Learn more about the technique: The 20 principles of the Alexander discipline, R.G. "Wick" Alexander, DDS, MSD, p.145, Quintessence
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"All stainless steel archwires are heat treated before they are ligated in the arch. The heat treatment relieves stress in the wire and improves its elastic properties. This is especially true when large curves are present in the mandibular arch. The wire is then allowed to "cook" over several months of treatment. If the wire has to be removed and adjusted and an additional curve has to be placed, the archwire should then be heat treated again."
The 20 principles of the Alexander discipline, R.G. "Wick" Alexander, DDS, MSD, p.148, Quintessence
Clinically, when the orthodontist makes loops, bends or establishes a new arch form, the wire reaches a high internal pressure and should be thermally treated in order to release these tensions. The increased elastic strength is the most significant effect of heat treatment.
The heat treatment provides a greater shape stability of the archwires which demonstrates a smaller tendancy to transverse changes in the anterior and posterior regions, when compared to archwires without heat treating. The results of a study* showed that the heat treatment performed in daily clinical practice establishes a favourable and determinant condition to preserve intercanine width which is very important for the long stability.
The archwires heat treatment device WTU is a source of a low voltage current. By running of current through the orthodontic stainless steel archwire, it is tempered through its heating and gradual cooling. The heating process of the archwire is controlled by the user, until the material reaches a colour of "golden wheat" through several short pushes of the START button. The waiting time for the archwire to cool down, while it is fixed in the tongs of the device allows the heat treating process to complete.
All types of stainless steel archwires could be heat treated:
The heat treatment of archwires device WTU-1 is manufactured according to the requirements of Directive 2014/35/ЕС and standards EN 61558-1:2006, EN 61558-1:2006/A1:2009, EN 61558-2-6:2009. The device is designed and manufactured in Bulgaria.
Device Housing Material Chromium Nickel (CrNi)
Device Dimensions 131мм х 138мм х 76мм (5.16" х 5.43" х 2.99")
Pad Material Chromium Nickel (Cr/Ni)
Pad Dimensions 150мм х 240мм (5.91" x 9.45")
Clamps Copper (Cu)
Tempering Rate Low rate (L) and High rate (H)
Supply voltage 220-240V
Frequency of the AC supply 50/60 Hz
Working Voltage of The Tongs 6 V
Fuse 0.25A
Weight 2600 gr. (5,73Ib)
The heat treatment of archwires device WTU-1 is manufactured according to the requirements of Directive 2014/35/ЕС and standards EN 61558-1:2006, EN 61558-1:2006/A1:2009, EN 61558-2-6:2009. The device is designed and manufactured in Bulgaria.
Step 1 After finishing the shaping of the archwire for a specific patient (making of bends, loops, Spee curve, forming the archwire shape from a template etc.) and removing the excessive ends, it is ready to be tempered.
Step 2 Place firmly the two ends of the archwire in the device’s tongs by pressing the spring buttons, so the wire stays passively fixed in them, without getting expanded or compressed. The passiveness is checked, when the archwire is placed in the tongs and you press each of the spring buttons, one after another, until you make sure that the archwire is not placed expanded or compressed.
Step 3 Select the heat treating rate: L - low or Н – high.
Step 4 Make several short and quick consecutive pressings of START button, until the wire changes its colour to light yellow "golden wheat" colour.
Step 5 Wait for 30 seconds for the wire to cool down before touching it.
Step 6 When the wire has cooled down, press the spring buttons in order to open the tongs and to release the wire. It is ready to be used as intended.
Download WTU Operation and Warranty Manual (PDF 8.8MB)