Can clear aligners move every tooth? What Invisalign does well — and where it reaches its limits

No — and that is the useful answer, not the disappointing one. Clear aligners (Aligner) move teeth reliably in some directions and with difficulty in others, and the difference is a matter of physics rather than brand. Tipping a tooth, closing a gap, levelling mild to moderate crowding and rounding out a narrow arch are what the method does best. Rotating a round tooth such as a canine or a premolar, moving a root bodily through bone, pulling a tooth down into the arch, and closing the large gap left by an extraction are all considerably harder, and some of them are done better with fixed braces (feste Zahnspange) or with fixed braces used for part of the treatment. And there is one boundary no plastic tray can cross: aligners move teeth, they do not reposition jaws. Knowing which side of that line your case sits on is the entire point of a proper diagnosis.

A tooth is not cemented into the jaw. It sits in a socket, suspended by a thin ligament, and the bone around it is living tissue that is constantly being broken down and rebuilt. Apply a light, sustained force and the bone gives way on the side under pressure and fills in behind — the tooth migrates through the jaw. This is the same biology that fixed braces use; the aligner is simply a different way of applying the force.

Each tray is manufactured a fraction of a step ahead of where your teeth currently are. When you put it in, it does not fit passively — it presses. That pressure is the treatment. It also explains two things patients often find counter-intuitive: that a tray which feels tight is working as intended, and that a tray which slips on and off effortlessly from day one may not be doing much at all.

Two consequences follow, and they shape everything below.

Force has to be aimed. Smooth plastic gripping a smooth, rounded tooth can push it over easily but struggles to twist it or to move it sideways without tipping. Where the geometry works against the material, the movement is hard.

Force has to be present. The tray only works while it is in your mouth. As a rule aligners are worn around 20 to 22 hours a day, out only for meals and cleaning. Wear them for twelve hours a day and you have not halved the speed — you have largely stopped the process, because teeth begin to settle back between wearing periods.

These are the movements where the method is at its strongest, and where most everyday cases live.

Tipping teeth into line. Tilting a crown into position is the movement plastic delivers most naturally. Mild to moderate crowding of the front teeth is the classic aligner indication for exactly this reason.

Closing gaps between front teeth. Spacing responds well and often visibly early, which is why gaps are the change patients notice first.

Widening a narrow arch — within limits. Where teeth have tipped inwards and the arch has become V-shaped, aligners can push them outward into a rounder form. This creates space without removing anything. What it cannot do in an adult is widen the bone — dental expansion has a ceiling set by the jaw and by the gum covering the roots.

Levelling small height differences. Front teeth that sit slightly higher or lower than their neighbours can usually be evened out.

Correcting a mild relapse after childhood braces. Teeth that have drifted back over a decade or two are one of the most common and most straightforward reasons adults come in, because the underlying architecture was already corrected once.

Minor rotations of flat-sided teeth. Incisors have edges and corners for a tray to grip. Turning them a few degrees is manageable.

This is the section most product pages skip. None of it means “impossible” — it means longer, more technical, more dependent on additional tools, and in some cases better done another way.

Large rotations of round teeth. Canines and premolars are close to cylindrical in cross-section. A smooth tray has almost nothing to grip on a cylinder, so twisting one severely rotated tooth back into place can be harder than aligning six others. This is the single most common reason a treatment needs attachments, extra trays or a refinement stage.

Bodily movement — shifting the whole root, not just the crown. Pushing the top of a tooth sideways is easy; carrying the root along with it so the tooth stays upright is not. Where a plan requires several millimetres of true translation, difficulty rises steeply.

Root torque. Fine control over the angle of the root inside the bone — crucial when upper front teeth are tipped too far forward or back — is one of the areas where fixed braces retain a real technical advantage, because a wire engaged in a bracket slot can twist a root in a way a tray cannot easily reproduce.

Extrusion — pulling a tooth down into the arch. A tray works by pressing. Pulling is the opposite instruction, and plastic is poorly suited to it. A tooth that sits too high is a known challenge and usually needs bonded attachments, sometimes elastics, occasionally brackets.

Intrusion — pushing a tooth up into the bone. Better handled than extrusion, but still slow and demanding, and relevant in deep bites where front teeth overlap heavily.

Closing extraction gaps. Where a premolar has been removed to create space, the surrounding teeth must travel a long way, bodily, without tipping into the gap. This is demanding orthodontics by any method and a well-recognised limit of aligner-only treatment.

Severely tilted molars. A molar that has drifted and tipped into an old gap — common after a tooth was lost years ago and never replaced — needs uprighting, another movement that plastic finds awkward.

Modern aligner treatment is rarely trays alone. Three additions do most of the work of widening what is possible, and it is worth knowing what they are before someone attaches them to your teeth.

Attachments. Small tooth-coloured composite bumps bonded to specific teeth, shaped so the tray has something to push against. They are what makes rotation, extrusion and bodily movement feasible at all. They are removed at the end and leave the tooth intact. Patients are sometimes surprised by them because they make the trays slightly more visible up close — which is a fair thing to ask about at the planning stage rather than on fitting day.

IPR — interproximal reduction. A very thin layer of enamel is polished from between certain teeth to create space, typically a fraction of a millimetre per contact. Done properly and within accepted limits, it is a routine and long-established orthodontic technique, and it is often what allows crowding to be resolved without extracting anything. It should always be explained and quantified in advance.

Elastics. Small rubber bands hooked between the upper and lower arches, used to shift the bite relationship. They add a dimension trays cannot supply on their own — and they depend entirely on you actually wearing them.

The honest summary: with attachments, IPR and elastics, aligner treatment reaches considerably further than the trays alone would suggest. It still does not reach everywhere.

This is the distinction that decides more cases than any other, and almost nobody arrives knowing it.

A dental problem means the teeth are badly positioned within jaws of essentially normal size and relationship. Crowding, gaps, rotations, tipped teeth — these are exactly what tooth movement is for.

A skeletal problem means the jaws themselves sit in the wrong relationship: a lower jaw noticeably set back, one set noticeably forward (an underbite), a marked open bite where the front teeth do not meet at all. The teeth may be perfectly arranged within each jaw and still meet badly, because the foundations are offset.

Aligners move teeth. They can camouflage a mild skeletal discrepancy by tilting teeth to compensate, and for many adults that is a perfectly reasonable, deliberate compromise. Beyond a certain degree, camouflage stops being harmless: teeth get pushed out of the bone that supports them, gums recede, and the result becomes unstable. The right conversation at that point involves orthodontics combined with jaw surgery, or a clearly acknowledged partial improvement — and the decision belongs to you, once the trade-off has been named out loud.

In growing children, some skeletal relationships can genuinely be influenced by guiding growth, which is why the timing of orthodontic assessment matters so much for children and hardly at all for adults. There is more on underbite and overbite specifically in Correcting an underbite: causes, treatment and why the diagnosis decides everything.

Beyond the movement itself, the rest of your dentition sets constraints.

Implants do not move. A dental implant (Implantat) is fused to the bone. It can be a fixed point in the plan or an obstacle to it, but it will not be repositioned. Crowns and bridges on implants therefore have to be worked around, and occasionally remade after alignment.

Crowns, veneers and large fillings. A tooth can be moved perfectly well with a crown (Krone) on it, but attachments bond less reliably to ceramic than to enamel, which sometimes changes where the plan can place them. Veneers and old composite restorations may also look wrong once the tooth has moved and need renewing afterwards — a cost worth anticipating rather than discovering.

Gum disease. Teeth are moved through bone, so the bone has to be healthy. Active periodontitis (Parodontitis) must be treated and stabilised before orthodontics begins, without exception. Where bone has already been lost, movement is still often possible but must be planned with lighter forces and closer monitoring.

Untreated decay and inflammation. Caries and root problems are dealt with first. Sealing a tooth under a tray for a year is not a plan.

Missing teeth and old gaps. A long-standing gap changes how neighbouring teeth have drifted and often needs to be coordinated with the plan for replacing the tooth. Orthodontics is sometimes used precisely to open a gap to the right width for an implant.

There is a false choice in most of the online discussion: aligners or brackets. In practice, one of the most sensible plans for a difficult case is both.

A short phase of fixed braces — sometimes on just a few teeth, sometimes only in one arch — handles the movement that plastic finds hardest: the severely rotated canine, the tipped molar, the root that needs torquing. The trays then take over for the rest, which is usually the visible majority of the treatment. Patients who had assumed brackets were an all-or-nothing commitment are often surprised at how short and how localised that phase can be.

Anyone who tells you aligners can do absolutely everything is selling. Anyone who tells you they can barely do anything has not looked at the field for ten years. The truthful position sits in between, and it is specific to your mouth.

The comparison in full is here: Clear aligners or fixed braces? An honest comparison.

Pain and pressure in more detail: Do braces hurt? Pressure, pain and what really helps in the first days.

Teenagers. Aligners work in adolescents, with the added requirement of consistent wear at exactly the age when consistency is hardest. Where a case in an under-18 is severe enough to qualify for statutory support, the cover is assessed through the KIG grading system and applies to standard care, which is fixed braces rather than aligners — the mechanics are set out in What clear aligners cost in Wuppertal.

Adults with a full dental history. Crowns, bridges, implants, old root treatments and previous gum treatment all belong in the planning conversation. They rarely rule out treatment; they routinely change it.

If your German is limited. This is a treatment built on explanation — which movements are planned, why an attachment goes on that tooth, what a refinement means. Trying to follow that in a second language is a genuine handicap. Aligner patients travel to us in Wuppertal from Düsseldorf, Cologne and Bonn, and from further across Germany, partly for exactly this reason: the whole plan can be discussed in English. See also English-Speaking Dentist in NRW.