Scissor Bite: What It Is and Whether Clear Aligners Can Correct It

Most people who have heard of a crossbite picture the common version — an upper tooth sitting inside a lower one, on the tongue side, rather than overlapping it as it should. A scissor bite is the opposite problem, and it is considerably less common.

In a scissor bite, the upper back tooth sits entirely outside the lower one. The two teeth do not meet at all. They pass one another like the blades of a pair of scissors, which is where the name comes from. When it affects an entire segment of the arch, it is sometimes called a Brodie bite.

It is an easy thing to overlook, because it happens at the back of the mouth where it is not visible in the smile. Patients often have no idea it is there until it is pointed out.

Normal posterior occlusion depends on the upper and lower teeth interdigitating — the cusps of one sitting into the grooves of the other, like a well-fitting lid. That arrangement distributes the forces of chewing along the long axis of each tooth, which is the direction teeth and their supporting bone are built to withstand.

In a scissor bite, that interdigitation is lost entirely. The upper tooth's inner surface may contact the lower tooth's outer surface, or the two may miss each other completely and simply pass by. Either way, there is no functional chewing contact at that point in the arch.

The discrepancy can involve a single tooth, several teeth, or an entire posterior segment. It may be on one side only or on both. The upper arch may be too wide, the lower arch too narrow, or — commonly — a bit of each.

There are several routes to a scissor bite.

Skeletal discrepancy. The most fundamental cause is a mismatch in the width of the upper and lower jaws themselves. If the maxilla is broad relative to the mandible, the teeth follow the bone and end up in a scissor relationship. This is largely developmental and, in adults, cannot be altered by moving teeth alone.

Dental tipping. Sometimes the jaws are reasonably proportioned but the teeth are tipped — the uppers leaning outwards towards the cheek, the lowers leaning inwards towards the tongue. This is a dental problem rather than a skeletal one and is far more amenable to orthodontic correction.

Drift after tooth loss. Losing a tooth and leaving the space unrestored allows neighbouring teeth to tip into the gap, sometimes producing a scissor relationship where none existed before. Our article on whether to fix one tooth or plan for future tooth loss discusses why this drift matters.

Impacted or ectopically erupting teeth. A tooth that erupts in the wrong direction, or that is displaced by an impacted neighbour, can end up outside the arch entirely. Wisdom teeth are frequently involved in scissor bites affecting the very back of the mouth, and our wisdom teeth page covers their assessment.

Habits during development. Prolonged thumb sucking, mouth breathing and abnormal tongue posture can influence arch width in a developing child. Early identification through children's dentistry appointments makes intervention considerably simpler than waiting until adulthood.

A scissor bite is not merely a curiosity of tooth arrangement. It has consequences.

Reduced chewing efficiency. Teeth that never meet do no chewing. The work is transferred to the remaining contacting teeth, which then take a disproportionate share of the load. Over years, this shows up as accelerated wear on those teeth.

Soft tissue trauma. Because the upper tooth sits outside the lower arch, its outer surface is closer to the cheek than it should be, and its inner surface may be exposed. Patients with scissor bites frequently report repeatedly biting the cheek on the affected side.

Cleaning difficulty. The unusual relationship creates areas that are awkward to brush and floss effectively. Plaque accumulates, and gum inflammation follows. If you notice bleeding gums when brushing consistently in one particular area, unusual tooth position may be part of the reason.

Jaw joint and muscle effects. Where the scissor bite is unilateral, the jaw may adopt a shifted closing path to find a comfortable position. Over time, an asymmetric closing pattern can contribute to muscle fatigue and joint discomfort. Our TMJ treatment page covers how jaw joint symptoms are assessed. Our article on whether aligners can address a functional shift explores this in more detail.

Over-eruption. Teeth without an opposing contact continue to erupt slowly. A scissor bite left untreated can lead to progressive vertical drift of the unopposed teeth, which complicates any later attempt at correction.

Correcting a scissor bite requires moving the upper teeth inwards, the lower teeth outwards, or both — and doing so bodily, not just tipping the crowns, if the correction is to be stable.

Clear aligners can perform these movements. The plastic shell delivers force across the whole crown, and with well-designed attachments it can achieve a degree of bodily movement rather than pure tipping. There are also two features of aligners that are genuinely useful in scissor bite cases.

The first is that aligners cover the biting surfaces. In a scissor bite, the teeth are locked in their positions by the way they pass one another — the upper tooth cannot move inwards because the lower tooth is in the way. The thickness of the aligner material separates the arches slightly, unlocking the bite and allowing the teeth to move past one another. This effect can be enhanced by designing bite ramps or blocks into the aligners.

The second is precision. The amount of transverse movement required can be planned and staged in small increments, which is important because expanding the lower arch outwards has to be done cautiously to avoid pushing roots through the thin bone on the cheek side.

Our clear aligner treatment page explains how these plans are constructed and monitored. In many scissor bite cases, elastics used alongside aligners are essential — cross-elastics running from the inside of the upper tooth to the outside of the lower tooth apply the transverse force that aligners alone struggle to generate.

It would be misleading to suggest that all scissor bites can be corrected with aligners.

Skeletal cases. If the underlying cause is a genuine width mismatch between the jaws, moving teeth can only compensate so far. Pushing upper teeth inwards and lower teeth outwards to camouflage a skeletal discrepancy risks tipping them out of their supporting bone, producing recession and instability. In adults with significant skeletal discrepancy, surgical options may need to be discussed.

Severity. A complete Brodie bite affecting an entire segment, where the teeth pass one another by a large margin, is among the more difficult problems in orthodontics. Aligner treatment alone may not generate the necessary force.

Bone limits. The buccal bone on the outside of lower molars is thin. There is a real limit to how far lower teeth can be moved outwards before root surface is pushed beyond the bone, which leads to recession. This is a hard biological constraint, not a matter of technique.

Anchorage demands. Correcting a scissor bite means pushing two groups of teeth in opposite directions. Without adequate anchorage, both groups move partway and neither ends up where it should. Temporary anchorage devices — small bone screws — are sometimes used to provide a fixed point.

Long-standing cases with drift. Where over-eruption has occurred, correction becomes a multi-stage problem: the vertical drift may need addressing before the transverse correction can be completed.

Where aligners are not suitable, other routes exist.

Fixed appliances with auxiliaries. Conventional braces combined with transpalatal arches, lingual arches or skeletal anchorage can generate the controlled transverse force that a scissor bite demands.

Orthognathic surgery. For genuinely skeletal discrepancies in adults, surgical repositioning of the jaws combined with orthodontics is the route that addresses the actual cause rather than compensating for it.

Restorative camouflage. In selected cases — a single tooth, mild discrepancy, patient not wishing to undergo orthodontics — reshaping or crowning the teeth to create some functional contact can improve chewing without moving anything.

Extraction. Where a single badly positioned tooth, often a wisdom tooth or a heavily compromised molar, is the entire problem, removing it may be the most proportionate answer.

Monitoring. Not every scissor bite requires treatment. If it is stable, the patient is comfortable, cleaning is manageable and there is no progressive wear, regular review at dental check-ups may be entirely appropriate.

Can a scissor bite get worse over time?

It can. The main mechanism is over-eruption of teeth that have no opposing contact, which gradually increases the vertical discrepancy and can make later correction more complex. Tooth loss elsewhere in the arch can also allow further drift. This is why a scissor bite that is being monitored rather than treated should genuinely be monitored, with periodic records to compare against, rather than simply noted once and forgotten.

Will correcting a scissor bite change my face?

Correcting a dental scissor bite by moving teeth generally has little effect on facial appearance, because the movements are at the back of the mouth. Where a scissor bite is associated with a unilateral functional shift of the jaw, correction may improve facial symmetry when the jaw settles into a more centred closing position. Substantial facial change is usually only associated with surgical correction of skeletal discrepancies.

Is a scissor bite the same as a crossbite?

They are related but opposite. In a posterior crossbite, the upper tooth sits inside the lower one. In a scissor bite, the upper tooth sits entirely outside the lower one. Both represent a transverse discrepancy between the arches, and both can affect chewing and jaw function. Our article on posterior crossbite and aligners covers the more common variant.

Does a scissor bite cause headaches?

The relationship between bite discrepancies and headache is complex and often overstated. Some patients with an asymmetric bite develop muscle fatigue from an altered closing pattern, and that can contribute to headache. Many others have significant bite discrepancies and no symptoms at all. Headache has many causes, and attributing it to the bite without proper assessment risks missing something else. If you have persistent headaches, they warrant medical assessment as well as dental.

How long does aligner treatment take for a scissor bite?

Transverse corrections generally take longer than simple alignment because the movements are more demanding and must be staged carefully. Treatment for a mild single-tooth scissor bite may be relatively short; a segmental Brodie bite is a substantially longer undertaking, and refinement stages are common. Your specific plan should give an estimate based on the amount of movement required.

Can a scissor bite be corrected in a child more easily than an adult?

Generally, yes. In a growing child, arch width can be influenced in ways that are no longer possible once growth is complete, and appliances that widen the upper jaw work with the developing bone rather than against it. This is one of the clearer arguments for regular dental attendance during childhood, so that transverse discrepancies are identified while intervention is simpler.

If a scissor bite has been identified, or you have noticed that some of your back teeth do not seem to meet, an assessment will establish whether the cause is dental or skeletal — because that distinction largely determines what treatment can realistically achieve.

That assessment typically involves clinical examination, digital scans, photographs and radiographs, and possibly a jaw joint assessment where a shift is suspected.

You can contact our team to arrange a consultation at our Wimpole Street practice. Our teeth straightening pages set out the options available, and pricing explains how treatment fees are structured.

This article provides general information and does not constitute individual dental advice. Suitability for clear aligner treatment and the outcomes achievable in any individual case depend on factors including the skeletal relationship, bone support, gum health and the severity of the discrepancy, and can only be determined following clinical examination and appropriate records. Orthodontic treatment carries risks including gum recession, root shortening, relapse and discomfort, which will be discussed with you before treatment. Wimpole Dental is regulated by the Care Quality Commission, and our clinicians are registered with the General Dental Council.

Next review due: 11 September 2027