This is an interventional prospective randomized clinical trial (RCT) in parallel groups. The sample size is 74 patients who were randomly divided into two groups depending on the surgical intervention used. First group - patients who underwent surgery to excise the affected oral mucosa with a fiber laser with a wavelength of 1.94 micrometers (LSP-IRE- Polyus, Moscow, Russia). Second group - patients who underwent surgery using the traditional scalpel technique (No. 15C). At the examination stage, patients were referred for evaluation of interferon status according to the following indicators: biological activity of serum interferon (IFN), spontaneous IFN, IFN-alpha/beta, IFN-gamma.

In the postoperative period the dynamics of postoperative epithelialization, the severity of edema, hyperemia and pain syndrome were evaluated. Also, the postoperative material was sent for a molecular genetic study of HPV infection by PCR diagnostics and pathohistological examination followed by immunohistochemical analysis to determine the expression of oncoproteins p16 and p53.

The aim of this study is to improve the diagnosis and treatment of patients with oral epithelial dysplasia (OED) through the use of laser technologies and monitoring of interferon status, human papillomavirus invasion and oncoprotein expression. Examination and treatment of patients will be carried out on the basis of the Department of Surgical Dentistry of the Borovsky Institute of Dentistry of Sechenov University. The object of the study will be patients with oral potentially malignant diseases with signs of epithelial dysplasia. All patients will be randomly divided into two groups depending on the surgical procedure. In the first group (n=37), areas of the affected oral mucosa will be excised by radiation from a fiber laser with a wavelength of 1.94 micrometers. Patients in the second group (n=37) will undergo surgery using the traditional scalpel technique (No. 15C). The groups will be comparable in terms of gender and age characteristics. Patients will be divided into two groups by random sampling with the same opportunity to receive treatment using a high-intensity laser and a surgical scalpel.

Patients of the first group will undergo excision of the affected oral mucosa within healthy tissues using a fiber laser with a wavelength of 1.94 micrometers in a pulsed-periodic mode with a pulse duration of 100 ms and a pause duration of 100 ms, with a power of 2.5-3.0 watts. The impact on the fabric will be carried out with a freshly split end of the optical fiber after its preliminary activation by short-term contact with a wooden spatula. With a defocused 1.5-watt coagulation laser beam, the wound surface will be treated non-contact until a coagulation film, a "laser bandage," is formed that will cover the entire postoperative area, thus achieving complete hemostasis.

In patients of the second group, excision of the affected oral mucosa will be performed with a scalpel No. 15C within healthy tissues, followed by suturing the surgical area or closing the wound surface with an iodoform swab, fixed sutures.

Postoperative material in both groups will be sent for pathohistological examination. In the postoperative period, it is necessary to prescribe standard antibacterial and anti-inflammatory therapy in combination with the use of local antiseptics for daily care in the early postoperative period.

Inclusion Criteria:

1. The patient's written informed consent to participate in the study;
2. Men and women aged 18-80 years;
3. Verified diagnoses K 13.2 "Leukoplakia and other changes in the oral epithelium", L 43 "Lichen planus" with pathohistological signs of epithelial dysplasia.
4. Patients who, after conservative treatment of lesions of the oral mucosa, have not achieved a therapeutic effect and have indications for surgery.

Non-inclusion criteria:

1. Patients who have achieved the therapeutic effect of the disease after conservative treatment;
2. Patients who have symptoms of malignant transformation and who could not / did not want to make all necessary visits to the doctor;
3. Pregnant women and during lactation, women who planned pregnancy during this study.

Exclusion Criteria:

1. Patient's refusal to continue participating in the study;
2. Pregnancy;
3. The onset of an exacerbation of concomitant pathology;
4. Allergic reaction to medications used;
5. A change in the state of health that, in the researcher's opinion, prevents the patient from continuing to participate in the study.