A SIGNIFICANT portion of the human population has phobias.
Some are afraid of heights, some are scared of people in general and others fear death.
Fear is accompanied by worry, curiosity and insomnia.
Regarding dental phobia, the vast majority of people are unable to comprehend that a foreign object, particularly a metal, will be inserted in their mouths in order to perform a specific function.
Metal can be used in dentistry to restore lost function and anatomy through metal crowns or it can be used to close gaps and cure malocclusion (tooth misalignment) using braces.
Even though more sophisticated treatment options are being made available in dentistry every year, metal braces continue to be among the best options in orthodontics due to their durability, strength, effectiveness in moving teeth and affordability — they are significantly less expensive than ceramic braces which are white braces that resemble the colour of real teeth.
In the event that this proves to be the most effective course of treatment, we frequently overthink things before starting treatment and concerns about this kind of therapy option start to accumulate.
Could these materials, for instance, corrode in my mouth?
When corrosion occurs, what will happen to the corrosion products?
Are they absorbed by the body if they are produced and can they have local or systemic effects? And how does corrosion affect orthodontic appliances’ clinical effectiveness and physical characteristics?
Does corrosion really occur?
The answer is yes.
The term “corrosion” refers to metal degradation.
It could be caused by the dissolution of a surface coating, typically an oxide or sulfide or the loss of metal ions immediately into a solution.
In contrast to some metals, such as gold and platinum, which are noble and essentially inert, the metals commonly found in orthodontic appliances (braces), such as nickel-titanium (Ni-Ti wire) and stainless steel (a mixture of chromium, iron, nickel and other accessory materials) are not corrosion-free.
In order to get effective orthodontic treatment, orthodontic wires must be in ideal shape.
They must adhere to specific qualities including biocompatibility, formability, weldability, low coefficient of friction, resilience, shape memory, low stiffness and high elastic limit, even though no wire is entirely ideal for full treatment.
Regardless of the type of orthodontic wire you have, corrosion is unavoidable due to the simultaneous oxidation and reduction (redox) processes that take place when any metal is submerged in a solvent, in this case saliva.
Iron in a weak acid, for instance, dissolves when ferrous ions are created during the oxidation (anodic) reaction.
Unless a protective surface layer can be formed by the metal (passivation) or the cathodic reactant is consumed (eg, exhaustion of dissolved oxygen in solution), the corrosion process typically continues until the metal is completely destroyed.
The development of a passive surface oxide film buffers corrosion and it is the reason why titanium, cobalt-chromium and stainless-steel alloys continue to be used in orthodontic appliances.
Even with the build-up of protective layers, wires exposed to the oral environment can suffer corrosion, but could be reformed if there is an increase in exposure to oxygen.
For this effect patients are advised to drink more water and speak more. Corrosion of metals is mainly increased by:
- a diet rich in sodium chloride (a very salty diet)
- acidic carbonated drinks (Coca-Cola, Fanta, Sprite, Pepsi, etc.) provide a regular supply of corrosive agents.
Patients with braces are recommended to reduce the intake of carbonated drinks and salty foods.
Does corrosion of braces pose a concern?
It takes about a week for the nickel release to peak during corrosion, after which it gradually slows down.
On the other hand, the release of chromium rises for the first two weeks and then levels out over the next two weeks.
There is no discernible difference in the rates of nickel or chromium release from nickel-titanium arch wires and stainless steel.
Although corrosion may occur, research has indicated that the amount of metal ions released during orthodontic treatment is less than that consumed during a regular daily meal.
This implies that corrosion during the treatment period is negligible.
Thus, braces are regarded as a safe alternative.
Can nickel and chromium from braces cause cancer?
There is a school of thought which postulate that nickel and chromium are known to cause cancer, but is this accurate?
Almost all cases of nickel and chromium-induced carcinomas (cancer) have been caused by occupational exposure to inhalation of metal compounds, the lung and nasal mucosa (tissues) are the primary tumour locations.
We should bear in mind that not all nickel and chromium compounds have the potential to cause cancer; for nickel compounds, risk is inversely related to their solubility in an aqueous medium; for chromium compounds, carcinogenicity (cancer risk) has only been identified with compounds in which the chromium is in a certain oxidation state.
There is no experimental evidence that nickel or chromium compounds are carcinogenic when administered through oral or cutaneous routes.
It has been estimated that there is an average latency period of 20 to 25 years between the time of exposure to these metal compounds and the onset of cancer.
Since treatment for braces will only take five years or less, cancer brought on by metal braces is more of a thought than it is a reality.
Based on existing empirical evidence there is no reason to be perturbed about developing cancer through corrosion of braces or other dental appliances.
Patience Matambo is a final year BSc Dental Surgery student at the People’s Friendship University of Russia. She can be reached at patiencedental2024@gmail.com
