Primary implant stability is a prerequisite for implant survival, an important issue for clinicians. Correlation of insertion torque and bone quality has been reported. Systematic studies on optimization of implant insertion torque are lacking. The measure of bone quality using average Hounsfield unit in implant literature is misleading. Specific aims of the proposal are: to establish a power or linear regression relationship between the Hounsfield unit (HU) and modulus of elasticity of bone (MOE); to study relative contributions of implant insertion torque (IIT) by cortical and trabecular components of bone; and to use our 3D analytic models and computer simulation to study various conditions such as drill diameters and drill depths of various operation conditions that would optimize insertion torque values, particularly for poor quality bones. Our long-term goal is develop a predictive model using a series of experiments and theoretical models to test the predictive power of the algorithm. This project will provide basic information for clinicians to improve primary implant stability.