|dc.description.abstract||Craniofacial reconstruction surgeries are extremely challenging because of the complex anatomy of the region and its proximity to the vital tissues. These surgeries usually require custom implants. Fabrication of a custom implant is time consuming and delay the surgery which increase the risk of a successful operation. Therefore, a new surgical method is needed to treat bone defects with the least possible delay, and without compromising precision in fabrication and implantation. This study introduces in-situ printing (ISP) as a solution; by directly printing scaffolds into defects of patients, ISP can combine fabrication and implantation of micropatterned scaffolds and possibly eliminate fabrication delay, improve implantation precision and provide a capacity to modify the scaffold’s shape during surgery. This study consists of two main parts: the first optimizes a methacrylated gelatin (MAG), Laponite (LP) nanocomposite as a material for ISP and the other tests physical properties of the nanocomposite.
To optimize MAG, sucrose was added to the nanocomposite to reduce gelation and increase printability. Printing parameters including UV intensity for crosslinking MAG, extrusion rate, and printing speed were modified for the purpose of ISP. A critical sized calvarial defect in rat models were treated by ISP using the modified nanocomposite. Four weeks after the surgery, the treated region was characterized using SEM, EDS, µCT, Raman, and histological analysis. Results showed that more than 50% of the ISP treated defect was healed in 4 weeks with no inflammation or infection. The healed region was chemically and histologically similar to rat’s native bone.
Study on physical properties of nanocomposite revealed that increasing LP concentration from 0 to 6 %wt. reduced hydrolytic degradation, swelling, and protein release rates, while increasing MAG from 10 to 20 %wt. reduced enzymatic degradation, and increased swelling and protein release rates.
These findings suggest that ISP of MAG-LP nanocomposites can be used for bone defect treatment without introducing any complication and also physical properties of the nanocomposite can be modified by adjusting MAG and LP concentrations.||en