Skeletal palatal expansion for adults — without surgery.

Trained directly with the inventor of the technique

Most US orthodontists who offer MARPE learned the technique secondhand — from textbooks, brief weekend continuing-education courses, or peer demonstrations. Dr. Andros has trained directly with Dr. Won Moon at the UCLA School of Dentistry in small-group continuing-education courses on the MSE technique, where Dr. Moon has refined the protocol over more than a decade of clinical practice and research.

Direct instruction from the technique's originator is not the same as a downstream certification. Case selection, mini-implant placement, suture maturation assessment via CBCT, and the management of asymmetric or partial-opening cases all benefit from learning the technique in the operatory where it was invented. Dr. Andros has also completed additional MARPE-focused continuing education since 2018 — including the most recent appliance-protocol training in 2024 — to stay current as the technique evolves.

For patients researching MARPE providers, the practical question is not whether the orthodontist "does MARPE" — most US orthodontists at least claim to. The question is whether they have meaningful training in case selection, whether they use CBCT imaging to assess suture maturation before recommending treatment, and whether they have a peer network for difficult cases. Dr. Andros' OrthoPreneurs RD study group provides exactly this kind of peer review for complex skeletal expansion cases.

Who is MARPE for?

The textbook indication for MARPE is an adult with a narrow maxilla — that is, an upper palate that is constricted relative to the lower jaw. This often shows up clinically as one or more of the following:

• A posterior crossbite — upper back teeth biting inside the lower back teeth
• A narrow smile with visible dark corridors at the corners of the mouth
• Crowded upper teeth in an arch that's too small for the dentition
• Chronic mouth breathing or nasal obstruction related to a narrow nasal floor
• Sleep-disordered breathing with a suspected airway component
• A history of childhood palate expansion that was either not done or relapsed
• A diagnosis of maxillary hypoplasia that historically would have meant SARPE (surgical) or LeFort surgery

Not every adult with a "narrow palate" needs MARPE — some can still be treated with conventional braces or aligners. The decision turns on the skeletal contribution to the narrowness, the maturity of the midline palatal suture (assessed on CBCT), and the patient's broader orthodontic goals. The right answer for one patient is the wrong answer for another, which is why the consultation matters.

A quick word on anatomy

The upper jaw is not a single solid bone. It is two halves joined down the middle by a seam called the midpalatal suture — a thin strip of connective tissue running from front to back along the roof of the mouth. In children, that seam is still flexible, which is why pediatric palate expansion is straightforward. In adults, the seam has begun to harden into bone.

MARPE works by applying focused force directly to that seam through bone-anchored mini-implants. The two halves of the upper jaw separate in a controlled way. New bone then fills in the gap over the following months. The expansion is at the level of bone, not just teeth — which is what makes it stable in adults and what previously required surgery to accomplish.

How MARPE works — the procedure

The process is broken into four phases.

Phase 1 — Diagnostic and appliance fabrication

A cone-beam CT (CBCT) scan is the cornerstone of MARPE planning. It allows Dr. Andros to assess the maturity of the midpalatal suture, the thickness of the palatal bone where the mini-implants will sit, and the proximity of important anatomy (nasal floor, dental roots). The CBCT scan is also the diagnostic basis for the appliance design — number and position of the mini-implants, expansion screw type, and projected opening pattern.

How we determine the exact amount of expansion you need

In addition to CBCT, Dr. Andros uses a standardized transverse skeletal analysis to determine the precise amount of expansion required for each case. He adopted this protocol after attending Dr. Stuart Frost's continuing education course in New York in December 2025.

The analysis uses three measurements taken from the CBCT scan:

• Lower jaw width — at the bone, not the teeth. The lower measurement is taken at the midpoint of the mandibular body. This is a true skeletal reference: it's independent of where the lower molars happen to be positioned. A typical adult lower jaw measures around 51 mm at this reference.
• Upper jaw width — at the upper first molars. The upper measurement is taken at the cementoenamel junction (CEJ) of the upper first molars, on the CBCT coronal slice where the palatal root of those molars is clearly visible. That standardized landmark produces a consistent measurement from patient to patient.
• Molar inclination check. Dr. Andros also extends a vertical reference line through each lower first molar. In a healthy skeletal relationship, those lines parallel the lateral walls of the nasal cavity. If the lines diverge inward, the lower molars are dentally compensating for the underlying skeletal narrowness — masking the true transverse deficiency that MARPE/MASPE can correct.

The diagnostic target: in an ideal skeletal relationship, the upper maxillary measurement is approximately 10 mm larger than the lower jaw measurement. When the actual differential is less than that, the maxilla is transversely deficient. The exact shortfall — measured in millimeters — becomes the expansion target. This is the specific number that drives appliance design and activation planning.

The practical effect: when you finish the consultation, you have a defined treatment plan with a measured expansion target, not a "we'll figure it out as we go" approach.

The custom appliance is then fabricated to fit the patient's anatomy and produce the planned expansion. This typically takes 1–2 weeks.

Phase 2 — Appliance placement

Placement is an in-office procedure under local anesthesia. The mini-implants (similar in concept to dental implants but much smaller and temporary) are placed into the palatal bone, and the expansion appliance is attached to them. The procedure typically takes under an hour. Most patients leave the office, have lunch, and return to normal activity within a day.

Phase 3 — Active expansion (the slow MARPE protocol, known as MASPE)

A note on terminology — MARPE and MASPE

MARPE — Mini-Implant Assisted Rapid Palatal Expansion — is the widely-used name for this category of procedure, and it's the term most patients researching adult palate expansion have heard of. The original protocol called for rapid activation (one to two turns per day). That's still what's described in most patient-facing material and online write-ups.

A newer protocol within the same MARPE family is called MASPE — Mini-implant Assisted Slow Palatal Expansion. Same appliance type, same principle of bone-anchored expansion, same overall outcome. The only difference is the activation cadence: one turn per week instead of one to two per day. Both MARPE and MASPE are forms of mini-implant assisted palatal expansion in adults.

Dr. Andros uses the slow MASPE protocol as his standard approach — because for the standard adult case, slower activation produces a measurably better result on every axis that matters to the patient:

• Smaller gap between the front teeth during expansion — often barely noticeable rather than visible for months
• Better long-term stability — because new bone re-forms as the expansion happens, the skeletal result is more durable once the appliance comes off
• Shorter retention afterward — the consolidation phase is typically 3–4 months instead of 4–6
• More comfortable — gentler pressure with each weekly activation
• More predictable opening of the suture — slower force application tends to produce smoother, more uniform expansion

The rapid MARPE protocol is still well-documented in the orthodontic literature and is what built the evidence base for the technique. But for the standard expansion case in 2026, the question of rapid vs. slow is not a coin flip — slow MASPE wins for comfort, predictability, and stability. There is one exception, described next.

The one exception: maxillary protraction with face mask

A small subset of patients — usually growing children with a deficient upper jaw — benefit from advancing the upper jaw forward in addition to widening it. This is done with a face mask appliance applying forward force to the maxilla. For protraction to work effectively, the circummaxillary sutures (which hold the upper jaw in place) need to be loosened.

A specialty protocol described in the orthodontic literature uses repeated cycles of opening and closing the expander rather than a steady opening — sometimes called Alt-RAMEC (alternate rapid maxillary expansion and constriction). That cadence loosens the sutures so the face mask can more effectively pull the upper jaw forward. The total amount of expansion at the end of treatment is the same as a standard case; only the activation pattern changes.

This is the one scenario in which Dr. Andros uses a rapid MARPE activation cadence rather than the standard slow MASPE protocol. He'll discuss it at the consultation if your case (or your child's case) is a protraction candidate.

A gap between the front teeth is a sign of progress, not a problem

During expansion, many patients will notice a small space opening between the two upper front teeth. This gap is the visible indicator that the procedure is working. When the two halves of the upper jaw separate at the midline seam, the front teeth — which are attached to opposite halves — move apart slightly. The gap is not a complication; it's the proof of skeletal expansion.

With Dr. Andros' standard slow MASPE protocol, the gap is much smaller, develops gradually, and is often barely noticeable. With the original rapid protocol — used historically in the literature and still in specific protraction protocols — the gap can appear within the first 1–2 weeks and may be visible for several months. In either case, the gap closes on its own as treatment progresses and is fully addressed during the orthodontic alignment phase.

Phase 4 — Consolidation and follow-on orthodontics

After active expansion ends, the appliance stays in place while new bone forms in the expanded suture. Removing the appliance too early can lead to relapse, so this consolidation phase is essential.

How long consolidation takes depends on which activation cadence was used:

• After standard slow MASPE expansion: typically 3–4 months. Because new bone has been gradually re-forming as the expansion happens, less catching up is needed at the end.
• After rapid expansion (used in protraction protocols): typically 4–6 months. The suture opened quickly, so the bone has more catching up to do.

During consolidation, Dr. Andros generally begins orthodontic alignment with braces or aligners. The skeletal expansion is now stable, so the teeth can be moved into their final positions.

What results to expect

A successful MARPE case produces:

• A wider upper arch that matches the lower jaw — eliminating posterior crossbite and creating room for crowded teeth
• A broader smile with the corners of the mouth filled in
• Increased nasal cavity volume on follow-up CBCT — generally a 10–20% increase in nasal floor area, which often correlates with improved nasal breathing
• Improved tongue posture as the palate widens and the tongue has more room to rest against the roof of the mouth
• In some patients with airway involvement, improvements in sleep quality, snoring, and nasal congestion — though MARPE is not by itself a treatment for sleep apnea, and proper sleep diagnosis must come first

The cosmetic improvement from a broader smile alone surprises many patients, even when the original goal was skeletal correction or airway improvement.

MARPE vs. SARPE (surgical) — why this matters

Until MARPE was developed, adult palatal expansion required SARPE — Surgically Assisted Rapid Palatal Expansion. SARPE involves an oral surgery procedure under general anesthesia: the surgeon makes incisions and partially weakens the midline suture so a conventional tooth-borne expander can then open it. Patients face a hospital trip, surgical recovery, swelling and bruising for one to two weeks, and surgical fees often exceeding $5,000–$10,000 on top of orthodontic costs.

MARPE achieves the same skeletal expansion without the surgery. The mini-implants are placed in the office under local anesthesia, the recovery is minimal, and the cost is folded into the orthodontic treatment plan. For appropriate candidates — and that includes most adults — MARPE is the preferred path.

That said, not every patient is a MARPE candidate. Some skeletal patterns or suture maturation findings make SARPE the safer choice. The CBCT-based diagnostic process is what tells us which patient is in which category. Dr. Andros has a working relationship with regional oral surgeons for the cases where SARPE is the appropriate recommendation.

What MARPE doesn't fix on its own

Honesty here matters. MARPE is a tool, not a complete treatment plan. It does NOT, by itself, accomplish any of the following:

• Move individual teeth — the wider arch is the foundation; teeth still need braces or aligners afterward
• Diagnose or treat sleep apnea — sleep medicine evaluation is required first if airway is the goal
• Address tongue ties, large adenoids, or other airway anatomy — those require ENT or other specialist involvement
• Replace good airway hygiene — myofunctional therapy, nasal hygiene, and lifestyle changes still matter

For patients with airway as the primary concern, MARPE is usually one component of a multidisciplinary plan that may also involve sleep medicine evaluation, ENT consultation for adenoid/tonsil assessment, and myofunctional therapy. Dr. Andros' airway training under Stanford-affiliated faculty (Drs. Yoon, Liu, Rama) is specifically focused on coordinating MARPE within this kind of team-based approach.

Cost and insurance

MARPE is part of an orthodontic treatment plan. Costs vary based on case complexity, the amount of expansion required, and the orthodontic phase that follows. The Andros Orthodontics financial coordinator reviews specific fees during the consultation and discusses available payment plans. Many orthodontic insurance plans contribute to the overall case; MARPE itself is typically not billed as a separate procedure but as a component of the orthodontic plan.

Common questions

Does it hurt?

The placement procedure is comfortable under local anesthesia. The active expansion phase produces pressure and mild tightness that most patients describe as significantly less uncomfortable than expected.

Will I have a gap in my front teeth?

Sometimes a small one — and it's actually a useful sign that the procedure is working. When the two halves of the upper jaw separate at the midline seam, the front teeth move apart slightly. With Dr. Andros' standard slow MASPE protocol, the gap is small and develops gradually — often barely noticeable. With the original rapid protocol (used today in specific protraction scenarios), the gap can be more noticeable. Either way, the gap closes on its own as treatment progresses and is fully addressed during the orthodontic alignment phase.

Can I eat normally?

Yes, with minor adaptation. Soft foods are easier in the first few days after placement and during the active expansion phase. Patients return to a normal diet quickly.

How old do I have to be?

MARPE is most often performed in adults — typically late teens through the 50s. The technique exists precisely because adult palate expansion was historically difficult; younger patients can often be treated with conventional palatal expanders that don't require mini-implants.

Will my insurance cover MARPE?

MARPE is generally included in the orthodontic treatment plan and is subject to the same coverage rules as the broader case. Coverage varies widely by plan; our financial coordinator reviews benefits at the consultation.

Is MARPE permanent?

Yes — the skeletal expansion is bone-level and stable when consolidated properly. Like all orthodontic results, long-term retention (with retainers) is required for the dental alignment that follows.