Evaluation of expansion forces of five pure bone-borne maxillary expanders designs anchored with orthodontic mini-implants: An in vitro study

Autor: Andre Walter, Fernando de la Iglesia, Heinz Winsauer, Oliver Ploder, Brigitte Wendl, Andreu Puigdollers Perez
Rok vydání: 2023
Předmět:
Zdroj: Journal of Orthodontics. :146531252311525
ISSN: 1465-3133
1465-3125
Popis: Aim: This in vitro study investigates the limit of expansion forces and torque wrench forces develop by five skeletal bone expander designs (MICRO 2/4 expanders™) for clinical application. Material and Methods: A total of 30 skeletal expanders were placed in artificial bone blocks and mechanically tested, simulating maxillary expansion. Differences in jackscrew (Dentaurum™ [D], Superscrew™ [S] and Powerscrew™ [P]), number of orthodontic mini-implants (OMIs; two or four) and their inclinations placements (parallel 0° or 10° inclination) form five designs (D4/10°, S4/0°, S4/10°, P4/10° and P2/10°). Expansion forces and torque wrench values were registered, and radiographs were made initially and after 4 mm of expansion. Stress-strain curves were obtained after successive activations and the statistically analysis was performed as appropriate. Results: Plastic deformations in the OMIs and jackscrew occurred around the activation numbers 11–13, with torque wrench values in the range of 500–700 cN. The maximum expansion forces in expanders with four OMIs varies from 93.0 (D4/10°) to 166.6 N (P4/10°) whereas two OMI expanders (P2/10°) registered forces of 79.4 N. Radiographs revealed during loads bending forces (S4/00°, S4/10°) with jackscrew and OMIs deformation in a convex shape, and shear forces (P4/10°, P2/10°) demonstrated only OMIs deformation in a concave shape, providing 15% more expansive force. The jackscrew D4/10° did not have any deformation, but its wire key did not allow reliable activations from activation number 10 and compared to S4/10° and P4/10° these expanders provided greater expansion forces ( P = 0.000 and P = 0.032, respectively). Conclusion: The different results obtained in stability and expansion forces indicate that if the activations are carried out under extreme conditions, they may have clinical importance with deformations and not working expansion mechanics. Jackscrew designs play an important role in expansive forces and expander stability. Torque wrench values can be used clinically as a tool to asses the expansion forces and to avoid deformations.
Databáze: OpenAIRE
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