American Journal of Orthodontics and Dentofacial Orthopedics
Original articleEffect of screw diameter on orthodontic skeletal anchorage
Section snippets
Material and methods
The maxillae and mandibles of human cadavers were obtained from the Department of Anatomy and Cell Biology Deeded Body Program at the University of Iowa. Fully dentate and partially dentate specimens were considered acceptable. Fully edentulous or partially dentate specimens with visible, severely atrophic alveolar ridges were excluded. Maxillary specimens were dissected superior to the maxillary sinus to avoid damage to the maxillary alveolar bone and tooth roots and extended distally to the
Results
Data analysis showed (Fig 3, Fig 4) that the mean mandibular anchorage force values of the 2.5-mm monocortical screws were significantly greater than those of the 1.5-mm monocortical screws when the deflection increased from 0.04 to 0.6 mm (P <0.01). Moreover, the mean maxillary anchorage force values of the 2.5-mm monocortical screws were significantly greater than those for the 1.5-mm monocortical screws when the deflection increased from 0.14 to 0.6 mm (P <0.01).
No statistically significant
Discussion
Two principal findings resulted from this in-vitro study. The first was that larger-diameter monocortical screws provide increased anchorage force resistance compared with smaller-diameter monocortical screws. As illustrated in Figure 3, the mean anchorage force values of the 2.5-mm monocortical screws exceeded those of the 1.5-mm monocortical screws in both the mandible and the maxilla (P <0.01). The second finding was that smaller-diameter bicortical screws can provide anchorage resistance
Conclusions
- 1.
In vitro, larger-diameter (2.5 mm) monocortical screws provide increased anchorage force resistance compared with smaller-diameter (1.5 mm) monocortical screws in both the mandible and the maxilla.
- 2.
Smaller-diameter (1.5 mm) bicortical screws provide anchorage force resistance at least equal to larger-diameter (2.5 mm) monocortical screws.
- 3.
Miniscrew anchorage force resistance is independent of the side of either the maxilla or the mandible. Force resistance is independent of apical or coronal site
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Supported by the Dr. George Andreasen Memorial Fund.
The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.