Er:YAG laser treatments on dentine surface: micro-Raman spectroscopy and SEM analysis

Objective. This study aims to give an insight into the chemical and structural modifications occurring in laser treated dentine surface, as a tool to plan a new class of dental materials specific for the dental restoration when laser technologies are used. For this purpose the effect of Er:YAG (Erbium–Yttrium Aluminium Garnet) laser treatments on human dentine surface has been investigated. Methods. The dentine surface of periodontally compromised teeth cut along the main axis was treated in vitro with laser pulses having the same energy but time duration varying in the range of 100–1000 μs. The chemical characteristics and the morphology of the laser treated surface have been studied with micro-Raman spectroscopy (μ-RS) and scansion electron microscopy (SEM). Results. The μ-RS and SEM analysis of laser treated teeth have been compared with those of surfaces treated with conventional mechanical methodologies. The laser pulse time duration affects the surface morphology and the chemistry of dentine, mainly of organic components. The effects have been monitored by analysing the C–H group stretch vibration mode of the μ-RS spectrum. Conclusion. The laser treatment can determine different chemical microenvironments on the treated dentine surface, depending on the time duration of laser pulse used. Treatments with very long pulse results in a the dentine surface very similar to that obtained with a conventional mechanical drill, while with very short laser pulses a strong modification of the dentine organic components has been observed.