Who This Article Is For

This guide is for UK adults who are considering invisible braces and want to understand exactly what they would be putting in their mouths for months at a time. It is a reasonable question — and one that deserves a thorough, transparent answer.

You may find this article particularly useful if you:

• Have concerns about plastics, BPA, or chemical safety in dental products
• Have allergies or sensitivities and want to know what materials are involved
• Are comparing different aligner brands and want to understand material differences
• Simply want to make an informed decision before committing to treatment

Note: This article covers the science and safety of aligner materials. If you have specific medical concerns or known allergies, we would always recommend discussing these with your clinician before starting any treatment.

Key Definitions in Plain English

What Are Clear Aligners Made Of?

If you have ever wondered what clear aligners are made of, the short answer is: medical-grade thermoplastic polymers. But there is more nuance worth understanding.

The Core Material: Thermoplastic Polyurethane

Most premium aligner systems use a form of thermoplastic polyurethane (TPU) or a closely related co-polyester. These materials are specifically engineered for dental applications and are chosen because they offer:

• Optical clarity: The material is virtually transparent, making aligners far less noticeable than traditional metal braces
• Controlled flexibility: Stiff enough to apply gentle, sustained force to teeth, yet flexible enough to be inserted and removed comfortably
• Durability: Designed to resist cracking, staining, and deformation during the one-to-two-week wear period of each tray
• Biocompatibility: Tested for prolonged contact with oral tissues, saliva, and the fluctuating temperature and pH environment inside the mouth

How the Material Becomes an Aligner

The journey from raw material to finished aligner typically follows these steps:

1. A 3D scan of your teeth is taken, creating a precise digital model
2. Specialised software maps out the planned tooth movements, stage by stage
3. A 3D printer creates a physical model of each treatment stage
4. A flat sheet of thermoplastic is heated and vacuum-formed (or pressure-formed) over each model, creating the custom tray shape
5. The tray is laser-trimmed to follow the gum line accurately and polished smooth

The result is a set of trays, each slightly different from the last, that guide your teeth through a planned sequence of movements.

Material Variations Between Brands

Not all aligners use identical materials. Different manufacturers have developed proprietary formulations — some are single-layer, others are multi-layer laminates that combine a rigid outer shell with a softer inner layer for comfort. The specific material can affect:

• How much force the tray delivers (and how it changes over the wear period)
• Stain resistance and clarity retention
• Comfort during insertion and removal
• How well the tray maintains its shape over time

Your clinician selects an aligner system based on clinical suitability for your case — material quality is one of many factors in that decision.

Are Clear Aligners BPA-Free and Safe?

This is one of the most common questions patients ask, and it is an important one. Here is what the evidence shows:

A Balanced Perspective on Plastic Safety

While the safety profile of modern aligner materials is strong, it is fair to acknowledge the broader context:

• Micro-level leaching: Some laboratory studies have detected trace amounts of chemicals released from thermoplastics in simulated oral environments. However, the levels measured are typically far below thresholds considered harmful by regulatory bodies.
• Heat sensitivity: Exposing aligners to hot liquids (such as drinking hot tea while wearing them) can theoretically accelerate material degradation. This is one reason clinicians advise removing aligners before consuming hot drinks.
• Long-term data: Clear aligners have been in clinical use since the late 1990s, with no widespread adverse events linked to material toxicity. However, like all medical materials, ongoing research continues to refine our understanding.

The bottom line: plastic braces safety is well-supported by current evidence, regulatory standards, and decades of clinical use. If you have specific concerns about chemical sensitivities, discuss these with your clinician — they can provide information about the exact material used in your treatment.

What Clear Aligners Can Do (and What They Cannot)

What They Can Do

• Correct mild to moderate crowding, spacing, and certain bite issues
• Deliver controlled, gentle forces through a series of custom trays — each moving teeth incrementally (typically 0.2 mm per stage)
• Offer a discreet, removable alternative to fixed braces — often referred to as invisible braces
• Allow normal brushing and flossing, supporting better oral hygiene with aligners compared to fixed brackets
• Be combined with attachments and IPR to handle more complex movements

What They Cannot Do

• Treat severe skeletal discrepancies that require jaw surgery
• Reliably move teeth without patient compliance — 22 hours of daily wear is essential
• Guarantee perfect results; refinements are often needed to fine-tune the outcome
• Replace the need for retainers after treatment — teeth will shift without retention
• Address underlying dental health issues such as decay or gum disease (these must be treated first)

Cleaning and Wear Safety

How you care for your aligners affects both the material's integrity and your oral health. Here are the key points:

Step-by-Step: How Treatment Typically Works

Understanding the full process helps put the material science into practical context:

Suitability Checklist

This is a general guide — only a clinical assessment can confirm whether clear aligners are right for you.

Risks, Side Effects, and Limitations

All medical treatments carry some degree of risk. Being informed helps you make a balanced decision:

• Temporary discomfort: Mild pressure and tenderness are common when starting a new set of trays. This usually settles within a few days and is a sign that the aligners are working.
• Speech changes: Some patients notice a slight lisp when they first start wearing aligners. This typically resolves within a week as the tongue adjusts.
• Dry mouth or increased saliva: The mouth may react to a new object by producing more (or less) saliva initially. This usually normalises quickly.
• Root resorption: A small degree of root shortening can occur with any orthodontic treatment. Clinicians monitor for this with periodic X-rays.
• Gum irritation: Tray edges can occasionally irritate the gums, especially if trimming is not precise. Your clinician can smooth any rough edges.
• Allergic reaction: Extremely rare with modern materials, but possible. If you experience unusual swelling, rash, or irritation, remove the aligner and contact your clinician.
• Treatment may take longer than expected: Compliance, biology, and case complexity all influence treatment time. Refinements may extend the process.
• Relapse without retention: Teeth will shift if retainers are not worn as prescribed after active treatment.

How Long Treatment May Take

Treatment time varies considerably depending on the complexity of your case and how consistently you wear your aligners. Here is a general guide:

Key factors that influence timelines include: severity of misalignment, compliance with wear time (22 hours per day), biology (how quickly your bone remodels), and whether refinements are needed. Your clinician will provide an estimated timeline during your assessment — but it is important to understand this is always an estimate, not a guarantee.

Costs in the UK

Clear aligner treatment in the UK typically ranges from around £1,500 for straightforward cases to £5,500 or more for complex full-arch treatment. What drives the cost:

• Number of aligners: More stages of movement generally mean a higher fee
• Material and system: Premium aligner systems with advanced materials and software may cost more than budget alternatives — but the material quality, clinical support, and predictability can differ significantly
• Refinements: Some plans include refinements; others charge separately
• Retention: Retainers are usually an additional cost and are essential for maintaining results
• Clinic location: Fees tend to be higher in London and other major cities

For a more detailed breakdown, visit our clear aligner cost guide. Many clinics offer interest-free payment plans to help spread the cost.

Note: We cannot provide a specific quote without assessing your case. The figures above are indicative ranges and vary by provider and complexity.

Keeping Your Results: Retention and Aftercare

Active treatment is only half the journey. Retention is what keeps your teeth in their new positions long-term:

• Removable retainers: Custom-made clear trays (similar in material to your aligners) worn nightly. Most clinicians recommend indefinite nightly wear, or at minimum for the first 12 months.
• Fixed retainers: A thin bonded wire on the back of the front teeth, providing passive retention without daily effort. Not suitable for everyone.
• Retainer care: Clean retainers the same way you cleaned your aligners — soft brush, lukewarm water, no abrasive toothpaste. Replace them when they become worn or ill-fitting.
• Ongoing check-ups: Regular dental visits help catch any early signs of relapse, decay, or gum issues.
• Oral hygiene: Maintaining excellent brushing and flossing habits protects your investment in a straighter smile.

When to Seek Advice

If you are considering clear aligners and have any of the following concerns, it is worth speaking to a clinician:

• Known allergies to plastics, adhesives, or dental materials
• A history of severe gum disease or significant bone loss
• Concerns about a specific health condition and how it might interact with orthodontic treatment
• Previous orthodontic treatment that did not go as planned
• Uncertainty about whether your case is suitable for aligners versus other options

A good clinician will welcome these questions and take the time to address them. If a provider dismisses your concerns, consider seeking a second opinion.

Frequently Asked Questions

Disclaimer: This article is for general information only and does not constitute dental or medical advice. The safety and suitability of clear aligner materials may vary by manufacturer, and individual responses can differ. Treatment suitability, timelines, and costs can only be determined through an in-person assessment by a GDC-registered dental professional. If you have concerns about allergies or material sensitivities, please discuss these with your clinician before starting treatment.