Structural modifications induced in dentin by femtosecond laser.

Area of Science:

• Biomaterials Science
• Dental Materials
• Laser Physics

Background:

• Understanding laser-tissue interactions is crucial for developing precise dental treatments.
• Investigating ultrafast laser effects on dentin is essential for novel dental ablation techniques.

Purpose of the Study:

• To investigate the structural and chemical modifications in dentin induced by ultrafast laser ablation.
• To characterize the ablation surface morphology and composition at varying laser fluences.

Main Methods:

• Utilized a Yb:KYW chirped-pulse-regenerative amplification laser system (560-fs pulse duration, 1030-nm wavelength).
• Applied fluences ranging from 2 to 14 J/cm², at a 1-kHz repetition rate and 5 mm/s scanning speed.
• Characterized ablation surfaces using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).

Main Results:

• Low fluence (2 J/cm²) resulted in irregular morphology with exposed tubules and no thermal effects.
• Higher fluences (7 and 14 J/cm²) produced a weakly adherent layer of amorphous calcium phosphate debris.
• Ultrasonication easily removed debris, revealing a surface similar to low-fluence ablation.
• Dentin composition remained largely unchanged, indicating minimal structural modification.

Conclusions:

• Ultrafast laser ablation within the studied fluence range does not significantly alter dentin's structure or chemical composition.
• Collagen's preferential decomposition by laser radiation appears to be the primary ablation mechanism.
• The findings support the potential of ultrafast lasers for precise dentin modification with minimal thermal damage.