Imaging carious dental tissues with multiphoton fluorescence lifetime imaging microscopy

Area of Science:

• Biomedical Optics
• Dental Imaging
• Materials Science

Background:

• Noninvasive imaging of dental tissues is crucial for early diagnosis of caries.
• Conventional methods often lack specificity or require sample preparation.
• Multiphoton microscopy offers label-free imaging capabilities for biological tissues.

Purpose of the Study:

• To investigate the use of multiphoton excitation for noninvasive imaging of normal and carious dental tissues.
• To differentiate between sound and demineralized dental tissues using multimodal optical signals.
• To assess the potential of fluorescence lifetime analysis for caries detection.

Main Methods:

• Utilized multiphoton microscopy with second harmonic generation (SHG), autofluorescence (AF), and fluorescence lifetime analysis (FLA).
• Imaged normal and carious human dental tissues without exogenous labeling.
• Correlated optical findings with micro-computed tomography (micro-CT) for demineralization assessment.

Main Results:

• Collagen in dentin showed a strong SHG response.
• Autofluorescence from dentin and enamel revealed detailed morphological features like tubules and rods.
• Carious tissues exhibited significantly reduced autofluorescence lifetime compared to sound tissues, correlating with demineralization levels.

Conclusions:

• Multiphoton imaging provides label-free, high-resolution visualization of dental tissue microstructure.
• Autofluorescence lifetime analysis is a sensitive method to differentiate between sound and demineralized enamel and dentin.
• Two-photon excited fluorescence lifetime imaging shows promise as a tool for diagnosing and monitoring dental caries.