Mandibular reconstruction system reliability analysis using probabilistic finite element method.

The aim of this study was to design for mandibular reconstruction of large lateral defect with minimum target reliability with designated confidence interval under bite force range of 300 ± 102 N. The performance of the models has been evaluated by numerical analysis considering the uncertainty of input parameters. Computer-Aided design was used to develop the models of three designs according to the patient's anatomy and to achieve to near symmetry of the mandible. Stress-strength modeling was utilized for the probabilistic physics of failure analysis under assumption of a quasi-static load. Monte-Carlo simulation was also applied for probabilistic finite element analysis and reliability assessment. The sensitivity analysis of the models was developed to reflect the significance of the variables in the models. The deterministic stress analysis shows that the highest stress and the second maximum stress are 110 MPa and 85 MPa for cortical bone around the screws, respectively. Also, it is determined that the maximum plate stress of the titanium conventional plate model is 580 MPa. The reconstruction system success rate was improved in all models by observing the anatomy of the patient's mandible in the plate designs by computer-aided design and additive manufacturing techniques. Based on the results, the reliability of plate strength and pull-out screws strength are 99.99% and 96.71% for the fibula free flap model, respectively, and 99.99% and 94.17%, respectively, for the customized prosthesis model. Probability sensitivity factors showed that uncertainty in the elastic modulus of the cortical bone has the greatest effect on the probability of screws loosening.

Quality of life in patients with oral cancer treated by different reconstruction methods as measured by the EORTC QLQ-H&N43.

This was a prospective clinical study and the purpose was to assess the quality of life (QoL) as the primary endpoint for patients given prospective treatment for cancer of the oral cavity that required reconstruction using various reconstruction methods in Azerbaijan. All patients who were operated on during the year 2017 to 2018 were entered into the study. Quality of life was assessed six months postoperatively using the European Organization for Research and Cancer Treatment Core Cancer Quality of Life (EORTC QLQ-C30) and the Head and Neck Specific Quality of Life (QLQ-H&NN43) questionnaires. A total of 96 patients completed the questionnaires. There were 36 patients who did not receive a flap, 31 patients received a local flap, and 29 patients had distant-regional flaps. QoL assessed by the EORTC QLQ-C30, and the QLQ-H&N43 was lower in patients who received a local flap. In general, the results showed that the reconstruction with a distant-regional flap compared with no flap and local flap leads to improved quality of life of patients with oral cancer.

Bisphosphonate-related spindle cell carcinoma and osteonecrosis.

A 48-year-old female with a complaint of persistent pain referred to the Imam Khomeini (Tehran, Iran) in 2018. Based on the radiographic findings, radiolucent lesion found in the right mandible and she had alendronate administration approximately for 10 years. Since the past 6 months, the lesion detected in the right mandible. According to the computed tomography scan, a large lytic destructive lesion with a soft-tissue component was seen at the right mandibular ramus. Microscopic examinations revealed the proliferation of anaplastic spindle-shaped cells arranged in interlacing bundles and whorled patterns. Nuclear polymorphism, scattered cells with hyperchromatic nuclei and increased mitotic activity were notable. Immunohistochemistry findings for tissue section composed of spindle cell proliferation revealed Ki67 (20% positive in hotspots), scattered positive right side incisional biopsy was done. The observation revealed hyperplastic and disorganized squamous epithelial lesion, suggestive of spindle squamous cell carcinoma and osteonecrosis in this patient.

Clinicopathologic and molecular characterization of mammary analogue secretory carcinoma of salivary gland origin.

BACKGROUND: Mammary analogue secretory carcinoma (MASC) is a newly recognized salivary gland tumor that harbors a characteristic balanced chromosomal translocation t (12; 15) (p13; q25) resulting in an ETV6-NTRK3 fusion gene. METHODS: Retrospective study of 111 salivary gland carcinomas revealed 37 cases with secretory features and growth patterns resembling secretory carcinoma of breast. These 37 cases were originally diagnosed as acinic cell carcinoma, adenocarcinoma not otherwise specified and cystadenocarcinoma. Positive immunostaining for S-100 protein and mammaglobin, followed by detection of ETV6 gene rearrangement by FISH and/or ETV6-NTRK3 fusion transcript by RT-PCR were used to identify MASCs. RESULTS: In the cohort of 37 salivary carcinomas with secretory features we have identified 10 cases of MASC. All 10 MASCs were positive for mammaglobin, S-100 protein and SOX10, while staining for DOG1 and p63 protein were mostly absent. In 7/10 cases, both FISH and RT-PCR were positive while three remaining cases showed break of ETV6 gene by FISH analysis and the RT-PCR was negative. Clinical follow-up data were obtained in 6 out of 10 patients with MASC. In 3 patients cervical lymph node metastases developed, one patient with high grade transformed MASC died with multiple distant bone metastases, and local recurrence was observed in three patients. CONCLUSION: Our clinicopathological data are in keeping with previous studies; in most cases, MASC is a low-grade malignancy with overall favorable prognosis. In rare cases, however, MASC with high-grade transformation may behave aggressively, and these patients could benefit from targeted biological treatment using tyrosine kinase inhibitors.

The Effect of Locally Administered Pamidronate on Autogenous Bone Graft in Maxillofacial Reconstruction: A Randomized Clinical Trial.

BACKGROUND: Although bone grafts are commonly used in reconstructive surgeries, they are sensitive to local perfusion and are thus prone to severe resorption. Biphosphonates can inactivate osteoclasts and can be used to control the undesirable bone resorption. OBJECTIVE: To assess the effect of administration of biphosphonates on bone resorption. METHODS: 20 patients with bony defects who were candidates for free autogenous grafts were randomized into "pamidronate" and "control" groups. Bone segments were soaked in either pamidronate solution or normal saline and were inserted into the area of the surgery. Bone densities were measured post-surgery and in 6-month follow-up. Data were obtained via Digora software and analyzed. RESULTS: The mean±SD bone density in pamidronate group changed from 93.4±14.6 to 93.6±17.5 (p<0.05); in the control group the density decreased from 89.7±13.2 to 78.9±11.4 (p<0.05). The mean difference of bone density in anterior areas of the jaws showed higher DXA in comparison to posterior regions (p=0.002). CONCLUSION: Locally administered pamidronate affects reduction in bone resorption.