Spacing Between Teeth: What Causes Gaps and How Orthodontics Can Help

A gap between the teeth — whether a single wide space between the two upper front teeth or multiple smaller spaces distributed across the arch — is one of the most common reasons people seek orthodontic assessment. For some it is a lifelong feature; for others it appears over time. Some gaps are purely cosmetic; others have clinical implications. Whatever the cause or scale, spacing between teeth is one of the most straightforwardly treatable orthodontic problems, and the range of options available in the UK means it can be addressed discreetly and efficiently in most cases.

This guide explains what causes gaps in teeth, when they matter clinically versus cosmetically, which orthodontic treatments can close them, and what you need to know before starting treatment.

What Causes Gaps Between Teeth?

The clinical term for a gap between teeth is a diastema (plural: diastemas or diastemata). A midline diastema refers specifically to a gap between the two upper front teeth — the most commonly noticed and most frequently treated type of spacing. But gaps can occur between any teeth in the arch, and for different reasons:

Tooth-to-jaw size discrepancy

The most common underlying cause of spacing is a mismatch between tooth size and jaw size. If the teeth are naturally small relative to the available space in the jaw, gaps form naturally across the arch. This is a genetic variation — neither a disease nor a problem in the mechanical sense — and the teeth themselves are healthy. The spaces simply reflect an arch that has more room than the teeth require.

Missing teeth

When a tooth is missing — whether congenitally absent (never formed) or lost through decay, trauma, or extraction — the surrounding teeth tend to drift into the available space over time. This drift can create or worsen gaps in adjacent areas as the dental arch reorganises around the missing tooth. In the UK, congenitally missing teeth (most commonly upper lateral incisors and lower second premolars) affect around 5% to 7% of the population and are a common driver of combined orthodontic and restorative treatment planning.

Oversized labial frenum

The labial frenum is the small band of tissue that connects the inside of the upper lip to the gum above the upper front teeth. In some people, this frenum is particularly thick or extends down between the two upper central incisors, physically preventing them from meeting. This is a common cause of a midline diastema in children — and in some cases the frenum self-corrects as the adult teeth erupt and the canines push the front teeth together. Where it does not self-correct, a minor surgical procedure called a frenectomy may be recommended, usually followed by orthodontic treatment to close the remaining gap.

Gum disease and bone loss

Periodontitis (gum disease that has affected the underlying bone) can cause teeth to become mobile and drift apart, creating gaps that were not previously present. In adults who notice new gaps appearing — particularly accompanied by bleeding gums, loose teeth, or gum recession — gum disease should be investigated and treated before any orthodontic treatment begins. Orthodontic tooth movement through periodontally compromised bone carries additional risks and requires specialist assessment.

Habits

Prolonged thumb sucking, tongue thrusting, or lip sucking can exert forces on the front teeth that push them apart over time. These habit-related gaps can often be improved by stopping the habit — particularly in children — and may resolve without formal orthodontic treatment if addressed early enough.

Does a Gap Between Teeth Need to Be Treated?

Not all spacing requires treatment. Whether to treat depends on the clinical picture and the patient's priorities:

How Is Spacing Between Teeth Treated?

Treatment depends on the cause, the number of gaps, and whether there are associated problems like missing teeth or bite issues.

Clear aligners

Simple to moderate spacing — particularly where the cause is tooth-size to jaw-size discrepancy and no teeth are missing — is one of the most predictable and well-suited cases for clear aligner treatment. Closing spaces is mechanically simpler for aligners than rotating or moving crowded teeth, and cases with only spacing (no bite correction required) often complete faster than crowding cases of equivalent severity. A series of clear trays gradually moves the teeth together to close the gaps, with no dietary restrictions and minimal visibility during treatment.

Fixed braces

Fixed braces — whether metal or ceramic — are equally effective at closing gaps and offer the advantage of working continuously without compliance requirements. They are particularly useful where spacing is combined with bite issues or where more complex tooth movements are needed alongside gap closure. For spacing distributed across the full arch, fixed braces may be more efficient than aligners for complete closure in a single treatment phase.

Orthodontics combined with restorative dentistry

Where spacing is caused by missing teeth, closing the gap orthodontically may not always be the right approach. Sometimes the better solution is to use orthodontics to optimise the space and position the adjacent teeth correctly, then fill the gap with a dental implant, bridge, or other restoration. This combined approach requires coordination between the orthodontist and a restorative dentist or prosthodontist, and the treatment plan should be agreed between all clinicians before orthodontics begins.

Frenectomy

Where a prominent labial frenum is preventing the upper front teeth from closing together, a frenectomy (a minor surgical procedure to reduce or reposition the frenum) may be recommended. This is typically done before or during orthodontic treatment, and the gap is then closed with braces or aligners after the frenum is no longer obstructing.

Will the Gap Come Back After Treatment?

Closed spaces have a tendency to reopen if teeth are not retained properly after treatment — this is why retainers are essential after any orthodontic treatment that closes gaps. A fixed retainer bonded to the back of the front teeth is particularly effective at preventing a midline diastema from reopening. If the cause of the gap (such as a tongue thrust habit or active gum disease) has not been fully resolved, the risk of recurrence is higher. Discussing the retention plan in detail with your orthodontist before starting treatment is an important part of planning for a lasting result. The fixed vs removable retainer guide explains your retention options in detail.