Ultrashort Pulsed Laser-Assisted Direct Restoration Of Human Enamel Using 3D Printable Biocomposite

Restorative dentistry encounters the prevalence of secondary caries due to the formation of marginal defects during tooth restoration. The present study proposes a dual-wavelength ultrashort-pulsed laser system for the direct restoration of damaged enamel to overcome marginal defects. The 2D finite element (FE) laser-ablative model is developed for studying the laser-tissue interaction. The laser-ablated cavities (rectilinear and circular) are prepared on human enamel using 800 nm, Ti:Sapphire femtosecond (fs) laser (100 fs, 1 kHz, 1 mm s⁻¹) at average laser power of 200 mW. Subsequently, the cavity is filled with 3D printed biocomposite (65 wt.% of 3D-printing resin and 35 wt.% of Ce³⁺-ion doped hydroxyapatite) and photocured using 405 nm laser. Further, the postprocessing procedure is carried out using fs laser to remove excessive filler materials and improve surface finish at sub-ablation threshold of enamel. The surface morphology, chemical compositions, mechanical and interfacial properties of restored enamel surface are evaluated. The in vitro evaluation study confirmed that the enamel restored with fs laser and 3D printing biocomposite is mechanically and chemically robust for withstanding oral challenges. The proposed method of restoring damaged enamel opens an opportunity for a range of precision restorative dentistry procedures including caries and tooth augmentation.