Significance Traditional dental treatments utilize mechanical drills to remove surface tissue from the tooth through vibration. This makes it important for dentists to be highly skilled to avoid unnecessary damage to healthy tissue. Additionally, the vibration and noise generated during the procedure can cause significant physical and psychological discomfort for patients, which may negatively affect the treatment efficacy. With the development of laser technology, the dental field began adopting traditional continuous-wave and long-pulse lasers as alternatives to mechanical tools. However, these schemes still carry risks of mechanical damage, such as micro-cracks in the tooth, as well as thermal damage, including carbonization and pulp injury. Femtosecond lasers, with their ultra-short pulse duration and extremely high peak power, achieve cold ablation mediated by plasma when interacting with dielectric materials. Compared to traditional lasers, they significantly reduce thermal effects. By addressing the damage risks linked to traditional lasers, the application of femtosecond lasers in dental tissue ablation represents an important advancement for dental instrument technology.
Progress The cold ablation characteristic of femtosecond lasers endows them with immense application potential in dental treatment. Significant research has already emerged in areas such as caries treatment and prevention, tooth restoration and implant cavity preparation, and surface modification of materials, as shown in Fig.1, confirming the feasibility and superiority of femtosecond lasers as a new tool in dentistry. In the treatment of dental caries, by adjusting parameters like repetition rate, wavelength, and power of the femtosecond laser, it is possible to selectively and efficiently remove carious tissue while avoiding collateral damage to healthy tissue. Furthermore, it can be combined with necessary reagents to activate and promote the remineralization of tooth structure, thereby reducing the tooth's susceptibility to caries and achieving caries prevention. Additionally, the femtosecond laser can serve as an excitation source for spectroscopic systems, as shown in Fig.3, enabling the real-time identification and precise removal of carious tissue. During tooth restoration, the femtosecond laser can prepare high-quality cavities with superior precision compared to traditional mechanical drills, reducing secondary caries caused by marginal defects. Simultaneously, the femtosecond laser can induce micro- and nano-structures on the restored tooth surface, altering the roughness and wettability of the cavity walls. This significantly enhances the bonding strength and long-term stability between the restorative material and the tooth, preventing problems such as pulpitis, secondary caries, and postoperative sensitivity caused by poor adhesion between the filling material and the prepared cavity walls. For dental implant surgery, traditional methods of implant cavity preparation not only depend critically on the surgeon's skill for precision but also carry the risk of damaging bone tissue through vibration and heat. In contrast, the femtosecond laser offers the advantage of high precision and cold ablation, enabling the process with significantly superior precision compared to traditional methods, thereby reducing vibration and thermal damage during the procedure. By controlling laser parameters and scanning paths, the femtosecond laser can be used to precisely fabricate various micro- and nano-structures, such as LIPSS, grooves, and grids, on the surfaces of titanium-based and zirconia-based implants. This allows for the precise control of surface topography, wettability, and chemical state, significantly enhancing the osseointegration capacity and improving the antibacterial properties of the implant. Beyond the fields mentioned above, the feasibility of femtosecond lasers as tools for other dental procedures like periodontitis treatment and root canal disinfection, as well as subgingival calculus detection, has been confirmed by numerous studies. Moreover, new research is gradually emerging in areas such as the mechanisms and novel phenomena of the interaction between femtosecond lasers and biological tissues, the application of new types of femtosecond lasers in dental surgery, and the integration of femtosecond lasers into dental medical instruments and robotics. These developments are stimulating both clinical adoption and research into femtosecond lasers, extending their impact from dentistry to the broader biomedical arena.
Conclusions and Prospects Despite the significant advantages of femtosecond lasers in dental treatment, several challenges remain. Firstly, treating different dental conditions requires the laser to interact with various tissues like carious tissue, healthy hard tissue, and surface biofilms. This necessitates targeted adjustments of laser parameters—including wavelength, energy density, and scanning speed—to determine the optimal parameter combinations. There is a need to establish standardized protocols for applying femtosecond lasers across various dental treatment areas to achieve better therapeutic outcomes. Additionally, the long-term durability of surface modifications on restorations and implants treated with femtosecond lasers requires more extended studies for validation. Procedures such as the removal of carious tissue and root canal disinfection using femtosecond lasers need to progress from extensive in vitro experiments to in vivo and clinical trials. As clinical applications continue to be validated, femtosecond laser-based dental technologies are expected to evolve toward intelligence and automation. The development of integrated micro-robotic laser systems for real-time diagnosis and treatment could address issues such as limited surgical visibility and the high skill requirements for laser operation. By incorporating material recognition, AI assistance, and real-time feedback for optimizing laser parameters, automated systems could achieve optimal treatment outcomes. Furthermore, verifying the biosafety of femtosecond lasers will expand their clinical applicability. As the cost of femtosecond laser systems gradually decreases, it will lay a foundation for the widespread adoption of femtosecond lasers in dental treatment.
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