Effects of femtosecond laser on hard dental tissues: A scoping review

Traditional tooth preparation can cause patient discomfort, thermal damage to tissues, and occupational health risks for clinicians. Laser-based techniques, particularly femtosecond lasers, offer an alternative due to precise, non-invasive treatment without the thermal and mechanical drawbacks. The objective of this study was to assess available evidence on the effects of femtosecond laser treatment on enamel and dentin. The study design included in vitro or in vivo studies on human teeth reporting on qualitative and quantitative parameters of laser-dental tissue interaction. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement. The review was registered in the Open Science Framework registry. A comprehensive literature search of PubMed, Scopus, EMBASE/Ovid, Cochrane Library, DARE, LILACS and Pro Quest databases was conducted by three reviewers until 10th January 2024 and then updated on 18th August 2024. Eligibility criteria included peer-reviewed articles published in English, focusing on human teeth, with available full text excluding reviews, conference proceedings and gray literature. The outcomes of interest were the quality of tooth preparation, surface characteristics, bond strength, thermal effects and damage to adjacent tissues with variables being laser parameters and tooth types. Methodological quality of studies was not conducted. The search yielded 48 articles after the removal of duplicates, irrelevant and non-retrievable articles. All were original in vitro studies investigating reporting on the outcomes of interest. Measurement methods included a range of microscopy, spectroscopy, optical coherence tomography, universal force testing and thermal imaging. Sapphire lasers were most commonly used with a wide range of parameters. Laser produced sharp-edged cavities with ablated surfaces free of melting (seen in approximately 10% of the craters), cracking, debris, with open dentinal tubules, increased wetting (Contact angle mean range 39.63 ̊(± 1.84 ̊) to 70.47 ̊(± 10.27 ̊) and roughness mean range 0.82 (± 0.05) to 4.20 (± 1.10)µm). Effects of femtosecond laser on bonding efficiency were inconsistent when compared to no treatment, conventional acid etching or Er:YAG laser. Femtosecond laser was shown to achieve precise tooth preparation with no or minimal thermal, mechanical and structural effects on adjacent tissue, however with variable bonding efficiency. Further research is needed to optimize laser parameters, investigate antibacterial effects, and establish long-term clinical outcomes and safety profiles.Date of registration: July 1st, 2024.Registration ID: OSF.IO/UQMNB.