What really orders the teeth around aka THE MEMORY WIRE

Remember when my ortho told me that my wire has a memory?

Well, I finally figured it out! (Sort of. I am not sure if this was done to my wire, but it does say it is used in orthodontics).

Wikipedia help me understand some of it.

If I sum it up; A shape memory alloy (SMA ) is an alloy that “remembers” its original, cold-forged shape, and which returns to that shape after being deformed by applying heat. Now, there are two ways to do that; 

There is One -way memory effect – when a shape memory alloy is in its cold state the metal can be bent or stretched and will hold those shapes until heated above the transition temperature. Upon heating, the shape changes to its original. When the metal cools again it will remain in the hot shape, until deformed again.


 The two-way shape memory effect – the effect that the material remembers two different shapes: one at low temperatures, and one at the high temperature shape.

So how did this happen to find its way into orthodontics?

The nitinol archwire was developed in 1972 by orthodontist George Andreasen.This revolutionized clinical orthodontics and has also had an effect on fiber optic development. Andreasen’s alloy has a patterned shape memory, expanding and contracting within given temperature ranges because of its geometric programming.

That was the explanation for people born with a technical gene.


Here is for people like me, who need it to be told as a story.

The straight wire is actually a flexible metal wire that works by placing pressure on your teeth to move them in the right direction. Your ortho will place a bracket in a predetermined position on each tooth. These brackets are pre-adjusted in torque and tip — meaning they are customized to move your tooth’s root in the right direction while correcting the angle of the tooth’s crown.

After the brackets are secured, the straight wire is connected to them, causing it to bend. The straight wire works by trying to return to its original shape. As it bends back into shape, it forces the teeth to move, eventually lining your brackets into the correct position. Once your treatment is complete, your teeth should line up perfectly along the straight wire.

Many modern straight wire braces are now made of a nickel-titanium alloy, which adjusts to your body temperature. At room temperature, these wires are extremely flexible and easy to place on your brackets. As the metal warms, the wire becomes active to gradually move your teeth. Because they require less attention, these high-tech straight wires are commonly used today. (more here)

The explanation below solves my problem why I once read somebody had to “shock” his braces with hot and cold water every day and if that was a memory wire, why I don’t have to do this;  

The three types of archwires that we routinely use are nitanol, thermal titanium and stainless steel. Nitanol and thermal titanium archwires are both memory type wires. Thermal titanium is temperature sensitive and at a few degrees below body temperature, the wire memory becomes activated after being placed in the mouth. When these wires are threaded through the brackets, their memory preprograms them to return to their original shapes which applies pressure to move the teeth. By placing the brackets as accurately as possible, the braced appliance becomes self-adjusting and self-tightening. As these “smart braces” guide the teeth into straight alignment, your smile will look better within several visits.

Again, I have no idea if this is really what’s in In-Ovation C, my braces. I just wanted to sum up all I could find at how memory wire works, and how it moves the teeth.

You know what, this could also be called The Most Technical Post I will Ever Write In My Life.



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