Dr. Simone Currim shares insights on the crucial role of stainless steel in orthodontics, highlighting its durability, biocompatibility, and recent technological advancements that enhance patient care and treatment efficiency.
How does stainless steel contribute to the effectiveness and durability of orthodontic appliances such as braces and wires?
Stainless steel is one of the most important materials in all our instruments and appliances. As orthodontists, we use various instruments. One set of instruments is what we call basic screening or basic checkup appliances, which includes a kit containing an intraoral mirror, tweezers, and an explorer or probe. All of these are made with surgical stainless steel. The type of stainless steel commonly used is martensitic stainless steel.
In dentistry, there are three basic types of stainless steel in use. First, there is ferritic stainless steel, which is used very little in my practice. Second, there is martensitic stainless steel, which is used in our instruments, such as orthodontic pliers and cutting instruments. These include a distal-end cutter, pin and ligature cutter, and various pliers used for placing appliances. All of these are generally made from martensitic stainless steel.
Lastly, we have austenitic stainless steel, which also comes in two different types: 302 and 304, based on the carbon content. Austenitic stainless steel is used for brackets in fixed orthodontic treatment. Additionally, all the wires, bands, tubes, hooks for elastics, and ligature wires we use are made of austenitic stainless steel.
In my orthodontic practice, stainless steel is instrumental because almost every aspect of what I do involves it. Stainless steel forms a crucial backbone for both orthodontic and general dental practices.
What qualities of stainless steel make it an ideal material for use in orthodontics, especially compared to other materials?
For any material to be used in dentistry, it must be biocompatible. The fact that steel is biocompatible and possesses tarnish and corrosion resistance, due to the addition of chromium, is crucial. The chromium forms a layer of chromium dioxide, which prevents other materials from permeating the alloy. This ensures the safety and stability of the material in the mouth, even though the oral environment undergoes changes in temperature from the intake of warm foods and liquids. Additionally, the pH or acidity of the oral environment can vary based on factors such as whether the patient is fasting, their diet, metabolic disorders, or illnesses.
The oral environment is not static; it is highly dynamic. Despite this, having a material that remains stable in the oral cavity over a prolonged period—ranging from as little as six months to as much as two to three years—is essential. It is critical that the material does not change in phase or state, ensuring it does not cause harm to the patient. My primary goal is to improve the patient’s condition without causing any harm, and steel provides that assurance with its stability and biocompatibility.
Steel offers various other advantages, including its strength and formability, which allows for the creation and retention of bends, especially in arch wires. This is extremely helpful in orthodontics. Additionally, steel can be soldered and welded, enabling the fabrication of more complex appliances by adding other components. The ability to draw steel into wires allows for the creation of essential adjuncts in my profession.
When using martensitic stainless steel, the treated nature of the material provides strong instruments, which are crucial in my practice. Many of my instruments, some dating back to my student days, have been in use for 27 to 28 years and continue to perform well. They are durable and can be sterilized through cold sterilization or autoclaving, which is a significant advantage in dentistry.
Furthermore, the resilience of the material is beneficial, particularly in wires, as it has an energy-storing capacity. This energy is gradually dissipated over several weeks. Typically, my patients are seen every four to six weeks, and the material’s ability to absorb and slowly release energy helps achieve the desired orthodontic outcomes. This property of stainless steel is highly valuable in my practice.
Can you discuss any advancements in stainless steel technology that have improved patient outcomes or treatment efficiency?
Several advances have taken place, many of which are due to an extensive understanding of stainless steel methodologies. For instance, the addition of nickel and titanium to the material has led to the formation of highly flexible wires. In the initial stages of orthodontic treatment, I prefer flexible wires that exert very low forces.
This is crucial because, while waiting for the bone response to develop, we need low-force materials that provide comfort and minimize patient complaints of soreness. The addition of nickel and titanium has resulted in what we call “super flexible” wires. These wires can be attached early in treatment, regardless of how crooked the teeth are, while ensuring that the force applied is not excessive. This helps keep patient discomfort within manageable limits, significantly improving the early stages of treatment.
Another significant advancement is the incorporation of copper along with nickel and titanium, leading to the development of heat-sensitive wires. These wires have a transition temperature of around 35 degrees Celsius, while the oral cavity typically maintains a temperature of 37 degrees Celsius. At room temperature, the wire remains inactive or “dead,” but it becomes activated once placed in the mouth, utilizing its shape memory. This allows the wire to exert the necessary forces to gradually move the teeth into the desired arch form with minimal adjustments throughout the treatment. This innovation allows for maximum results with minimal changes in arch wires.
Additionally, the development of stainless steel wires combined with titanium and molybdenum has been invaluable in the later stages of treatment. For example, in cases involving extractions where gap closure is necessary, titanium molybdenum wires (TMA) are used. These wires can create a force system involving loops and bends, delivering controlled forces over six to nine weeks. Once these wires are placed with specific specifications and angulations, patient visits can be spaced out by as much as three months, ensuring gradual and systematic space closure.
These advancements in metallurgy, through the addition of various elements, have been transformative for orthodontics.
With the rise of aesthetic orthodontic options, like clear aligners, what role does stainless steel continue to play in moder orthodontics?
As far as orthodontic treatment is concerned, whether I’m using braces (brackets and wires) or clear aligners, stainless steel can never be replaced in my dental or orthodontic practice. Even when using plastic-based clear aligners, I still require instruments.
All of my instruments, whether they are examination tools, pliers, or working instruments, are made exclusively of stainless steel. Additionally, when using clear aligners, there are certain adjuncts involved in the treatment. These could include hooks for elastics, buttons, or components designed to apply additional elastomeric forces, making extraction cases more predictable. All of these adjuncts are primarily made of stainless steel.
While my practice has undergone a significant shift with the increase in aligner cases, stainless steel remains an essential part of my practice, especially in the newer equipment and pliers I use, as well as the adjuncts that accompany the aligners.
How does sustainability and recyclability of stainless steel influence its continued use in orthodontics?
Stainless steel is a very versatile material that is widely used in my practice. When it comes to my equipment—such as pliers and cutters—they are highly sustainable and reusable. In fact, some of the pliers I bought when I was a student, almost 27 or 28 years ago, are still in use today. We can effectively cold sterilize these instruments using chemicals, and we can also heat sterilize them using autoclaves, which are pressure cooker-like devices where steam under pressure disinfects the instruments to a level that ensures no cross-contamination of patients. From this perspective, stainless steel in my instruments is highly sustainable.
However, when it comes to brackets and wires, it is ethical and recommended to use them as single-use components. Once a kit is opened and placed in a patient’s mouth—whether it’s to begin or abort treatment, or to replace a component—the materials are disposed of properly. At my clinic, we use a special disposal box containing chemicals to neutralize germs and bacteria, ensuring safety and hygiene.
For safety, any sharp edges, such as those from wires, which are as sharp as needles, are collected in a separate box. The materials are then placed in a biohazard bag for proper disposal, making sure they are handled with care. While sustainability is a priority when it comes to equipment and instruments, sustainability in brackets and wires is not as relevant because these components are single-use only. We strongly discourage reusing them from one patient to another.
Given that stainless steel is one of the most suitable metals in use today, how does the skill of welding contribute to sustainability in this field?
We ensure quality in two key ways. First, we select very reputable companies to supply my materials and equipment. From the outset, I source my supplies only from a select few companies that have been in the industry for over 55-60 years. This long-standing reputation gives me confidence in the quality of the instruments and materials they provide, ensuring they will last a long time.
Second, for certain items like pliers and day-to-day instruments, we look for an AISI mark on the inside surface of the handles. This mark indicates that the instruments have been tested and meet the AISI standard, assuring me that the quality meets the required specifications.
However, for smaller items like brackets and wires, due to the size and nature of these products, it’s not feasible to stamp or certify them for quality in the same way. In these cases, our due diligence involves sourcing materials from companies we trust—companies that are ethical and consistently provide high-quality products.
What would you like to see from stainless steel manufacturers to better meet the evolving needs of orthodontic practices and patient care?
One of the challenges we’ve always faced, especially with our cutters, is that when these wire cutters are heat sterilized—meaning they are placed in an autoclave where steam under pressure is used for sterilization—we’ve noticed that the cutting edge tends to blunt over time. This makes trimming wires more difficult, and after a period of use, we end up struggling because the cutting edge becomes less sharp. As a result, we need to replace them every few months or years. To avoid this issue, we often opt for cold sterilization, which involves dipping the instruments in chemicals to neutralize any germs, spores, or bacteria, as opposed to steam sterilization, which is the gold standard.
In recent times, especially during COVID, I invested in a UV machine. The machine has a stainless steel drum, and the inner surfaces of the stainless steel are designed to reflect UV light. The UV-C radiation used in this process helps inactivate germs, viruses, and bacteria, and this method has reduced the blunting of our instruments.
However, if there are studies within the stainless steel industry that could improve the longevity of the cutting edges of these cutters and wire holders, that would be a huge step forward. While I am not overly concerned with the quality of brackets and wires, as much of our practice is now shifting towards aligner treatments, improving the quality of our instruments would be a valuable advancement for my practice.