Cortication around the developing bony cyst confine the expansion and growth of the relative cyst. However, the mechanisms for cortication around the bony cyst walls have remained unclear. Bone is highly responsive to functional strain, which may lead to physiological changes resulting in the laying down and resorbing of calcified tissue by osteoblasts and osteoclast respectively. The aim was to explore the role of functional strain on the cortication of cysts in the mandible.
Method:
A three-dimensional finite element analysis (FEA) model of a cyst at the angle of the mandible was created and loaded with masticatory forces to simulate both unilateral molar biting and incisal biting. FEA uses a novel approach of modelling mandible biomechanics, with similar results found using strain gauges on cadavers. The model was created in ScanIP and the strain values were computed using FEA program ABAQUS. A non-cyst containing mandible was also loaded with the same masticatory forces and used as a control.
Result:
The analysis showed a relative greater concentration of strain within the bone lining the cyst compared to the non-cyst containing model. The surface layer of cancellous bone bordering the outside of the cyst showed a relative increase of up to 70% in equivalent strain and 75% in strain energy density (SED) over biting loads.
Conclusion:
It is suggested that the comparative higher strain values in cancellous bone may provide the necessary transduction signals to induce bone apposition and cortication around the cyst to limit further the cyst’s growth