Ong, H. (Henry) (2012) Biomechanical properties of the human orbital floor for selection of reconstruction materials using a mathematical engineering model. thesis, Dentistry.
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Abstract
A blowout fracture is a fracture of the orbital floor which can cause displacement of the orbital content into the maxillary sinus. Even after the reconstruction of the orbital floor, this risk on enophtalmos is enlarged, as sagging of the reconstruction material leads to an orbital volume increase. The amount of orbital floor deflection depends on the size of the defect and the mechanical properties of the reconstruction material used. In order to compare these material properties with the mechanical properties of the human orbital floor, the latter had to be determined in an experimental study. The study included 15 fresh‐frozen cadavers, from which the orbital floors were harvested bilaterally and shaped into 1×2 cm test samples. The thickness of the samples was measured by micro‐CT. The samples were tested in a 3‐point bending test stage and they were assessed histologically using an optical microscope and toluidin blue stain. The mean thickness was 0.269 mm with a standard deviation 0.100 mm. The elastic modulus varied strongly along the samples, the distribution was non‐parametrical and the median value was 2.55 GPa. The Interquartile Range (IQR) was 1.26‐4.55 GPa. Histological examination of the orbital floors did not reveal an explanation for these variations. These values were used in an analytical mathematical model in order to compare the orbital floor and several reconstruction materials based on their mechanical properties. The model shows that flexible reconstruction devices like MedPor and Perthese support the orbital content poorly and create a high risk on enophtalmos, especially when used in large defects. Due to several simplifications, the use of this model is limited to the comparison of reconstruction materials. For more advanced analyses of the (reconstructed) orbital floor, Finite Element Analysis (FEA) promises to be a useful alternative in making models that describe blow‐out fractures in greater detail.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Begeleiders: and Bos, Prof.dr. R.R.M. and Leeuwen, Drs. A.C. van |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 11:06 |
| Last Modified: | 25 Jun 2020 11:06 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/2604 |
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