## 1 Introduction  
Numerous articles have recently been published in different countries describing atypical lesions of the jaw bones related to treatment with medications based on phosphorus or analogs of its compounds, particularly bisphosphonates (BP) [1; 2; 3; 4; 5; 6]. According to various authors, the number of medication-related osteeonecrosis cases has increased from single clinical cases to a 27% occurrence in the practice of dentistry when using so-called bisphosphonate therapy [7; 8]. It has been found that, in addition to bisphosphonates, some other classes of drugs (cytostatics, hormones, etc.) are also able to induce specific changes in the bones of the jaw, which often manifest clinically as osteeonecrosis. Thus, a more general, separate condition was formulated: medication-related osteeonecrosis. Medication-related osteeonecrosis of the jaw is characterized by pathognomic symptoms that distinguish it from other inflammatory, dystrophic, and iatrogenic diseases of the orofacial area; therefore, it is reasonable to separate it as an independent nosology that requires comprehensive study. The definitive pathophysiology of drug-associated osteeonecrosis is not clear yet. However, up-to-date articles examine modern theories of the pathogenesis of this nosology. The pathophysiology of the osteeonecrotic process in bone tissue is associated with patterns of metabolism and the effects of bisphosphonate drugs prescribed for osteoporosis or bone metastasis. In our article, we examined patients with various types of cancer. Changes in the jaws can occur due to impaired bone remodeling or increased suppression of bone resorption, inhibition of angiogenesis, persistent microtrauma, and the toxic effects of bisphosphonates on soft tissues. From the circulatory system, 20 to 80% of bisphosphonates are absorbed by the bone tissue, and the remainder is rapidly excreted in the urine. The level of bone remodeling of the jaw tissue is quite high; as a result, there is a greater accumulation of bisphosphonates in jaws, especially in the tissues of the lower jaw. Often, patients who are indicated for radical surgery are classified as AAOMS stage 3, and one of the most common complaints is numbness in the affected area. For example, a study by [PERSON] et al., 2018, found that Numb Chin Syndrome (NCS) is a consequence of drug therapy in patients with MRONJ. The results obtained indicate that numbness is a sign of necrosis; therefore, attention should be paid to this complaint, since this indicates a direct relationship between numbness as a diagnostic complaint and osteeonecrosis. Numb chin syndrome (NCS) or mental neuropathy (MN) may be the first sign of malignant neoplasm, but also a prodormal sign of MRONJ. Patients belonging to the main group in our study, also complained frequently of numbness in the affected area, which persisted before and after surgery. All of them were previously diagnosed with MRONJ stage 2 or 3 according to AAOMS. Up-to-date articles, including the studies of [PERSON] et al., [PERSON] et al., 2016; [PERSON] et al., 2016, show that odontogenic infection, as well as peri-implantitis, is a clear risk factor for the development of MRONJ. It is worth noting that dental practitioners are not sufficiently aware of the risk of osteeonecrosis of the jaw in patients treated with BP following oral interventions, which leads to errors in diagnosis and treatment. In particular, the exposure of bone tissue after removal is regarded as exostosis, a sharp edge of the socket, etc. Attempts to eliminate this condition using traditional methods of surgical treatment can aggravate the course of osteeonecrosis, leading to an acceleration in its spread, a deterioration in the patient's quality of life, and a deterioration in the prognosis of the disease [9; 10]. A specialist diagnosing medication-related osteeonecrosis of the jaw (MRONJ) should first rule out neoplastic bone infiltration and osteomyelitisitis within the framework of differential diagnosis.