Palatal Expansion and MARPE: Who Needs It, When to Do It, and What It Really Does for the Airway

Palatal expansion is one of the oldest and most useful tools in orthodontics for correcting a narrow upper jaw, also called transverse maxillary deficiency.

A narrow upper jaw can show up as a posterior crossbite, a high narrow palate, crowding, or a constricted smile. Some patients also have chronic mouth breathing or sleep-disordered breathing.

The principle of expansion is simple: widen the two halves of the upper jaw at the midpalatal suture and allow new bone to form as the expansion stabilizes.

What has changed is how we accomplish this at different ages.

In a growing child, a conventional expander can produce a very predictable skeletal change. In an older teenager or adult, the same appliance may produce more dental tipping and less true skeletal expansion. Miniscrew-assisted rapid palatal expansion, or MARPE, has extended our ability to achieve skeletal expansion later in life, while some skeletally mature adults still require surgically assisted expansion.

But the most important question isn't simply, "Can we expand?"

Who actually needs expansion, and what are we trying to accomplish?

When Can We Get True Skeletal Expansion?

Conventional rapid palatal expanders such as the Hyrax or Haas are generally most predictable in growing children.

As a patient matures, resistance at the midpalatal suture and surrounding maxillary structures increases. The response gradually shifts from predominantly skeletal expansion toward a greater dentoalveolar component, including movement or tipping of the teeth.

But there is no single birthday when the palate suddenly becomes impossible to expand.

Two 14-year-olds may have very different skeletal maturity.

Angelieri and colleagues developed a CBCT-based classification describing five stages of midpalatal suture maturation, from an immature suture at Stage A through progressive interdigitation and fusion at later stages.¹ Their research demonstrated substantial individual variation in suture maturation.

That is why, particularly in adolescents and young adults, skeletal maturity and individual anatomy may be more informative than chronological age alone.

Before choosing an appliance, the question I want to answer is:

Where will my expansion force actually go—to the skeleton, the teeth, or both?

RPE, MARPE, or Surgical Expansion?

I think about these treatments as a continuum rather than rigid age categories.

Conventional Rapid Palatal Expansion

For a growing child with a true transverse maxillary deficiency, conventional rapid palatal expansion remains an extremely effective treatment.

This is one reason I believe an orthodontic evaluation during growth is so valuable. If a significant transverse discrepancy is present, correcting it while the maxillary sutures are more responsive can be much easier than waiting until skeletal resistance increases.

MARPE

MARPE stands for miniscrew-assisted rapid palatal expansion.

Rather than relying primarily on the teeth to transmit expansion forces, MARPE uses temporary skeletal anchorage in the palate to direct more of the expansion force to the maxillary skeleton.

This can be particularly useful in later adolescents and adults.

A systematic review of patients age 16 and older reported an average MARPE success rate of approximately 92.5%, although the authors emphasized that the quality of the available evidence was very low and that most of the included studies were observational.²

That qualification is important.

MARPE is a powerful tool, but it is not guaranteed to work in every adult.

Custom and Computer-Guided MARPE

CBCT and digital planning allow us to evaluate an individual patient's palatal anatomy and customize miniscrew placement.

This can be particularly useful when:

• Palatal bone is thin
• Root proximity is a concern
• The palate is asymmetric
• Greater skeletal engagement is needed
• The patient is borderline for nonsurgical expansion

The goal isn't simply to use more screws.

It is to place the skeletal anchorage where that individual patient's anatomy gives us the best opportunity to achieve the desired skeletal response safely.

Surgically Assisted Expansion

Some skeletally mature maxillae simply will not separate predictably with orthopedic force alone.

For patients with substantial transverse deficiency or significant skeletal resistance, surgically assisted expansion may remain the most predictable option.

MARPE has moved this boundary. Some older patients who previously would have been considered surgical candidates can now potentially achieve nonsurgical skeletal expansion.

But not every adult can—or should—be expanded nonsurgically.

The appliance should follow the diagnosis, not the other way around.

Which Type of Palatal Expansion Is Used at Different Ages?

I think about expansion as a continuum rather than using a strict age cutoff. Age gives us useful information, but skeletal maturity, anatomy, periodontal support, and the amount of transverse deficiency are ultimately more important when choosing an approach.

Important: Age is a guide, not an absolute rule. Two patients of the same age may have very different skeletal maturity. This is particularly important during adolescence, when the midpalatal suture can vary considerably from one patient to another.¹˒¹¹

The patient matters more than the age printed on the chart.

Does Palatal Expansion Really Improve the Airway?

Yes, but this is where we need to be precise.

Anatomically, the relationship makes sense:

The roof of the mouth is also the floor of the nose.

When true skeletal maxillary expansion occurs, the maxillary base and nasal floor widen.

Research has demonstrated increases in nasal dimensions and improvements in measures of nasal airflow following maxillary expansion. However, systematic reviews also caution that the evidence is not strong enough to recommend expansion as a primary treatment for nasal breathing problems in every patient.⁴

The most consistent anatomical changes occur in the nasal cavity and nasopharyngeal region.

Expansion may also provide more room for the tongue to rest in a higher and more favorable position.

But there is a very important distinction:

A larger airway on a CBCT does not automatically mean that obstructive sleep apnea has been cured.

Expansion May Help Breathing, But It Is Not a Universal Treatment for Sleep Apnea

Obstructive sleep apnea is multifactorial.

Airway obstruction may involve:

• Enlarged tonsils or adenoids
• Nasal turbinate hypertrophy
• Septal deviation
• Allergies or chronic nasal inflammation
• Obesity
• Mandibular or maxillary retrusion
• Tongue and soft-tissue anatomy
• Neuromuscular factors
• A combination of several of these

A narrow maxilla may be one important contributor, but it may not be the only one.

Studies in children with obstructive sleep apnea have reported reductions in apnea-hypopnea index, or AHI, following rapid maxillary expansion.⁵⁻⁸

In adults, the evidence continues to evolve. Surgically assisted expansion has been associated with short-term improvements in AHI, although the quality of evidence is limited.⁹ Emerging MARPE research also reports improvements in AHI and nasal and nasopharyngeal dimensions in selected patients with maxillary constriction, but larger and longer-term studies are still needed.¹⁰

I would therefore never tell a patient:

“Your palate is narrow, so expansion will cure your sleep apnea.”

I would say:

“Your upper jaw is narrow. Expansion may improve nasal airflow and may contribute to better breathing, but we need to understand the entire airway before deciding what treatment you need.”

That distinction matters.

Can Orthodontists Diagnose Obstructive Sleep Apnea?

Orthodontists can recognize craniofacial findings and symptoms that warrant screening and referral for sleep-disordered breathing. However, screening is not the same as diagnosing obstructive sleep apnea (OSA). Neither a narrow palate nor an airway measurement on CBCT establishes an OSA diagnosis.

The American Association of Orthodontists’ 2019 White Paper and its 2026 AJODO update clarify the orthodontist’s role in identifying concerns and coordinating appropriate evaluation.¹³˒¹⁴ A definitive OSA diagnosis requires evaluation by an appropriately qualified medical clinician, with sleep testing when indicated.

This is why I discuss possible breathing benefits of expansion separately from diagnosing or treating sleep apnea.

An orthodontic indication for expansion and a medical diagnosis of OSA are two different questions.

Dental Expansion vs. Skeletal Expansion: What's the Difference?

This is one of the most important concepts for patients to understand.

Not all expansion is the same.

Dental Expansion

Dental or dentoalveolar expansion occurs when the teeth move or tip outward.

Imagine a patient who has no crowding.

If I simply tip the posterior teeth outward, I have increased the dental arch perimeter. If I later upright or retract those teeth to eliminate the resulting spacing, much of that increase may disappear.

In that situation, we essentially moved the teeth outward and then moved them back.

That is not the same thing as permanently enlarging the maxillary skeleton.

Skeletal Expansion

True skeletal expansion is different.

When the midpalatal suture separates, the maxillary bony base and nasal floor widen. Bone subsequently remodels within the expanded suture during retention.

The teeth can then be positioned within that broader skeletal foundation.

Some dental relapse can still occur, which is why retention matters.

But the underlying concept is very different.

Increasing intermolar width by tipping teeth is not biologically equivalent to widening the maxillary skeleton.

This distinction is particularly important when we talk about tongue space, nasal airflow, and possible airway benefits.

If There Is No Crowding, Won't Moving the Teeth Back Undo the Expansion?

This is one of my favorite questions because the answer depends on what we actually expanded—and whether we created any lasting additional space.

If the expansion was primarily dental, then yes. Moving the teeth outward temporarily increases the width and perimeter of the dental arch. But if there was no crowding to begin with, that expansion may create spacing between the teeth. When those spaces are subsequently closed by moving the teeth back inward, the dental arch can return close to its original dimensions.

If the original goal was to create more room for the tongue, what have we actually gained?

If the teeth end up close to where they started, the additional dental arch space may also be lost. In other words, we may have temporarily created more room for the tongue, only to eliminate that space when we close the gaps between the teeth.

True skeletal expansion is different. When the midpalatal suture separates, the underlying maxillary bony base and nasal floor widen. The teeth can then be repositioned within that broader skeletal foundation. Although some dental changes may relapse, the skeletal widening is not necessarily reversed when dental spacing is closed.

This is why simply measuring how far apart the molars are immediately after expansion doesn't tell the whole story.

We need to distinguish between temporarily moving teeth outward and actually creating a wider skeletal foundation.

And if our goal is to improve tongue space or breathing, we need to ask an even more important question:

How much additional space will actually remain after treatment is finished?

Should We Expand Someone With No Crossbite or Crowding Just to Create a Bigger Airway?

Not routinely.

This is where I think orthodontists need to be careful not to turn an interesting biological observation into an indication for treatment.

If a patient has a genuine transverse skeletal deficiency, posterior crossbite, constricted maxilla, or another orthodontic indication for expansion, improved nasal airflow may be an important additional benefit.

But expanding an otherwise normally proportioned maxilla solely because “a wider airway must be better” is a very different proposition.

More treatment is not automatically better treatment.

My philosophy is to identify the problem first, educate patients about their options, and then choose the least invasive treatment capable of correcting the problem predictably.

Sometimes that means expansion.

Sometimes it doesn't.

Who Should Be Evaluated for Palatal Expansion?

I look more carefully for a transverse maxillary deficiency when I see:

• Posterior crossbite
• High, narrow palate
• Constricted upper arch
• Crowding associated with transverse deficiency
• A significant discrepancy between upper and lower jaw width
• Chronic mouth breathing combined with clinical evidence of a narrow maxilla

Breathing and sleep symptoms deserve a broader evaluation.

Habitual snoring, witnessed apnea, gasping during sleep, chronic nasal obstruction, significant daytime sleepiness, or persistent mouth breathing should not automatically result in an expander.

Depending on the patient, evaluation may involve an orthodontist, pediatrician, ENT, sleep physician, allergist, or other appropriate specialist.

When obstructive sleep apnea is suspected, an appropriate sleep evaluation—and when indicated, polysomnography—is important.

The Bigger Lesson: Treat the Diagnosis, Not the Appliance

The most important question isn't:

“Should this patient get an expander?”

It is:

“Does this patient actually have a transverse skeletal problem, and if so, what is the safest and most predictable way to correct it?”

For a young child, that may mean conventional expansion.

For an older teenager, it may mean conventional expansion or MARPE depending on skeletal maturity and anatomy.

For an adult, it may mean MARPE, a customized skeletal expander, or surgically assisted expansion.

And sometimes the correct answer is:

Don't expand at all.

Expansion is not a wellness upgrade, and it is not something every child—or every adult—needs.

But in the right patient, for the right diagnosis, and at the right stage of development, palatal expansion remains one of the most powerful tools we have for changing maxillary anatomy.

The goal is not to expand everyone.

The goal is to recognize when a true transverse problem exists, understand what is contributing to it, educate the patient about the options, and choose the treatment most likely to provide a healthy, stable, long-term result.

References

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2. Kapetanović A, Theodorou CI, Bergé SJ, Schols JGJH, Xi T. Efficacy of miniscrew-assisted rapid palatal expansion (MARPE) in late adolescents and adults: a systematic review and meta-analysis. Eur J Orthod. 2021;43(3):313–323.
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