The aim of this study was to investigate the effect of different span lengths, material type, and storage conditions on the flexural properties of orthodontic FRC and stainless steel twisted retainers. Two different span, lengths of both FRCs and stainless steel retainers (11.0 mm and 8.0 mm) were investigated. Six specimens of FRCs (OrthoStick, StickTech, Turku, Finland) and six specimens of multistranded orthodontic wires (Penta One, Masel, Bristol, PA, USA) were prepared for each group. The FRCs were divided into 4 group according to: a) different span length during the three-point bending test; b) different storage modality: dry and wet (distilled water T=37°). The three point bending test was proceeded with material testing machine (Lloyd LRX, Fareham, UK). Load-deflection curves were recorded for 1.0 mm deflection with Nexygen 4.0 (Lloyd LRX, Fareham, UK). From the load trials carried out on various samples of FRCs and on steel orthodontic wires, it was possible to derive the average curves of their mechanical behavior. Conditions being equal (span length and deflection), the steel wires reach loads decidedly inferior and demonstrate more elasticity compared to the glass fibers. The fibers with a lesser span length support lesser loads but demonstrate more elasticity and therefore are more similar to the steel wires. One difference in the results was also observed in relation to the storage conditions of the fibers (wet or dry). The wet fibers, in fact, reach inferior loads, showing characteristics more similar to steel and demonstrate more elasticity compared to the dry fibers. In all the tests carried out there were never cases of complete fractures, only micro fractures clinically observable as white spots. In conclusions, the results of the present investigation demonstrate that in patients who present aesthetic concerns or allergies to traditional wires, FRCs might represent an advantageous alternative for the orthodontic retainers.
Mechanical properties of FRCs and orthodontic twisted wires, a three point bending test.
LUCCHESE, Alessandra;
2005
Abstract
The aim of this study was to investigate the effect of different span lengths, material type, and storage conditions on the flexural properties of orthodontic FRC and stainless steel twisted retainers. Two different span, lengths of both FRCs and stainless steel retainers (11.0 mm and 8.0 mm) were investigated. Six specimens of FRCs (OrthoStick, StickTech, Turku, Finland) and six specimens of multistranded orthodontic wires (Penta One, Masel, Bristol, PA, USA) were prepared for each group. The FRCs were divided into 4 group according to: a) different span length during the three-point bending test; b) different storage modality: dry and wet (distilled water T=37°). The three point bending test was proceeded with material testing machine (Lloyd LRX, Fareham, UK). Load-deflection curves were recorded for 1.0 mm deflection with Nexygen 4.0 (Lloyd LRX, Fareham, UK). From the load trials carried out on various samples of FRCs and on steel orthodontic wires, it was possible to derive the average curves of their mechanical behavior. Conditions being equal (span length and deflection), the steel wires reach loads decidedly inferior and demonstrate more elasticity compared to the glass fibers. The fibers with a lesser span length support lesser loads but demonstrate more elasticity and therefore are more similar to the steel wires. One difference in the results was also observed in relation to the storage conditions of the fibers (wet or dry). The wet fibers, in fact, reach inferior loads, showing characteristics more similar to steel and demonstrate more elasticity compared to the dry fibers. In all the tests carried out there were never cases of complete fractures, only micro fractures clinically observable as white spots. In conclusions, the results of the present investigation demonstrate that in patients who present aesthetic concerns or allergies to traditional wires, FRCs might represent an advantageous alternative for the orthodontic retainers.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
