**7. Clinical aspect of MRONJ**

To diagnose medication related osteonecrosis of the jaws the following criteria must be filled:


Medication-related osteonecrosis significantly impairs the quality of life of the patient and represents problems with speech, chewing, swallowing, feeding, often there is pain in the swollen mucosa, as well as chronic sinusitis [3]. In almost 94% of cases of medication-related osteonecrosis, exposed bone is present [56]. It is also the main feature of osteonecrosis (**Figure 1**). Variations can be different, from the small exposed edges around the empty alveoli all the way to complete involvement of one or both jaws [57]. We often find next to the exposed bone and signs of inflammation of the surrounding soft tissues that present as swelling that may or may not be purulent. The most lesions are asymptomatic, and when the patient develops pain,

**Figure 1.** *Clinical appearance of MRONJ-exposed bone (Zometa).*

**Figure 2.** *Spontaneous bilateral mandibular fracture (Aredia).*

we often find signs of acute inflammation in the surrounding tissue. In two-thirds of cases, medication-related osteonecrosis is found in the lower jaw [58]. The reason for this is a thinner mucosa than in the upper jaw and poorer blood supply to the lower jaw. Patients suffering from malignant diseases are most predisposed to MRONJ so it is very important to estimate whether the symptoms of progression are consequences osteonecrosis itself or are symptoms of secondaryism. After removal of the necrotic part of the bone, it is recommended to send materials for pathohistological analysis to determine the persistence of necrosis or some other lesions.

## **7.1 The course of the disease**

The course of the disease itself can vary. Lesions can be limited and at dormancy stage or can spread to surrounding structures. MRONJ can spread all the way to the mandibular canal or maxillary sinus. In such cases, there are symptoms such as numbness, sinus infection and even the formation of oroantral communication. By spreading necrotic lesions it can also lead to pathological fractures of the jaw, which are serious, therapeutic and functional problems. Pathological fractures (**Figure 2**) are not common, they occur in 3% of patients who are treated from MRONJ [3].
