Methods: Hydroxyethyl methacrylate terminated poly-lactic-co-glycolic acid (HEMA-terminated-PLGA) was synthesised via ring opening polymerisation of lactide and glycolide, (85 : 15 Mol %, 123 kDa). Commercially available PLGA (85 : 15, Sigma Aldrich) was used as the control. HEMA-terminated-PLGA was mixed with hydroxyapatite (HA) (<63 µM, 10% w/w) and composite/polymeric plates were prepared using compression moulding. The plates (n = 5) were placed into vials containing phosphate buffered saline (PBS) (8 mL) in an incubator (37 ᵒC) for 0, 1, 2, and 6 weeks, the PBS was changed weekly. On removal the plates were assessed for their mechanical properties (Instron 3-point bend test, 1mm/min).
Results:
Table 1: Young’s modulus of composite/polymer plates (standard deviations can be seen in parenthesis, * indicates a statistical difference between the composite and control polymer).
|
HEMA-term PLGA HA composite |
PLGA |
Time / weeks |
Young’s modulus / GPa |
Young’s modulus / GPa |
0 |
4.4 (1.1) |
4.1 (0.3) |
1 |
4.5 (0.5) |
4.1 (0.8) |
2 |
4.4 (0.2) * |
2.5 (1.1) * |
6 |
3.8 (0.2) * |
0.4 (1.5) * |
Analysis (1-way ANOVA) of the data reveals a statistical difference between the Young’s modulus of PLGA and HEMA-terminated-PLGA after 2 and 6 weeks, indicating the composite is able to maintain its stiffness for longer than the PLGA. The results suggest that HEMA-terminated-PLGA would be able to maintain its stiffness for 6 weeks which is a feasible time frame for healing of a mandibular fracture.
Conclusion: This study has demonstrated that HEMA-terminated-PLGA HA composite shows potential (compared to commercially available PLGA) as a material for use in maxillofacial bone fracture fixation.