Class III cases can be tricky—because what you see clinically may not always be what’s truly happening skeletally.
A major reason for this confusion is the mandibular closure path.

In simple terms, you must ask:

👉 Does the mandible really sit forward?
or
👉 Is it just sliding forward because the incisors collide during closure?

This distinction is essential for correct diagnosis and avoiding overtreatment.

True vs Pseudo Class III — The Core Difference

Feature	True Class III 😬	Pseudo Class III 🙂
Cause	Skeletal discrepancy	Premature incisor contact
Forward mandibular shift	❌ Minimal / None	✅ Present (functional slide)
Ceph ANB	Negative due to skeletal	Improves when edge-to-edge
Profile	Concave	Straight / near normal
Treatment	Growth modification / Surgery	Remove interference + limited ortho

Why Functional Shifts Matter So Much

A patient may appear severely Class III when teeth are in habitual occlusion.
But once you guide them into edge-to-edge, the face and ceph often tell a different story.

This happens because many Class III patients have a:

Functional forward mandibular displacement

Also described as:

• forward displacement
• functional protrusion
• anterior slide
• mandibular slide

🦷 Premature incisor contact → Mandible slides forward → Posterior teeth finally occlude

This functional shift can exaggerate the skeletal discrepancy and lead to misdiagnosis.

The closure path also involves a vertical component. As the mandible moves forward, it may also rotate downward, further altering the apparent skeletal relationship

What Actually Happens During Closure (Based on the Study)

1. Closure begins → incisors touch edge-to-edge

→ This causes an initial forward shift of the mandible.

2. As closure continues → condyles move backward

→ This cancels most of the forward movement.

3. Final result

✅ Most Class III patients show little to no real mandibular displacement when the posterior teeth are in occlusion.

This means the apparent Class III worsening is mostly positional, not skeletal.

Role of Overbite in the Functional Shift

Overbite depth determines how much shift can happen:

Deep overbite

➡️ Less functional forward displacement
➡️ Hinge closure pushes condyles backward effectively

Shallow overbite

➡️ More chance of a genuine functional slide
➡️ Slight displacement may persist even in full occlusion

What Two Cephs Really Tell You

Taking both:

1. Edge-to-edge ceph, and
2. Habitual occlusion ceph,
   usually does not dramatically change your skeletal assessment.

Typical Changes Seen

Parameter	Edge-to-edge	Habitual Occlusion	Interpretation
SNB	↓ by ~3°	↑	Hinge closure effect, not forward displacement
ANB	↑ by ~3°	↓	Mostly due to vertical change from overbite

Key insight:

The ANB difference is largely due to vertical position changes—not true mandibular forward movement.

When Does Residual Functional Shift Still Matter?

For most patients → minimal to none.

But in patients with shallow overbite (<4 mm) a small functional shift may be measurable:

• SNB decreases slightly (≈ –0.4°)
• ANB increases slightly (≈ +0.28°)

These differences are statistically significant, but rarely large enough to alter your diagnosis.

Practical Chairside Screening

A. Suspect Pseudo-Class III if:

• A noticeable forward jump during closure
• Edge-to-edge looks less Class III
• Shallow overbite
• Strong anterior interferences

B. Suspect True Skeletal Class III if:

• No forward shift on closure
• Edge-to-edge still looks Class III
• Deep overbite (hinge movement dominates)
• Minimal ceph difference between both positions

Should You Take Two Cephs?

According to the study:

❗ Routine second ceph is not necessary in most cases.

Habitual occlusion ceph is usually sufficient because:

• The functional slide is often neutralized during full closure.
• Skeletal interpretation remains largely unchanged.

✔ Use a second ceph only when evaluating a suspected functional shift.

Quick Exam Tips

• When asked about functional mandibular slide in Class III, emphasize rotation vs. translation.
• Remember the relationship between overbite depth and angular changes.
• Understand the clinical implications of study results: Use edge-to-edge ceph only when absolutely necessary.
• For cephalometric interpretation, ANB changes can be influenced by vertical mandibular rotation.
• Be able to describe how mandibular closure path affects ceph interpretation.

Class III malocclusions aren’t just “reverse overjet cases.” They involve a combination of:

• Skeletal discrepancies (maxillary deficiency, mandibular prognathism, or both)
• Dental compensations (retroclined lower incisors, proclined upper incisors)
• Growth patterns (vertical growers complicate everything)
• Functional shifts (apparent vs true Class III)

The difficulty?
Growth often exacerbates the problem—especially mandibular growth. So the treatment plan you choose at 12 years of age can dramatically influence whether that patient avoids or needs orthognathic surgery at 18.

1. Non-Extraction Approach

👉 When to choose:

• Mild–moderate Class III
• Little or no mandibular crowding
• Early permanent dentition
• Forward functional shift present
• Patient accepts extraoral appliances

2. Extraction Approach

👉 When to choose:

• Marked lower arch crowding
• Dental compensation is needed to correct overjet
• Patient is in the late mixed/early permanent dentition
• Non-compliance expected for extraoral appliances

Parameter	Non-Extraction + Headgear	Extraction + Fixed Appliances
Upper Incisors	Proclined	Usually stable / mild retroclination
Lower Incisors	Spontaneous retroclination	Controlled orthodontic retroclination
Mandible	Downward–backward rotation	Tends to grow forward
ANB Change	Improves	Minimal improvement
Profile	More convex, softer appearance	Mostly dental correction
Best For	Mild skeletal Class III	Crowding cases
Treatment Time	Shorter	Longer
Long-term Stability	Depends on growth control	Depends on dental compensation

👩‍⚕️👨‍⚕️ What Exam Answers Must Include

If an examiner asks:
“How would you decide between extraction and non-extraction in Class III?”

Your ideal answer should include:

1. Crowding analysis (most important)
2. Growth pattern & age
3. Severity of skeletal discrepancy
4. Incisor inclination (U1-SN, L1-MP)
5. Soft tissue profile
6. Compliance for extraoral appliances
7. Future orthognathic surgery considerations

🧩 Clinical Case Tip for PG Examination

• A skeletal Class III child with minimal lower crowding, reverse overjet, and acceptable profile → Non-extraction + headgear
• A Class III adolescent with >5 mm crowding, upright upper incisors, and camouflaging need → Extraction-based camouflage

Remember

Class III = growth-driven problem.
Your treatment choice must consider future mandibular growth and potential need for surgery.

Every orthodontic student eventually faces one of the toughest decisions in treatment planning — what to do with borderline Class III malocclusion cases. These are patients whose skeletal discrepancy is neither mild enough for camouflage nor severe enough to demand immediate orthognathic surgery. So, how do we decide?

A landmark study by A-Bakr Rabie and colleagues (2008) explored exactly this question, comparing treatment outcomes of orthodontic camouflage (extraction-based) and orthognathic surgery in borderline Class III patients.

The Study at a Glance

• Sample: 25 Southern Chinese adults
  • 13 treated orthodontically (extraction protocol)
  • 12 treated surgically (bimaxillary or mandibular setback)
• Selection criteria: Pretreatment ANB > −5°, with clear Class III skeletal tendency.
• Aim: Identify cephalometric differences and outcomes between the two treatment paths.

Parameter	Camouflage (Orthodontic)	Surgery
ANB angle	> –5°	≤ –5°
Holdaway angle	> 12° ✅	< 12° 🚩
Wits appraisal	> –7.5 mm	< –7.5 mm
Go-Me / S–N ratio	~111	↑ 119
U1–L1 angle	↓ (≈120°)	↑ (≈129°)

Previous research (https://dentowesome.org/2025/11/12/class-iii-malocclusion-surgery-or-orthodontics/) tried to give us some hard rules. Kerr suggested that if the ANB angle is less than -4°, go surgical. Stellzig-Eisenhauer threw a whole formula at us using four variables. But honestly? These didn’t really help us distinguish between the borderline cases. It turns out, this research paper discovered something much more practical.

Key Finding — The Magic Number: Holdaway Angle

Among the many cephalometric parameters analyzed, the Holdaway angle stood out as the best predictor for treatment modality.

🔹 Holdaway angle ≥ 12° → Orthodontic camouflage likely to succeed
🔹 Holdaway angle < 12° → Orthognathic surgery indicated

This single angle correctly classified 72% of the cases — making it a practical clinical guide for borderline cases.

How the Two Treatments Differed

Aspect	Camouflage (Extraction)	Orthognathic Surgery
Mechanism	Retraction of lower incisors + downward/backward mandibular rotation	Surgical setback of the mandibular dentoalveolus
Cephalometric effects	↓ L1–ML angle (retroclined incisors)	↑ L1–ML angle (uprighting)
Facial changes	Increased lower facial height; improved profile via dental compensation	Setback of chin and lower lip, harmonious soft-tissue correction
Soft tissue	No significant difference post-treatment between groups	Comparable esthetic improvements

Both treatments target the lower dentoalveolus, emphasizing incisor position and mandibular rotation.

The orthodontic group in this study retracted the lower incisors by an average of 4.9 mm at the incisal tip and 1.9 mm at the incisor apex. That’s not a typo—the roots barely moved. Why? Because you’re using lingual root torque to prevent the incisors from tipping back excessively. You want to maintain incisor inclination while achieving anterior-posterior movement.

In Short

Holdaway angle ≈ 12° may be your cephalometric compass when planning for borderline Class III cases —
but the final direction still depends on your patient’s goals and your clinical judgment.

Rabie A.-B.M., Wong R.W.K., Min G.U. (2008). Treatment in Borderline Class III Malocclusion: Orthodontic Camouflage (Extraction) Versus Orthognathic Surgery.
The Open Dentistry Journal, 2:38–48. DOI: 10.2174/1874210600802010038.

Author: Kerr W.J.S., Miller S., Dawber J.E.
Journal: British Journal of Orthodontics (1992)

🎯 Why This Topic Matters

Every orthodontic student eventually faces this critical question:

When does a Class III malocclusion cross the line from orthodontic correction to surgical intervention?

Understanding this boundary is essential—not only for diagnosis and treatment planning but also for effective communication with patients and surgical colleagues. The study by Kerr and colleagues provides timeless, cephalometrically based guidance that remains clinically relevant even today.

🦷 The Study in a Snapshot

The researchers compared two groups of 20 patients with severe Class III malocclusion:

• Group 1: Treated with orthodontics alone
• Group 2: Recommended for orthognathic surgery

All patients had negative overjets, ensuring comparable skeletal severity.

📈 Key Cephalometric Findings

Parameter	Surgery Group (Mean)	Ortho Group (Mean)	Significance
ANB Angle	-6.9°	-2.6°	p < 0.001
M/M Ratio (Maxilla/Mandible Length)	0.78	0.89	p < 0.001
Lower Incisor Inclination	78.5°	85.4°	p < 0.01
Holdaway Angle	0.9°	6.1°	p < 0.01

These four parameters clearly differentiated surgical from orthodontic cases.

What About Vertical Dimensions and Overbite?

Surprisingly, vertical measurements like facial proportions, gonial angle, or Y-axis didn’t strongly differentiate surgical cases from orthodontic ones in this study. Nor was an open bite tendency common. So while vertical control is important in treatment, it might not be the clincher in Class III treatment decisions.

🧩 What These Numbers Mean Clinically

Kerr et al. proposed “threshold values”—practical cut-offs to guide treatment choice:

Cephalometric Parameter	Threshold Value Suggesting Surgery
ANB Angle	≤ -4°
Lower Incisor Inclination (IMPA)	≤ 83°
Holdaway Angle	≤ 3.5°
M/M Ratio	≤ 0.84

🦷 Interpretation:
If your patient’s ANB is more negative than -4° and the lower incisors are retroclined below 83°, it’s likely beyond orthodontic camouflage. Surgical correction—usually mandibular setback or bimaxillary surgery—is indicated.

🧠 The Soft Tissue Factor

An underrated but critical insight from the study:

The soft tissue profile often drives the decision more than skeletal numbers.

Even if occlusion could be camouflaged, an unattractive concave profile or reduced Holdaway angle may push the decision toward surgery for facial balance and esthetics.

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📚 Final Thoughts

This 1992 study by Kerr et al. remains a cornerstone for understanding the borderline Class III dilemma. It reinforces that:

Good orthodontics begins with good diagnosis—and great orthodontists know when to call the surgeon.

So, the next time you evaluate a challenging Class III case, remember these cephalometric yardsticks. They just might help you make the right call between brackets and bone cuts.

If you’ve ever wondered whether aligner thickness really matters — spoiler alert: it does! A recent study in the Korean Journal of Orthodontics (2025) by Wang et al. dives deep (literally, histologically deep) into how the thickness of clear aligners affects tooth movement and the surrounding periodontal tissues.

🧪 The Setup

Researchers used New Zealand rabbits fitted with aligners of two different thicknesses — 0.38 mm and 0.68 mm. Using 3D scanning, micro-CT, and histological analysis, they explored how each aligner influenced:

• Tooth movement speed
• Root resorption
• Periodontal ligament (PDL) changes
• Inflammatory and bone-remodeling markers

⚙️ The Science in Motion

• The thicker aligners (0.68 mm) delivered stronger forces, causing more PDL deformation, larger resorption craters, and higher inflammatory marker expression (IL-6, IL-1β).
• The thinner aligners (0.38 mm) produced gentler forces, enabling slightly faster tooth movement with less inflammation and more balanced bone remodeling (more osteoclasts on the compression side, stable ALP and OPN expression).

🧠 Mnemonic — “THIN” aligners are KIND:

• T — Tiny force, tissue-friendly
• H — Higher biological harmony
• I — Inflammation less
• N — Natural remodeling prevails

Category	Parameter	0.38 mm Aligner (Thinner)	0.68 mm Aligner (Thicker)
1. Mechanical Characteristics	Initial Force → Steady Force	~0.88 N → 0.45 N	~1.58 N → 0.80 N
	Force Profile	Lower, more physiologic	Higher, more stressful
	Tooth Movement Speed	Slightly faster (efficient force decay)	Slower (higher sustained force)
2. Periodontal Ligament (PDL) Response	PDL Deformation	Minimal, controlled	Pronounced, compressive
	PDL Stress Distribution	Even and well-distributed	Concentrated, deeper compression
3. Root Integrity	Root Resorption Pattern	Small, shallow craters	Larger, deeper craters
4. Cellular Response	Osteoclast Distribution	Surface-based, well-organized	Deeper, scattered, disorganized
	Osteoblast/Osteogenic Activity (ALP, OPN)	Higher early osteoblastic activation → rapid bone formation	Delayed osteogenic response
5. Molecular Response: Inflammatory Markers	IL-6	Low	High
	IL-1β	Lower expression	High expression
	Overall Inflammatory Load	Controlled	Amplified
6. Molecular Response: Bone Remodeling Markers	TRAP (qRT-PCR)	Controlled, efficient osteoclastogenesis	Elevated but disorganized
	RANKL Expression	Balanced → supports controlled resorption	Elevated → promotes excessive resorption
	VEGF Expression	Balanced angiogenesis, stable remodeling	Increased angiogenesis due to stress
7. Compression- and Tension-Side Biology	Tension Side	↑ OPN, ↑ ALP → early osteoblast differentiation	Low osteogenic activity
	Compression Side	Controlled inflammatory markers	High IL-6 → heavy inflammatory burden
8. Overall Biological Pattern	Remodeling Outcome	Harmonious, biologically efficient tooth movement	Stress-driven remodeling with higher risk of adverse effects
	Clinical Interpretation	Safe, physiologic forces → predictable movement	Higher forces → slower movement, more inflammation, increased resorption risk

📍 The Challenge: Making Open Bite Correction Stay That Way

If you’ve ever treated (or even just planned) a patient with an anterior open bite, you know the struggle is real.
The correction is dramatic, but so is the potential relapse.
That’s why one of the classic questions in orthognathic literature is:

“How stable are Le Fort I intrusion osteotomies — and what happens when we combine them with mandibular surgery?”

A landmark paper by Hoppenreijs et al. (1997, Int. J. Oral Maxillofac. Surg. 26:161–175) tackled exactly this, and it remains one of the most cited long-term studies on skeletal and dento-alveolar stability.

Study Design

• Retrospective 3-centre study (Nijmegen, Arnhem, Amsterdam)
• 267 patients (210F, 57M) with anterior open bite (Class I / II)
• Mean age: 23.6 years
• Mean follow-up: 69 months (20–210 months)

Procedures Evaluated

Procedure	n	Fixation	Additional surgery
Le Fort I (1-piece)	77	Wire / Rigid	± Genioplasty
Le Fort I (segmented)	67	Wire / Rigid	± Genioplasty
Le Fort I + BSSO	98	Wire / Rigid	± Genioplasty
Total	267	153 wire, 114 rigid	136 with genioplasty

Key Findings

1. Overall Stability

• Both Le Fort I and bimaxillary osteotomies showed good skeletal maxillary stability.
• Rigid fixation provided superior stability for both maxilla and mandible compared to wire fixation.
• Mean final overbite: +1.24 mm
• Residual open bite: 19% (no vertical incisal overlap at long-term follow-up)

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2. Le Fort I Osteotomy Alone

• Vertical and horizontal stability: Excellent when rigid fixation used.
• Wire fixation: Showed slight superior movement during IMF (4–6 weeks) followed by mild downward relapse later.
• Maxillary downward movement: ~0.28 mm anteriorly, ~0.52 mm posteriorly over entire follow-up.
• Dentoalveolar changes: Minimal but present; posterior tooth extrusion contributed to late relapse.

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3. Bimaxillary Osteotomy (Le Fort I + BSSO)

• Initial stability: Comparable to Le Fort I alone.
• Late vertical changes: Slightly greater downward movement and posterior rotation of maxillomandibular complex due to molar extrusion.
• Mandibular relapse tendency: Mild clockwise rotation and posterior movement observed, especially in wire fixation cases.
• Rigid fixation: Reduced mandibular relapse significantly during early postoperative phase.

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4. Effect of Fixation Method

Fixation Type	Maxillary Stability	Mandibular Stability	Long-Term Relapse
Rigid fixation	Best vertical & horizontal control	Excellent early stability	Minimal (<1 mm)
Wire fixation	Good initial, but mild late downward drift	Clockwise rotation tendency	Greater overjet relapse

• Rigid fixation minimized both vertical relapse and mandibular rotation, providing superior long-term occlusal stability.

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5. Segmentation of Maxilla

• One-piece vs. multi-segment Le Fort I showed no significant differences in overall skeletal stability.
• Minor trends:
  • Multi-segment group → Slightly less early relapse of overbite
  • One-piece group → Greater posterior molar extrusion in long term
• Conclusion: Segmentation can improve arch coordination but does not compromise skeletal stability.

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6. Dento-Alveolar Changes

• Maxillary incisors: orthodontically retruded pre-op, gradually protruded post-op.
• Mandibular incisors: stable post-op (minor change).
• Overbite at final follow-up: +1.24 mm
• Open bite relapse (no overlap): 19% of cases.
• Overbite relapse not significantly different between procedures due to compensatory dental changes.

Factor	Effect on Stability
Fixation type	Rigid > Wire (esp. in long-term)
Segmentation	Minor effect; slightly better overbite stability early post-op
Orthodontic treatment / Genioplasty	No significant effect
Le Fort I vs. Bimaxillary	Comparable maxillary stability; bimaxillary had slightly more dental relapse
Institution / Surgeon variation	No significant impact after statistical correction

At-a-Glance Summary

Parameter	Observation	Implication
Maxillary relapse	<1 mm vertical, 0.18° horizontal	Clinically minimal
Mandibular relapse	Slight clockwise rotation in wire group	Use rigid fixation
Overbite at 6 yrs	+1.24 mm	Acceptable stability
Open bite recurrence	19%	Mostly dental, not skeletal
Rigid fixation	↑ Stability (maxilla + mandible)	Preferred protocol

Q1.

A 23-year-old female with a Class II skeletal pattern and anterior open bite undergoes a Le Fort I intrusion osteotomy with bilateral sagittal split advancement (BSSO). Six months later, you notice mild clockwise rotation of the mandible and a 1 mm increase in overjet.
Which of the following is the most likely cause of this relapse pattern?

A. Incomplete mandibular advancement during surgery
B. Posterior molar extrusion due to dento-alveolar adaptation
C. Condylar resorption after fixation
D. Maxillary segmental instability
E. Excessive postoperative orthodontic intrusion of anterior teeth

✅ Correct Answer: B. Posterior molar extrusion due to dento-alveolar adaptation
Explanation:
Hoppenreijs et al. observed that most long-term vertical relapse in anterior open bite cases was dento-alveolar, not skeletal. Posterior molar extrusion leads to downward–backward rotation of the mandible and mild relapse in overjet/overbite.

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Q2.

A 25-year-old male undergoes a Le Fort I intrusion osteotomy stabilized with intraosseous wire fixation. At 3 months post-op, cephalometric analysis shows further superior migration of the maxilla compared to the immediate postoperative position.
What is the most plausible explanation for this unexpected superior movement?

A. Sutural remodeling after intrusion
B. Tightening and remodeling of suspension wires during IMF
C. Loss of vertical dimension due to occlusal settling
D. Postoperative condylar compression
E. Reduction in nasal septal resistance

✅ Correct Answer: B. Tightening and remodeling of suspension wires during IMF
Explanation:
Hoppenreijs et al. found that patients with wire fixation often exhibited continued superior migration of the maxilladuring IMF. This was attributed to wire tension and bony remodeling, not relapse.

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Q3.

You are planning a Le Fort I osteotomy for a 21-year-old patient with anterior open bite and posterior dento-alveolar hyperplasia. The case requires segmentation to correct arch form discrepancies.
Based on evidence from Hoppenreijs et al., what is the anticipated effect of segmentation on long-term skeletal stability?

A. Significantly reduces stability of the maxilla
B. Increases relapse risk due to multiple osteotomy sites
C. Comparable stability to one-piece osteotomy
D. Leads to more posterior rotation of the maxilla
E. Requires rigid fixation to maintain stability

✅ Correct Answer: C. Comparable stability to one-piece osteotomy
Explanation:
Segmented Le Fort I osteotomies showed no significant difference in long-term skeletal stability compared to one-piece procedures. Minor trends included slightly better early overbite control and more posterior molar extrusion over time.

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Q4.

A 24-year-old female underwent a Le Fort I + BSSO procedure with rigid fixation. At 1-year follow-up, cephalometric data show <1 mm maxillary vertical change and stable mandibular position.
Which statement best explains this stability outcome?

A. Rigid fixation neutralizes early skeletal remodeling and dental compensation
B. Rigid fixation prevents posterior rotation by controlling condylar movement
C. Rigid fixation minimizes both skeletal and dento-alveolar relapse tendencies
D. Rigid fixation enhances post-surgical eruption of molars to stabilize occlusion
E. Rigid fixation alters growth pattern of the anterior cranial base

✅ Correct Answer: C. Rigid fixation minimizes both skeletal and dento-alveolar relapse tendencies
Explanation:
Rigid internal fixation offers superior control of both vertical and horizontal stability in the maxilla and mandible. It significantly reduces relapse compared to wire fixation, as confirmed in Hoppenreijs’ study.

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Q5.

A 26-year-old female treated with Le Fort I intrusion osteotomy presents with a 2 mm open bite recurrence five years later. Radiographs show stable skeletal landmarks but slight molar extrusion.
How would you classify this relapse according to Hoppenreijs et al.?

A. Skeletal relapse due to vertical maxillary instability
B. Dento-alveolar relapse due to posterior dental extrusion
C. Surgical relapse due to fixation failure
D. Compensatory mandibular resorption
E. Combined skeletal-dental relapse

✅ Correct Answer: B. Dento-alveolar relapse due to posterior dental extrusion
Explanation:
Hoppenreijs et al. emphasized that most relapse in open bite correction is dento-alveolar, not skeletal. Posterior molar extrusion results in mild mandibular clockwise rotation and open bite recurrence without significant skeletal displacement.

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Q6.

You’re comparing outcomes between two patients:

• Patient A: Le Fort I osteotomy + wire fixation
• Patient B: Le Fort I osteotomy + rigid fixation

At long-term follow-up, Patient A shows 0.5 mm more downward maxillary drift and mild overjet relapse.
Which clinical decision could have prevented this difference?

A. Use of IMF for longer duration
B. Inclusion of genioplasty
C. Use of rigid internal fixation during osteosynthesis
D. Multi-segment instead of single-piece Le Fort I
E. Additional intermaxillary elastics post-surgery

✅ Correct Answer: C. Use of rigid internal fixation during osteosynthesis
Explanation:
Rigid fixation (plates/screws) offers superior vertical and horizontal control, reducing both skeletal and dental relapse. Wire fixation, though historically common, allows more downward drift and mandibular clockwise rotationpostoperatively.