Can Smileie Clear Aligners Fix Gap Teeth? UK Diastema Guide

What is diastema?

Diastema is the clinical term for a gap or space between two teeth. While it can occur anywhere in the mouth, the most common and noticeable form is a gap between the two upper front teeth — known as a midline diastema. A gap is typically classified as a diastema when it measures more than 0.5mm in width.

Diastema is extremely common. Research shows that the prevalence of midline diastema in adults ranges from roughly 1.6% to 25% depending on the population studied, age group, and how the gap is defined. In children, it's even more widespread — nearly all six-year-olds have some degree of spacing between their front teeth, which usually closes naturally as permanent teeth erupt.

For many adults, however, the gap persists. And while some people embrace it as a distinctive feature, others find it affects their confidence or raises concerns about food trapping and oral hygiene.

What causes gap teeth?

Gaps between teeth develop for a variety of reasons, and understanding the cause helps determine the best treatment approach:

Can clear aligners fix gap teeth?

Yes. Clear aligners are one of the most effective and popular methods for closing gaps between teeth. They work by applying gentle, controlled pressure through a series of custom-made transparent trays that gradually move your teeth into their target positions.

Each set of aligners is designed using advanced 3D scanning technology, allowing your treating dentist to map every millimetre of movement before treatment begins. For diastema closure specifically, the aligners guide the teeth on either side of the gap closer together, step by step, until the space is fully closed.

Clear aligners are particularly well-suited to gap closure because:

• The movements required are typically straightforward — bodily translation (sliding teeth together) rather than complex rotations
• Gaps are often accompanied by otherwise well-aligned teeth, making the case simpler overall
• The gradual, incremental forces allow for controlled closure without overstressing the teeth or surrounding bone

Which types of gaps can aligners treat?

Not all gaps are the same, and different types respond differently to aligner treatment. Here's a breakdown:

Assess your gap

Use this interactive tool to get a general idea of what your gap treatment might look like. Select the option that best describes your gap:

How long does it take to close gap teeth with aligners?

Treatment timelines vary depending on the size of the gap, the number of teeth involved, and how closely you follow your aligner wear schedule:

Consistent wear is critical. Clear aligners work best when worn 20 to 22 hours per day, removing them only to eat, drink (anything other than water), and brush your teeth. For more on keeping your treatment on track, read our guide on the do's and don'ts of wearing clear aligners.

Clear aligners vs other gap-closing treatments

Clear aligners aren't the only option for treating diastema. Here's how they compare:

For most UK adults with gap teeth who also want to improve their overall alignment, clear aligners offer the best balance of effectiveness, comfort, and discretion. For a broader comparison, see our guide to the best teeth straightening options for UK adults.

Your treatment journey with Smileie

Here's what the process looks like from start to finish:

For more on managing any discomfort during treatment, see our guide to managing aligner discomfort.

Keeping your gap closed: retention matters

Closing a gap is one thing. Keeping it closed is another. Research consistently shows that diastema closure is one of the orthodontic results most prone to relapse — particularly midline gaps. Studies have found relapse rates of around 49–60% in cases where proper retention wasn't maintained.

This is why retainers are essential after treatment. Smileie includes two sets of retainers with every treatment package. Your options typically include:

• Removable retainers — Clear trays worn at night to hold your teeth in position. The most common post-aligner option.
• Fixed retainers — A thin wire bonded to the back of your front teeth (invisible from the front) providing permanent retention.

Why dentist-led treatment matters for gap teeth

Not all gaps are as simple as they look. A gap between the front teeth might be straightforward spacing — or it could be a sign of gum disease, a frenum issue, a missing tooth, or even a supernumerary (extra) tooth hidden in the bone. Only a proper clinical examination can determine the underlying cause and the safest treatment approach.

This is where Smileie's model stands apart. Every treatment plan involves:

• A GDC-registered dentist assessing your teeth in person — not just remotely reviewing photos
• A full 3D intraoral scan to precisely measure the gap and plan movements
• Clinical oversight throughout treatment — your dentist monitors progress and adjusts the plan if needed
• Free refinement aligners if the gap doesn't close perfectly with the initial set

For gap closure — where the cause of the gap matters and retention planning is critical — having a real dentist involved from start to finish makes a measurable difference. Visit Smileie's results page to see what real patients are achieving.