Use of XRD and SEM/EDX to predict age and sex from fire-affected dental remains

Zapico S. Partners in Postmortem Interval Estimation: X-ray Diffraction and Fourier Transform Spectroscopy

The postmortem interval (PMI) is difficult to estimate in later stages of decomposition. There is therefore a need to develop reliable methodologies to estimate late PMI. This study aims to assess whether there is a correlation between changes in the mineral composition of human teeth and the estimation of PMI. X-ray diffraction (XRD) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy techniques were performed to address this challenge. Forty healthy human teeth obtained from odontological clinics were stored at different times (0, 10, 25, 50 years; N = 10/group). XRD and ATR-FTIR parameters related to the structure and composition of teeth were studied. Our results showed that the crystallinity index, crystal size index, mineral-to-organic matrix ratio (M/M) and carbonate/phosphate ratio (C/P) had the strongest association with PMI. For larger PMIs, there was a significant increase in crystallinity, crystal size and M/M ratio, while the C/P ratio showed a specific decrease with increasing PMI. According to our results, the parameters of crystallinity, crystal size, M/M ratio and C/P ratio can be considered highly accurate in determining a PMI of 10 years of data; crystallinity and mineral maturity can be considered useful in determining a PMI of 25 years; and crystallinity and mineral maturity can be considered highly accurate in determining a PMI of 50 years. A particular XRD index was identified as the most suitable parameter to estimate PMI: crystallinity. The joint use of XRD and ATR-FTIR analyses could be a promising alternative for dating human teeth.

The impact of remineralization agents on dental bleaching efficacy and mineral loss in bleached enamel

This study evaluated the effect of remineralization agents on bleaching efficiency, enamel mineral changes, and post-bleaching color stability. A total of 112 enamel-dentin blocks were prepared from bovine teeth. Following initial color measurements, separate treatment regimens were carried out as follows: negative control (no treatment); positive control (bleaching only); bleaching, then NaF; bleaching + NaF (mix); bleaching, then CPP-ACPF; bleaching + CPP-ACPF (mix); bleaching, then nHAP+F; bleaching + nHAP+F (mix). Color measurements were repeated after immersion in distilled water for 7 days, and again after staining with coffee solution for 14 days. The CIELAB-based whiteness index was used to evaluate bleaching efficiency, and the CIEDE2000 color difference formula for color stability. Chemical investigation was performed using scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction analyses. The experimental groups showed significant increases in whiteness compared to the negative control, and the staining after bleaching did not result in statistically significant differences between the groups. Energy dispersive spectroscopic analysis revealed that bleaching protocols had no impact on elemental levels as well as the ratio of Ca/P. The combined use of bleaching agents with remineralization agents did not affect bleaching effectiveness but also did not provide an additional contribution.

Efficacy of Rice Husk Nanosilica as A Caries Treatment (Dentin Hydroxyapatite and Antimicrobial Analysis)

OBJECTIVE

 Rice husk nanosilica has a porous, amorphous structure with a silica (SiO₂) surface. Silica interacts with calcium ions to form hydroxyapatite and can induce the formation of reactive oxygen species (ROS), which harm microorganisms. This research determines the effect of rice husk nanosilica on the increase in dentin hydroxyapatite and its antimicrobial effects against Streptococcus mutans.

MATERIALS AND METHODS

 We divided 27 dental cavity samples into three groups (n = 9). Group 1: normal dentin, Group 2: demineralized dentin, Group 3: demineralized dentin treated with rice husk nanosilica. The samples were analyzed using X-ray diffraction (XRD) to evaluate the formation of dentin hydroxyapatite. To analyze the viability of S. mutans after exposure to 2% nanosilica rice husk, we conducted an antimicrobial MTT assay.

STATISTICAL ANALYSIS

 The Kruskal-Wallis test evaluates the formation of dentin hydroxyapatite, and the t-test evaluates the viability of S. mutans.

RESULTS

 There was an increase in the amount of dentin hydroxyapatite after the application of rice husk nanosilica compared with the control group (normal dentin), and 2% rice husk nanosilica had an antimicrobial effect (p < 0.005) in the group exposed to it.

CONCLUSION

 Rice husk nanosilica can induce the formation of dentin hydroxyapatite and has antimicrobial effects.

Selected Spectroscopic Techniques for Surface Analysis of Dental Materials: A Narrative Review

The presented work focuses on the application of spectroscopic methods, such as Infrared Spectroscopy (IR), Fourier Transform Infrared Spectroscopy (FT-IR), Raman spectroscopy, Ultraviolet and Visible Spectroscopy (UV-Vis), X-ray spectroscopy, and Mass Spectrometry (MS), which are widely employed in the investigation of the surface properties of dental materials. Examples of the research of materials used as tooth fillings, surface preparation in dental prosthetics, cavity preparation methods and fractographic studies of dental implants are also presented. The cited studies show that the above techniques can be valuable tools as they are expanding the research capabilities of materials used in dentistry.