## 1 Introduction  
The primary goals of root canal therapy are a sufficient reduction in bacteria and their by-products from the root canal system and the prevention of reinfection [1]. It is accomplished traditionally with a combination of mechanical instrumentation and irrigation with a disinfecting solution. However, the complexity of the root canal anatomy and the limited penetration depth of irrigation make it a challenge to achieve optimal results [2]. Reinfection of the root canal system causes root canal treatment to fail, and _Enterococcus faecalis_ (_E. faecalis_) is a facultative anaerobic Gram-positive bacteria that is frequently associated with recurrent root canal infections [3]. It has shown resistance to calcium hydroxide [4] and the ability to colonize 800-1000 \(\mu\)m into dentinal tubules, while sodium hypochlorite with the conventional method has been shown to only be effective by penetrating up to 300 \(\upmu\)m [5]. In order to overcome these limitations, irrigant activation methods such as sonic and ultrasonic activators are sometimes used, but achieving complete sterilization of the root canal system with these methods remains difficult [6]. To address this limitation, lasers have been suggested as an adjunct method to enhance endodontic treatment. When lasers come into contact with living tissue, they can produce various effects, depending on the wavelength and the optical properties of the irradiated tissue [7]. Er/YAG and Nd/YAG lasers have demonstrated the ability to reduce microorganisms [8] and remove the smear layer [9]. Previous studies [10,11] have shown that lasers as an adjunct therapy achieve more efficient bacterial elimination than traditional chemo-mechanical preparation due to their greater penetration into deep radicular dentin. Combined treatment with MBG-Ag and Er/YAG lasers not only contributes to bacterial reduction but also improves the mechanical properties of dentin through the formation of hydroxyapatite-like structures [12]. Furthermore, Er/YAG laser-assisted antimicrobial treatment has been explored as a means to enhance biofilm disruption and improve denitnal tubule disinfection [12,13]. In addition to biomaterial-based disinfection methods, the integration of optical fiber technology in antimicrobial light-based therapy has gained attention. However, the limitations of these techniques include undesirable thermal damage and morphological changes and ablations in the dentin structure in the case of inadequate energy levels and durations [14, 15, 16]. A recent study demonstrated that UVC LED at wavelengths of 265 nm and 280 nm effectively kills oral microorganisms within 30-90 s, showing potential as an alternative or adjunct to sodium hypochlorite (NaOCI) with its inherent limitations. This therapeutic approach is based on the principle that UVC, a source of bactericidal light energy, penetrates small microbial cells (0.5-2.0 \(\upmu\)m) and disrupts DNA transcription, translation, and replication by forming cyclobutyl pyrimidine dimers in the DNA structure [17]. The germicidal efficiency of UV light is strongest in the UV-C range, as the shorter wavelength possesses the ability to reach the DNA in the cytoplasm of smaller microbial cells, especially in the range of 255-280 nm [18]. Recently, advancements in light-emitting diode (LED) technology have led to the development of UV-C-range LEDs, which have been shown to be efficient in disinfection while using less power than other sources of UV energy [19]. Several studies have suggested its potential as an adjunct disinfection method for root canal treatments [17,20]. [PERSON] et al. [21] also reported that LED-UV on denture surfaces devitalizes bacteria without producing thermal damage on surrounding periodontal tissues, which presents an advantage over high-power lasers. The potential of combining antimicrobial biomaterials with advanced light-based technologies has been recognized; however, challenges remain in effectively integrating and optimizing these approaches for practical use in root canal disinfection.