In the last decades, lasers have become widely used in oral surgical procedures gradually. Based on their different functions, lasers in this field are categorized into hard tissue lasers and soft tissue lasers.

Lasers like the Er:YAG laser, operating at 2940 nm, and the Er,Cr:YSGG laser, with a wavelength of 2780 nm, exhibit strong absorption by water and hydroxyapatite. This property allows them to effectively cut and vaporize both soft and hard tissues. Given that their wavelengths are close to the water absorption peak (∼2950 nm), they achieve high absorption rates in water, minimizing thermal damage to surrounding tissues. However, these lasers are less effective in achieving hemostasis [[1], [2], [3]]. The CO₂ laser, emitting at 10,600 nm, is a gas laser that also demonstrates strong absorption by water and hydroxyapatite. Its small beam spot and high power density make it suitable for surgical procedures on soft and hard tissues, with the added benefit of effective hemostasis. Nevertheless, it poses a higher risk of thermal damage to adjacent tissues [4]. The Nd:YAG laser, with a wavelength of 1064 nm, is a solid-state laser composed of neodymium-doped yttrium aluminum garnet (Nd:YAG) crystals. It is efficiently absorbed by hemoglobin and melanin, enabling it to perform coagulation and cutting on soft tissues with good hemostatic outcomes. However, due to its deep tissue penetration, it can inadvertently damage surrounding tissues, such as causing thermal injury.

The diode laser operating within a wavelength range of 800–980 nm, exhibits a certain degree of absorption by water, melanin, and hemoglobin. It has been demonstrated to be the most efficient laser in oral soft tissue surgery, offering several advantages over traditional surgical techniques. These benefits include its hemostatic properties, bactericidal effects, anti-inflammatory effects, a notable reduction in postoperative pain and beneficial biological effects [5,6]. The diode lasers exert their effects by being absorbed by oral soft tissues at specific wavelengths, inducing a photothermal effect and the biostimulation effect, that is, during laser irradiation, the photon energy is transformed into thermic energy in oral tissues where absorption occurs producing thermal changes that result in tissues vaporization and ablation, along with simultaneous blood vessel sealing. Furthermore, the residual energy left over from the cutting process serves as a biostimulant for the cells, minimizing postoperative pain and inflammation. This increased energy intake enhances mitochondrial metabolism and promotes cell regeneration, thereby enabling a smoother and faster recovery process [[7], [8], [9], [10], [11], [12]].

In recent years, the rapid evolution of technology has led to the increasing incorporation of various laser types into the biomedical domain. A thulium fiber laser has garnered significant attention due to its remarkable photoelectric conversion efficiency, fiber coupling efficiency, and balanced absorption characteristics by both water molecules and hemoglobin. The thulium fiber laser represents a novel gain fiber configuration, achieved through the doping of thulium ions into a large mode area silica-based quartz fiber. This system utilizes direct pumping by a cladding semiconductor laser and wavelength selection via narrow linewidth fiber gratings to enable laser emission around the 1940 nm water absorption peak. It supports both high-power continuous-wave (CW) laser operation and high-peak-power pulsed laser emission. Since 2005, lasers operating within this wavelength range have been granted FDA approval for clinical trials.

Currently, this thulium fiber laser has found extensive application in urology, particularly in procedures such as prostatectomy and urinary tract lithotripsy [[13], [14], [15], [16], [17]]. Additionally, thulium fiber lasers are being explored for use in surgical treatment research in fields such as otolaryngology, hepatobiliary surgery, and neurosurgery [[18], [19], [20], [21]]. Regarding soft tissue surgery: The pioneering in vitro study by Fried et al. [22] utilized a canine prostate model to assess the tissue-incising capabilities of the thulium fiber laser. Li’s et al. findings revealed that when employing the thulium fiber laser for renal tissue resection in animals, a pulsed mode coupled with low power settings facilitated not only efficient soft tissue excision but also rapid hemostasis, all while mitigating thermal damage [23]. In a separate in vitro investigation, Zywicka et al. [24] explored splenic incision and partial resection procedures, discovering that both the thulium fiber laser and the diode laser demonstrated comparable efficacy in terms of cutting precision and hemostatic control. Notably, the thulium fiber laser excelled in minimizing the extent of thermal injury.

Researchers have also explored the application of Thulium lasers in oral soft - tissue surgical procedures. Güney et al. [25] employed a 1940 nm Thulium fiber laser for in - vitro incision of ovine tongue tissue. The results showed that the laser could cut and ablate the tissue efficiently. And with higher laser power and more passes, the cutting depth grew linearly, up to a maximum of 1.2 mm. Kang et al. [26] performed tonsillectomies on 22 patients, comparing the use of Thulium lasers with traditional electrosurgery. Their findings indicated that the 1940 nm Thulium laser was both safe and feasible for tonsillectomy. When compared to conventional electrosurgery, patients who underwent the Thulium - laser procedure experienced significantly less early postoperative pain and had reduced tissue damage.

Given the comparable absorption behavior of oral soft tissues to thulium lasers as seen with diode lasers, thulium lasers hold promise for applications within the oral field.

However, there are limited studies on the application of thulium fiber lasers in oral clinical practice. Therefore, this clinical research utilizes thulium lasers to treat oral soft tissue diseases, with diode lasers serving as the control group, to evaluate the effectiveness of thulium lasers in such conditions. The null hypothesis (H₀) was that there would be no significant difference in coagulation efficacy, postoperative pain, or healing condition between the thulium laser and diode laser groups for oral soft tissue surgeries.