[Osteosynthesis in facial bones: silicon nitride ceramic as material]

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Ceramic Engineering

Background:

• Silicon nitride (Si3N4) ceramic possesses favorable properties, including high stability and biocompatibility, making it a candidate for biomedical implant applications.
• The study aimed to evaluate the suitability of Si3N4 for osteosynthesis, a surgical procedure to repair bone fractures.

Purpose of the Study:

• To assess the efficacy and biocompatibility of a silicon nitride (Si3N4) ceramic minifixation system for osteosynthesis.
• To compare the performance of Si3N4 implants with traditional materials like titanium in bone reconstruction.

Main Methods:

• A prototype Si3N4 minifixation system was surgically implanted for osteosynthesis of artificial frontal bone defects in three minipigs.
• Histological analysis, CT, and MRI scans were performed after 3 months. Finite element modeling (FEM) was used to simulate stress and strain on the implants.

Main Results:

• The Si3N4 miniplates and screws demonstrated satisfactory intraoperative handling, with no instances of implant loss, displacement, or fracture.
• Complete bone healing was observed in all subjects, with new bone formation directly contacting the implants.
• FEM analysis indicated favorable stress distribution and high survival probabilities for the Si3N4 implants.

Conclusions:

• Silicon nitride (Si3N4) ceramic exhibited excellent biocompatibility in both in vitro and in vivo settings.
• Si3N4 shows potential as a biomaterial for osteosynthesis, particularly for midface reconstructions, including the orbit floor and skull base.
• Advantages over titanium include no risk of mucosal attachment, no need for explantation, and no interference with radiological imaging.