Is thermoplastic polymer the only materials clear aligner outsourcing? Or it is the best among several materials? Let’s figure it out in today’s topic with XDENT Clear Aligner Outsourcing Dental Lab
The days of simply having the choice of wire-and-bracket braces to treat crowding, malocclusion, and other orthodontic problems are long gone. Patients now have a more attractive alternative to conventional braces thanks to the invention of transparent aligner treatment.
Harold Kesling stated in 1945 that “major tooth movements could be accomplished with a series of positioners by changing the teeth on the setup slightly as treatment progresses.” This statement laid the groundwork for clear aligner therapy. Kesling promoted the progressive repositioning of misaligned teeth using rubber-based tooth positioners based on wax models. Although thermoplastic materials, rather than rubber, are used to make today’s aligners, Kesling’s essential ideas lay the foundation for the transparent aligner therapy that we employ today.
When Align Technology introduced its removable polyurethane aligners for Invisalign in 1998, clear aligner treatment as we know it became a reality. Although Invisalign continues to be a key participant in the clear aligner market, several other businesses have successfully created their own clear aligner treatments.
And there is a demand for solutions for transparent aligners. Today, clear aligners are a staple of orthodontic treatment and are growing in popularity. This is brought on by significant advancements in CAD/CAM and biomaterials, as well as a rise in adult patients seeking comfier and more aesthetically pleasing alternatives to permanent equipment. The development of clear aligner technologies has also been spurred by the quick uptake of CAD/CAM technology. The market for clear aligners, which was estimated to be worth $3.1 billion in 2021, is anticipated to reach $11.6 billion in 2027.
Despite the excellent figures, patient outcomes alone can determine whether clear aligner treatment is indeed successful. The materials used to make clear aligners have a significant impact on how well they operate in clinical settings, and the mechanical, chemical, optical, thermal, and biological properties of these materials are crucial to the treatment’s ultimate effectiveness. The results of a 2022 study stated that “Clear aligner therapy will be significantly limited [because of] its inherent biomechanical constraints and clear aligners would continue to underperform clinically, especially in comparison with conventional fixed orthodontic appliances. Advances in aligner material chemistry possess the potential to bring about radical transformations in the therapeutic applications of clear aligner therapy.
Understanding the materials utilized and the production procedures is crucial since the materials in clear aligners have such a significant impact on clinical performance. In order to produce aligners that function better during orthodontic treatment, experts say it is important to first understand the qualities of the materials and how they react to different stressors.
There are several strains placed on clear aligners in the mouth. Temperature changes, moisture, saliva and beverage chemical stressors, sporadic mechanical load pressures, and the thermal stress brought on by the aligner formation process are all factors that affect them. According to research findings, a perfect aligner material would be able to withstand these stresses by having “high resilience, low hardness, sufficient elasticity, adequate resistance to varied stress and distortion, excellent transparency, low cytotoxicity, and high biocompatibility”.
Additionally, aligners must be sufficiently stiff to apply the force required to carry out the intended tooth movement. However, the aligner will be rigid and difficult for the patient to insert and remove if the manufacturing material has a high modulus of elasticity (an excessively high amount of stiffness). On the other hand, if an aligner is not stiff enough, it won’t be able to produce the necessary amounts of force to move the teeth.
Fabricators of clear aligners have carefully navigated this precarious path. Although thermoplastic materials (mainly polymers) make up the majority of aligners, differing material compositions react differently to heat and mechanical pressures. As a result, producers are always researching and developing the optimum materials and combination for better results.
In an effort to improve clinical effectiveness and the capacity to treat problems more esthetically, comfortably, and efficiently, clear aligners have undergone a number of changes. Without any extra features built into the aligner system, the initial generation of aligners solely depended on the thermoformed plastic aligner material to move the teeth. Attachments were added to second-generation aligners to provide dentists more precise control over tooth movement. By 2013, improvements have been made to make deep bite correction more predictable. Over the years, these innovations have persisted, with new methods and materials frequently hitting the market.
The Materials
There are four main categories to take into account, despite the fact that clear aligner manufacture uses a variety of materials. Thermoplastic polymers, polymer blends, 3D-printed materials, and bioactive materials fall under these categories.
Thermoplastic polymers
Thermoplastic polymers are categorized as either amorphous or semicrystalline polymers based on their innate molecular structure. While semicrystalline polymers consist of both randomly ordered regions (or amorphous regions) and uniformly and tightly packed crystalline domains, amorphous polymers feature molecular structures with irregular arrangements and low levels of molecular packing. Amorphous polymers often have minimal shrinkage, strong impact resistance, and are translucent and softer. Semicrystalline polymers have a higher melting point, are more chemically resistant, and are tougher and more opaque. The crystalline domains, which give the material hardness and stiffness like a filler in a composite material, permit these qualities.
All in all, polypropylene, polyurethane or copolyester, polycarbonate, polyvinyl chloride, ethylene vinyl acetate, and polyester are the polymers most frequently utilized for clear aligners. Because of their exceptional optical and mechanical qualities, the polyesters polyethylene terephthalate and its amorphous copolymer polyethylene terephthalate glycol are frequently utilized in the manufacture of clear aligners. Other widely used materials include polycarbonate (recognized for its durability, transparency, and hardness), and thermoplastic polyurethane (which has advantageous attributes including strong mechanical and elastomeric capabilities, abrasion and chemical resistance, and simplicity of manufacture).
Polymer blends
The mechanical characteristics of the polymers are enhanced even further when the strengths of these substances are combined. In the production of transparent aligners, polyester, polyurethane, and polypropylene polymer mixes are frequently employed. This is because research has shown that mixing thermoplastic polymers improves their mechanical and chemical characteristics, which can increase the therapeutic efficacy of clear aligners. The proportion of these polymers that are mixed together is crucial for establishing the characteristics of the final blend. For instance, whereas certain blends may have stronger tensile or impact strength, others may have better mechanical characteristics, delivering superior sustained orthodontic pressures.
3D-printed materials
The clear aligner market has radically transformed because to 3D printing. Aligners that are 3D printed have less chance of being inaccurate throughout the analog imprint or intraoral scan, following 3D model, and final thermoplastic procedure. In addition to increased precision and decreased mistakes, 3D printing may cut costs and speed up the production of aligners.
Direct 3D printing techniques also eliminate the drawbacks of the conventional thermoforming process, which can change the mechanical and aethetic properties of the material during manufacture. Thermoforming has been demonstrated to improve material surface hardness, increase water absorption and solubility, and decrease the transparency of thicker materials.
In a nutshell, 3D printing produces simplified results. The direct 3D printing of transparent aligners enables for the layer-by-layer construction of components as opposed to the traditional processes of moulding or machining. Various materials other than those used in conventional manufacturing are used in this method, including acrylonitrile butadiene styrene plastic, stereolithography materials (epoxy resins), polylactic acid, polyamide (nylon), glass-filled polyamide, silver, steel, titanium, photopolymers, wax, and polycarbonates. These materials can be printed directly using a variety of 3D printing techniques, such as stereolithography, continuous liquid interface production technology, selective laser sintering/melting, fused deposition modeling, direct pellet-based fused deposition, and multijet photo-cured polymer process.
This leads to greater geometric accuracy and precision, a better fit, and increased mechanical resistance effectiveness. Direct 3D printing also yields digitally specified undercut analysis, adjustable intra aligner thickness, and softer aligner edges that don’t require cutting or smoothing.
Bioactive materials
Oral hygiene is a major issue with any orthodontic treatment. Because the appliances are removable, clear aligner treatment proponents argue that transparent aligners are a more sanitary alternative to traditional orthodonture. The patient’s teeth and gingiva are covered by the aligner for 20 to 22 hours each day (apart from when it is removed for eating, etc.), but this might raise the risk of bacterial development, which could lead to periodontal or tooth damage. Studies on materials and potential uses of nanoantibacterial materials and bioactive properties that could be integrated within them have been prompted by the microbial accumulation of oral pathogens, such as Streptococcus mutans and Porphyromonas gingivalis, a frequent problem of orthodontic treatment..
One such study looked into the use of gold’s antimicrobial properties. In the study, gold nanoparticles modified with 4,6-diamino-2-pyrimidinethiol were coated on transparent aligners. This coating demonstrated good biocompatibility and antibacterial properties that inhibited the development of biofilm in a suspension of P gingivalis.
A second study team used essential oils to add cinnamaldehyde to a cellulose-based clear aligner substance. This substance displayed antibacterial activity against S mutans and S epidermidis. Cinnamaldehyde was proven to inhibit the development of biofilm in a laboratory setting, according to study findings. In addition to having antibacterial qualities, cinnamaldehyde also made some materials more hydrophobic, which might reduce early adherence and postpone the development of biofilm.
Although research is underway, there is still room for improvement in the antibacterial efficacy and biocompatibility of existing nanomaterials.
Conclusion
There are four main types of material that’s able to make clear aligners, which has differences pros and cons, anyway Thermoplastic polymers still be the main and most common material due to its specifications. At XDENT Outsourcing Dental Lab (LinkedIn) , we use the top-tier thermoplastic polymer material is Erkodur-al for every orders. It is proved that having tough-elastic-hard, break-resistant, with excellent dimensional stability. Made of copolyester with applied insulating film. For the fabrication of aligners, corrective splints and retainers. Compared to the proven Erkodur thermoforming foils, the material is approx. 35 % softer with a correspondingly lower initial force and a reduced feeling of tension during insertion. Due to the very flat memory loss curve, the effective force lasts comparatively longer.
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