Numeric approach to the biomechanical analysis of thermal effects in coated implants.

A two-dimensional, finite element method was used to examine the influence of material selection and suprabony exposure of the implant coating on thermal and mechanical stress distribution. Hydroxyapatite coating reduced the heat conduction to the surrounding tissue because of its low thermal conductivity. However, thermal stress resulted from thermal expansion of the hydroxyapatite and titanium core. This might influence the success of hydroxyapatite-coated implants because the biomechanical properties of ceramics are so poor for tensile and shearing stress. In addition, this tendency becomes more pronounced when the hydroxyapatite coating surface extends beyond the cortical bone.