Clear Aligners vs Braces: Do They Work as Well?

Reviewed 31 August 2026. Everything below is tied to a named study: five systematic reviews (one of them an overview of eighteen), two meta-analyses, a randomised trial of discomfort, a 2,644-patient compliance study, and payer documents with their effective dates. Written for two readers at once — the person comparing quotes, and the clinician who wants the numbers. Not medical advice.

The short answers

Clear aligners and fixed braces both work for mild-to-moderate crowding in adults who don’t need extractions. That is the one sentence the reviews agree on.
They are not equally good at every tooth movement. Measured accuracy: about 59% of planned movement achieved overall, 42% for incisor torque, roughly 40% for premolar derotation, and about 87–88% for upper molar distalization when at least 1.5 mm of bodily movement was prescribed. Extrusion is the documented weak spot at around 30% accuracy.
Treatment time is not “faster for everyone”. One meta-analysis found aligners finished on average about 6.3 days sooner (WMD −6.31, 95% CI −8.37 to −4.24) — a result that is statistically significant and clinically almost irrelevant, and it came from eight mostly non-randomised studies.
Relapse is the under-discussed finding. In an overview of 18 systematic reviews, relapse was greater with aligner treatment than with fixed appliances, while periodontal outcomes were better and the trend in root resorption favoured aligners.
Compliance is the treatment. In a cohort of 2,644 aligner patients measured against a ≥22 hours/day threshold, only 36.0% were fully compliant, 38.3% fairly compliant, and 25.7% poorly compliant.
Cost is mostly a coding and contract question. Adult orthodontics is billed as D8090 (comprehensive) or D8080 (adolescent), is frequently excluded as “cosmetic”, and in Utah Medicaid orthodontia requires prior authorisation with a scored necessity form (the state’s IOTN sheet, which replaced the older Salzmann index) and is limited to once per lifetime.

How an aligner actually moves a tooth

An aligner is a thin thermoformed or printed shell that fits over the whole arch. It delivers force by presenting the tooth with a shape it does not yet match, so the tooth is pushed toward the plastic. Two consequences follow, and they explain almost every finding in this article.

First, the plastic has to grip. A smooth shell on a smooth tooth slips, so treatment plans add composite bumps (attachments), sometimes ridges, elastics and hooks, and interproximal reduction (IPR) to create space. Each of those is a dependency: an attachment that debonds, an elastic the patient doesn’t wear, a contact point that never closes. Second, the shell only delivers what it was milled or printed to deliver. If a planned movement needs a force system the geometry cannot generate — a root moving bodily, an incisor extruding, a molar uprighting — the software can still show the endpoint, and the tooth can still refuse to go there. That gap between “planned” and “achieved” is exactly what the accuracy studies measure.

Materials and manufacturing are the fastest-moving part of this field: a 2023 review of aligner polymers in Bioactive Materials (%citeBichu%) tracks the elastomer and shape-memory research, and a 2024 open-access review in Polymers (%citeNarongdej%) covers direct 3D printing of aligners in the office, which shortens the lab chain and changes the cost structure of refinements. Both are relevant to your quote: “printed here” and “sent away to a factory” are not the same workflow, and a workflow that makes refinements cheap tends to produce more of them.

Predictability: the numbers behind “just as good as braces”

The most-used table in this debate comes from a systematic review in the Angle Journal of Clinical Orthodontics (Rossini et al., 2015; %citeRossini%), which pooled 11 studies (2 randomised, 5 prospective non-randomised, 4 retrospective; six at moderate risk of bias, the rest unclear). Its measured results, quoted as reported:

mean intrusion achieved: 0.72 mm;
extrusion was the hardest movement to control, at about 30% accuracy, with rotation next;
upper molar distalization was the most predictable, around 88% — when at least 1.5 mm of bodily movement had been prescribed;
arch alignment measured by Little’s Index improved by roughly 5 mm in the mandibular arch and 4 mm in the maxillary arch.

The authors’ conclusion is the sentence to hold on to: aligners align and level the arches, control anterior intrusion and posterior buccolingual inclination, and distalize upper molars — but they do not reliably produce anterior extrusion or anterior buccolingual control.

A laser-scan study of single movements in 30 patients (BMC Oral Health, 2014; %citeSimon%) gives the same picture in a different currency. Overall mean efficacy 59% (SD 0.2); incisor torque 42% (SD 0.2); premolar derotation the worst, roughly 40% (SD 0.3); upper molar distalization the best, about 87% (SD 0.2). Auxiliaries (attachments, power ridges) and staging were analysed as modifiers — and this is why a plan with fewer, better-chosen movements often finishes more predictably than an ambitious one.

A third review (Progress in Orthodontics, 2018; %citePapadimitriou%) included 3 RCTs plus 19 non-randomised studies, found the overall level of evidence moderate, and stated plainly that heterogeneity and the absence of standardised protocols precluded a valid pooled interpretation. Its synthesis: aligners are a viable alternative for mild-to-moderate malocclusions in non-growing patients who do not require extractions; they can predictably level, tip and derotate (with cuspids and premolars excluded); and they show limited efficacy for arch expansion by bodily movement and for extraction-space closure.

What “low to moderate certainty” actually means here

A dedicated review of effectiveness (Orthodontics and Craniofacial Research, 2020; %citeRobertson%) found only seven eligible studies — one RCT and six retrospective cohorts — rated six at moderate risk of bias and one at high, and graded the certainty for tooth-movement efficiency as low to moderate. Its sentence is the antidote to both hype and dismissal: aligners may produce clinically acceptable outcomes comparable to fixed appliances for buccolingual inclination of upper and lower incisors in mild-to-moderate cases, but “most of the tooth movements may not be predictable enough to be accomplished with only one set of trays.”

Read that last clause twice. The literature does not primarily say “aligners don’t work”. It says a single series of trays is not a reliable way to deliver every movement, and that finishing normally depends on re-impression and further aligners — refinements. Refinements are the mechanism by which aligner treatment reaches equivalence, and they are also where time, fees and expectations quietly go.

Head-to-head: what the comparison studies found

A systematic review comparing the two modalities (BMC Oral Health, 2019; %citeKe%) pooled 8 comparative papers (2 RCTs, 6 cohort studies). Findings as reported:

aligners may not be as effective as braces in producing adequate occlusal contacts, controlling torque, increasing transverse width, and in retention;
final treatment quality scores were not significantly different (Objective Grading System, WMD 8.38, 95% CI −0.17 to 16.93, P = 0.05);
treatment duration was significantly shorter with aligners (WMD −6.31, 95% CI −8.37 to −4.24);
and both approaches were effective for malocclusion overall.

Note what that confidence interval does. On quality, the interval crosses zero — the honest reading is “no demonstrated difference, in a small and mostly non-randomised evidence base”. On duration, a significant difference of about six days in a treatment measured in hundreds of days is real but should not be the reason you choose a modality.

Severe and extraction cases

Because marketing shows mild crowding, the severe-case question matters most when your own plan includes extractions. A systematic review of complex and severe malocclusions treated with aligners versus fixed appliances (Cureus, 2023; %citeJaber%) identified six trials (3 RCTs, 2 retrospective cohorts, 1 controlled clinical trial; 283 patients — 186 female, 97 male). Three studies found no difference when finished results were scored with the ABO Objective Grading System or the PAR index; two found differences between predicted and achieved tooth movements with aligners. Small, mixed-quality, and split down the middle — which is a fair summary of what is currently known, and an argument for asking your orthodontist what they measure in your case type.

The overview of reviews

The broadest source is an umbrella overview (Clinical Oral Investigations, 2022; %citeYassir%), which screened 361 reviews and kept 18 of moderate or high quality. Its summary of aligner treatment: effective for mild-to-moderate malocclusions; inferior outcomes in severe cases and for specific movements; conflicting results on duration with a possible advantage in mild-to-moderate cases; greater relapse; better periodontal outcomes; a trend toward less root resorption; unclear pain results but better comfort and less impact on eating and chewing. The authors add that the overall level of evidence is moderate and that high-quality randomised trials are still needed.

A narrower meta-analysis of aligner efficiency measured by PAR, ABO indices and ClinCheck-to-model similarity (Cureus, 2023; %citeShrivastava%) illustrates the evidence-size problem rather than resolving it: after screening 61 reports, six studies with 166 participants could be pooled. It concluded aligners performed successfully with an efficiency advantage in mild-to-moderate cases, while flagging insufficient evidence of efficacy across multiple cross-sectional comparisons.

Evidence at a glance

Study (year, journal)	What it covered	Result as reported	Why it is limited
Rossini 2015, Angle Orthod	11 studies (2 RCT); control of tooth movement	Intrusion mean 0.72 mm; extrusion accuracy ≈30%; upper molar distalization ≈88% with ≥1.5 mm prescribed; Little’s Index −5 mm lower, −4 mm upper	Six of eleven at moderate RoB, rest unclear; movement-specific pooling only
Simon 2014, BMC Oral Health	30 patients, split-mouth, laser scans vs ClinCheck	Overall efficacy 59% (SD 0.2); torque 42%; premolar derotation ≈40%; distalization ≈87%	Single centre, small n, one system
Papadimitriou 2018, Prog Orthod	3 RCT + 8 prospective + 11 retrospective	Viable for mild–moderate, non-growing, non-extraction; expansion by bodily movement and space closure limited	Heterogeneity precluded pooled estimates
Robertson 2020, Orthod Craniofac Res	7 studies (1 RCT)	Low-to-moderate certainty; comparable for incisor buccolingual inclination; “most movements may not be predictable with one set of trays”	Mostly retrospective cohorts
Ke 2019, BMC Oral Health	8 comparative studies	OGS WMD 8.38 (95% CI −0.17–16.93; P=0.05); duration WMD −6.31 (−8.37 to −4.24); weaker on contacts, torque, transverse width, retention	6 of 8 non-randomised; CI touches zero
Yassir 2022, Clin Oral Investig	Overview of 18 systematic reviews (361 screened)	Mild–moderate effective; severe inferior; relapse greater; periodontal better; resorption trend lower; comfort better	Narrative synthesis; moderate evidence level overall
Correa 2025, Orthod Craniofac Res	Anterior open bite in adults; 14 studies, 12 meta-analysed	Correction MD 2.76 mm (95% CI 2.23–3.28) via incisor extrusion (0.85 and 0.86 mm); no molar intrusion; no mandibular plane change	13 of 14 at moderate RoB
Timm 2021, J Clin Med	2,644 patients, wear time ≥22 h classification	36.0% fully compliant; 38.3% fair; 25.7% poor; males more compliant (p = 0.000014)	Single commercial provider, retrospective, self-reported app data

A worked example: anterior open bite

Open bite is a good case study because the numbers are specific and because they show how “it worked” and “it may not hold” can both be true. A systematic review and meta-analysis of clear aligner therapy for anterior open bite in adults (Orthodontics and Craniofacial Research, 2025; %citeCorrea%) searched without time or language limits to August 2024, kept 14 studies for qualitative assessment and 12 for pooling, and found significant bite closure: mean difference 2.76 mm (95% CI 2.23–3.28). The mechanism was visible in the cephalometric data: maxillary incisor extrusion MD 0.85 mm (95% CI 0.43–1.26) and mandibular incisor extrusion MD 0.86 mm (95% CI 0.29–1.44), with no significant molar intrusion and no change in the mandibular plane angle.

Two things follow. First, aligners closed this bite by lengthening the front teeth, not by seating the back teeth — the authors’ own numbers say so, and they rated the confidence high for that specific outcome. Second, extrusion-driven change is the kind of result that has to be read together with the review finding that relapse was greater with aligners (%citeYassir%). The honest conclusion is not “aligners can’t fix an open bite” but “they can improve it, by a route that needs a retention plan and realistic expectations, and if your open bite is skeletal, this is the wrong tool”.

Comfort, pain and your mouth

Comfort is the strongest and best-supported argument for aligners, and it is worth reading with the numbers rather than the anecdotes. A blinded randomised trial of 41 adult Class I non-extraction patients (Angle Orthod, 2017; %citeWhite%) had participants keep daily discomfort diaries after the initial appointment, at one month and at two months. Initial discomfort was similar between groups; patients with fixed appliances reported greater discomfort and used more analgesics; there were no significant sex differences. The authors also note the trial was not registered — a transparency detail worth knowing when you cite it.

A larger comparative study using visual analogue scales (Progress in Orthodontics, 2014; %citeFujiyama%) followed 145 cases (55 edgewise, 38 aligner, 52 combined) across the first three stages of treatment. Pain was significantly higher in the fixed-appliance group on days 3–4 of stage 1, days 1–3 of stage 2 and days 2–3 of stage 3, and overall differences were significant for pain intensity, number of painful days and discomfort. It also catalogued the causes of aligner-side problems: unsmoothed marginal ridges or missing material, deformed attachments, deformed trays. That list is the practical truth of aligner care — the device creates its own irritation sources, and they are fixable at a visit.

Roots, gums and hygiene

Root resorption is the fear that keeps orthodontists cautious. A systematic review of force systems and resorption (AJODO, 2015; %citeRoscoe%) retrieved 259 articles and kept 21 (samples of 10 to 73 patients), concluding that increased force levels and longer treatment time were positively associated with resorption, and that a pause in movement appears beneficial because resorbed cementum gets time to heal. The review’s criticism of the field is worth remembering when you see any “safe” claim: absence of control groups, unclear patient selection and missing pre/post examinations. The 2022 overview found the resorption trend favouring aligners rather than against them (%citeYassir%), but a trend from an overview is not a guarantee — and long roots, prior trauma or thin bone are questions for your own records, not for the literature.

The periodontal finding is more useful: aligners were associated with better periodontal outcomes in the same overview. Removable trays allow brushing and flossing and, importantly, they can be taken out before a meal — which changes plaque behaviour entirely. The trade-off is that the same removability puts the whole burden on you, and 20 hours of non-wear per day is a different treatment than the one that was planned.

Compliance is not a footnote; it is the treatment

A retrospective cohort of 2,644 aligner patients (75.0% female, ages 18–64, median 27 years), all treated through one provider and finishing in 2019, classified wear against a ≥22 hours/day threshold (%citeTimm%):

953 patients (36.0%) fully compliant;
1,012 (38.3%) fairly compliant;
679 (25.7%) poorly compliant.

Males were significantly more compliant than females (p = 0.000014), and patients without previous orthodontic treatment were more compliant than those who had it before (p = 0.023). Age and pre-treatment satisfaction with one’s smile were not meaningfully associated. A quarter of patients wearing their trays poorly is the most actionable number on this page: it is why a plan that fails at month four is usually a compliance problem rather than a material problem, and it is why recommending aligners to a teenager without a way to verify wear is a defensible-but-risky decision. Some practices now check wear with monitoring apps or photogrammetry; a 2020 qualitative study of a remote-monitoring aligner programme (Progress in Orthodontics, 2020; %citeDM%) is one of the better-documented attempts at exactly this problem.

At-home and mail-order aligners

Direct-to-consumer orthodontics is where the “aligners are simple” framing was taken to its end point, and the evidence base is thin in a revealing way. A literature review titled after that problem (Turkish Journal of Orthodontics, 2019; %citeTamer%) examines the gap between the marketing scope of aligner systems and what has actually been shown, including stability and side effects. Two dental-journal content analyses of provider websites (Australian Dental Journal, 2020, %citeReadability%; 2021, %citeDTCsites%) assess the readability and completeness of the treatment information given online — including limits on what a patient can know about supervision and monitoring before starting. A survey of users’ experiences published in JADA in 2020 (%citeDTCusers%) reports the patient side of the same arrangement.

Then the market itself produced the most persuasive cautionary evidence. SmileDirectClub filed for Chapter 11 in September 2023 and shut down global operations in early December 2023, with reported debt near $900 million; unshipped orders were cancelled, its “Lifetime Smile Guarantee” ceased to exist, customer-care support stopped, and customers were told to find a local dentist — while those on instalment plans were expected to keep paying (company statements as reported by Retail Dive, 11 December 2023; ADA News, December 2023). The ADA’s president at the time described the outcome as “patient abandonment” and warned that direct-to-consumer dentistry risks “irreversible harm to individuals, who are treated as ‘customers’ rather than patients”.

The lesson is not about one company’s balance sheet. Aligner treatment is a supervision-dependent process: refinement decisions, attachment placement, root and bone limits, and the moment to stop and refer are the treatment. A model that removes the in-person clinician from the loop removes the part the trials actually studied.

Money: the codes, the exclusion, the questions

Orthodontic billing runs through a handful of CDT codes, and knowing them converts a vague conversation into a checkable one. D8090 is comprehensive orthodontic treatment of the adult dentition — appliance type is not what the code describes, so a full aligner course for an adult is billed under it; D8080 is the adolescent/limited counterpart used while growth remains; D8670 covers periodic orthodontic treatment visits during active therapy; D8999 is the unspecified catch-all used when something (a retainer repair, an extra refinement phase) does not fit the standard codes.

The exclusion is written into plan documents, not hidden. A representative payer guideline states that when clear aligners, cosmetic or specialised brackets are elected by the patient for cosmetic purposes, the added laboratory cost is not a covered benefit and the dentist must explain that those charges are patient-responsibility (HDS procedure code guidelines for orthodontics, revised 1 January 2023). Typical adult plans either exclude orthodontics entirely or pay a fixed percentage of a lifetime maximum — and the distinction between “comprehensive” and “limited” treatment matters, because it decides whether a short aligner course burns the whole lifetime benefit. The American Association of Orthodontists’ own notes on the 2022 CDT changes spell out what counts as limited treatment: cases not involving the entire dentition, not addressing the full scope of the problem, or where comprehensive treatment was deferred.

For Utah specifically, two documents matter. Utah Medicaid’s orthodontia policy requires prior authorisation, limits treatment to once per lifetime, and defines non-covered services to include “orthodontic services for cosmetic or aesthetic reasons”, limited and removable-appliance therapy, re-banding/multistage treatment and TMJ treatment; it requires pre-treatment models, photographs and panoramic radiographs with the PA form. The medical-necessity instrument changed: the state replaced the older Salzmann Handicapping Malocclusion Assessment Record (which used a score of 30 or more, and — note this — counted a rotated tooth only at 30 degrees or more of rotation) with its own Index of Orthodontic Treatment Need sheet, under which approval follows either one “automatic qualifying condition” or two or more “other qualifying conditions” (Utah Medicaid IOTN form and instructions, versions dated 2025). Age windows for covered dentition run from 10 up to 14 for transitional, 10 to 21 for adolescent, and 14 to 21 for adult dentition in the published benefit summary; orthodontic retainers are covered once per lifetime at the end of a child’s comprehensive treatment, with lost or broken replacements generally not covered (InsureKidsNow Utah Medicaid dental summary).

There is a neat, slightly ironic connection between that rule and the research above: a 30-degree rotation threshold for medical necessity sits on top of the movement type that aligners achieve least accurately (~40% for premolar derotation, rotation named as the second-worst movement in the 2015 review). Whether that matters for your case is a question for your own records, but it is exactly the sort of thing worth asking about before you assume “aligners will fix it, the state will pay”.

Seven questions that make the number real

Which code will be submitted for the active phase — D8090 or D8080 — and is my case “comprehensive” or “limited” in your documentation?
How many refinement stages are included in the price, and what is the per-stage fee after that?
What is the total quoted chair time and number of monitored visits, and what happens if I miss the retention window?
Is a retainer included, for how long, and what does a replacement cost?
If I want braces instead, what changes in price, in duration and in monitoring?
Is there any medical-necessity documentation you can provide that my plan will accept, and what score does it use?
Who owns my scans and records, and what happens to my treatment if the provider or the printing partner stops?

Two structural notes on price. First, in-office printing and digital workflows (Narongdej 2024) genuinely reduce the cost of an extra stage, which is why the same brand of aligner can differ by a factor of two between offices — you are partly buying a lab supply chain. Second, if cost is the binding constraint, dental-school and resident clinics (in Utah: the University of Utah College of Dentistry and Roseman University) are where orthodontic cases are done under supervision at substantially reduced fees; the trade is scheduling flexibility and longer visits.

Who should choose aligners, who shouldn’t

Fits well: an adult with mild-to-moderate crowding or relapse after previous braces who is not growing, does not need extractions, and can actually wear the trays; a patient whose job or social circumstances make fixed appliances costly in a way that predicts non-completion; a case where oral hygiene is the priority risk (aligners allow brushing); a patient needing limited anterior alignment with clear documentation of that scope.

Fits poorly: growing patients needing skeletal or transverse correction; extraction cases and space closure; movements that need root control, extrusion or derotation of premolars and cuspids; patients whose work makes 22 hours a day unrealistic (night-shift eating, sports, wind); anyone told “one set of trays will do it” for a complex plan; and anyone choosing between at-home aligners and no treatment — the supervision, not the plastic, is what protects the result.

What the evidence does not support

That aligners are “as good as braces for everything”. They are comparable for alignment and levelling in selected cases, and demonstrably weaker for specific movements, with relapse a consistent concern.
That aligners are faster in a way worth paying for. One pooled estimate says about six days, in an evidence base of eight mostly non-randomised studies.
That refinements are optional. “Most tooth movements may not be predictable enough to be accomplished with only one set of trays” is a finding, not a sales technique.
That at-home aligner programs have the same evidence as supervised care. No review in this set supports substituting remote monitoring plus mail for diagnosis, attachment design, and the decision to stop.
That “no pain” equals “no risk”. Root resorption associations in the orthodontic literature track force level and treatment duration, not whether anyone felt it.
Any lifetime-comparison claim. Trials run for months; relapse data is about retention, not about your teeth at 55.

Frequently asked questions

Do clear aligners work as well as braces? For mild-to-moderate crowding in non-growing adults who don’t need extractions, reviews find comparable final quality scores with no statistically significant difference on the grading indices used. For specific movements and for relapse, they are not equivalent.

Are they faster? Sometimes, by days rather than months: pooled difference ≈6.3 days shorter (95% CI 0.4 to 8.4 days) in a 2019 meta-analysis. Reviews call duration results conflicting, and a possible advantage appears only in mild-to-moderate cases.

Do they hurt less? Yes, on the measured outcomes. A randomised trial of 41 adults found similar initial discomfort but greater discomfort and more analgesic use with fixed appliances; a 145-case VAS study found significantly higher pain in the fixed-appliance group at defined early time points.

Can I take them out whenever I want? That is the selling point and the risk in one sentence. The compliance cohort above shows what actually happens: 25.7% of 2,644 patients wore them poorly.

How many hours a day? Protocols in the studies are usually 20–22 hours. Ask your own provider what number their plan assumes, because it changes the timeline more than any material choice.

Will I need refinements? Plan on it. Ask how many are included and what each costs after that, because predictability data for rotations and torque is the reason they exist.

Are attachments and IPR safe? They are routine parts of most plans; the recorded aligner-side problems in the pain study were unsmoothed edges, deformed attachments and deformed trays — i.e. mechanical irritation, fixable at a visit. Attachments need bonding and debonding care, and IPR needs enamel-thickness judgement from your own records.

Do aligners cause gum problems? In the 2022 overview, periodontal outcomes were better with aligners than with fixed appliances — plausibly because you can brush. The reverse risk is different: trays worn over plaque, or worn too few hours, cause their own problems.

What about root resorption? The 2022 overview found a trend favouring aligners; the systematic review of force systems associates resorption with higher force levels and longer active treatment, with methodological weaknesses across the field. Nobody can tell you your roots are safe from a review; that’s a question for radiographs and your own risk factors.

Is one brand better than another? The reviews measure systems in use, not marketing tiers. Ask your provider about staging, refinement policy and monitoring — those vary more by practice than by brand.

Should my 13-year-old get aligners? The evidence base for compliance-heavy treatment in adolescents is the weakest part of this literature. Ask how wear is verified (app, photogrammetry, inspection), what happens after two consecutive poorly-worn stages, and what the fallback to fixed appliances costs.

Are at-home aligners safe? Read as a supervision question rather than a product question: the reviews of the field stress stability and side effects, content analyses of provider websites ask whether patients can even understand what they’re buying, and in December 2023 the largest at-home provider shut down mid-treatment with its guarantee voided. If you choose a remote model, ask specifically who reviews your progress, how often, and what happens when movement stalls.

Does insurance cover them? Adult orthodontics is commonly excluded or capped, and where a plan pays, “cosmetic” selection usually means the extra lab fee for a clear-appliance system is the patient’s responsibility. Ask what code will be submitted and whether your case is documented as comprehensive or limited.

Does Medicaid pay in Utah? Yes, with conditions: prior authorisation required, once per lifetime, cosmetic/aesthetic treatment explicitly not covered, and medical necessity judged on the state’s IOTN sheet (automatic qualifying condition or two other conditions) after records, photos and panoramic films are submitted. Children’s coverage runs to age limits by dentition type; ask for the current form version, since the state changed instruments in 2025.

What about relapse? The overview found greater relapse with aligner treatment. Practically: the retainer phase is part of the treatment and not an accessory — ask what’s included, for how long, and what a replacement costs.

Glossary: patient words ↔ clinical words

“will it finish as well?” ↔ final outcome indices: PAR, ABO Objective Grading System (OGS), GOAC/APAO (AO). Different indices are not interchangeable, and a “no difference” finding on one index is not a general guarantee.
“will the tooth actually go where the plan says?” ↔ accuracy/predictability — declared vs achieved movement; in the literature often expressed as a percentage of planned movement.
“the 3D preview” ↔ ClinCheck or equivalent treatment plan; a simulation of intent, not a contract of outcome.
“the bumps on my teeth” ↔ attachments; composite features that give the plastic something to push against.
“shaving between the teeth” ↔ interproximal reduction (IPR).
“extra round of trays” ↔ refinement; re-impression and new series, and the usual route to equivalence.
“how much did the roots shorten?” ↔ external apical root resorption (EARR), assessed radiographically.
“will it move back?” ↔ relapse and retention protocol; the weakest point of aligner evidence.
“how sure is the research?” ↔ certainty of evidence (GRADE: high/moderate/low/very low) plus risk-of-bias ratings; most aligner literature sits at low-to-moderate.
“what does the difference mean in millimetres?” ↔ WMD/MD with a 95% confidence interval; if the interval crosses zero, nothing was shown.

How to read this field like a clinician

Three habits will outlast any headline. Check the comparator: “aligners are 59% accurate” is a statement about planned-versus-achieved movement in one system with 30 patients, not about braces. Check the index: PAR and OGS disagree about what “good” is, and a review’s conclusion can be an artefact of which one it accepted. Check the pooling: the 2018 Invisalign review said outright that heterogeneity and non-standard protocols precluded a valid pooled estimate, and the 2023 efficiency meta-analysis was built on 166 participants.

And check what a consent form should contain in this field: planned tooth movements with the difficult ones named, the expected number of refinements, the staining/attachment/IPR discussion, the wear-time requirement and what happens if it is missed, the retention plan, and the criteria for stopping and referring out. A practice that treats aligners as a product rather than a supervised mechanical process is not following what the reviews support.

How this page was built, and what it cannot tell you

Sources were selected from the top of the evidence hierarchy downward: an overview of 18 systematic reviews, four further systematic reviews including two that performed meta-analysis, one randomised trial of discomfort with VAS-based comparison, one large retrospective compliance cohort, and payer/regulatory documents for the coverage and coding sections. Bibliographic details — authors, journal, volume, issue, pages, DOI, PMID — were pulled programmatically from Europe PMC for each item below and checked there rather than reconstructed; each is linked to its DOI where one exists. Regulatory and payer statements are cited with their documents and dates (HDS guidelines revised 2023; Utah Medicaid orthodontia policy and IOTN forms dated 2025; InsureKidsNow Utah dental benefit summary; company closure reporting from December 2023).

What it cannot tell you: whether your specific movements are achievable in trays (that is a records question — roots, bone, prior orthodontics, crowding), what your plan will approve, how much a local office will actually charge after refinements, and what your retention will look like at ten years. It can tell you that the field’s evidence base is moderate at best for the marketing’s strongest claims — and that the questions above are the ones that change the outcome.

This article summarises published research for information only. It is not medical or dental advice and does not replace an examination and records review by an orthodontist. Seek prompt assessment for loose teeth, unexplained mobility, pain that persists between aligner changes, or swelling.

Sources

Peer-reviewed evidence

Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL. Efficacy of clear aligners in controlling orthodontic tooth movement: a systematic review. Angle Orthod 2015-09-01;85(5):881-889. doi:10.2319/061614-436.1 · PMID 25412265 · PMCID PMC8610387 · cited by 507 (Europe PMC)
Simon M, Keilig L, Schwarze J, Jung BA, Bourauel C. Treatment outcome and efficacy of an aligner technique–regarding incisor torque, premolar derotation and molar distalization. BMC Oral Health 2014-06-01;14():68. doi:10.1186/1472-6831-14-68 · PMID 24923279 · PMCID PMC4068978 · open access · cited by 266 (Europe PMC)
Papadimitriou A, Mousoulea S, Gkantidis N, Kloukos D. Clinical effectiveness of Invisalign® orthodontic treatment: a systematic review. Prog Orthod 2018-09-01;19(1):37. doi:10.1186/s40510-018-0235-z · PMID 30264270 · PMCID PMC6160377 · open access · cited by 230 (Europe PMC)
Robertson L, Kaur H, Fagundes NCF, Romanyk D, Major P, Flores Mir C. Effectiveness of clear aligner therapy for orthodontic treatment: A systematic review. Orthod Craniofac Res 2020-05-01;23(2):133-142. doi:10.1111/ocr.12353 · PMID 31651082 · cited by 202 (Europe PMC)
Ke Y, Zhu Y, Zhu M. A comparison of treatment effectiveness between clear aligner and fixed appliance therapies. BMC Oral Health 2019-01-01;19(1):24. doi:10.1186/s12903-018-0695-z · PMID 30674307 · PMCID PMC6343314 · open access · cited by 192 (Europe PMC)
Jaber ST, Hajeer MY, Sultan K. Treatment Effectiveness of Clear Aligners in Correcting Complicated and Severe Malocclusion Cases Compared to Fixed Orthodontic Appliances: A Systematic Review. Cureus 2023-04-01;15(4):e38311. doi:10.7759/cureus.38311 · PMID 37128600 · PMCID PMC10148732 · open access · cited by 40 (Europe PMC)
Yassir YA, Nabbat SA, McIntyre GT, Bearn DR. Clinical effectiveness of clear aligner treatment compared to fixed appliance treatment: an overview of systematic reviews. Clin Oral Investig 2022-03-01;26(3):2353-2370. doi:10.1007/s00784-021-04361-1 · PMID 34993617 · cited by 104 (Europe PMC)
Shrivastava A, Mohanty P, Dash BP, Jena S, Sahoo N. Proficiency of Clear Aligner Therapy: A Systematic Review and Meta-Analysis. Cureus 2023-09-01;15(9):e45072. doi:10.7759/cureus.45072 · PMID 37842499 · PMCID PMC10568240 · open access · cited by 8 (Europe PMC)
Correa E, Michelogiannakis D, Barmak AB, Rossouw PE, Javed F. Efficacy of Clear Aligner Therapy for the Treatment of Anterior Open Bite in Adults: A Systematic Review and Meta-Analysis. Orthod Craniofac Res 2025-04-01;28(2):261-270. doi:10.1111/ocr.12868 · PMID 39445659 · cited by 4 (Europe PMC)
White DW, Julien KC, Jacob H, Campbell PM, Buschang PH. Discomfort associated with Invisalign and traditional brackets: A randomized, prospective trial. Angle Orthod 2017-11-01;87(6):801-808. doi:10.2319/091416-687.1 · PMID 28753032 · PMCID PMC8317568 · cited by 114 (Europe PMC)
Fujiyama K, Honjo T, Suzuki M, Matsuoka S, Deguchi T. Analysis of pain level in cases treated with Invisalign aligner: comparison with fixed edgewise appliance therapy. Prog Orthod 2014-11-01;15():64. doi:10.1186/s40510-014-0064-7 · PMID 25416143 · PMCID PMC4240829 · open access · cited by 108 (Europe PMC)
Roscoe MG, Meira JB, Cattaneo PM. Association of orthodontic force system and root resorption: A systematic review. Am J Orthod Dentofacial Orthop 2015-05-01;147(5):610-626. doi:10.1016/j.ajodo.2014.12.026 · PMID 25919107 · cited by 179 (Europe PMC)
Timm LH, Farrag G, Baxmann M, Schwendicke F. Factors Influencing Patient Compliance during Clear Aligner Therapy: A Retrospective Cohort Study. J Clin Med 2021-07-01;10(14):3103. doi:10.3390/jcm10143103 · PMID 34300269 · PMCID PMC8303492 · open access · cited by 41 (Europe PMC)
Hansa I, Semaan SJ, Vaid NR. Clinical outcomes and patient perspectives of Dental Monitoring® GoLive® with Invisalign®-a retrospective cohort study. Prog Orthod 2020-06-01;21(1):16. doi:10.1186/s40510-020-00316-6 · PMID 32537723 · PMCID PMC7293972 · open access · cited by 40 (Europe PMC)
Tamer İ, Öztaş E, Marşan G. Orthodontic Treatment with Clear Aligners and The Scientific Reality Behind Their Marketing: A Literature Review. Turk J Orthod 2019-12-01;32(4):241-246. doi:10.5152/turkjorthod.2019.18083 · PMID 32110470 · PMCID PMC7018497 · cited by 92 (Europe PMC)
Meade MJ, Dreyer CW. Web-based information on orthodontic clear aligners: a qualitative and readability assessment. Aust Dent J 2020-09-01;65(3):225-232. doi:10.1111/adj.12776 · PMID 32358804 · cited by 29 (Europe PMC)
Meade MJ, Dreyer CW. An assessment of the treatment information contained within the websites of direct-to-consumer orthodontic aligner providers. Aust Dent J 2021-03-01;66(1):77-84. doi:10.1111/adj.12810 · PMID 33237579 · cited by 23 (Europe PMC)
Wexler A, Nagappan A, Beswerchij A, Choi R. Direct-to-consumer orthodontics: surveying the user experience. J Am Dent Assoc 2020-08-01;151(8):625-636.e4. doi:10.1016/j.adaj.2020.02.025 · PMID 32718492 · PMCID PMC7391059 · cited by 23 (Europe PMC)
Bichu YM, Alwafi A, Liu X, Andrews J, Ludwig B, Bichu AY, Zou B. Advances in orthodontic clear aligner materials. Bioact Mater 2023-04-01;22():384-403. doi:10.1016/j.bioactmat.2022.10.006 · PMID 36311049 · PMCID PMC9588987 · open access · cited by 199 (Europe PMC)
Narongdej P, Hassanpour M, Alterman N, Rawlins-Buchanan F, Barjasteh E. Advancements in Clear Aligner Fabrication: A Comprehensive Review of Direct-3D Printing Technologies. Polymers (Basel) 2024-01-01;16(3):371. doi:10.3390/polym16030371 · PMID 38337260 · PMCID PMC10856925 · open access · cited by 38 (Europe PMC)

Guidelines, coding and payer documents

American Association of Orthodontists. Changes Coming to CDT 2022 (aaoinfo.org) — definitions separating comprehensive from limited orthodontic treatment; note that a code’s presence in the CDT does not imply coverage.
HDS. Procedure Code Guidelines — Orthodontics, revised 01 January 2023 — elective cosmetic choice of clear aligners or specialised brackets: added laboratory charges not covered (PDF).
Utah Medicaid. Dental, Oral Maxillofacial and Orthodontia Services (dhhs.utah.gov manuals) — prior authorisation required; once per lifetime; cosmetic/aesthetic orthodontics non-covered; required records.
Utah Medicaid. Index of Orthodontic Treatment Need (IOTN) form and instructions, 2025 versions (medicaid-documents.dhhs.utah.gov) — replaces the Salzmann record; one automatic or two other qualifying conditions.
InsureKidsNow (CMS). Summary of Benefits Report for Utah, Medicaid — dental — orthodontics with prior authorisation, age windows by dentition type, retainers once per lifetime.
ADA News, December 2023 — ADA dentists can help patients abandoned by SmileDirectClub; Retail Dive, 11 December 2023 — closure, voided guarantee, payment plan terms.

Each bibliographic record (authors, journal, volume, issue, pages, DOI, PMID) was retrieved and verified programmatically from Europe PMC for this page; payer and regulatory statements are cited with their documents and dates and must be checked against the current version before you rely on them.