Imaging of gradient structure of titanium/apatite functionally graded dental implant

Abstract

Various imaging methods were applied to observe and evaluate the functionally graded structure of dental implant and tissue reaction around the implant inserted in an animal experiment. To optimize the mechanical properties and biocompatibility the dental implant with the graded structure that increases the content of hydroxyapatite(HAP) in the longitudinal direction, from pure titanium (Ti) at one end up to 20% or 100%HAP at the other end, was fabricated through the process of powder metallurgy. After the external appearance was observed either with the naked eye or by optical microscopy, X-ray tranmission image was taken. The cross-section was then investigated by the secondary electron image and the compositional image using reflection electrons in a scanning electron microscope, line analysis and elemental mapping in EPMA (electron probe microanalysis) and the features of these methods were compared. All the methods for the optical images based on the reflection and scattering of light due to surface morphology, the X-ray transmission and reflection electron images based on the atomic number dependence, line analysis and mapping based on the characteristic X-ray emission confirmed the gradient structure. For the observation of the new bone formation around the implant which was inserted in the femora of rats, the compositional image by reflection electrons and EPMA elemental mapping were applied. These imaging methods whose contrast is based on the electronic structure of the specimens have the features that specimen preparation is simple without ultra thin sectioning and staining, and the recognition and evaluation of new bone area is easy. It would be more effective to use together with the conventional method to observe histologically the stained thin specimen by optical microscopy.