Today, we’re going to discuss asymmetries related tovarious midfacial expansion techniques. This topic is widely debated and stillsomewhat misunderstood. Many of the differing opinions stem from variations inproviders’ techniques and approaches.
This contentis not sponsored. No monetary compensation or other form of reimbursement wasreceived for mentioning any products or services.
Thispresentation reflects personal opinion of the speaker and may differ from otherproviders` approaches.
The renderings shown in this lecture are not depictionsof real individuals; any resemblance to actual persons is purely coincidentaland unintentional.
Before we begin, I’d like to introducemyself.
My name is Dr. Svitlana Koval, and I practicein Boca Raton, Florida. My practice is focused exclusively on airway-centeredorthodontics and features several unique aspects. Notably, we have an in-houselaboratory, which serves as our digital hub for designing and printing ShapeMemory Aligners.
We have also developed an advanced approach to 3D-guidedmid-palatal piezocorticotomy, which we’ll discuss a bit later. Our patientsrange from as young as 3½ years old to adults — in fact, we’ve successfullyplaced MARPE appliances in patients as old as 62.
Here, we also host our research and educationcenter, which focuses on techniques and approaches related to mandibularadvancement and MARPE expansion. Our MARPEFACE protocol integrates bothmandibular advancement and midfacial expansion, performed entirely throughorthodontic methods—with no orthognathic surgical involvement.
You can learn more about this in my recent interview onShape Memory Aligners, published in Orthodontic Products magazine, October 2025issue.
The part I’d like to focus on today is our 3D-guidedmid-palatal piezocorticotomy approach, which aims to prevent asymmetries inadult patients through precise planning of the piezocortical incision. Thistechnique is detailed in an article published in the Journal of ClinicalMedicine (2025) by our research team. You can access the full PDF of thearticle via the QR code on the right, which links directly to it on ourwebsite.
Why is this important, and what benefits does3D-guided piezocorticotomy offer?
The main rationale for guiding the incisionlies in the nonlinear orientation of the nasal septum, which, notably, does notfollow the soft tissue landmarks visible from the oral cavity. The septum’sorientation can vary significantly—sometimes reaching extreme deviations andtaking on a curved, snake-like, or spiral path. When viewed from below, thenasal septum may lean toward one side of the nasal cavity in an entirelyunexpected way.
This is why we design the surgical guide to follow theexact orientation of the nasal septum. The guide also accounts for variationsin bone thickness at each point along the hard palate. As a result, it ensuresa precise and parallel separation from the anterior nasal spine (ANS) to theposterior nasal spine (PNS), effectively reducing the risk of unwantedfractures and improving surgical accuracy and safety.
The article itself presents a series of cases treatedwith and without 3D-guided piezocorticotomy. On the right side, cases using theguided approach demonstrate symmetrical separation, with the nasal septumremaining centered within the nasal cavity. On the left side, a case usingnon-guided piezocorticotomy—where the incision was made based solely on visualorientation, without reference to the underlying skeletal structures—resultedin asymmetrical separation.
Another important rationale for 3D-guidedmid-palatal piezocorticotomy is the quality and quantity of bone. In ourpractice, we treat patients of varying ages and bone densities. Applianceplanning and design must therefore be tailored to each patient, depending onbone thickness as illustrated above.
Thicker bone presents specific challenges, asthe forces generated at the mid-palatal suture during expansion can lead tofractures in surrounding structures. The most vulnerable areas include:
The alveolar process where the appliance isattached
The transverse suture
The zygomaticomaxillary suture
Diagonal fractures of the transverse bone
Other nearby structures
By using a 3D-guided approach, we can better anticipatethese risks and plan the piezocortical incision to minimize unwanted fractures.
The orientation of the piezocortical mid-palatal sutureincision, guided by the 3D guide, is highly precise and positioned directlybeneath the base of the nasal septum. The depth of the incision is crucial—itmust be measured beforehand and incorporated into the guide’s design. On theslide, the left side shows an incision that is shallower than the base of theseptum, while the right side demonstrates correct depth, properly aligned withthe septum.
Returning to challenging patient groups in terms ofpredictability of suture opening and risk minimization: the highest-riskcategory in our experience is males aged 20 to 40, particularly skewed towardthe younger end (around 20 years old). This age group typically has the highestbone density and thickness, requiring meticulous treatment planning. We havesuccessfully addressed the challenges in this population using the 3D-guidedmid-palatal piezocorticotomy approach.
As mentioned earlier, zygomaticomaxillary suture fractureis a potential unwanted side effect of pressure buildup during MARPE expansion.In this particular case, an MSE design with predominantly bone-borne anchoragewas used. The authors reported a fracture in the zygomaticomaxillary sutureregion, despite minimal separation of the mid-palatal suture.
What can we expect from MARPE treatment, andwhat are its indications based on current literature?
With the growing body of published datahighlighting the multiple effects of MARPE intervention, the range ofindications for MARPE expansion has expanded well beyond the correction ofunilateral or bilateral crossbites.
MARPE expansion offers several additionalbenefits, including:
Increased nasal cavity volume
Improved nasal airway patency
Separation of the peri-maxillary sutures, corroboratingskeletal expansion
Two studies have reported improvement in nasal septumdeviation following MARPE treatment. Research by Cantarella and Moon hascontributed to our understanding of the center of rotation with this type ofexpansion. They demonstrated that the bifacial skeleton rotates around thetemporo-zygomatic junction during MARPE treatment.
Going further, beneficial outcomes of MARPEinclude an increase in upper airway volume and cross-sectional area, extendingbeyond the nasal passages. On average, most published studies report 1 to 3 mmof mid-palatal suture separation, as summarized by Kapetanovic in a 2021systematic review.
I would also like to draw your attention to the widevariety of MARPE appliance designs currently available on the market.
Appliance designs grouped under the umbrella term MARPEvary significantly, with the most commonly reported being the MSE. Some authorsuse modified Hyrax screws attached to a rigid, bone-anchored framework. Morerecently, custom MARPE designs—including Tiger Screw and the FME (FacegenicsMidfacial Expander)—have emerged as predictable alternatives to SARPE, ofteneliminating the need for surgical intervention.
A randomized controlled trial (RCT)represents the highest level of credibility among observational andexperimental study designs. The RCT conducted by Brunetto and colleaguesdemonstrated that MARPE treatment leads to:
Decreased OSA-related daytime sleepiness
Improvement in the apnea–hypopnea index (AHI)
Improved oxygen saturation
Reduction in snoring
The pyramid of evidence visually representsthe strength and impact of different levels of scientific evidence. While mostpublished data focus on MSE and its modifications, there is a lack ofsubstantial studies on custom MARPE appliances, such as Tiger Screws and FME.
The results reported so far are generalizable, with anaverage mid-palatal suture expansion of approximately 3 mm.
Unfortunately, it has become increasinglycommon for patients to seek guidance on MARPE/FME treatment from other patientsor patient advocates through online forums and social media groups. This canlead to misunderstandings and confusion, as the information is not delivereddirectly by providers.
To address this, we initiated a collaborative effort withJean-Paul and Patrick from GetExpanded to provide first-hand informationdirectly from providers, giving patients the opportunity to ask questions abouttheir individual treatment protocols.
Now lets dive into the topic of todayspresentation, Asymmetries and go over why this matters.
Asymmetries matter for several reasons eventhough sometimes presence of the asymmetry may not pose any significant risksor impact quality of life of the patient.
Asymmetries may potentially impact aesthetic perceptionand be reported by the patient or by other people, by function, which is purelysubjective. Asymmetry, when evaluated by the provider may become the reason ofasymmetric TMJ condylar loads leading to degenerative changes in one or both.Head posture is most of the times affected when evaluating all sorts of facialasymmetry. Neck curvature is a big quarto to be discussed in detail latertoday. Airway shape, orientation, and bending are those variables that can bepotentially corrected when diagnosed and recognized.
As you know, I am a MARPE patient and havepersonally experienced every step of my own pre-planned treatment protocol andsequence.
Clearly, there is a significant asymmetry inmy face in these two pictures. But the question is: which one looks better?
If you focus on the right-hand image, it appears slightlymore symmetrical. Why is that, and what accounts for the difference?
Head orientation is the primary factor toconsider when analyzing facial symmetry. In all cases of facial asymmetry,there is often a natural head tilt that can visually exacerbate the asymmetry.Conversely, if there is a head tilt, some degree of apparent asymmetry willalways be present.
In the example shown, the left image demonstrates thehead misaligned relative to the true horizontal plane, with pupils not leveled.The right image shows the interpupillary line aligned with the true horizontal,providing grounds for more accurateassessment of facial symmetry.
When the true horizontal line is established,the true vertical line is constructed as a perpendicular to the horizontalthrough a specific reference point. In this example, the reference point is theglabella, which is the most prominent point of the skin slightly above theeyebrows.
Once the head is re-oriented with the interpupillary linealigned and the midfacial midline constructed, a systematic analysis of facialasymmetry can be initiated.
We evaluate the three thirds of the face,divided by horizontal reference lines:
Upper third: Extends from the hairline to thelower level of the orbits.
Middle third: Bounded by the lower level ofthe orbits and a line passing through the subnasal point.
Lower third: Corresponds to the mandible,located below the subnasal line.
In the example shown, the two purple lines—drawn throughthe nasal alae and the corners of the mouth—are parallel but canted, and eachis located within different facial thirds. Specifically, the upper line belongsto the middle third (maxilla), while the lower line corresponds to themandible.
Smile analysis represents the second step infacial analysis.
The smile line may or may not follow the horizontalasymmetry lines established on the face in a relaxed facial view. In the twophotographs shown, the images are aligned differently. Notice that the leftimage exaggerates the asymmetry, whereas the right image slightly evens it out,providing a more balanced appearance.
When orientation lines are constructed, itbecomes much easier to identify and locate existing asymmetries.
In the left image, the nasal alae line (theuppermost line, belonging to the maxilla) is more canted than in the rightimage.
The second line from the top, representingthe upper lip at maximum smile, is leveled on the right side but more canted onthe left.
The lower line, indicating the incisal edgesof the maxillary front teeth, remains canted in both images.
I present this example without drawing specificconclusions, to illustrate the observational level of our assessment. At thisstage, we cannot yet determine the nature, degree, or potential correctivestrategies for the existing asymmetry.
The head tilt observed in the left image highlights amuscular component that both affects head position and is influenced by thebite arrangement. On the left side of the face, the chewing muscles and othermuscles associated with head posture have shorter lever arms compared to thoseon the right side, contributing to the observed asymmetry.
Now, let’s look beneath the surface of theskin and explore the underlying soft tissues. This CBCT rendering of the softtissues of the same patient (myself) shows that when the head is orientedrelative to the true horizontal and true vertical planes, there is a pharyngealairway bend leaning toward the left side (the shorter side).
We observe a certain, though not yet fully understood,relationship between the head tilt and the orientation and shape of thevertical portion of the upper airway.
The head tilt and canted orientation planes, which arerelated to the position of the upper teeth, are reflected in the subsequentpositioning of the lower jaw, following the same pattern. You may notice thatthe upper portion of the vertical pharyngeal airway, located within themaxilla, is well aligned, whereas the lower portion of the pharyngeal airway,located below the upper incisor line, is bent and mirrors the asymmetryassociated with the position of the mandible.
The takeaway here is: If we don’t adjust head positionfor our assessment, the actual head tilt aligns neck and the area with theleast cross-section to put it upright relative to the underlying compartmentsof the system.
When we analyze the frontal (coronal) view ofthe CBCT, we observe the same pattern: the nasal base level is aligned with thetrue horizontal, the occlusal plane of the upper jaw is canted, and theocclusal plane of the lower jaw follows the cant of the upper jaw.
At this stage, what we are doing is collecting data fromdifferent layers of the system to identify associations and underlying causesof the observed asymmetry.
Now, let’s examine this busy slide, whichschematically describes different types of asymmetries and their relationshipto treatment.
We propose that asymmetries be classifiedbased on the timing of their occurrence: before, during, or after expansion.They may manifest in different planes of space, and frequently in multipleplanes simultaneously.
Asymmetries can also involve differentanatomical levels, including:
The maxillary body through the nasal base
The dentoalveolar level of the maxilla
The dental arches
The mandible and condyles
Similarly, the correction of asymmetries canbe classified according to the timing of intervention: before, during, or afterexpansion. This classification allows for a differential approach to diagnosisand treatment planning.
I can also create a slide-friendly version with a cleartable or diagram showing timing, location, and treatment approach for each typeof asymmetry.
Several major studies have focused on theanalysis of facial asymmetries. These studies examine key factors contributingto their development, such as asymmetrical separation of the pterygomaxillarysutures.
Zarate-Guerra concluded that asymmetries inadults are related to asymmetrical disarticulation of the pterygomaxillarysutures.
Almaqrami investigated the impact ofmid-palatal suture orientation and shape, reporting that in 43% of cases, themid-palatal suture was asymmetrical, contributing to post-expansion asymmetry.
Most of these studies focus on pre-existing asymmetries,which must be carefully diagnosed before planning treatment.
Now let’s have a closer look at some of them.
Pre-expansion asymmetries include unilateral andbilateral cross-bite, condylar dysplasia, orbital asymmetry, anteriorcross-bite, hemifacial asymmetry, nasal base cant. We will touch base on someof them for the sake of time of the presentation.
Nasal base cant can be pre-existing asymmetry. In themajority of expansion cases the initial can’t is repeated with Midfacialexpansion unless otherwise planned. Regardless of the nasal septum orientationand location after midplaatal diasrticualtion, the base of the nose cant willfollow the cant of the alveolar processes.
Lets look at the unilateral cross-bite case. Its one ofthe most accepted and agreed upon indications for both child and adultmaxillary expansion. Nevertheless, there are specific features that hide behinda well-known picture of the unilateral cross-bite.
We have looked into the soft tissue analysis, bothsuperficially and at the level for the pharyngeal part of the upper airway. Ifyou look at both images, the left side shows skull orientation with themidfacial midline and superimposition of the pharyngeal airway. The right sideshows the inclination of the pharyngeal airway relative to the facial midline.In this case, the unilateral cross bite is skewed left while the pharyngealairway is leaning right.
Same patient, right image shows deeper sliceof the soft tissues and the orientation of the pharyngeal airway.
Right side shows bending of the pharyngeal airway at thelevel of the mandibular rami.
We are going deeper into the slices here. The left sideof the screen shows previous slice of the pharyngeal airway while the rightside is the slice at the level of the cervical spine (neck). The axis andorientation of the pharyngeal airway and the cervical curvature are similar andfollow each other.
The bilateral cross-bite. The image on theleft is the actual soft tissue rendering of the patent on the right side of theslide. While the bilateral cros-sbite is deemed to be more symmetrical than aunilateral, the asymmetry of the pharyngeal airway, as you might notice, stillpersists.
Asymmetries are layered, superficial layers might notdescribe existing asymmetry completely.
The right side of the slide shows the beloworientation of the skull and soft tissues. You may notice that the neck is notaligned with the pharyngeal part of the airway while the nasal passage part(horizontal) in this particular case is well aligned with the nose, nasalseptum, and centered relative tot he mid facial midline.
Bilateral cross-bite: left side - asymmetry of thepharynx gel prt of the upper airway, no asymmetry at the level of the maxilla.Asymmetry of the pharyngeal part of the upper airway that follows portion ofthe mandible and neck.
This video is slicing of the upper airway and its softtissue anatomy. This patient present with particularly asymmetric nasalpassages and septum orientation that produces significant impact on theresistance of the nasal airway and further resistance of the pharyngeal airway.
What may happen intra-expansion or duringexpansion?
We have witnessed different outcome and have analyzedcased from our colleagues. This includes mandibular displacement, maxillarydento-alveolar vertical step, transverse suture separation, alveolar processunilateral protraction, and is not limited to these.
Mandibular displacement. Is inevitable part of thetreatment related to the wider size of the maxillary arch regardless of theappliance design and technique and narrower corresponding size of the mandible.Mandible will gradually align itself while in treatment with Midfacial skeletalExpansion and lean to the ‘preferred side’ to establish decent area of occlusalcontact to maintain chewing efficiency and level of mandibular positionalstability.
Vertical step needs to be recognized before treatment anddiscussed ahead of expansion. Vertical step us related to the different initialheights of the maxillary incisors related to their different positions insidethe bone. If you look at both of these teeth the gingival margins are alignedwhile the dental margins are slightly misaligned with the left side beinglonger.
This is caused byso called altered passive eruption and will behave adversely during expansionresulting in a vertical step between two teeth.
Transverse sutur separation. This is something that needsto prevented with the appliance design, and proper planning. Transverse sutureis the horizontal suture in the back of the palate that separates anteriorportions of the hard palate form the two small palatine bones. If a unilateralseparation of the transverse suture happens patent might experience forwardmovement of one of the side of the upper arch.
The mechanism is moving the segment that includes sixtech of one side of the upper jaw from midline in the direction of the firstmaxillary molar of a certain side.
In case this happens patent might experience fullnessunder the upper lip on one side compared to the upper.
Asymmetry correction may take place at different levelsof intervention: maxillary base and nasal base, dental asymmetry correction,dento-alveolar correction, mandiabular/TMJ condylar correction.
Neck autocorrection happens within the first severalmonth of treatment and may progress further with augmenting changes related tothe mandibular position. We have already seen that neck orientation, curvatureand overall position are evaluated insvereal planes, they includelordotic/kyphotic curve ,and scoliotic changes.
How do we correct asymmetries? Pre-expansion correction includes appliance design/planning/positioning; teeth positions correction,planning for symmetric tooth positions and equal number of teeth on each side(in each quadrant), timing of the spot-and rhinoplasty if applicable.
Intra-treatment correction includes nasal cantcorrection, dento-alveolar step correction (even though it is preventable),teeth migration correction. Use of the facemask and its alternatives.
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Thank you being her with us, I hope youenjoyed this presentation. You can find more information about the proceduresby scanning this QR code, It will take you to our website. More stored isstored under the Big section.
Please submit your questions and suggestionsfor the next sessions.