A clinical trial of aligning archwires

Abstract

The physical properties of a super-elastic archwire alloy (Titanol) and Nitinol were investigated by the means of a bending test. It was found that the alloy possessed super-elastic properties. A clinical trial was then carried out to compare the properties of two types of aligning archwire. Two groups of 20 patients with crowded dentitions were randomly allocated either Titanol or Nitinol, a conventional nickel-titanium alloy aligning archwire. High quality alginate impressions were taken after archwire placement in Edgewise fixed appliances and were repeated after a mean period of 35 days. The impressions were cast in dental stone and digitized using the Reflex Metrograph. The contact points of the teeth of the labial segments, together with four stable points in the rugae were recorded. This enabled the co-ordinates for the sequential study models to be superimposed upon one another, allowing tooth movement in three dimensions to be calculated. The measurement error expressed as error variance was 0.028 mm. The coefficient of reliability was 97 per cent. When tooth movement was analysed the mean movement per contact point for Titanol was 1.7 mm and for Nitinol 1.42 mm. This difference was not statistically significant (P less than 0.05, t-test). However, a clinical impression was that the super-elastic archwire proved superior to the Nitinol, because it was more readily engaged into grossly displaced teeth.

Supplemental Vibrational Force During Orthodontic Alignment

“…Sample size calculation was based on previous data relating to initial rate of orthodontic tooth movement using a Titanol aligning arch wire (O'Brien et al 1990). Mean contact point change within the labial segment in a group with initial irregularity index of 3.12 mm was reported as 1.7 mm over 34 d, corresponding to a mean alignment rate of 0.05 mm/d.…”

A systematic review of clinical trials of aligning archwires

“…It is important to analyse data on an intention to treat basis because otherwise attrition bias (systematic differences between comparison groups in terms of withdrawals or exclusions of participants) is possible. O'Brien et al 5 Jones et al 6 and Dalstra et al 9 analysed data on an intention to treat basis but this was only by virtue of the fact that there were no drop outs.…”

Alignment efficiency of superelastic coaxial nickel-titanium vs superelastic single-stranded nickel-titanium in relieving mandibular anterior crowding

“…2 Clinical trials conducted to assess the alignment efficiency of these archwires failed to demonstrate any significant advantage of any particular wire in overall alignment of the arches. [3][4][5][6][7][8][9][10][11] Multistranding of archwires to gain mechanical advantages such as increased flexibility and a reduced load deflection rate has been successfully attempted with the use of stainless steel. [12][13][14][15] The same concept was applied in the case of superelastic NiTi by Hanson (cited by Berger and Waram 16 ); this led to the introduction of Supercable, a seven-stranded round coaxial superelastic NiTi archwire.…”