📍 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)
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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