Non destructive analysis of hydroxyapatite materials is an active research area mainly in the study of dental pieces and
bones due to the importance these pieces have in medicine, archeology, dentistry, forensics and anthropology. Infrared
thermography and photothermal techniques constitute highly valuable tools in those cases. In this work the quantitative
analysis of thermal diffusion in bones is presented. The results obtained using thermographic images are compared with
the ones obtained from the photothermal radiometry. Special emphasis is done in the analysis of samples with previous
thermal damage. Our results show that the treatments induce changes in the physical properties of the samples. These
results could be useful in the identification of the agents that induced modifications of unknown origin in hydroxyapatite
The analysis of the surface of teeth is an important field of research and technological development due to the
importance of dental pieces in health and aesthetics. The presence of cracks as well as the etching effects on
teeth surface, due to different chemical agents, affects not only the appearance of teeth but its integrity. In this
work, laser thermography analysis of dental pieces with damage in the form of cracks is presented. The technique
consists in the illumination of the surface at the center of the sample, using a 300 mW pulsed solid state laser
beam focused with a gradium lens, and monitoring the spatial and temporal distribution of the temperature
field. The heating of the sample is monitored using a focal plane array infrared camera, sensitive in the spectral
range 7.5-13 μm with a noise equivalent temperature difference of 0.12°C. The data acquisition was performed
by the PC firewire port using a PCI-8254R card and a home-made program in Labview 8.0 was used for data
acquisition. The images were processed in a home-made linux program to obtain the experimental table values.
Our results are compared with position and frequency scans obtained by infrared photothermal radiometry. It
is shown that the crack in the tooth appears as an increase in the photothermal signal. In contrast, the thermographic
image shows a more detailed structure in which close to the crack the temperature increases, but at the
crack the signal falls.
In this work the possibilities of infrared thermography for the study of burned human bones of outstanding
interest in archaeology and anthropology are explored. The technique used consisted in the illumination of the
sample using an infrared solid state laser beam and the observation and the monitoring of the surface temperature
with an infrared camera. The bones analyzed were previously thermally treated in a furnace and boiled
in water. It is shown that the effect of the thermal treatments can be observed in the infrared images, from
which the dynamics of the cooling process of the sample is obtained. It is shown that the cooling process of the
samples could be used to identify the possible burning treatment at which a given material could have undergone
previously. As an auxiliary technique X-ray diffraction was used to analyze the crystallization of the material
and to look for a correlation with different thermal treatments.
The analysis of teeth is an interesting field, given the importance of these pieces for the individual or for humanity in the case of remains recovered from an archeologically site; therefore, the development of non-destructive techniques is important to study these materials. Photothermal techniques are ones of the most interesting possibilities; they are based in the generation of a train of thermal waves inside of a material due to the illumination with modulated light. Among these techniques photothermal radiometry has an outstanding role, since it is a non-contact technique, based in the detection of infrared emission of the samples heated with the laser. The experimental configuration consists of an Ar laser beam that impinges on the surface of the teeth and the infrared radiation generated is measured using a HgCdTe IR detector. Results for the analysis of cracks on teeth and the low frequency profiles are presented. A strong influence of the signal due to the microstructure of teeth is observed. Furthermore, surface effects are analyzed changing the color of teeth when whitening products are applied. The process of whitening is monitored in real time by optical spectroscopy in the visible and by photothermal radiometry.