L’effet mémoire de forme est-il une réalité clinique pour le 35° Copper Ni-Ti® ? Étude par calorimétrie différentielle à balayage. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Orthodontie Française Année : 2013

L’effet mémoire de forme est-il une réalité clinique pour le 35° Copper Ni-Ti® ? Étude par calorimétrie différentielle à balayage.

Résumé

Copper-nickel-titanium alloys are supposed to deliver a shape memory effect: when they are brought to a low temperature phase and subjected to a plastic deformation, they should recover their initial shape by simple heating. Nickel-titanium alloys can display different crystallographic phases: martensite, austenite and an inconstant intermediate R-phase. The shape memory effect is generally associated with the transition from martensite to austenite but it could also accompany the transition from R-phase to austenite. Since oral temperatures are not compatible with a fully martensitic alloy, this study aims, for 35° Copper Ni-Ti®, to assess the R-phase presence at oral temperatures and to verify the possibility of using the R-phase shape memory effect under clinical conditions. Materials and methods: Thirty consecutive 35° Copper Ni-Ti® archwires from two different batches were examined by differential scanning calorimetry with partial cycles limited to temperatures encountered within the oral cavity (from 0 °C to 50 °C). The presence of an intermediate crystallographic phase was assessed on the thermograms. The transformation temperatures were determined and the two batches were compared using the Mann-Whitney U Test. Results: Upon heating, all wires transformed directly from martensite to austenite. Af (mean = 33.5 °C, SD = 0.8 °C) was generally below the temperature stated by the manufacturer and a statistically significant difference (p ≤ 0.01) was found between the two batches. Conclusions: No R-phase was detected and transformation temperatures were not constant. This study questions the supposed shape memory effect displayed by 35° Copper Ni-Ti® wires under clinical conditions.

Dates et versions

hal-01299748 , version 1 (08-04-2016)

Identifiants

Citer

D. Kanter, Yves Bolender, Christophe Rapin, M-P. Filleul. L’effet mémoire de forme est-il une réalité clinique pour le 35° Copper Ni-Ti® ? Étude par calorimétrie différentielle à balayage.. Orthodontie Française, 2013, 84 (3), pp.259 - 269. ⟨10.1051/orthodfr/2013057⟩. ⟨hal-01299748⟩
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