Variable-stiffness composite panels: Defect tolerance under in-plane tensile loading

Automated Fiber Placement is being extensively used in the production of major composite components for the aircraft industry. This technology enables the production of tow-steered panels, which have been proven to greatly improve the structural efficiency of composites by means of in-plane stiffness variation and load redistribution. However, traditional straight-fiber architectures are still preferred. One of the reasons behind this is related to the uncertainties, as a result of process-induced defects, in the mechanical performance of the laminates. This experimental work investigates the effect of the fiber angle discontinuities between different tow courses in a ply on the un-notched and open-hole tensile strength of the laminate. The influence of several manufacturing parameters are studied in detail. The results reveal that 'ply staggering' and '0% gap coverage' is an effective combination in reducing the influence of defects in these laminates

Traumatic bone cyst: a retrospective study of 21 cases

Objective: To describe the clinical and radiological characteristics, and surgical findings of traumatic bone cysts. Study Design: A retrospective observational study was made of 21 traumatic bone cysts. The diagnosis was based on the anamnesis, clinical examination, and complementary tests. Panoramic and periapical X-rays were obtained in all cases, together with computed tomography as decided by the surgeon. A descriptive statistical analysis was made of the study variables using the SPSS v12.0 for Windows. Results: There was a clear female predominance (14:7). The mean age was 26.5 years (range 8-45 years). The cysts in all cases constituted casual findings during routine radiological exploration. In those cases where computed tomographic images were available, preservation of the vestibular and lingual cortical layers was observed. Five of the 21 patients (23.8%) reported a clear antecedent of traumatism in the affected zone. All the lesions were subjected to surgery, and the cavities were found to be vacant in 90.5% of the cases. In only two patients were vascular contents seen within the cavity. Two of the patients presented postoperative paresthesia of the inferior dental nerve that subsided within two weeks. The 19 patients in whom adequate postoperative follow-up proved possible all showed complete bone healing. Conclusions: Traumatic bone cysts were a casual finding. During the surgery, most cases showed to be vacant cavity without an ephitelial lining. Careful curettage of the lesion favors progressive bone regeneration, offering a good prognosis and an almost negligible relapse rate. Other treatment options only would be justified in cases of relapse.

Sharp mandibular bone irregularities after lower third molar extraction: Incidence, clinical features and risk factors

Objectives: The purpose of this study was to determine the incidence and clinical symptoms associated with sharp mandibular bone irregularities (SMBI) after lower third molar extraction and to identify possible risk factors for this complication. Study Design: A mixed study design was used. A retrospective cohort study of 1432 lower third molar extractions was done to determine the incidence of SMBI and a retrospective case-control study was done to determine potential demographic and etiologic factors by comparing those patients with postoperative SMBI with controls. Results: Twelve SMBI were found (0.84%). Age was the most important risk factor for this complication. The operated side and the presence of an associated radiolucent image were also significantly related to the development of mandibular bone irregularities. The depth of impaction of the tooth might also be an important factor since erupted or nearly erupted third molars were more frequent in the SMBI group. Conclusions: SMBI are a rare postoperative complication after lower third molar removal. Older patients having left side lower third molars removed are more likely to develop this problem. The treatment should be the removal of the irregularity when the patient is symptomatic

Splat-based surface reconstruction from defect-laden point sets

We introduce a method for surface reconstruction from point sets that is able to cope with noise and outliers. First, a splat-based representation is computed from the point set. A robust local 3D RANSAC-based procedure is used to filter the point set for outliers, then a local jet surface - a low-degree surface approximation - is fitted to the inliers. Second, we extract the reconstructed surface in the form of a surface triangle mesh through Delaunay refinement. The Delaunay refinement meshing approach requires computing intersections between line segment queries and the surface to be meshed. In the present case, intersection queries are solved from the set of splats through a 1D RANSAC procedure

A Quantitative method for the characterization of lytic metastases of the bone from radiographic images

The aim of our study was to assess the diagnostic usefulness of the gray level parameters to distinguish osteolytic lesions using radiological images. Materials and Methods: A retrospective study was carried out. A total of 76 skeletal radiographs of osteolytic metastases and 67 radiographs of multiple myeloma were used. The cases were classified into nonflat (MM1 and OL1) and flat bones (MM2 and OL2). These radiological images were analyzed by using a computerized method. The parameters calculated were mean, standard deviation, and coefficient of variation (MGL, SDGL, and CVGL) based on gray level histogram analysis of a region-of-interest.Diagnostic utility was quantified bymeasurement of parameters on osteolyticmetastases andmultiplemyeloma, yielding quantification of area under the receiver operating characteristic (ROC) curve (AUC). Results: Flat bone groups (MM2 and OL2) showed significant differences in mean values of MGL ( = 0.048) and SDGL ( = 0.003). Their corresponding values of AUC were 0.758 for MGL and 0.883 for SDGL in flat bones. In nonflat bones these gray level parameters do not show diagnostic ability. Conclusion: The gray level parametersMGL and SDGL show a good discriminatory diagnostic ability to distinguish between multiple myeloma and lytic metastases in flat bones.

Maxillary dentigerous cyst and supernumerary tooth. Is it a frequent association?

Dentigerous cysts, also known as follicular cysts, are a relatively common pathology in our field. They are associated with unerupted or semi-erupted teeth and are usually not related to supernumerary teeth. OBJECTIVE: To describe a dentigerous cyst case associated to a supernumerary tooth. CASE-REPORT: A large-sized dentigerous cyst is described, associated with a supernumerary tooth, affecting the whole maxillary anterior area. Appropriate treatment consists of performing root canals and a Partsch II procedure with a cystectomy, extracting the unerupted teeth, carrying out an apicoectomy and retro-filling the affected teeth. The defect is filled with a bone xenograft. Possible therapeutic alternatives and the connection between the dentigerous cysts and supernumerary teeth are considered in the discussion.