IADR Abstract Archives
Analysis of Young and Old Human Dentin Using Raman Spectroscopy
Objectives: The objective of this study was to evaluate the potential of Raman spectroscopy in the investigation of the crystallographic structure of human dentin. The method determines the vibrational modes of the molecules within a material, by analyzing the interaction of light with its chemical bonds. This provides information on its chemical structure and phase. Furthermore, our aim was to look into the composition changes that might occur in crown dentin with aging.
Methods: The samples used were taken from crown dentin of intact extracted human teeth. They were ultrasonically cleaned, stored in a 0.2% thymol solution at 4 degrees Celsius for up to 3 months. The “young dentin” samples (G1) were taken from impacted third molars in patients aged 20-30, “old dentin” samples (G2) were extracted premolars of patients aged 40-65. Each sample was embedded in epoxy resin and polished with a silicone carbide paper of 1200 grit size. Raman spectroscopy was performed using a Horiba Jobin-Yvon T64000 triple-grating spectrometer.
Results: The ν1(PO4) stretching corresponds to hydroxyapatite and is the strongest observed peak – near 960 cm-1. The ν2(PO4) stretching (at around 432 cm-1) is more visible in G1, and scattered in G2. The ν4(PO4) stretching at 591 cm-1 is clear in G1, but fragmented in G2, and with a decreased intensity (and observed at 585 cm-1). The peak observed at 1003 cm-1 is assigned to octacalcium phosphate. It has a higher intensity in G2.
Conclusions: The changes in the ν4(PO4) stretching in G2 could be an indication of the transition of α-carbonated hydroxyapatite into b-carbonated hydroxyapatite. The detected presence of octacalcium phosphate, as well as the less intensity of the peaks is a sign of an increased concentration of mineral substances with a lesser calcium content. This, in turn, could lead to a decreased toughness in the old dentin group.
Methods: The samples used were taken from crown dentin of intact extracted human teeth. They were ultrasonically cleaned, stored in a 0.2% thymol solution at 4 degrees Celsius for up to 3 months. The “young dentin” samples (G1) were taken from impacted third molars in patients aged 20-30, “old dentin” samples (G2) were extracted premolars of patients aged 40-65. Each sample was embedded in epoxy resin and polished with a silicone carbide paper of 1200 grit size. Raman spectroscopy was performed using a Horiba Jobin-Yvon T64000 triple-grating spectrometer.
Results: The ν1(PO4) stretching corresponds to hydroxyapatite and is the strongest observed peak – near 960 cm-1. The ν2(PO4) stretching (at around 432 cm-1) is more visible in G1, and scattered in G2. The ν4(PO4) stretching at 591 cm-1 is clear in G1, but fragmented in G2, and with a decreased intensity (and observed at 585 cm-1). The peak observed at 1003 cm-1 is assigned to octacalcium phosphate. It has a higher intensity in G2.
Conclusions: The changes in the ν4(PO4) stretching in G2 could be an indication of the transition of α-carbonated hydroxyapatite into b-carbonated hydroxyapatite. The detected presence of octacalcium phosphate, as well as the less intensity of the peaks is a sign of an increased concentration of mineral substances with a lesser calcium content. This, in turn, could lead to a decreased toughness in the old dentin group.