How Many Aligners for Invisalign?

How Many Aligners for Invisalign
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When considering Invisalign treatment, one of the most common questions is just how many clear aligner trays will be needed to straighten your smile. The total number of Invisalign aligners varies based on factors like the severity of your case and how closely you follow recommendations. 

This article will provide an in-depth look at all aspects related to Invisalign aligner numbers. We’ll start by reviewing how the Invisalign system works and its advantages over braces. Next, we’ll cover the ideal timeline for changing trays, typical aligner counts for mild to complex cases, and what elements can extend your total treatment time. With information on average aligner quantities and guidance on shortening your treatment, you’ll have a clearer picture of what to anticipate with your Invisalign journey.

How Invisalign Works

Invisalign is a popular orthodontic treatment that uses clear aligners to gradually shift and straighten teeth. The process begins with a consultation, where the patient’s teeth are examined and a custom treatment plan is developed. Digital 3D images of the patient’s teeth are created and used to map out the movement of teeth over time.

Patients receive a series of custom-made aligners, each set slightly different to gradually move teeth into their desired positions. Aligners should be worn for 20-22 hours per day, removing them only to eat, drink, brush, and floss. Every 1-2 weeks, the patient switches to the next set of aligners, continuing the gentle movement of the teeth.

Invisalign treatment duration varies depending on the individual’s needs, but most cases are completed within 12-18 months. Regular checkups with the orthodontist are required to monitor progress and make any necessary adjustments. After treatment, patients typically need to wear retainers to maintain the new position of their teeth.

Advantages of Invisalign Aligners

Invisalign aligners offer several benefits over traditional braces:

  • Improved Self-confidence: Many patients appreciate the discreet appearance of Invisalign and feel more confident in social or professional situations compared to wearing traditional braces.
  • Removable: Invisalign aligners can be removed for eating, drinking, brushing, and flossing, leading to better oral hygiene compared to traditional braces which can trap food and be difficult to clean.
  • Comfort: With no metal brackets or wires, Invisalign often results in less mouth irritation. 
  • Predictable Treatment: The Invisalign process involves computerized planning, allowing both the orthodontist and the patient to see the expected progression and final result before starting treatment.
  • Fewer Office Visits: Compared to traditional braces, which may require frequent tightening, Invisalign patients often have fewer office visits since they’re provided with multiple sets of trays to switch out at home.
  • No Dietary Restrictions: Since aligners are removed when eating, there aren’t the same dietary restrictions as with traditional braces. 

How Often the Trays Should Be Changed

We’re familiar with Invisalign’s mechanics and benefits. Now, let’s discuss the recommended frequency for changing the aligners.

The timing for changing your Invisalign trays is tailored to your unique treatment plan, guided by your dentist or orthodontist’s advice. Most patients switch their trays every one to two weeks, provided they wear them for 20 to 22 hours each day. With the latest advancements in Invisalign technology, options like AcceleDent Aura are available, potentially shortening the interval between aligner changes to a mere 5 to 7 days.

What Factors Affect the Number of Trays

Dentists use a step-by-step process to determine the number of Invisalign trays necessary for each patient. First, they take a 3-D digital scan of the patient’s teeth. Using Invisalign technology, dentists then plan precise tooth movements and create a 3-D model illustrating these movements. Several factors can influence the number of trays required for Invisalign treatment:

  • Severity of Misalignment: Patients with severe crowding, spacing, or bite issues generally need more trays compared to those with minor adjustments.
  • Treatment Goals: More comprehensive goals, such as moving molars, can require more trays.
  • Patient Compliance: Invisalign works best when worn 20-22 hours a day. Inconsistent wear can affect progress and potentially increase the number of trays needed.
  • Age: Adult teeth, being more settled, might require a different number of trays compared to teens whose mouths are still developing.
  • Orthodontist’s Expertise: The experience and skills of the treating orthodontist play a role in the treatment planning and, subsequently, the number of trays prescribed.
  • Refinements: Sometimes, after the initial set of trays, additional trays (refinements) are required to achieve the desired results.

See also: Candid vs Invisalign

How Many Aligners for Invisalign?

Now that we have covered the factors that impact the number of Invisalign trays required, let’s examine what the average number of aligners is for mild, moderate, and severe cases.

Mild Cases

These are cases that involve relatively minor adjustments. Typically, for issues such as minimal crowding, slight overbites, or minor spacing problems, a patient might require around 5 to 7 trays

According to Pan Orthodontics, in mild cases, Invisalign treatment usually occurs within a shorter time frame, averaging around 6 months. 

Moderate Cases

These represent a middle ground in terms of orthodontic needs. Moderate cases often involve noticeable crowding, moderate spacing issues, or bite discrepancies that aren’t extremely severe but still require attention. In these situations, patients might need between 14 to 26 trays for optimal results. The treatment period for moderate cases can often last between 12 to 18 months.

Severe Cases

Severe cases entail complex dental issues that demand comprehensive intervention. This can be significant crowding where teeth overlap considerably, large gaps between teeth, pronounced overbites or underbites, or other major bite anomalies. For these rigorous cases, the number of trays required can go beyond 30, sometimes reaching up to 50 or even more. Understandably, the treatment time for such cases can take up to 24 months or even longer.

See also our review of Invisalign.

ProductExpress 5ExpressGoLiteModerateComprehensiveFirst ComprehensiveFirst Comprehensive Phase 2
Patient typeAdults  and TeensAdults and TeensAdults and TeensAdults and TeensAdults and TeensAdults and TeensChildrenChildren
MalocclusionVery mild to mildVery mild to mildMild to moderateMild to moderateMild to moderateModerate to severe
Maximum number of trays57201420UnlimitedUnlimitedUnlimited

Factors That Can Extend Treatment Time

There are a few factors that may increase treatment time:

  • Patient Compliance: One of the most common reasons for extended treatment is not wearing aligners for the recommended 20-22 hours each day. Inconsistent wear can halt or slow the progress of teeth movement.
  • Complexity of Dental Issue: The initial condition of the teeth matters. Severe crowding, substantial gaps, deep overbites, or other pronounced bite discrepancies may require a longer duration of aligner therapy than straightforward cases.
  • Individual Biological Response: Each individual’s mouth responds differently to treatment. Some people’s teeth naturally move slower than others, even with diligent aligner wear.
  • Unforeseen Situations: Accidents happen. Losing an aligner, damaging it, or experiencing other unexpected dental issues can introduce significant delays in the treatment timeline.
  • Regular Check-ups: Regular visits to the orthodontist ensure that the treatment is on track. Missing or delaying these appointments can result in an extended treatment time because issues might go unaddressed.
  • Adjustments to Treatment Plan: Occasionally, the initial treatment plan might not produce the desired results. When this happens, adjustments may be required, leading to the introduction of additional aligners or procedures.
  • Use of Auxiliary Appliances: In some cases, supplementary orthodontic tools like buttons or elastics might be necessary, and these can sometimes extend the treatment duration.
  • Oral Health Issues: Unaddressed dental problems like cavities, gum disease, or other oral health conditions can delay Invisalign treatment as these issues typically need to be resolved before or during orthodontic procedures.

Frequently Asked Questions

How often are Invisalign trays changed?

Invisalign trays are typically changed every 1-2 weeks, depending on the individual treatment plan prescribed by a dental professional. Patients must wear their aligners for 20-22 hours a day to achieve desired results.

What is the duration of 12 Invisalign trays?

Considering each tray is worn for about 1-2 weeks, the duration of 12 Invisalign trays would typically take 12-24 weeks or approximately 3-6 months to complete the treatment.

What is the average number of Invisalign aligners?

The average number of Invisalign aligners varies depending on the complexity of the case. Generally, a treatment plan may include 20-30 trays; however, some treatments may require fewer or more aligners.

How long does it take to complete 20 Invisalign trays?

To complete 20 Invisalign trays, it generally takes around 20-40 weeks or 5-10 months. Patients are advised to wear each tray for 1-2 weeks as recommended by their dental professional.

How does Invisalign compare to SmileDirectClub?

Invisalign and SmileDirectClub both utilize clear aligners to correct teeth alignment. However, Invisalign is overseen by a dental professional with periodic in-person visits, while SmileDirectClub primarily involves remote consultations and monitoring by licensed dental professionals.

What can be expected from Invisalign before and after?

Prior to starting Invisalign, a dental professional creates a customized treatment plan that includes a 3D digital scan of the teeth. During the treatment, patients move through a series of custom aligners that gradually shift teeth into the desired position. After treatment, most patients achieve a straighter, more aesthetically pleasing smile and may need to wear a retainer to maintain results.


Alajmi S., Shaban A, Al-Azemi R. Comparison of short-term oral impacts experienced by patients treated with Invisalign or conventional fixed orthodontic appliances. Medical Principles and Practice. 2019. Available online at:

Tamer, I. et al. Orthodontic Treatment with Clear Aligners and The Scientific Reality Behind Their Marketing: A Literature Review. Turkish Journal of Orthodontics. 2019. doi: 10.5152/TurkJOrthod.2019.18083. Available online at:

Khosravi R, et al. Management of overbite with the Invisalign appliance. Am J Orthod Dentofacial Orthop 2017;151:691e699.e2. Available online at:

Olsen, J., Comparison of Patient Factors Influencing the Selection of an Orthodontist, General Dentist, or Direct-To-Consumer Aligners for Orthodontic Treatment. Virginia Commonwealth University. (2019). Available online at:

Jaber, S. T., Hajeer, M. Y., Sultan, K., Treatment Effectiveness of Clear Aligners in Correcting Complicated and Severe Malocclusion Cases Compared to Fixed Orthodontic Appliances: A Systematic Review, Cureus. 2023 Apr; 15(4): e38311. DOI: 10.7759/cureus.38311. Available online at:

Iza Wojnarowski

Content contributor

Iza is a dedicated content contributor for Toothific. Having worn braces twice and currently using Invisalign to correct a mild overbite, Iza brings a unique perspective to her writing. She spends her time staying updated on the latest dental trends and treatments, ensuring her readers have the most current information for their dental care needs.

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