IADR Abstract Archives
An evaluation of the elastic recovery of nickel titanium archwires following ligation in palatally-displaced lateral incisors
Objectives: Compare permanent deformation of superelastic 0.012” and 0.014” NiTi archwires following ligation in a simulated set up
Compare the maximum force imparted by these archwires at varying magnitudes of tooth displacement
Methods: 3D-printed models were created of a typodont with the lateral incisor palatally displaced at varying increments (3-, 4- or 5- mm) incorporating conventional brackets. A total of 288 archwires from two brands (Euroform (EO) and American Orthodontics (AO)) of two cross-sectional diameters (0.012” and 0.014”) were tested for deformation. Deformation was measured objectively using linear and angular measurements and subjectively using a validated index to categorise archwires based on the degree of deformation and their clinical usability. 3-point bending tests were used to examine the load deflection characteristics, including the maximum force at displacements of 3-, 4- and 5- mm and the unloading force, of a sample of 72 archwires from the same 36 batches used in the typodont component.
Results: EF archwires had lower distortion compared to AO archwires(P=0.008). There was no statistically significant difference in deformation between 0.012” EF and AO archwires(P=0.89). However, the 0.014” EF archwire had significantly lower deformation than AO archwires(P=<0.001). A wide variation in force levels at maximum archwire displacement was observed, influenced by archwire size and type, with differences also noted within wire batches. The mean force produced by the 0.012” archwires was significantly less than that produced by the 0.014” archwires at 3-, 4- and 5- mm displacements. Additionally, the mean force produced by the AO archwires was significantly less that for the EF archwires at the same magnitudes of displacement for both 0.012” and 0.014” sizes
Conclusions: Based on this artificial set-up, the use of an 0.012” archwire for tooth displacements of 3 mm or more may be considered in order to permit the delivery of safe orthodontic forces. EF archwires underwent a lesser degree of deformation than AO archwires. A high degree of variability in the performance of narrow dimension nickel titanium archwires can be expected and is influenced by manufacturer, archwire dimension and the degree of tooth displacement. Susceptibility to deformation appears to vary within batches of identical wires
Compare the maximum force imparted by these archwires at varying magnitudes of tooth displacement
Methods: 3D-printed models were created of a typodont with the lateral incisor palatally displaced at varying increments (3-, 4- or 5- mm) incorporating conventional brackets. A total of 288 archwires from two brands (Euroform (EO) and American Orthodontics (AO)) of two cross-sectional diameters (0.012” and 0.014”) were tested for deformation. Deformation was measured objectively using linear and angular measurements and subjectively using a validated index to categorise archwires based on the degree of deformation and their clinical usability. 3-point bending tests were used to examine the load deflection characteristics, including the maximum force at displacements of 3-, 4- and 5- mm and the unloading force, of a sample of 72 archwires from the same 36 batches used in the typodont component.
Results: EF archwires had lower distortion compared to AO archwires(P=0.008). There was no statistically significant difference in deformation between 0.012” EF and AO archwires(P=0.89). However, the 0.014” EF archwire had significantly lower deformation than AO archwires(P=<0.001). A wide variation in force levels at maximum archwire displacement was observed, influenced by archwire size and type, with differences also noted within wire batches. The mean force produced by the 0.012” archwires was significantly less than that produced by the 0.014” archwires at 3-, 4- and 5- mm displacements. Additionally, the mean force produced by the AO archwires was significantly less that for the EF archwires at the same magnitudes of displacement for both 0.012” and 0.014” sizes
Conclusions: Based on this artificial set-up, the use of an 0.012” archwire for tooth displacements of 3 mm or more may be considered in order to permit the delivery of safe orthodontic forces. EF archwires underwent a lesser degree of deformation than AO archwires. A high degree of variability in the performance of narrow dimension nickel titanium archwires can be expected and is influenced by manufacturer, archwire dimension and the degree of tooth displacement. Susceptibility to deformation appears to vary within batches of identical wires