Quantitative fluoride imaging of teeth using CaF emission by laser induced breakdown spectroscopy

Area of Science:

• Analytical Chemistry
• Materials Science
• Dental Research

Background:

• Fluoride is crucial for dental health, but its distribution in teeth as a biomarker for exposure is challenging to quantify.
• Laser-Induced Breakdown Spectroscopy (LIBS) is a sensitive technique for elemental analysis in solids.
• Teeth, being calcium-rich, offer a suitable matrix for LIBS analysis of fluoride.

Purpose of the Study:

• To develop and validate a quantitative method for imaging fluoride distribution in teeth using LIBS.
• To investigate the relationship between fluoride exposure dose and tooth fluoride concentration.
• To assess the applicability of the developed method for epidemiological studies on early-life fluoride exposure.

Main Methods:

• Utilized molecular emission of calcium fluoride (CaF) at 530 nm via LIBS.
• Developed calibration standards using hydroxyapatite pellets doped with fluoride.
• Optimized LIBS conditions, including argon flow (1 L min⁻¹), and established a calibration curve (0-400 μg g⁻¹) with a limit of detection (LOD) of 18 μg g⁻¹.

Main Results:

• The LIBS method successfully quantified fluoride distribution in teeth.
• A rat model showed increased tooth fluoride levels with higher fluoride exposure doses.
• Human teeth from fluoridated water regions exhibited higher fluoride concentrations in dentine compared to those from non-fluoridated regions.

Conclusions:

• LIBS analysis of CaF molecular emission provides a quantitative method for fluoride distribution imaging in teeth.
• This technique can differentiate fluoride levels based on water fluoridation status.
• The developed method holds potential for epidemiological research on critical windows of early-life fluoride exposure.