1️⃣ Background
- Traditional approach: Maxillary impaction (LeFort I) was standard for open-bite correction due to instability of early mandibular-only approaches.
- Current advancement: Rigid internal fixation allows mandibular-only surgery using bilateral sagittal split osteotomy (BSSO) with counterclockwise rotation of the distal segment.
2️⃣ Surgical Concept
| Step | Description |
|---|---|
| Presurgical orthodontics | Level maxillary arch via maxillary incisor extrusion → creates level occlusal plane for mandibular autorotation. |
| Osteotomy | Bilateral sagittal split osteotomy with counterclockwise rotation of mandibular distal segment. |
| Fixation | Rigid internal fixation using 4 screws per side. |
| Objective | Establish positive overbite/overjet with stable posterior occlusion. |
3️⃣ Indications
- Moderate anterior open bite (6–7 mm)
- Patients where maxillary impaction undesirable (esthetic concerns, nasal morphology)
- When cost or morbidity of double-jaw surgery is to be minimized
4️⃣ Advantages
✅ Single-jaw procedure → reduced cost & surgical morbidity
✅ Avoids nasal esthetic changes (widened alar base, nares exposure)
✅ Comparable stability to maxillary impaction
✅ Favorable mandibular plane flattening & improved chin–neck contour
5️⃣ Stability Evidence
| Study | Surgery Type | Relapse (No incisal overlap long-term) |
|---|---|---|
| Lo & Shapiro (1998) | Maxillary impaction | 25% (10/40) relapsed |
| Denison et al. (1989) | Maxillary impaction | 21.4% (6/28) relapsed |
| Horwitz et al. (2004) | Mandibular BSSO (CCW rotation) | 10% (2/20) relapsed at 4.5 years |
➡ Mandibular osteotomy shows equal or better long-term stability.
6️⃣ Key Clinical Pearls
- Maintain stable incisor extrusion before surgery—no significant relapse noted.
- Ensure level occlusal plane before rotation to prevent posterior open bite.
- Rigid fixation is critical for stability.
- Post-op orthodontic detailing essential for final intercuspation.
7️⃣ Limitations / Cautions
⚠ Not suitable for severe open bites (>7–8 mm) or complex vertical discrepancies.
⚠ Limited long-term data; ongoing follow-up advised.
⚠ Requires precise planning of occlusal plane leveling to prevent over-rotation.
8️⃣ Clinical Summary
Mandibular counterclockwise rotation via BSSO is a viable and stable alternative to maxillary impaction for moderate anterior open-bite correction, providing both esthetic and economic benefits.
Dentowesome 