Influence of Radius of Curvature at Gingival Embrasure in Connector Area on Stress Distribution of Three-Unit Posterior Full-Contour Monolithic Zirconia Fixed Partial Denture on Various Amounts of Load Application: A Finite Element Study.

OBJECTIVES: To test the hypothesis that radius of curvature at gingival embrasure in connector area significantly affects the fracture resistance of full-contour monolithic zirconia three-unit posterior Fixed partial denture (FPD) on various amounts of load application. MATERIALS AND METHODS: In this study, two types of three-dimensional finite element models of a three-unit posterior full-contour monolithic zirconia FPD with two gingival embrasure radii (rGE I, 0.45 mm and rGE II, 0.25 mm) were constructed. The components modeled through finite element modeling were subjected to 400, 600, and 800 N vertical loads at the central fossa of the pontic, and further analysis was carried out. RESULTS: All the results were displayed by post-processor finite element analysis software (ANSYS). The study revealed that with increase in the amount of load application as well as decrease in the gingival embrasure radii, stress concentration values were increasing gradually for both the full-contour monolithic zirconia FPD. CONCLUSION: The fracture resistance of the zirconia posterior FPD was significantly affected by the gingival embrasure radii and the mode of load application. When there is a clinical situation of heavier occlusal forces, the fracture resistance can be increased by designing greater gingival embrasure radii in the connector region.

A Prospective Comparison of Computed Tomography and Magnetic Resonance Imaging as a Diagnostic tool for Maxillofacial Space Infections.

AIMS AND OBJECTIVES: The aim of this work was to assess the advantages and disadvantages of magnetic resonance imaging (MRI) versus computed tomography (CT) in the initial evaluation of maxillofacial space infections by comparing various parameters of the imaging studies and comparing them on a three-point scale. MATERIALS AND METHODS: We prospectively evaluated 15 patients with head and neck space infections. All patients underwent CT and MRI using similar slice thickness. We reviewed all imaging studies with special attention to location, extension, source of infection, extent of bone involvement, odontogenic or nonodontogenic, and presence of gas/calcium in the lesions. All the parameters were graded based on a three-point scale and were compared statistically by paired t-test. RESULTS: According to the results we arrived at, MRI was superior to CT in regard to lesion conspicuity, extension, number of anatomic spaces involved, and source on infection. Although not significant, MRI detected a greater number of abscess collections. However, in the aspects of detection of intralesional gas and calcium and motion artifacts, CT was superior to MRI. However, these advantages of CT over MRI are not significantly better than those of MRI. CONCLUSION: MRI was considered superior to CT in the initial evaluation of head and neck space infections. Our study thus concludes that MRI may be used as the primary modality to evaluate patients with head and neck infections when clinically feasible.