Design Life-Cycle

Kacey Martinez

Christina Cogdell

Des 040A

5 June 2024

Materials: Hawley Retainer

In the dental world, retainers are arguably one of the most valuable assets. Most people who use braces end up needing a retainer to maintain the desired shape of their teeth. They come in various forms, with removable Hawley retainers being one of the most used due to their durability, adjustability, and effectiveness. Hawley retainers are a product derived from both an acrylic base and a wire, that sits on both the roof of your jaw as well as the lower jaw. With retainers being so essential and in high demand, they become mass-produced. There is a general understanding that we need them and therefore have no problem with their production, but it is important to understand what the effects of this are as well as what retainers are made of. Despite their importance, the environmental impact of producing and disposing of retainers is too big to be overlooked. Grasping an understanding of the life cycle of this product and focusing on the materials that go into it are vital in understanding how sustainable they really are.

Retainers are crucial to maintaining the results achieved from braces. Even after correcting one’s teeth, they will typically shift back to their original shape if not appropriately maintained. This happens because “Your gum fibers stretch while you are in braces. Once they are removed, these fibers act like a rubber band and want to pull the teeth back to their original position. This creates the potential for teeth to shift very rapidly” (Coles, 2022). Retainers work to counteract this process by holding the teeth in place. They are custom-made to fit everyone's specific mouth shape, often done so by hand. 

With a general understanding of why retainers are needed among hundreds of thousands of patients, it is also important to know the process of getting them, seeing that this segment gives insight into a small aspect of the entire production process. The procedure of getting retainers happens after someone's teeth have been aligned, typically after the use of braces or another teeth-correcting substitute like Invisalign. The patient will go to their orthodontist, where they will take an impression of the patient's teeth. This is done using a dental putty that creates a mold to fit the patient's teeth precisely. The mold is then sent to a lab where the retainer is made, which is then fitted with a wire that is bent and secured using acrylic. From here, the acrylic is hardened, pressurized, and cured (Charleston Orthodontics, 2022). From there, it undergoes some finishing touches, in which it is simply trimmed or shaped to fit a patient comfortably. The last step is to sterilize the retainer and give it to the patient. Sometimes, there may be some slight discomfort, which can be easily fixed with a few minor adjustments.

With a more developed insight into the basic information behind retainers, we can look at the materials that go into them to be able to see what their effects are. As mentioned before, Hawley retainers are made up of several different materials, each chosen for their properties that allow the retainer to maintain its functionality and durability. The first step in making retainers requires the impression made with dental putty. There are two different types of dental putty that are made up of different materials. One dental putty is made up of alginate and the other is made up of silicone. Alginate is a “hydrocolloid material made from seaweed. A hydrocolloid material is a gelatinous substance dispersed in water. It is described as being irreversible as it cannot return to a solution once set.” It is also made up of ester salts, calcium sulfate, zinc oxide, potassium titanium fluoride, diatomaceous earth, sodium phosphate, as well as coloring or flavoring properties (Gibbons, RDN, PTTLS). Alginate is favored for its cost-effectiveness and ease of use. Though it is a good option, the downsides of using alginate are its lack of dimensional stability and the messiness that comes with working with it. On the other hand, silicone putty is made of a base and an accelerator. The base is made of Hydroxy terminated polysiloxane polymer and fillers, while the accelerator comprises of Divinylpolysiloxane prepolymers, Chloroplatinic acid, Palladium, and fillers (Gupta and Brizuela). Silicone putty is favored for its excellent stability and accuracy. The next part of making retainers requires a stainless steel wire. These wires are made of iron, chromium, nickel, and carbon and are chosen for their strength and ease of manipulation. The process of creating the steel wire happens when its raw materials undergo a procedure referred to as hot rolling, in which they are melted with each other to create a strong alloy. It is then sheet rolled to reduce its thickness and make it more uniform (Chicago Metal Rolled Products). From there, it goes through wire drawing, where the metal is pulled through several dies to increase its length and decrease the diameter. Modeling wax is also used to hold the wires in place during the production process. The holding wax, also known as paraffin wax, is primarily made up of an oil known as petroleum. The oil is primarily obtained with the use of drills and then undergoes dewaxing and molding to form the wax. The last section of a retainer is the base. This is made up of both acrylic powder and liquid, also referred to as polymer and monomer. The former is made of sodium hydroxide, benzoyl chloride, hydrogen peroxide, and polymethyl methacrylate, otherwise known as PMMA, and the latter is made up of methacrylic acid and ethylene glycol (Timothy You Da Tan, Brett Duane, Ahmed Hussein, et al.). Acrylic polymer is created when it experiences additional polymerization to add monomer units to a growing polymer molecule (Wang and Sun). It is then put through radical polymerization to create the polymer. The acrylic monomer is created through a single process referred to as polymerization in which a group of small monomer molecules combine with each other to create a network molecule known as polymer (Britannica).  This specific acrylic is used for its ability to be easily shaped, so it can custom fit the unique dimensions of any patient's mouth, making it an asset to the dental industry. 

Like many other products that are produced today, Hawley retainers are best described as a “cradle-to-grave” system. The process starts with the extraction of the needed raw materials, which are then processed through many stages to become a retainer. Usage varies from patient to patient and can span months or years, as each patient's needs are different. Other factors also play a role in durability and longevity, such as whether they need a replacement or their retainers break. However, like many other dental products, retainers are classified as hazardous waste. They are typically thrown away at the end of their use, and the materials in them are not biodegradable. The product often ends up in a landfill or gets incinerated. The process of retainers being made from raw materials but eventually becoming disposed of and not recyclable is the reasoning for why it is listed under a “cradle-to-grave” category.

The production of the materials that make up retainers has significant environmental impacts that are not sustainable because they are incredibly energy-demanding and highly use non-renewable sources. PMMAs require the extraction of petrochemicals, which contributes to greenhouse emissions and environmental degradation. The material is also not biodegradable, contributing to its inability to be recycled properly. The wires used in retainers also require vast amounts of energy, which significantly adds to carbon emissions. The product is not very sustainable, as can be seen in studies conducted. An Oxford Academic journal conducted a study in which they compared Hawley and Essix retainers, looking at the life cycle of both and comparing their sustainability as well as their environmental effects. Overall, when compared to Essix retainers, Hawley retainers are found to be a more significant environmental burden in 12 different impact categories (European Journal of Orthodontics). A lot of the environmental damage caused by retainers occurs during production and manufacturing due to the fossil fuels and oils used. With this information in mind, it is important to try to find other alternatives that do not impact the environment as drastically.

Although Hawley retainers play a pivotal role in post-orthodontic treatment, it is important to note that their production has significant impacts on the environment. The manufacturing process of Hawley retainers requires massive amounts of energy, primarily extracted from non-renewable sources. The end-of-life of these retainers, which leads to their eventual disposal, is not environmentally friendly because the products are not biodegradable. These retainers lead to larger landfill usage and play a role in the environmental damage happening around the world today. Though the product is effective and essential, understanding its impact is important to explore ways in which the sustainability of this product can be increased. By using more renewable forms of energy as well as finding biodegradable alternatives, the production of retainers can become more ethical and less harmful to the environment. 

Bibliography

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Alexander, Gemma. “Recycling Mystery: Dental Appliances.” Earth911, 28 Apr. 2024, earth911.com/home-garden/recycling-mystery-dental-appliances/#:~:text=Hazardous%20Waste&text=Some%20clinics%20may%20steam%20sterilize,items%20that%20contact%20body%20fluids.  

BS Stainless Limited. “Stainless Steel Wire.” BS Stainless Limited, 3 Oct. 2023, www.bsstainless.com/how-its-made-stainless-steel-wire.  

Da Tan, Timothy You, et al. “Environmental Sustainability of Post-Orthodontic Dental Retainers: A Comparative Life-Cycle Assessment of Hawley and ESSIX Retainers.” OUP Academic, Oxford University Press, 15 Mar. 2024, academic.oup.com/ejo/article/46/2/cjae012/7629837?login=true.  

Drtyler. “Teeth Shift after Braces - Here’s Why It Happens & How to Prevent It.” Premier Orthodontics, 1 July 2022, yourazbraces.com/teeth-shift-after-braces/#:~:text=Your%20gum%20fibers%20stretch%20while,teeth%20will%20get%20more%20stable.  

Gibbons, R, et al. “Home.” Dental Nurse Network, www.dentalnursenetwork.com/news/dental-nursing-library/1073-the-difference-between-impression-materials.html.  Accessed 4 June 2024. 

GmbH, Röhm. “How Is Acrylic Made?” ACRYLITE®, www.acrylite.co/resources/knowledge-base/article/how-is-acrylic-made?category=product-properties.  Accessed 4 June 2024. 

Gupta, Ranjan, and Melina Brizuela. “Dental Impression Materials.” StatPearls [Internet]., U.S. National Library of Medicine, 19 Mar. 2023, www.ncbi.nlm.nih.gov/books/NBK574496/#:~:text=Addition%20Silicone:%20they%20are%20the,impression%20materials%20in%20fixed%20prosthodontics.&text=base%20and%20accelerator-,The%20base%20contains:,Fillers%20%2D%20control%20viscosity.  

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Ian Kim

Professor Cogdell

DES40A, Spring 2024

30 May 2024

Energy: Retainers

The retainer was created in 1919 and is still widely used to this day. Being such a vital tool for many people, they are mass-produced across the world. Yet, many people do not think about the process of how they are created. We know the basics, such as the creation of the mold. However, we do not think about everything down to the raw materials. Even better yet, nobody thinks about the energy consumption and use during these processes either. Energy is a big factor in the processes of every life cycle and needs to be acknowledged more for the future sustainability of our world. Retainers use a variety of energies in its production and understanding the amount and uses of these energies are essential.

There are many different types of retainers but the one my group decided to focus on is the Hawley retainer. The Hawley retainer was one of the first retainers made and is one of the better known ones as well. The main parts to the Hawley retainer are the stainless steel wire, wax, powdered acrylic, and liquid acrylic. Throughout the rest of the essay, I will explain how energy ties into each of these parts and the overall making of the Hawley retainer.

Usually, only the final materials like the stainless steel are thought about in the process of creating them. However, each of these parts all come down to the raw materials which make them what they are. We will start off with the stainless steel wire. Stainless steel wire is made up of iron, chromium, nickel, and carbon. These ores are mined in the mines which are mainly worked by fuel powered machines (chemical energy) and human labor (mechanical energy). From this, the selected materials are put into an electric arc furnace which uses electricity and natural gasses to produce its heat. Electric arc furnaces reduce the carbon emissions since they do not rely on coal. After solidifying, the stainless steel goes through a hot-rolling process. This process consists of heating the metal and then proceeding to slide it through multiple rollers to flatten the stainless steel into rods. The heating process gets the steel up to over 1700 degrees fahrenheit in a furnace. This temperature gets the steel to above its recrystallization temperature which helps make it more malleable. The last step is the wire drawing process which takes up a lot of energy. This process consists of using a machine pulling the rod through multiple dies to eventually thin it out enough to become what we know as stainless steel wire. The average power consumption of a wire drawing machine is 75 kw. Overall, the stainless steel process takes a lot of energy. 15-25 gigajoules are used to make 1 ton of stainless steel. This is a mindblowing amount of energy considering that 1 gigajoule can produce 1000 pots of coffee.

There are two types of acrylics that go into the making of the retainer base. One is acrylic polymer which is a powder acrylic. The other acrylic is acrylic monomer which is known as a liquid acrylic. Both of these consist of the main process of polymerization. Polymerization is a chemical process in which monomers react with each other to form bigger molecules called polymers. During the process of making acrylic, there are multiple machines being used and a lot of changes in temperature. These all make the process of making acrylic very energy intensive.

Wax is used in the process of making the retainer by helping to hold the stainless steel wires together when being made. This wax is known as paraffin wax which is made from petroleum. Petroleum is a fossil fuel and uses a drilling and pumping technique to extract it from the ground. The problem with this is that this technique is not sustainable. This process is fueled by 20 to 45 cubic meters of diesel fuel per day. Slack wax goes through a dewaxing process to remove the oils. This process is very chemical based and most of the energy consumption comes from the cooling process. This process involves refrigeration equipment to cool the oil to the desired level for wax crystallization. 

The manufacturing process of retainers brings in new machines and processes than what was seen for the raw materials. The process requires mainly human labor but also uses the help of machines to create the retainer. The first step is to bend wires around the mold that will represent the essential part of the retainer. The wax comes in on this step by holding the wire in place so the acrylic can be poured on. Using the powdered acrylic and liquid acrylic, they are alternated when poured to fill in the space around the teeth and wires. Mixing the powdered and liquid acrylic allows the acrylic to harden and there will be a wait process for it to fully cure. To cure the retainer, the acrylic is placed in a pressure cooker where it helps the retainer cure with pressure and heat. Once the curing process is done, the retainer is taken out to be trimmed so that it will be comfortable and shaped to the right size. The retainer is finally put through the polishing process. There is the coarse polishing machine which is the initial polishing stage and removes all of the early imperfections like scratches or rough surfaces. The next stage is to go through a fine polishing machine which gives the retainer those last smooth and high level refinements. 

Knowing the manufacturing process for retainers, we can see that the main machines used are the fume hood, pressure pot, coarse polishing machine and fine polishing machine. Fume hoods are essential in labs to exhaust bad air out and push clean air in. One fume hood uses enough energy to power 3.5 homes and there could be multiple fume hoods in one lab. They annually use up 33,500 kwh of electricity. There is not a lot of information on dental pressure pots but assuming the work it does in applying pressure and heat (thermal energy) to the acrylic, we can only assume that a lot of energy goes into it. The coarse and fine polishing machines are quite similar and are run on electricity. Using kinetic energy, the acrylic gets sanded down into a nice glossy finish. In total, the manufacturing process includes a multitude of human labor and the work of machines to create the retainer.

 One of the essential components of energy usage when it comes to making retainers is transportation. Depending on where the lab or dental building is placed, the distribution of the goods can be brought through lorries, boats, or planes. However, the transportation process does not just start from the distributor to the labs. The process starts when we get raw materials and transfer them to the places that turn those raw materials into the actual parts to make the retainer. After the factories have made the parts, they deliver it to a distributor which then finally sends the parts to dental labs. We know the future of travel is trying to go towards being electric. However, the case right now is that most are still using fossil fuels (chemical energy). Transportation in the world takes up around a quarter of the total global carbon dioxide emissions. This makes transportation one of the contributing factors to global climate change. This process can definitely be benefited by using cleaner sources of energy to help reduce carbon emissions and save the Earth.

When it comes to the usage of retainers, there is not much work that goes into it. The main requirement is to simply clean them using water and a cleaning agent. This only takes human labor as you just put the retainer in water with the cleaning agent and let it do its job. Another factor is if the retainer gets damaged. If this happens, the retainer is taken back to the orthodontist to get the repair it needs with steps similar to the manufacturing process.

The final step to a retainer’s life is when they finally get tossed out. Many people forget that they should replace their retainers. There is not an exact measure to how long a retainer lasts but many say 1-5 years. Since retainers are not considered to be recyclable considering the materials, they can only be thrown away to municipal waste. The main process in dealing with municipal waste is incineration (thermal energy). The process of incineration can actually produce many hazardous pollutants that destroy the environment even further.

Retainers may seem like something simply made right in the lab. Yet, there are many other factors that contribute to the making of them. From the raw materials to the thorough manufacturing process, we can see that every step uses a large amount of energy. We can always work to cut this amount down and help towards a more sustainable future. 

Bibliography

“Stainless Steel Wire.” BS Stainless Limited, BS Stainless, 3 Oct. 2023, www.bsstainless.com/how-its-made-stainless-steel-wire.

Da Tan, Timothy You, et al. “Environmental Sustainability of Post-Orthodontic Dental Retainers: A Comparative Life-Cycle Assessment of Hawley and ESSIX Retainers.” OUP Academic, Oxford University Press, 15 Mar. 2024, academic.oup.com/ejo/article/46/2/cjae012/7629837?login=true.

“Steel Industry Pivoting to Electric Furnaces, Analysis Shows.” Steel Industry Pivoting to Electric Furnaces, Analysis Shows, Yale E360, 20 July 2023, e360.yale.edu/digest/steel-industry-carbon-coal-electric-arc-furnaces.

“Exploring Energy Consumption in Stainless Steel and Aluminum Production.” Exploring Energy Consumption in Stainless Steel and Aluminum Production., Double Stone Steel, 16 Aug. 2023, www.linkedin.com/pulse/exploring-energy-consumption-stainless-steel-aluminum#:~:text=On%20average%2C%20producing%201%20ton,them%2C%20and%20fuelling%20the%20furnaces.

Thompson, Joseph. How Are Orthodontic Hawley Retainers Made?, Ask an Orthodontist.com, 8 Sept. 2016, askanorthodontist.com/braces/how-are-orthodontic-hawley-retainers-made/.

Replace Your Fume Hood and Reduce Electricity Use by at Least 50%, Better Buildings Initiative, betterbuildingssolutioncenter.energy.gov/replace-your-fume-hood-and-reduce-electricity-use-at-least-50#:~:text=Assuming%20that%20a%20conventional%20bypass,that%20high%2Dperformance%20fume%20hoods. Accessed 31 May 2024.

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GmbH, Röhm. “How Is Acrylic Made?” ACRYLITE®, ACRYLITE®, www.acrylite.co/resources/knowledge-base/article/how-is-acrylic-made?category=product-properties. Accessed 3 May 2024. 

Seo. “How Are Retainers Made?” Charleston Orthodontics Powered By Smile Doctors, 24 Nov. 2022, charlestonorthodonticspecialists.com/how-retainers-are-made/.

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Si Yan

Professor Cogdell

DES 40A

1 June 2024

The Waste, Emissions, and Byproducts of Retainers

Retainers are one of the most commonly used dental products in the world, which in turn makes their impact on global outputs quite significant. Many sustainability challenges arise regarding the waste and emissions of retainers. The custom fit and cumulative oral bacteria of retainers make them impractical to reuse, and the chemical compounds, composition of various plastic polymers, and sanitation issues of retainers make them difficult to repurpose and properly dispose of. Because retainers are considered to be medical waste, they are banned in most communal and residential garbage services. With orthodontics being such a large market in the world, the extraction techniques, manufacturing and transportation processes, and the complicated disposal process of retainers mark them as a major contributor to environmental waste. 

To begin, we must understand the significance of the environmental impacts and waste created by retainers. Braces are the most used orthodontic appliance in the world, with over 4 million people in the U.S. wearing braces at any given time, meaning at any given time, there are also 4 million people in the U.S. using retainers (Pennsylvania Dental Association). With how large the global market is for braces and retainers, the environmental impact of the waste and pollutants cannot be overlooked. In order to make retainers a more sustainable product in terms of their life cycle, we must understand the sources of their sustainability challenges and learn how to minimize their global impact, beginning with the extraction process of their raw materials.

Retainers are made up of two main components: the plate and the wiring. The plate of the retainers is primarily made up of acrylic plastic, more specifically a thermoplastic polymer known as polymethyl methacrylate (PMMA). PMMA is created through the polymerization of methyl methacrylate (MMA), which is derived from coal, natural gas, and crude oil (Plastics Europe). The raw extraction of coal, natural gas, and crude oil all require drilling processes, which create large outputs of waste and pollution in the environment. Drilling fluid is an essential material in the drilling process that carries drill cuttings from the drill bit to the surface. However, drilling fluid often leaks during the drilling process and is often disregarded afterward, leaving it to mix with the soil and groundwater. The chemicals in the drilling fluid combined with the metals and in soil and groundwater create all sorts of pollutants including volatile organic compounds (VOCs), air pollutants, and other harmful substances that can harm the environment and health of humans. The contaminated groundwater additionally can leak into the drinking water of residents, potentially causing significant harm to the health of nearby residents. This is not the end of the environmental challenges that come with the extraction of raw materials for retainers, as the extraction of iron to create the wiring also comes with significant environmental outputs.

The wiring of retainers is made from stainless steel, which also possesses an environmentally significant extraction process. The raw iron to create the stainless steel wiring is extracted from the earth mostly through open-pit mining, a mining technique that extracts materials from a large pit (UKGBC). Open-pit mining is a heavily destructive and energy-intensive process that emits large amounts of air pollutants. Silica dust is a common byproduct of open-pit mining that along with other particulates from the mining process can cause respiratory diseases and conditions to those exposed to it. Open-pit mining also produces tailings, a toxic waste material consisting of minerals, chemicals, and other byproducts from the mining process that can contaminate water, destroying aquatic ecosystems as well as polluting drinking water. Iron ore tailings often consist of mercury, selenium, lead, and other metals that are harmful to the environment and humans even at low levels (Da Silva et. al). As tailings can be carried away by wind or water, they often end up in other areas, causing further damage. After the extraction of the raw materials, they need to be manufactured and transported, whose processes also contribute heavily to global emissions and waste. 

The manufacturing process of turning raw iron into steel is both energy-intensive and significant in waste and pollutant outputs. Steel production processes contribute to 7% of global CO2 emissions (Kullman). Nowadays, steel is mostly produced by electric arc furnaces, where an electrical current melts iron and scrap to make steel. Stainless steel is produced by simply melting iron with high chromium content, as chromium is what gives the steel its corrosion-resistant property. Electrical arc furnaces use natural gas as a fuel source, which releases methane into the atmosphere, as well as other gasses such as carbon monoxide, sulfur dioxide, and nitrogen oxides that worsen air quality (MET). Electric arc furnaces additionally produce fine dust often called electric arc furnace dust (EAFD), which contains heavy metals that contaminate groundwater. (Nair et. al) Steel production also produces waste byproducts in the form of slag, which is residue made up of metals and oxides (Nair et. al). Slag often contaminates soil and water and needs to be disposed of in landfills, reducing land availability. 

To turn the molten iron into stainless steel wires, the molten iron then needs to undergo a hot-rolling process, where the molten iron gets elongated through a series of rollers at high temperatures, typically over 1700 degrees Fahrenheit, and becomes rods. The energy to produce this immense amount of heat can also emit nitrogen oxides and sulfur oxides (UKGBC). After, the rods are passed through a series of wire-making dies under tension to increase the wire’s length. To make the wiring for retainers, the rods are cut and bent into shape. Overall, the natural gas used to fuel the manufacturing of steel emits many pollutants and puts both the environment and humans at risk with its hazardous outputs. The acrylic plastic plates of the retainers are made through the polymerization of PMMA, whose process itself does not produce any significant waste or byproducts. The acrylic plastic is then cut to fit the shape of the teeth. Any excess materials from the production process are disposed of as municipal waste. 

As retainers are in most cases hand-made in the dental office itself and distributed to the user immediately, it omits the need for long-distance transportation of the product itself. However, the energy used for transportation of the raw materials to produce retainers contributes to CO2 emissions. Because stainless steel and acrylic plastic are relatively simple to produce, they are made in various locations across the globe. There does not seem to be a monopoly for steel or acrylic plastic manufacturing, meaning that they can be obtained through transportation from almost anywhere on the planet. As coal and natural gas are often used to fuel cargo ships, aircraft, and freight trains to transport these materials, air pollutants and CO2 emissions are emitted in the process. 

Retainers are made to last for eight to ten years and reused indefinitely until replacement to ensure teeth alignment. Retainers do not produce any waste when being used, as they are usually always in the retainer case or the mouth. Maintenance in most cases only really consists of cleaning the retainer with water and a cleaning agent, which does not produce any sort of waste. Because of the inevitable built-up oral bacteria, it would be too much work to sterilize them and repurpose them. Additionally, the custom fit of the retainers makes them unable to be reused by others. These implications require the need to dispose of them, however, doing so is a complicated and environmentally-challenging process. 

Due to the unique compounds that make up the retainers, it makes them difficult to properly dispose of. Because the plastics used to make retainers differ between different dental labs and orthodontic offices, it is almost always unknown of the exact composition of the plastic in retainers, making them difficult to recycle. If retainers were to be thrown away as municipal waste, they would end up in a landfill and stay there, as plastic can take up to thousands of years to degrade while also simultaneously releasing toxic particles to nearby soil and water. Retainers are often given to orthodontists after use to be thrown away as part of contaminated medical waste, which is often incinerated to reduce further medical waste and the amount of material that needs to be landfilled (EPA). However, doing so also releases a handful of harmful pollutants and byproducts. Coal, natural gas, and oil are often used to fuel the incinerators, contributing to CO2 emissions and air pollutants. Stack gas emissions are gasses released into the air after the incineration process and can include carbon monoxide, methane, sulfur, dioxins, furans, and many other gasses that are all harmful to air quality, the environment, and human health (National Library of Medicine). Fly ash, a powdery material, is another byproduct of incineration and can cause respiratory problems in humans as well as pollute the environment with toxic metals such as selenium, arsenic, uranium, etc. Bottom ash is a waste product that is a byproduct of coal combustion and also contains toxic metals such as lead, mercury, and uranium (Energy Education). Bottom ash is hazardous to humans and can contaminate soil and groundwater. Not only are these byproducts very harmful to the environment and human health, but they are also very difficult to dispose of due to high costs, lack of available land, and regulations, which causes further harm (Zhao et.al). Creating more sustainable practices for disposing of retainers will ensure the longevity and health of the environment and humans.

While retainers are used by so many individuals around the world, the waste and environmental harm they cause cannot be overlooked. Nearly every stage of a retainer’s life cycle is a contributor to global emissions as well as waste outputs. With how prominent retainers are in the daily lives of so many individuals, more sustainable practices need to be employed during the extraction, manufacturing, transportation, and disposal processes. The air pollutants, waste products, harmful gas emissions, and other harmful byproducts caused by these processes additionally need to be addressed in order to ensure the health of the environment and human lives. By raising awareness about the implications of these processes and the harmful waste, pollutants, and byproducts they produce, we can build a sustainable future where no more waste comes with their creation. 

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