Mechanical properties of orthodontic wires covered with a polyether ether ketone tube

Abstract

Objectives: To evaluate the esthetics and frictional force of an orthodontic wire passed through a newly designed tube made of a polyether ether ketone (PEEK) resin.

Materials and methods: Two types of standard PEEK tubes were prepared at 0.5 × 0.6ф and 0.8 × 0.9ф, and different archwires were passed through the tubes. Color values were determined according to brightness and hues. Friction was assessed with different bracket-wire combinations, and surface roughness was determined by stereomicroscopy before and after the application of friction.

Results: The PEEK tube showed a color difference that was almost identical to that of coated wires conventionally used in clinical practice, indicating a sufficient esthetic property. The result of the friction test showed that the frictional force was greatly reduced by passing the archwire through the PEEK tube in almost all of the archwires tested.

Conclusions: Use of the new PEEK tube demonstrated a good combination of esthetic and functional properties for use in orthodontic appliances.

Keywords: Esthetics; Orthodontic archwire; Polyether ether ketone tube; Static friction force; Superengineering plastics.

Figure 1

A pre-formed metal archwire and an archwire passed through a PEEK tube, which covers the wire up to the mesial portion of the first molar bracket.

Figure 2

Upper: conventional coated wire; Lower: wire covered by the PEEK tube.

Figure 3

(a) Seven segments tightly arranged and fixed with transparent wax at both ends. (b) The measurement was conducted with a colorimeter using a shade tab.

Figure 4

Friction testing device. The stainless-steel plate with the bracket was attached to the friction-testing device (A: left); a 5-cm segment of wire (B: right) obtained from the posterior straight portion of the archwire was tested.

Figure 5

The tube and bracket are ligated and fixed, only the wire passing through the tube slides.

Figure 6

Friction test results for the (a) 0.016-inch and (b) 0.017 × 0.025-inch wires. Blue indicates no tubes, red indicates wires covered with tubes. (c) Maximum static friction force of each wire. The measured value represents the average of five experiments. * Significant difference at P < .05; ** Significant difference at P < .01.

Figure 7

The state of the base surface of the bracket slot after the friction test for the PEEK-covered wire (A: left) and the non–PEEK-covered wire (B: right); magnification 60×.