Maxillomalar Monoblock Removal, Reshaping, and Reinsertion in Paget’s Disease: 15-Year Follow-Up

Abstract

Paget’s disease (PD) was described at the end of the 19th century “as osteitis deformans.” The disease consists of chronic alteration of skeletal metabolism. Bone remodeling processes (resorption-neoformation) are increased. Its etiology is still unknown, although lines of investigation focus on the theory of viral infection, because paramyxovirus nucleocapsids have been detected in osteoclasts (rubella, RSV, etc). Immunohistochemical and hybridization studies support this theory. As a result of the high rates of bone formation and resorption mechanisms, a series of biochemical alterations appear, such as increased alkaline phosphatase and calcium serum concentrations (anabolism) and increased hydroxyproline and hydroxylipine excretion in urine (catabolism) as well as hypercalciuria. The disease affects adults in their 40s and 50s. There may be a monostotic or polystotic pattern, and in the latter case, it is very common to have involvement of the pelvis, lumbar, and sacral region, sometimes with a characteristic outward bowing of the femur and anteroposterior bowing of the tibia. Clinical signs and symptoms include joint pain, neurovascular compression, pathologic fractures, and bone deformity. The location of lesions often shows a highly anarchical pattern, as well as evolution of radiologic findings with alternating osteolytic, sclerotic, and mixed phases. Monostotic lesions may be confused on radiography with neoplastic processes. Malignant degeneration is uncommon. In the face, the maxilla is more frequently affected than the mandible and the common consultation is due to lack of fit of dental prostheses. Histologically, there are 3 phases that can be differentiated in PD: 1) an initial phase characterized by rapid bone resorption. The number of osteoclasts is increased; they are much larger and localized in irregular resorption cavities. The bone marrow is replaced by a fibrous vascular tissue. 2) In an intermediate phase, compensatory increase in bone formation occurs, and there is a great number of osteoblasts forming irregular trabeculae of woven bone. The functional arrangement of the trabeculae is markedly altered and fibrous vascular tissue continues to replace the bone marrow. 3) In a late phase, the chaotic remodeling is less prominent. Trabeculae are very thickened with intersecting cement lines that form a “mosaic” pattern. Woven bone has been converted to lamellar bone, and the marrow tissue reappears. The disease is diagnosed through clinicoradiologic studies, radionuclide bone scanning, serum and urine laboratory analysis, and histopathologic tests .The disease is essentially treated medically with bone resorption inhibitors (bisphosphonates and calcitonins) that improve the altered bone metabolism and the biochemical pattern. Surgical treatment is limited to nerve decompression, arthroplasty, and correction of deformities.