Tumor-induced hypophosphatemic osteomalacia caused by a mesenchymal tumor of the mandible managed by a segmental mandibulectomy and microvascular reconstruction with a free fibula flap.

BACKGROUND: Tumor-induced osteomalacia is a rare paraneoplastic syndrome in which patients develop hypophosphatemia and osteomalacia. METHODS AND RESULTS: Here, we report a unique case of a 42-year-old man who presented to our institution with a 1-year history of pain in his ribs, hips, lower back, and feet. Radiologic examination revealed a decrease in bone density and multiple insufficiency fractures. Laboratory evaluation revealed hypophosphatemia, low serum 1,25 dihydroxy vitamin D3 , and elevated fibroblast growth factor 23 (FGF23). A positron emission tomography/CT scan showed increased uptake in the right mandibular third molar region. Panoramic radiography and CT scanning showed a lytic expansile bone lesion. A mandibular bone biopsy revealed a mixed connective tissue tumor. A right segmental mandibulectomy was performed, followed by microvascular reconstruction. The resection was confirmed by normalization of serum phosphate and FGF23. CONCLUSION: Successful management of this condition was achieved, with complete surgical resection of the tumor and reconstructive surgery.

Retentive strength and marginal discrepancies of a ceramic-reinforced calcium phosphate luting agent: An in vitro pilot study.

STATEMENT OF PROBLEM: Information on the properties of a relatively new luting agent with a unique formulation (ceramic-reinforced calcium phosphate) is limited. PURPOSE: The purpose of this in vitro study was to compare the retentive strengths and marginal discrepancies of a ceramic-reinforced calcium phosphate luting agent (CM) with a self-adhesive resin luting agent (RX) and to determine and compare the mode of failure of dislodged cemented copings. MATERIAL AND METHODS: Forty extracted human molar teeth were prepared to receive zirconia copings. After cementation, the specimens were divided into 4 subgroups (n=10): CM A (axial loading), CM OA (off-axis loading), RX A (axial loading), and RX OA (off-axis loading). For each subgroup, 9 of the specimens received experimental treatment (thermocycling and dynamic loading), and the tenth received no experimental treatment. Eight copings were pulled off in a universal testing machine (MTS Insight; MTS). The ninth specimen was treated experimentally but was not pull tested. The marginal discrepancy and the dentin interface of the specimens that were not pull tested were analyzed with scanning electron microscopy and energy dispersion spectroscopy. The mode of failure of the dislodged copings was also subjectively evaluated. RESULTS: The mean retentive strengths were 5.92 MPa for CM A, 5.81 MPa for CM OA, 5.75 MPa for RX A, and 5.69 MPa for RX OA. The marginal discrepancy recorded for both CM and RX ranged from 30 to 45 µm, (mean, 36 ±4.6 µm). Energy dispersion spectroscopy analysis showed the presence of calcium, phosphorus, silicon, and aluminum for the CM marginal discrepancy and the presence of aluminum in the dentinal tubules adjacent to the CM. Calcium and phosphorus were detected in lesser amounts adjacent to the RX marginal discrepancy. The mode of failure for CM was primarily adhesive to the tooth preparation, and, for RX, the failure mode was predominantly adhesive to the coping. CONCLUSIONS: CM had statistically significantly higher mean retentive strength compared with RX. Subgroups loaded axially had statistically significantly higher retentive strengths compared with those loaded off axis.