An 8-year-old boy has thickening of the lower jaw body in the area of the 83rd, 84th and 85th teeth. In the given area a rounded painless tissue protrusion can be detected; the Dupuytren's symptom is positive. Deciduous teeth are intact. X-ray image of the lower jaw made in lateral projection shows the focus of bone destruction with clear margins in the area of the 83rd, 84th and 85th teeth. The 44th tooth follicle is shifted down in distal direction, the crown is projected on the destruction focus. What is the clinical diagnosis?