Comparative clinical study of phosphorous-necrosis and medical-related osteonecrosis of the jaws

Abstract

Abstract Background: Phosphorous necrosis of the jaw (PNJ) shares similar clinical and pathological features to medical-related osteonecrosis of the jaw (MRONJ). This study aims to compare the similarities and differences between PNJ and medical-related osteonecrosis of the jaw (MRONJ) in terms of clinical and pathological features, and to provide a theoretical basis for the clinical diagnosis and management of PNJ. Material and Methods: A retrospective analysis assessed clinical differences among 38 PNJ patients and 31 MRONJ patients diagnosed and treated between January 2009 and October 2022. Pathological alterations in bone tissue were assessed using EDS, H&E, Masson and TRAP staining on five specimens from both MRONJ and PNJ cases, and immunohistochemistry was used to determine the expression levels of OPG, RANKL, and Runx2. The mandibular coronoid process was removed from individuals with temporomandibular joint ankylosis as control. Results: CBCT imaging indicated necrotic bone formation in block, strip, or plaque shapes. EDS analysis revealed that the calcium/phosphorus ratio in the bone tissue of PNJ and MRONJ was significantly lower than that of the control group (P<0.05). Additionally, staining indicated reduced osteoblast counts, disrupted bone trabecular structure, and decreased collagen fiber content in the bone tissues of PNJ and MRONJ. Immunohistochemistry revealed that RANKL expression was significantly lower in MRONJ compared to PNJ and control groups (P<0.05). Conversely, Runx2 expression was significantly higher in PNJ than in MRONJ and control groups (P<0.05), with no significant difference in OPG expression. Conclusion: PNJ and MRONJ exhibit comparable clinical manifestations and pathological traits, although disparities may exist in their underlyingexhibit comparable clinical manifestations and pathological traits, although disparities may exist in their underlying molecular mechanisms.