Nasal Floor Changes After MARPE:
Coronal CBCT
What the Slices Tell You
Master the coronal perspective on cone-beam imaging to assess skeletal widening, nasal cavity gain, and treatment stability. Evidence-based interpretation for the modern orthodontist.
TL;DR Nasal floor changes after MARPE are best visualized on coronal CBCT slices, where clinicians observe widening at the greater palatine foramen, increased nasal cavity dimensions, and anterior-to-posterior skeletal expansion patterns. These morphologic shifts reflect true bone-level expansion rather than alveolar tipping, with greater nasal width gains in MARPE versus conventional rapid palatal expansion.
Coronal cone-beam computed tomography slices have become the gold standard for assessing skeletal outcomes after miniscrew-assisted rapid palatal expansion. Yet many clinicians rely on axial and sagittal views alone, missing critical nasal floor anatomy changes that determine long-term airway benefit and treatment stability. In this article, Dr. Mark Radzhabov reviews what the coronal slice reveals about nasal morphology post-MARPE—how to identify genuine skeletal widening, where bone remodeling occurs, and why this imaging perspective matters for your case documentation and patient communication at ortodontmark.com.
Understanding Nasal Anatomy on Coronal CBCT
coronal imaging
Why This View Matters
The coronal plane provides the clearest visualization of midpalatal suture separation and lateral nasal floor expansion—two hallmarks of successful skeletal MARPE. Unlike axial slices, which show suture opening but compress three-dimensional nasal cavity changes, coronal sections reveal the true width gain at multiple landmarks: the anterior nasal spine, the molar region (M-NW), and critically, the greater palatine foramen (GPF). A prospective randomized clinical trial comparing RPE and MARPE documented that nasal width increased significantly more in the molar region with MARPE than conventional rapid palatal expansion, observable immediately post-expansion (T1) and maintained through consolidation (T2). The nasal septum, which runs perpendicular to the coronal plane, is seen in profile, allowing you to assess deviation, posterior displacement from expansion forces, and asymmetric widening patterns. Coronal CBCT also permits measurement of nasal floor thickness—bone density surrounding the greater palatine foramen—a critical safety metric when evaluating miniscrew-assisted expansion outcomes. This anatomic perspective is essential for distinguishing genuine skeletal change from dentoalveolar compensation.
Critical Measurement Points on the Coronal Slice
skeletal expansion
Successful MARPE interpretation requires systematic assessment of four coronal landmarks. First, the anterior nasal spine (ANS) at the apex of the incisal vault marks the furthest anterior point of skeletal expansion. Widening here is purely skeletal. Second, the greater palatine foramen (GPF) region—located at the junction of the hard palate and posterior nasal floor—shows dramatic expansion in MARPE cases. Research indicates GPF widening is greater in MARPE than RPE groups across both immediate post-expansion and consolidation intervals. Third, molar-region nasal width (M-NW) represents expansion at the broadest point of the palate. This measurement directly correlates with transverse maxillary gain and is the most clinically relevant for crossbite resolution and airway volume. Fourth, assess nasal septum position—in symmetric expansion, the septum remains centralized. Deviation or posterior shift suggests asymmetric force distribution or inadequate midpalatal split. Each landmark should be measured at baseline (T0), immediately post-activation (T1), and after consolidation (T2). Clinicians who integrate these four points into their CBCT interpretation protocol gain predictive power for treatment stability and can identify expansion failures early.
Systematic Coronal CBCT Interpretation: A Four-Step Workflow
CBCT analysis
To maximize diagnostic yield from coronal imaging, adopt a standardized four-step workflow. Step 1: Establish baseline nasal anatomy. On pre-treatment (T0) coronal slices, document the transverse dimension at ANS, GPF, and M-NW using digital calipers. Record any septal deviation, palatal vault asymmetry, or bone thinning at planned miniscrew sites. Step 2: Assess midpalatal suture opening pattern. At immediate post-expansion (T1), the suture should show parallel separation in the axial plane and symmetric widening in the coronal view. If opening is asymmetric (wider on one side), suspect uneven miniscrew loading or inadequate bilateral activation. Step 3: Measure nasal floor expansion gains. Compare T1 to T0 dimensions at all four landmarks. Greater nasal width in the molar region paired with maintained anterior nasal spine position indicates true skeletal expansion without posterior tipping. Step 4: Consolidation assessment (T2, 3 months post-expansion). Repeat measurements to confirm stability. Minor dimensional loss (<1 mm) is normal; losses >1.5 mm suggest insufficient retention or early relapse. Document your findings in a standardized measurement table for medicolegal protection and to track your protocol efficacy over time. Orthodontist Mark recommends adding serial photography of the coronal slice at each time point to your case file—this visual record is invaluable for case presentations and peer consultation.
Comparing Nasal Changes: MARPE vs. RPE and Bone-Borne Expanders
nasal cavity expansion
Head-to-head comparative studies using low-dose CBCT have quantified nasal floor expansion differences across expansion modalities. The greater increase in nasal width in the molar region (M-NW) and at the greater palatine foramen (GPF) was observed in MARPE compared to RPE immediately post-expansion and maintained through consolidation, with statistical significance (P < 0.05). This superior nasal gain reflects MARPE's skeletal anchoring—miniscrews bypass dental roots, allowing pure palatal expansion without buccal crown tipping. When comparing MARPE strategies, pure bone-borne expanders (BAME) demonstrated greater skeletal contributions (83% of total expansion) versus hybrid tooth-bone MSE designs (56% skeletal contribution), yet both showed robust midpalatal suture opening (100% and 95% respectively). The trade-off: BAME designs produced less dental tipping and less buccal bone loss, making them attractive for patients with pre-existing periodontal concerns. Coronal imaging reveals these nuances clearly—MARPE and BAME cases show parallel suture opening and minimal dentoalveolar compensation, whereas RPE cases often display V-shaped suture opening with buccal tooth tipping visible as bone resorption on the faceal cortex. For clinicians evaluating miniscrew-assisted expansion outcomes, the coronal slice is the imaging plane that most directly demonstrates these skeletal versus dentoalveolar distinctions.
Red Flags and Early Detection on Coronal CBCT
nasal morphology
Several imaging findings on coronal CBCT warrant clinical concern and potential protocol adjustment. Asymmetric suture opening—widening more on one side (>1.5 mm difference between sides)—suggests unequal miniscrew loading or tilting of the appliance. Reassess screw torque and bilateral activation force. Nasal septum deviation during expansion, especially posterior displacement, may indicate excessive posterior palatal force or inadequate anterior skeletal split. Consider reactivation pattern or miniscrew repositioning in future cases. Minimal GPF widening (<1 mm) despite adequate suture separation signals that expansion is occurring primarily in the anterior vault—common in high palatal vault anatomies; this may predispose to relapse if bone maturity is borderline. Bone thinning or perforation at miniscrew sites (visible on coronal sections) is rare but catastrophic. Digital planning with CBCT and 3D-printed positioning guides, as described in advanced MSE protocols, minimizes this risk. Loss of dimension between T1 and T2 (>1.5 mm) suggests inadequate retention phase or patient non-compliance. Extend passive holding and reinforce retention instructions. Early detection of these red flags via systematic coronal CBCT review allows you to intervene before relapse or complications occur. Digital documentation—serial coronal measurements—builds a clinical database that refines your expansion protocols over time.
Interpreting and Presenting Coronal Expansion Data
skeletal expansion
Patients and referring dentists benefit from clear, visual explanation of nasal floor changes. Create a side-by-side coronal comparison—place baseline (T0) and post-expansion (T1) slices adjacent on your presentation screen or printed report. Use digital annotations (arrows, measurement lines) to highlight widening at the ANS, GPF, and M-NW. Quantify the gains in millimeters. For example: “At the molar level, we achieved 4.2 mm of nasal widening—this is skeletal expansion of the upper jaw, not tooth movement.” Explain that true skeletal expansion delivers airway benefit—patients often notice easier nasal breathing post-consolidation, especially if they had mouth-breathing habits. For clinicians, frame the coronal findings as objective evidence of treatment success: “The symmetric midpalatal suture opening and nasal floor widening confirm that the miniscrew-assisted expansion is working at the skeletal level, not compensating through dental tipping.” This language reinforces the biologic advantage of MARPE over conventional approaches and justifies the miniscrew investment to skeptical payers. When presenting to orthodontists in study clubs, coronal CBCT data showing nasal cavity expansion becomes your strongest argument for skeletal expansion in transverse deficiency cases—it is radiographic proof of the mechanism.
Learn the full MARPE protocol from Dr. Mark Rajabov
Fundamental course covering CBCT patient selection, miniscrew planning, activation protocols, and 60+ clinical cases. Choose the access level that fits your practice.
Essentials of rapid palatal expansion for practicing orthodontists.
- Core RPE concepts and biomechanics
- 6 structured video lessons
- Clinical decision checklists
- Lifetime access to recordings
Deep-dive into MARPE protocol, diagnostics, and clinical execution.
- 6 modules covering MARPE from A to Z
- CBCT case selection walkthroughs
- Miniscrew placement and activation
- 60+ annotated clinical cases
- Direct Q&A with Dr. Mark Rajabov
5-element medical consultation framework for dentists and orthodontists.
- Trust-building consultation protocol
- 5 lesson modules
- Templates for treatment plan delivery
- Works with any clinical specialty
Clinical FAQ
How does nasal floor anatomy change on coronal CBCT slices immediately after MARPE activation?
Coronal slices show widening at the greater palatine foramen and anterior nasal spine, with symmetric separation of the midpalatal suture. Nasal cavity dimensions increase, particularly at the molar region, reflecting true skeletal expansion rather than alveolar tipping.
What is the expected nasal width gain at the molar region (M-NW) after MARPE versus conventional RPE?
MARPE produces significantly greater nasal width increase in the molar region compared to RPE (P < 0.05), both immediately post-expansion and at 3-month consolidation. This skeletal advantage reflects miniscrew anchoring without dental tipping.
Why is the greater palatine foramen (GPF) region a critical measurement point on coronal CBCT?
GPF widening indicates posterior nasal floor expansion and validates true skeletal palatal separation. Minimal GPF widening despite suture opening suggests anterior-dominant expansion and may predispose to relapse in borderline skeletal maturity cases.
What does asymmetric midpalatal suture opening on coronal slices indicate clinically?
Asymmetric opening (>1.5 mm difference between sides) suggests unequal miniscrew loading or appliance tilting. This finding warrants reassessment of bilateral activation force and possible miniscrew positioning adjustment in future cases.
How should I interpret nasal septum position changes during MARPE on coronal imaging?
The septum should remain centralized during symmetric expansion. Posterior displacement or deviation may indicate excessive posterior palatal force or inadequate anterior split, signaling need for protocol adjustment or reactivation pattern revision.
What is the optimal consolidation period, and how do coronal measurements predict relapse stability?
Standard consolidation is 3 months (T2). Measure dimensions then to establish stability. Losses >1.5 mm between T1 and T2 signal inadequate retention or non-compliance. Extend passive holding phase and reinforce retention instructions.
Can coronal CBCT imaging alone assess midpalatal suture maturity before MARPE?
Coronal slices show suture morphology and bone density but do not definitively determine skeletal maturity. Combine coronal CBCT with cervical vertebral maturation staging or anteroposterior cephalometrics for complete pre-treatment maturity assessment.
How do bone-borne (BAME) and hybrid (MSE) miniscrew designs differ in nasal floor expansion on coronal imaging?
Both achieve robust midpalatal suture opening. However, BAME produces greater skeletal contribution (83% vs. 56%) with less dental tipping. Coronal sections show parallel suture opening in both but less buccal bone resorption with BAME designs.
What are the measurement landmarks for nasal floor expansion assessment on the coronal plane?
Four landmarks: anterior nasal spine (ANS), greater palatine foramen (GPF), molar-region nasal width (M-NW), and nasal septum position. Measure all at baseline (T0), immediate post-expansion (T1), and consolidation (T2) for complete protocol documentation.
How does digital planning with CBCT and 3D-printed miniscrew guides improve nasal floor expansion predictability?
Digital planning evaluates palatal bone morphology and nasal floor thickness pre-treatment, optimizing miniscrew positioning and expansion vectors. This approach reduces anatomic damage risk and improves skeletal expansion consistency across cases.
The coronal CBCT slice is your window into true skeletal expansion and nasal cavity adaptation after MARPE. By systematically evaluating nasal floor changes—particularly at the greater palatine foramen and anterior nasal spine—you gain objective evidence of treatment success and can counsel patients on expected airway gains. As Orthodontist Mark emphasizes, this level of detailed imaging analysis separates evidence-based skeletal expansion from appliance-dependent outcomes. Schedule a case review or explore Dr. Radzhabov's clinical protocols on ortodontmark.com to refine your MARPE imaging interpretation skills.
