What are the main criteria for the selection of an orthodontic wire?
1. Force delivery characteristics,2. elastic working range,
3. ease of manipulation by permanent deformation to desired shapes,
4. capability of joining individual segments to fabricate more complex
appliances,
5. corrosion resistance and biocompatibility in the oral environment,
6. Cost: The beta-titanium and nickel-titanium archwires are much more
expensive than the traditional stainless steel alloys, but they offer
unique properties that should be carefully considered when selecting
wires.
You need to explain these in a little more detail.
ReplyDeleteSee Sunil Kapila and Rohit Sachdeva, Mechanical properties and clinical applications of orthodontic wire.
For example:
Springback is required by the wire as a properties as it is related to the ratio of the yield strength to the modulus of elasticity of the material, higher springback value provide the ability to apply large activation.
You can continue with the rest
Wire characteristics of clinical relevance
ReplyDeleteSeveral characteristics of orthodontic wires are considered desirable for optimum performance during treatment. These include a large springback, low stiffness, high formability, high stored energy, biocompatibility and environmental stability, low surface friction, and the capability to be welded or soldered to auxiliaries and attachments. A brief description of each of these desirable wire characteristics is provided.
1. Springback. This is also referred to as maximum elastic deflection, maximum flexibility, range of activation, range of deflection, or working range. Springback is related to the ratio of yield strength to the modulus of elasticity of the material (YS/E). Higher springback values provide the ability to apply large activations with a resultant increase in working time of the appliance. This, in turn, implies that fewer arch wire changes or adjustments will be required. Springback is also a measure of how far a wire can be deflected without causing permanent deformation or exceeding the limits of the material.
2. Stiffness or load deflection rate. This is the force magnitude delivered by an appliance and is proportional to the modulus of elasticity. Low stiffness or load deflection rates provide:
(1) the ability to apply lower forces,
(2) a more constant force over time as the appliance experiences deactivation, and
(3) greater ease and accuracy in applying a given force.
3. Formability. High formability provides the ability to bend a wire into desired configurations such as loops, coils, and stops without fracturing the wire.
4. Modulus of resilience or stored energy (MR) This property represents the work available to move teeth. It is reflected by the area under the line describing elastic deformation of the wire
5. Biocompatibility and environmental stability. Biocompatibility includes resistance to corrosion and tissue tolerance to elements in the wire. Environmental stability ensures the maintenance of desirable properties of the wire for extended periods of time after manufacture. This, in turn, ensures a predictable behavior of the wire when in use.
6. Joinability. The ability to attach auxiliaries to orthodontic wires by welding or soldering provides an additional advantage when incorporating modifications to the appliance.
7. Friction. Space closure and canine retraction in continuous arch wire techniques involve a relative motion of bracket over wire. Excessive amounts of bracket/wire friction may result in loss of anchorage or binding accompanied by little or no tooth movement. The preferred wire material for moving a tooth relative to the wire would be one that produces the least amount of friction at the bracket/wire interface
Well done. Topic Complete
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