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Does Counterclockwise Rotation Affect Fixation Stability? An In Vitro Biomechanical Study of Large Mandibular
Beethoven Estevão Costa1, Maísa Pereira-Silva1, Bianca Tiemi Uehara Lima1
1Department of Diagnosis and Surgery, School of Dentistry, São Paulo State University (UNESP), Araçatuba 16010-380, SP, Brazil.
Bioengineering (Basel, Switzerland)
|July 28, 2026
Summary
Two miniplates offer superior stability for sagittal split ramus osteotomy (SSRO) with large mandibular advancements and rotation. This fixation method enhances postoperative stability in complex orthognathic surgery cases.
Area of Science:
- Biomechanical Engineering
- Oral and Maxillofacial Surgery
- Orthodontics
Background:
- Maintaining stability after sagittal split ramus osteotomy (SSRO) is crucial for successful orthognathic surgery.
- Large mandibular advancements and rotational movements increase mechanical stress, potentially compromising outcomes.
Purpose of the Study:
- To evaluate and compare the biomechanical stability of five different fixation systems after SSRO.
- To assess fixation performance under conditions of linear advancement and combined advancement with counterclockwise rotation.
Main Methods:
- An in vitro study using 50 polyurethane hemimandibles, divided into two groups: 10-mm linear advancement and 10-mm advancement with 20° counterclockwise rotation.
- Five fixation subgroups were tested: straight plate, angled plate, sagittal plate, 10-hole miniplate, and two 4-hole miniplates.
- Biomechanical testing included compression tests, strain gauges, and digital image correlation.
Main Results:
- The two 4-hole miniplate configuration (subgroup E) demonstrated the highest resistance values in both advancement conditions.
- Statistically significant differences in stability were observed among fixation systems (p < 0.05).
- Fixation systems B, C, and D showed higher resistance in Group 1 compared to Group 2, though not significantly.
Conclusions:
- Fixation with two miniplates provides superior biomechanical stability for SSRO, especially with significant mandibular advancements and rotational movements.
- This fixation strategy may enhance postoperative stability in complex orthognathic surgery.
- The findings support the use of dual miniplate fixation for challenging SSRO cases.