Background: The aim of this study is to evaluate the mechanical properties of the screws used for rapid expansion of the upper jaw. Methods: Ten types of expansion screw were assessed, seven with four arms: Lancer Philosophy 1, Dentaurum Hyrax Click Medium, Forestadent Anatomic Expander type "S", Forestadent Anatomic Expander type "S" for narrow palates, Forestadent Memory, Leone A 2620-10 with telescopic guide, and Leone A 0630-10 with orthogonal arms; and three with two arms: Dentaurum Variety S.P., Target Baby REP Veltri, and Leone A 362113. A test expander with the mean dimensions taken from measurements on a sample of 100 expanders was constructed for each screw. The test expanders were connected to the supports of an Instron 4467 (Instron Corp., USA) mechanical testing machine equipped with a 500 N load cell, and the compression force exerted after each activation was measured. The mean forces expressed by the two-and four-arm expanders were then compared. Results: After five activations, the forces expressed by the two-arm devices were double than those expressed by the four-arm devices on average (224 +/- 59.9 N vs. 103 +/- 32.9 N), and such values remained high after subsequent activations. Conclusions: The expanders tested demonstrated stiffness characteristics compatible with opening of the palatine sutures in pre-adolescent patients. The stiffness of such devices can be further increased during the construction phase.

Evaluation of the stiffness characteristics of rapid palatal expander screws

LOMBARDO, Luca;SACCHI, Eleonora;LAROSA, MARIA;MOLLICA, Francesco;MAZZANTI, Valentina;SICILIANI, Giuseppe
2016

Abstract

Background: The aim of this study is to evaluate the mechanical properties of the screws used for rapid expansion of the upper jaw. Methods: Ten types of expansion screw were assessed, seven with four arms: Lancer Philosophy 1, Dentaurum Hyrax Click Medium, Forestadent Anatomic Expander type "S", Forestadent Anatomic Expander type "S" for narrow palates, Forestadent Memory, Leone A 2620-10 with telescopic guide, and Leone A 0630-10 with orthogonal arms; and three with two arms: Dentaurum Variety S.P., Target Baby REP Veltri, and Leone A 362113. A test expander with the mean dimensions taken from measurements on a sample of 100 expanders was constructed for each screw. The test expanders were connected to the supports of an Instron 4467 (Instron Corp., USA) mechanical testing machine equipped with a 500 N load cell, and the compression force exerted after each activation was measured. The mean forces expressed by the two-and four-arm expanders were then compared. Results: After five activations, the forces expressed by the two-arm devices were double than those expressed by the four-arm devices on average (224 +/- 59.9 N vs. 103 +/- 32.9 N), and such values remained high after subsequent activations. Conclusions: The expanders tested demonstrated stiffness characteristics compatible with opening of the palatine sutures in pre-adolescent patients. The stiffness of such devices can be further increased during the construction phase.
2016
Lombardo, Luca; Sacchi, Eleonora; Larosa, Maria; Mollica, Francesco; Mazzanti, Valentina; Spedicato, Ga; Siciliani, Giuseppe
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2369580
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