Evaluation of The Optical and Mechanical Properties of The Human Mandible

Abstract

Statement of the problem: It is important to understand the mechanical properties of the mandible that has nonhomogeneous structure.

Objective: The aim of this study is to determine the optical density, ap-parent density, modulus of elasticity and strength values of mandible in vitro and to evaluate their relations.

Materials & Methods: Specimens obtained from six cadaver human mandibles. The sample figure dimensions was set as 2.8 cm length, 1.2 cm width, 0.6 cm mid-section, 0.5 cm height. Optic density (OD) is evaluated with radiographs using an optic densitometer. Apparent density (AD) is determined by mercury overflow tests. Modulus of elasticity (E) and strength(S) is deter-mined using strain gauges and mechanical press. Data evaluated with simple regression analyzes (SRA), multiple regression analyzes (MRA), fuzzy algo-rithm.

Results: Values were found to be 1.115-1.586 for OD, 1.08 g/cm³-1.46 g/cm³ for ADA, 0.6-16.5 GPa for E, and 4.74 MPa-23.93 MPa for S. Simple reg-ression analyzes revealed reverse-geometric relationship between OD-AD, re-verse-linear relationship between OD-S, and reverse-logarithmic relationship between OD-E. MRA results pointed to a reverse relation between S-E. Fuzzy model was found to have a higher prediction performance.

Conclusion: Mandible has a nonhomogeneous and anisotropic struc-ture. Modulus of elasticity is controlled by many parameters such as the mate-rial porosity, physical density, mineral quality, and texture. By using fuzzy al-gorithm, more reliable results can be obtained particularly in making classifica-tions involving uncertainty.