**4. Discussion**

Laser-assisted treatment has some advantages compared to traditional surgical techniques.

The main advantage common to all types of laser treatment is photocoagulation of lymphatic, hematic and nerve endings thus giving less intraoperative bleeding, less oedema and post-intervention pain. The placement of sutures is rarely necessary.

The diode laser is not indicated as the main laser for soft tissue surgery but its versatility of use led us to choose it for the study.

The diode laser is a semiconductor laser and exists in different wavelengths: from 980 nm that has greater cutting capacity and fibres that do not need to be activated, up to 810 nm which has a more biostimulatory capacity. This laser therefore has dual functionality [14,17,20]. The protocol used in this study aimed to exploit both the cutting capacity and the biostimulatory capacity; in particular, the latter was always used after the surgical phase. This helped to further reduce postoperative discomfort, oedema and to have a better, faster healing without retractable cicatrized outcomes or functional outcomes. Studies report that the laser beam activity on myofibroblasts result in reduced proliferation which results in minor dysfunctional outcomes and furthermore impacts on vessel proliferation, the synthesis of collagen and the anti-inflammatory capacity. These effects are closely related to the laser settings (fibre, power, exposure time). The best results, in terms of healing, occur with a fluency of about 4 J/cm<sup>2</sup> [21–24].

Some studies refer to the use of lasers to treat leukoplasic and hyperkeratotic lesions but the various studies do not report the same parameters with regard to power settings, exposure time and application distance and fibre diameter [9,10,25–27].

Consequently, in our study it was difficult to compare our parameters with previously reported in the literature, because of a non-homogeneous number of terms of comparison.

Other studies reported the evaluation of the recurrence rate and the rate of malignant transformation [1,7,23,28], however no mention about the efficacy of the treatment in the short term, sustainability or invasiveness was reported.

Our protocol involves the use of the diode laser in pulsed mode with a Ton and a Toff of 110−<sup>3</sup> s and a frequency of 5000 Hz. These settings were chosen in order to allow, during the emission phase of the ray, a thermal relaxation time corresponding to the Toff, which resulted in diminished overheating of tissues.

The pulsed mode was chosen in order to avoid the harmful overheating of the tissue already mentioned above; this mode allowed us to alternate a lower average power, that corresponded to the percentage of Ton in the period, with a high power peak equal to the maximum power set. In our protocol the percentage of Ton in the period is 50%, thus setting an average power of 0.9 W and a peak power of 1.8 W. With these settings anaesthesia was not required to perform the treatment unlike all the other protocols found in literature.

In order to prevent the treatment from becoming unsustainable for the individual, it was decided to irradiate the tissue for a relatively short time (about 1 min) and then leave 30 s of relaxation. This was a variation of what was found in the literature where the irradiation time was on average over 8 min [8,9,23,29].

To evaluate the effectiveness of laser-assisted treatment, the following parameters and their behaviour were taken into account during the observation period:


The treatment was defined effective if there was a decreasing trend of all the parameters listed above, partially effective if only some parameters reduced or not effective if, compared to the beginning of the observation, the parameters have remained unchanged.

In order to evaluate the efficiency of the treatment and its sustainability for the patient, the pain and discomfort perceived during the irradiation of the lesion were considered. Treatment is considered sustainable for the patient if these parameters show medium-low values and have a decreasing trend during the four weeks of observation, if this does not happen the treatment is considered unsustainable for the patient.
