Clear Aligners in General Practice: Case Selection, Evidence and Working With a Lab

A patient who finished braces as a teenager is back with a drifted lower incisor. Another wants the upper anteriors straightened before veneers. Clear aligners look like a natural fit for both. The hard part is telling which cases will track and which will end in extra refinements, a switch to braces or a late referral.

Below: what reviews and trials up to 2026 say about accuracy, case selection, aligners versus braces, attachments, IPR, refinements, wear time and retention, and what to send your lab.

Quick Answer

Clear aligners suit general practice best for mild crowding or spacing, mild relapse after braces and small pre-restorative movements, where randomized trials show results similar to braces. Aligners achieve about half of each planned movement on average, and rotation of round teeth, extrusion, intrusion and extraction space closure are least reliable. Refer skeletal, extraction, severe rotation and periodontally compromised cases, plan for refinements, and send full-arch scans, a bite, photos and written goals.

How Accurate Are Aligners, Movement by Movement?

Accuracy studies superimpose the software's planned end position on a scan of the finished teeth; percentages are the share of planned movement achieved.

Tipping

Buccolingual crown tip was the most accurate movement in the 2020 study (56%). Mesiodistal tipping is weaker: 26.9% for mandibular canines in the 2009 study.

Bodily movement

A 2015 systematic review found upper molar distalization 88% predictable when a bodily movement of at least 1.5 mm was prescribed; a 2025 review put upper molar predictability at 61.1% for movements of 0.45 to 3.2 mm. In 79 patients treated by expert operators, angular movements (tip and torque) and rotation of round teeth lost about 0.4° per 1° prescribed. In premolar extraction cases, a 2026 meta-analysis found excessive mesial tipping of maxillary first molars (6.08°) and incisor under-retraction (1.93 mm).

Rotation

A 2021 meta-analysis found maxillary canines reached 47.9% of planned rotation, against 70.7% for mandibular incisors. In the 2020 study, distal rotation of maxillary canines reached 37% and mesial rotation of mandibular first molars 28%; in the 2009 study, maxillary canine accuracy fell significantly beyond 15°.

Extrusion and intrusion

Extrusion was the least accurate movement in the 2009 study (29.6%), and only 18.3% for maxillary central incisors. Attachment design helps: in a 2023 randomized trial on maxillary lateral incisors, horizontal attachments achieved an estimated 76% of the planned extrusion, against 62% with optimized attachments. Mandibular incisor intrusion reached 35% in the 2020 study, and a 2025 review reported 35% to 65% predictability for lower incisor intrusion.

Expansion

A 2026 systematic review of 23 studies found 75.5% average predictability for transverse expansion in the maxilla and 80.6% in the mandible, expressed mainly as buccal crown tipping. The certainty of evidence was very low.

Which Cases Suit a General Dentist?

In a 2017 survey, 38.3% of general dentists provided clear aligners. In another survey, general dentists were more confident than orthodontists about treating deep bite, severe crowding and Class II malocclusion with aligners, cases that lean on intrusion, distalization or extractions. An overview of 18 systematic reviews found aligners effective for mild to moderate malocclusion but inferior in severe cases.

Good fits for general practice

• Mild crowding or spacing in a Class I occlusion, solved mainly by tipping and modest IPR.
• Mild relapse after braces, typically lower incisor irregularity.
• Pre-restorative alignment or space redistribution before crowns, veneers or an implant.

No published index sets a cut-off for general practice, so this list is our reading of the evidence: these cases rely on the movements aligners express best.

Cases to refer or co-manage

• Skeletal discrepancies.
• Premolar extractions: fixed appliances gave better treatment quality in extraction cases in a 2025 meta-analysis of 15 trials.
• Severe rotations of canines and premolars, especially beyond about 15°.
• Large extrusions and deep bites needing substantial intrusion.
• Periodontal compromise: the European Federation of Periodontology's stage IV guideline places tooth movement after active periodontal therapy, and a 2026 review stresses periodontist and orthodontist coordination.

A published difficulty tool

The Clear Aligner Treatment Complexity Assessment Tool (CAT-CAT) scores casts, cephalometric values (ANB, U1-SN, SN-MP) and findings such as periodontitis and TMD, weighting what aligners do poorly: an overbite over 9 mm adds 10 points. It matched expert ratings closely (R² = 0.80) but was built on 120 patients from one hospital and sets no referral threshold.

How Do Aligners Compare With Braces?

Occlusal outcome and treatment time

A 2020 meta-analysis of 11 studies and 887 patients found worse ABO Objective Grading System scores with aligners (mean difference 9.9 points) and more unacceptable results (relative risk 1.6). A 2025 systematic review of 21 randomized trials found no significant difference in ABO-OGS, PAR or Little's Index in simple non-extraction cases; a 2025 meta-analysis of 15 trials found fixed appliances better in extraction cases. Treatment time: one meta-analysis found aligners 6.31 months shorter, the 2020 one no significant difference.

Root resorption, pain and gums

A 2025 meta-analysis of 10 studies found 0.26 to 0.64 mm less apical root resorption with aligners at every incisor type except mandibular laterals. Pain was lower with aligners only on days 3 and 4 in a 2023 meta-analysis, and a 2026 meta-analysis found lower plaque and gingival indices and probing depths 0.33 mm shallower.

On stability, an overview of systematic reviews found more relapse after aligners, while the 2025 meta-analysis of 15 trials found limited evidence of similar stability. Plan retention from the start.

What Do Attachments, IPR, Refinements and Wear Time Change?

Attachments

A 2022 systematic review found that attachments mostly improve anterior root torque, rotation, mesiodistal movement and posterior anchorage. Type mattered less: a 2025 meta-analysis found no significant difference between optimized and conventional attachments for canine derotation or anterior extrusion, although the 2023 trial favored horizontal attachments for extrusion. And in the 79-patient study, 87% of maxillary canines had an attachment, yet a median planned rotation of 11° lost 4.7°.

Interproximal reduction

In 40 patients, the enamel removed was on average 0.55 mm less than planned in the upper arch and 0.82 mm less in the lower (accuracy 44.95% and 37.02%), differences the authors judged may not be clinically relevant. A 2022 systematic review found no increase in caries, periodontal change or sensitivity after IPR, on low to very low quality evidence.

Refinements

Among 324 non-extraction patients of 11 experienced orthodontists, 99.4% needed a refinement phase and received almost double the aligners of the initial plan. In the 500-patient study, treatment averaged 22.8 months, 5.1 months longer than estimated. Tell patients at consent that refinements are normal.

Wear time

The conventional protocol is 22 hours a day. In a 2025 randomized trial of 50 adults with very mild crowding, 12 hours a day aligned the maxilla adequately but corrected mandibular irregularity significantly less.

Which Retainer, and How Often?

The 2023 Cochrane review (47 studies, 4,377 participants) covers retention after braces, excluded aligner studies and rated its evidence low to very low certainty. Key findings, with two other sources:

• Removable vs fixed: in one trial, part-time lower clear plastic retainers allowed 0.92 mm more irregularity than multistrand fixed retainers, below the reviewers' 1 mm threshold, and failed less often.
• Clear plastic vs Hawley: similar stability (difference 0.01 mm); Hawley retainers failed less often (risk ratio 0.60) but were less comfortable.
• Part-time vs full-time: no difference for Hawley retainers (0.20 mm); a review of three trials found full-time vacuum-formed retainer wear no better than part-time.
• Minimum wear: in 42 patients with sensor-equipped thermoplastic retainers, a mean under 9 hours a day did not keep mandibular irregularity within acceptable limits.

Most Cochrane studies measured outcomes before one year, so no trial says when retention can stop. Choose the retainer and schedule before treatment starts.

What Should You Send the Lab?

An aligner can only be as accurate as the model it is made on. A systematic review found measurements from intraoral scans reliable and accurate compared with conventional impressions. Send:

• Full-arch scans of both arches, including the distal of the last molars and gingiva beyond the margins. In a 2024 systematic review, straight, extended trimlines delivered more force and retention than scalloped or shorter ones, and a trimline can only extend onto scanned tissue.
• A bite scan in maximum intercuspation.
• Photos: smile, retracted anterior and both buccal views.
• Goals and limits: which teeth to move, which to hold, and whether the aim is full correction or pre-restorative alignment.
• IPR and attachment preferences, including restored teeth you will not strip or bond.
• A retention plan: retainer type and wear schedule.

Export steps by scanner: How to Send a Scan to a Dental Lab. Not scanning yet? See Is an Intraoral Scanner Worth It?, and TRIOS vs iTero for aligner-system compatibility.

Clear Aligners at Elegant Dental Laboratory

• Full-service dental lab making clear aligners and orthodontic appliances, including night guards, anti-snoring devices and bleaching trays.
• Every case is made in house, with no outsourcing, by more than 35 technicians in our 7,000 sq. ft. facility at 2308 McDonald Ave, Brooklyn, NY.
• Digital scans are reviewed before production. Submit a digital case or send a case: our own drivers pick up in the New York area (call to confirm availability), and UPS shipping labels work for practices anywhere. Call 877-335-5221.

Related Guides

• Digital vs. Conventional Impressions in 2026: Accuracy, Fit and When Each Wins
• TRIOS 3 vs. TRIOS 6: Which 3Shape Scanner Fits Your Practice?
• How to Choose a Dental Lab: 7 Questions to Ask Before You Send a Case

FAQ

Should a general dentist offer clear aligners?

For mild crowding, spacing, mild relapse and pre-restorative alignment, yes: randomized trials find aligners and braces alike in simple non-extraction cases. Refer the rest.

How many hours a day should patients wear aligners?

The conventional protocol is 22 hours; in a randomized trial, 12 hours corrected lower crowding significantly less.

How many refinements should I expect?

Plan for at least one. In a 500-patient study the average was 2.5 refinement scans, and only 6.0% of patients needed none.

Are aligners easier on the gums than braces?

Meta-analyses find lower plaque and gingival indices with aligners; pain is lower only in the first days.

Which retainer should follow aligner treatment?

The evidence is low certainty and comes from braces patients. Clear plastic and Hawley retainers gave similar stability; sensor data point to at least 9 hours a day for thermoplastic retainers.

Reviewed by Gary Fingerman, founder and CEO of Elegant Dental Laboratory, Brooklyn, New York (founded 2007). Last reviewed: September 28, 2026. Study values are from published research; case selection and treatment decisions remain with the treating dentist.