract
Case reports have documented the use of titanium miniscrews in providing skeletal anchorage for orthodontic tooth movement. Success rates as low as 50% have been reported for screw retention in either the facial or the lingual cortical plates (monocortical placement). The purpose of this in-vitro study was to test the hypothesis that bicortical miniscrew placement (across the entire width of the alveolus) gives the orthodontist superior force resistance and stability (anchorage) compared with monocortical placement.
Forty-four titanium alloy screws, 1.5 × 15.0 mm, were placed in 22 hemi-sected maxillae and mandibular specimens between the first and second premolars. Half were placed monocortically, half were placed bicortically, and all were subjected to tangential force loading perpendicular to the miniscrew through a lateral displacement of 1.5 mm. Bone samples were sectioned and bone thickness at the screw sites measured. Statistical analyses, consisting of paired samples
t tests, 2-samples
t tests, Spearman rank correlation tests, and Fisher exact tests, were used to compare monocortical with bicortical screw force-deflection characteristics and stability. Additionally, 2-dimensional plane-stress finite-element models of bicortical and monocortical screw placement subjected to similar loading were analyzed.
As hypothesized, deflection force values were significantly greater for bicortical screws than for monocortical screws placed in both the maxilla and the mandible (
P <0.01 in each instance). Furthermore, force values at mandibular sites were significantly greater than those at maxillary sites for both types of screws. No significant differences in deflection force values were found between the right and left sides of the jaws, or between coronal and apical alveolar-process screw positions. A significant increasing relationship was found between mandibular buccal bone thickness and deflection force for monocortical screws only, and no relationship was found between maxillary bone thickness and deflection force for monocortical or bicortical screws. Monocortical screws were significantly more mobile after force application than bicortical screws. Finite-element analysis indicated lower cortical bone stresses with bicortical placement than with monocortical placement, and these results were consistent with in-vitro experimental findings.
Bicortical miniscrews provide the orthodontist superior anchorage resistance, reduced cortical bone stress, and superior stability compared with monocortical screws.
Details
- Title: Subtitle
- Bicortical vs monocortical orthodontic skeletal anchorage
- Creators
- Bryan T Brettin - Private practice, Hudson, WisNicole M Grosland - Assistant professor, Department of Biomedical Engineering, University of Iowa, Iowa City, IowaFang Qian - Associate research scientist, Department of Preventive and Community Dentistry, University of Iowa, Iowa City, IowaKarin A Southard - Professor, Department of Orthodontics, University of Iowa, Iowa City, IowaTony D Stuntz - Dental student research assistant, University of Iowa, Iowa City, IowaTeresa A Morgan - Assistant professor, Department of Oral and Maxillofacial Surgery, 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.134(5), pp.625-635
- DOI
- 10.1016/j.ajodo.2007.01.031
- PMID
- 18984394
- NLM abbreviation
- Am J Orthod Dentofacial Orthop
- ISSN
- 0889-5406
- eISSN
- 1097-6752
- Publisher
- Mosby, Inc
- Language
- English
- Date published
- 2008
- Academic Unit
- Preventive and Community Dentistry; Roy J. Carver Department of Biomedical Engineering; Orthodontics; Orthopedics and Rehabilitation; Oral and Maxillofacial Surgery; Injury Prevention Research Center; Dental Research; Hospital Dentistry
- Record Identifier
- 9984040493302771
Metrics
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