A Comparative Quantitative and Qualitative Analysis of Human Teeth

Objectives: In a broad term it has been reported that the tooth is composed of calcium-phosphate (mainly hydroxyapatite), however, the literature is still inadequate in data comparing different teeth. It is of a great scientific relevance the accomplishment of a reliable comparison among these substrates in order to establish specific protocols. The purpose of this study was to determine and compare in-vitro structural, phase and mineral composition of human enamel and dentin.
Methods: Human extracted and non-carious molar, premolar, canine and incisor were selected (n=8 each) and assigned to the groups, according to the analysis method performed i.e. Fourier Transform Infrared Spectroscopy (FTIR) (structural), X-ray Diffraction (XRD) (phase), Scanning Electron Microscopy (SEM) (morphological) and Energy Dispersive Spectroscopy (EDS) (composition). All selected teeth were sliced transversally and longitudinally at a distance of 1.5mm.
Results: FTIR spectroscopy showed variance in peaks positions and intensities among these groups. Significant difference was found in phosphate (1100-950cm^-1), carbonate (1400-1200cm^-1) and amide (1700-1500cm^-1) regions. The upper layer of enamel and dentin showed high phosphate peak intensities compared to inner layers. XRD patterns showed change in peak intensities and appearance of new peaks. Enamel region mainly showed calcium-phosphate, whereas, dentin showed the presence whitlockites as well. SEM/EDS showed that calcium, phosphorous percentage was high in enamel than dentin, where high phosphorous content was found in outer layer. Similarly, fluorine content was high in enamel, carbon and oxygen contents were high in dentin due to collagen matrix in this area. The magnesium, sodium, strontium difference was not significant among these groups. The calcium and phosphorous weight percentages were high in canine enamel and molar dentin compared to other teeth.
Conclusions: This study provided a comprehensive quantitative data of human teeth and it was found that average calcium-phosphate ratio of enamel and dentin was higher than previous reports.