Mechanical stability of 2-plate versus 4-plate osteosynthesis in advancement Le Fort I osteotomy. An in vitro study

Evaluation of cortical bone thickness at the nasomaxillary and zygomaticomaxillary buttresses using cone-beam computed tomography imaging for Le Fort I osteotomy

Background/Purpose

Studies have indicated that 50%-55% of the population have malocclusion, and approximately 5%-10% require orthognathic surgery to correct this condition. Optimal placement of plates and screws significantly affects the success rate of the surgery and postoperative stability. This study evaluates the cortical thickness of the maxillary bone in the nasomaxillary and zygomaticomaxillary buttress regions in Taiwanese patients based on cone-beam computed tomography (CBCT) images.

Materials and methods

128 Patients undergoing Le Fort I osteotomy were selected for this study. Their CBCT images were input into medical imaging software to simulate the placement of titanium screws and plates. The cortical bone thickness at these positions was measured to assess the thickness in the nasomaxillary buttress (surrounding the nasal opening) and the zygomaticomaxillary buttress (surrounding the maxillary zygomatic process). Associations of these thicknesses with gender, age, and screw position were analyzed.

Results

In the nasomaxillary region, cortical bone was thicker on the upper and lower vertical regions, with men generally having thicker bone. The zygomaticomaxillary region had increased thickness near the zygomatic end and distal region. Younger adults had significantly greater bone thickness in certain areas than those over 30 years.

Conclusion

The nasomaxillary region's upper and lower vertical regions and the zygomatic end in the zygomaticomaxillary region provide optimal screw placement sites. Bone thickness differences by gender and age suggest occlusal force and age-related bone resorption as influencing factors.

Comparison between 2- and 4-plate fixation in Le Fort I osteotomy: a mixed methods systematic review

OBJECTIVE

Achieving postsurgical skeletal stability is crucial for successful outcomes and patient satisfaction. Precision maxillofacial surgery, which integrates precision techniques with minimally invasive approaches, is increasingly recognized for its potential to enhance long-term stability and reduce surgical risks and complications. This study aimed to comprehensively evaluate the impact of fixation techniques (2 vs 4 plates) during Le Fort I osteotomy in orthognathic surgery on skeletal stability. The main focus was to compare the stability achieved and potential risks of relapse between these two fixation methods.

MATERIAL AND METHODS

A mixed-methods approach was employed, combining a systematic review, in silico analysis, and in vitro studies. The systematic review adhered to Joanna Briggs Institute methodology and Good Reporting of A Mixed Methods Study guidelines, focusing on comparative studies that evaluated skeletal stability as the primary outcome measure. In silico and in vitro analyses were conducted to assess the biomechanical principles and relapse risks associated with maxillary advancement using different fixation techniques.

RESULTS

The systematic review included three clinical trials, four finite element analysis studies, and two in vitro analyses. The meta-analysis revealed no significant difference in skeletal stability between the 2- and 4-plate fixation methods. However, biomechanical analysis showed an atypical increase in relapse risk with 2-plate fixation at 3 mm maxillary advancement, compared to a 10 mm advancement for 4-plate fixation.

CONCLUSIONS

While both 2- and 4-plate fixation methods are viable, the findings suggest that 4-plate fixation offers superior stability, particularly in cases of significant maxillary advancement, where 2-plate fixation showed an increased risk of relapse. Future research with larger sample sizes and addressing the biases identified in this study is needed to validate these findings and effectively guide clinical practice.

Comparison of the postoperative stability after repositioning of the maxilla with Le Fort I osteotomy using four- versus two-plate fixation

INTRODUCTION

Le Fort I osteotomy procedures requires miniplates fixation in both the aperture piriformis and zygomaticomaxillary buttress.

PURPOSE

The purpose of this study was to compare the postoperative stability of the Le Fort I osteotomy using four-plate versus two-plate fixation.

MATERIAL AND METHODS

This study involved 39 Class III patients who underwent one-piece Le Fort I osteotomy with bilateral sagittal split ramus osteotomy. In group I, four miniplates were placed at the apertura piriformis and the zygomaticomaxillary buttress, whereas, in group II, fixation was achieved with two miniplates bilaterally placed at the piriform apertura with no posterior fixation. Linear and angular measurements included maxillary sagittal and vertical positions. The primary outcome of this study was stability, as recorded by lateral cephalometric measurements of the preoperative, immediately postoperative and late postoperative periods.

RESULTS

Significant immediate postsurgical changes were found in both groups. In the late postoperative cephalometric measurements, all skeletal parameters showed significant stability in groups I and II. In terms of vertical and sagittal relapse, there was no significant difference between the four-plate and two-plate groups (p1=0.686 and p2=0.513, respectively).

CONCLUSION

A good postoperative stability can be obtained with a two-plate fixation after one-piece Le Fort I osteotomy.