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Purpose of the study To develop a finite element model (FEM) to study the effect of the stress and strain, in microvascular anastomoses that result from the geometrical mismatch of anastomosed vessels. Material and methods FEMs of end-to-end and end-to-side anastomoses were constructed. Simulations were made using finite element software (NISA). We investigated the angle of inset in the end-to-side anastomosis and the discrepancy in the size of the opening in the vessel between the host and recipient vessels. The FEMs were used to predict principal and shear stress and strain at the position of each node. Results Two types of vascular deformation were predicted during different simulations: longitudinal distortion, and rotational distortion. Stress values ranged from 151.1 to 282.4 MPa for the maximum principal stress, from −122.9 to −432.2 MPa for the minimum principal stress, and from 122.1 to 333.1 MPa for the maximum shear stress. The highest values were recorded when there was a 50% mismatch in the diameter of the vessels at the site of the end-to-end anastomosis. Conclusion The effect of the vessel's size discrepancy on the blood flow and deformation was remarkable in the end-to-end anastomosis. End-to-side anastomosis was superior to end-to-end anastomosis. FEM is a powerful tool to study vascular deformation, as it predicts deformation and biomechanical processes at sites where physical measurements are likely to remain impossible in living humans.

The aim of this study was to investigate the condition of the temporomandibular joint (TMJ) in patients with different rheumatic diseases, and report correlations between the clinical, radiographic and magnetic resonance imaging (MRI) findings. The 67 patients were divided into four groups: 16 with rheumatoid arthritis (RA), 15 with mixed connective tissue disease (MCTD), 18 with ankylosing spondylitis (AS) and 18 with spondyloarthropathy (SPA). They were clinically examined, and panoramic tomography, lateral panoramic radiography and MRI of the TMJ were performed. MRI showed reduced articular cartilage in 25% (4/16) of RA, 0% (0/15) of MCTD, 17% (3/18) of AS and 17% (3/18) of SPA patients. Condylar changes included erosion, osteophytes and abnormal shape. Disc alterations included perforation, abnormal anterior position and decreased movement. These abnormalities were most frequent in RA patients, and least frequent in MCTD and SPA patients. Crepitation and reduced maximum opening of the mouth correlated with abnormalities of the disc and articular cartilage as shown by MRI. Severe condylar erosion in panoramic tomograms significantly correlated with MRI findings of condylar erosion (P0.01), diminished thickness of condylar cartilage, abnormal condylar shape, and abnormal shape of the temporal surface of the TMJ (Por =0.001). The presence of crepitation, limited mandibular movement and/or pain on movement of the jaw often indicated structural damage to the TMJ. Panoramic radiographs provide an alternative method to MRI but, to obtain a more detailed anatomic picture, MRI is recommended for patients with acute unexplained pain or as part of preoperative work up. A panoramic recording is not indicated when MRI is planned.

Purpose The purpose of this study was to compare our clinical findings on the use of autogenous bone grafts and bioresorbable poly-L/DL-Lactide [P(L/DL)LA 70/30] implants to repair inferior orbital wall defects. Patients and Methods Thirty-nine patients who suffered orbital blow-out fractures with ≥2 cm2 bony defect in the inferior orbital wall took part in the study. Each inferior orbital wall was reconstructed using either an autogenous bone graft or a triangle form plate of P(L/DL)LA 70/30. Computed tomography scans were taken before the operation and at 2 and 36 weeks postoperatively. To describe the distribution of complications and facilitate statistical analysis, we categorized our findings into diplopia, enophthalmos, numbness, gaze restrictions, size of bony defect after treatment, bone growth, and implant resorption. A comparative study was carried out using χ2 test and the Fisher exact test. We considered P < .05 to be statistically significant. Results The clinical outcome was excellent in 19 of the 24 (79%) cases treated with autogenous bone grafts and in 13 of the 15 (87%) cases treated with P(L/DL)LA 70/30. No statistically significant differences were found between the 2 groups in overall type or number of complications. The most frequent type of complication found in both groups was enophthalmos, with 5 cases (bone graft, 3; P(L/DL)LA plates, 2). Diplopia was the second most frequent type of complication; however, both complications caused no need for the removal of the implants in either group. Conclusion Autogenous bone grafts and P(L/DL)LA 70/30 implant plates do not present statistically significant differences in the parameters studied. Taking into account the availability and the advantages of P(L/DL)LA 70/30 implants when compared with autogenous bone grafts, our results allow us to conclude that there is no compromise regarding successful bridging of orbital floor defects using biodegradable P(L/DL)LA 70/30 osteosyntheses.

Central intraosseous adenoid cystic carcinoma (ACC) of the mandible, formerly known as cylindroma, is a rare neoplasm with only 16 cases reported in the literature. We describe the diagnosis, etiology, and treatment of a central ACC located in the mandibular premolar region. We also review the literature. This case illustrates 2 key facts regarding the diagnosis and etiology of ACC. First, central salivary gland tumors should be considered in the differential diagnosis of cystic lytic lesions in the mandible. Second, even though the origin of this type of tumor is still unknown, the presence of ectopic tissue anterior to the submandibular gland in the submandibular area indicates that this tumor might be made up of ectopic embryogenic inclusions.

Purpose The purpose of this study was to develop a 3-dimensional finite element model (FEM) of the human orbit, housing the globe, to predict orbital deformation in subjects following a blunt injury. Materials and Methods A FEM of the human orbit including the eye, fatty tissues, and extraocular muscles was constructed. Simulations were performed with a computer using the finite element software NISA (EMRC, Troy, MI). The orbit was subjected to a blunt injury of a 0.5 kg missile with 30 m/s velocity. The FEM was then used to predict principal and shear stresses/strains at each node position. Results Two types of orbital deformation were predicted during different impact simulations: a) horizontal distortion and b) rotational distortion. Stress values ranged from 112.12 to 262.3 MPa for the maximum principal stress, from −226.8 to −552.1 MPa for the minimum principal stress, and from 111.3 to 343.3 MPa for the maximum shear stress. Conclusion This is the first finite element study that demonstrates different and concurrent patterns of orbital deformation in subjects following a blunt injury. FEM is a powerful and invaluable tool to study the multifaceted phenomenon of orbital deformation.