Richardson Richardson's blog : Classification of Nickel-Titanium Alloy Wires Evans and Durning Classification _ Orthodontics
Classification of Nickel-Titanium Alloy Wires Evans and Durning Classification
Classification of nickel-titanium alloy wires-Evans and Durning classification
1) In 1940, gold arch wire, cobalt-chromium alloy wire and stainless steel round
wire. 2) Martensitic stabilized alloys in 1960: most of them are made of
nickel-titanium alloys after deformation in the martensitic state. This kind of
arch wire has low rigidity and can produce light orthodontic force. There is no
martensitic transformation caused by stress or temperature, so there is no
memory effect and superelasticity. 3) In 1980, China Nitinol and Japan Nitinol
archwires were austenitic activated alloys: they were austenitic in any state,
and did not have martensitic state caused by temperature when placed inside or
outside the mouth. Martensitic state could only be caused by stress,titanium
plate gr7, and had superelasticity, but did not have shape memory function.
The archwire has excellent resilience and low stiffness, and can produce weak
orthodontic force. It is characterized by a constant force from the initial
start to the final stage,titanium
exhaust tubing, and has a better effect in the treatment of early tooth
irregularity. The point removal can not be bent and formed at normal
temperature, and is not easy to weld. If this wire is used as the main arch
wire, it will often cause unwanted arch expansion or arch contraction, and it is
difficult to establish a good premolar and molar alignment. 4) In 1990, nickel
titanium wire ,Titanium
6Al4V wire, the martensite activated nickel-titanium alloy: TTR is lower
than the oral temperature or very close to the oral temperature, it exists in a
multi-component state at room temperature and is easy to deform. When it is
placed in the oral cavity, the martensite caused by stress and room temperature
transforms to austenite at the same time, that is, it has shape memory function
and superelasticity. It is easy to deform at room temperature (about 25 oC) and
below, and when it reaches a certain temperature (about 32 oC), it will return
to its original shape, showing shape memory and superelasticity. Smart brand of
Beijing Shengmat Technology Co., Ltd. and Nitinol HA brand of 3m Company are
typical representative products. Because of this property, the heat-activated
nickel-titanium archwire can be easily shaped and placed in place in the bracket
when it is maintained at room temperature or below, and when it is activated by
body temperature and heat in the mouth, it can produce shape recovery force and
provide the required force for orthopedics. Because the heat-activated
nickel-titanium orthopedic wire has the characteristic of softening when cold
and becoming elastic when activated by heat, a patient can change the
orthodontic force by holding cold and hot water in the mouth under the guidance
of a doctor, which is more convenient for the orthodontist to correct and
reduces the discomfort of initial orthodontic treatment. 5) Graded
thermodynamic: increased thermodynamic nickel-titanium alloy: the TTR
temperature is higher than the oral temperature, about 40 oC, so that when the
nickel-titanium arch wire is placed in the oral cavity, it is still in a
multi-element state,titanium
bar grade 5, the arch wire is relatively soft, and the austenitic phase
transformation occurs only when the mouth contains hot water. Therefore, the
orthodontic force is weaker and can be used as the initial arch wire for adult
patients and patients with periodontal disease. The copper-containing
nickel-titanium archwire produced by Omcro Company and the low-hysteresis L-H
nickel-titanium archwire produced by Japan have this property. Contact us Back
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