Accuracy of CAD-CAM systems for removable partial denture framework fabrication: A systematic review

Statement of problemRemovable partial dentures (RPDs) are traditionally made by casting, a complex, error-prone, and time-consuming process. Computer-aided design and computer-aided manufacturing (CAD-CAM) RPD systems may simplify the clinical steps and minimize errors; however, the accuracy of CAD-CAM RPD systems is unclear.PurposeThe purpose of this systematic review was to determine whether CAD-CAM systems are accurate for the manufacturing of RPD frameworks.Material and methodsA literature search was conducted through Medline-PubMed, Scopus, Lilacs, Web of Science, and Cochrane Library databases using specific keywords for articles published up to November 2019. Three reviewers obtained data and compared the results. All studies evaluated the framework accuracy or fit of prostheses fabricated with conventional and digital techniques.ResultsA total of 7 articles, 2 clinical studies, and 5 in vitro studies that complied with the inclusion criteria were evaluated. One in vitro study compared indirect (extraoral) and direct (intraoral) scanning for partially edentulous ridges and shows that digital scans were better than conventional impressions in terms of trueness. In the other studies included, although the frameworks analyzed had clinically acceptable discrepancies (<311 μm), the material influenced the fit. Polyetheretherketone (PEEK) showed better fit than traditional metal cast RPDs. Co-Cr alloy RPDs produced by rapid prototyping exhibited the highest discrepancies when produced by sintering laser melting.ConclusionsThe results show that the digital technique for RPD frameworks is accurate. In the studies included, the analyzed frameworks had clinically acceptable gaps, but the results were heterogeneous among studies because the articles used different measurement methods with small sample sizes. Few studies discussed the long-term clinical performance. The digital technique for RPD frameworks was accurate because the misfits and mismatches found in in vitro and clinical studies were within the acceptable clinical limit for RPDs.     

Peripheral dentinogenic ghost cell tumor—report of two cases and review of the literature

Oral and Maxillofacial Surgery - Peripheral dentinogenic ghost cell tumor (DGCT) is a rare and non-aggressive benign odontogenic tumor. They usually affect the elderly and are predominantly located...     

Novel integrative genomic tool for interrogating lithium response in bipolar disorder

We developed a novel integrative genomic tool called GRANITE (Genetic Regulatory Analysis of Networks Investigational Tool Environment) that can effectively analyze large complex data sets to generate interactive networks. GRANITE is an open-source tool and invaluable resource for a variety of genomic fields. Although our analysis is confined to static expression data, GRANITE has the capability of evaluating time-course data and generating interactive networks that may shed light on acute versus chronic treatment, as well as evaluating dose response and providing insight into mechanisms that underlie therapeutic versus sub-therapeutic doses or toxic doses. As a proof-of-concept study, we investigated lithium (Li) response in bipolar disorder (BD). BD is a severe mood disorder marked by cycles of mania and depression. Li is one of the most commonly prescribed and decidedly effective treatments for many patients (responders), although its mode of action is not yet fully understood, nor is it effective in every patient (non-responders). In an in vitro study, we compared vehicle versus chronic Li treatment in patient-derived lymphoblastoid cells (LCLs) (derived from either responders or non-responders) using both microRNA (miRNA) and messenger RNA gene expression profiling. We present both Li responder and non-responder network visualizations created by our GRANITE analysis in BD. We identified by network visualization that the Let-7 family is consistently downregulated by Li in both groups where this miRNA family has been implicated in neurodegeneration, cell survival and synaptic development. We discuss the potential of this analysis for investigating treatment response and even providing clinicians with a tool for predicting treatment response in their patients, as well as for providing the industry with a tool for identifying network nodes as targets for novel drug discovery.     

B-cell lymphoma after angioimmunoblastic lymphadenopathy: a case with oligoclonal gene rearrangements associated with Epstein-Barr virus

We describe a patient with angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), who subsequently developed large-cell immunoblastic lymphoma of B-cell immunophenotype. At the time of the initial diagnosis, histologic examination of an inguinal lymph node showed typical features of AILD, and there was no evidence of a monoclonal B-cell population by immunohistochemical analysis. In situ hybridization and Southern blot analysis for Epstein-Barr virus (EBV) were negative. At autopsy 2 years later, the patient had widespread lymph node and organ involvement by large-cell immunoblastic lymphoma of B-cell immunophenotype. Southern blot analysis performed on DNA extracted from lymph nodes, liver, and spleen showed two patterns of Ig heavy chain and kappa light chain gene rearrangements. The T-cell receptor beta chain gene was in the germline configuration. Analysis with an EBV terminal repeat region probe showed two clonal populations that paralleled the Ig gene rearrangement studies. Double-labeling immunohistochemistry and in situ hybridization confirmed the presence of EBV within the neoplastic B cells. The data support the hypothesis that EBV was not etiologically related to AILD in this case, and that EBV proliferation may occur after the onset of the disease. Further, the data suggest that some B-cell lymphomas that arise in the setting of AILD resemble EBV-associated B-cell lymphomas that arise in other immunodeficiency states.     

From the Cover: Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5–12-fold compared with their conventional diffraction-limited LS analogs.Far-field nanoscopy (1, 2) methods discern features within subdiffraction distances by briefly forcing their molecules to two distinguishable states for the time period of detection. Typically, fluorophores are switched between a signaling “on” and a nonsignaling (i.e., dark) “off” state. Depending on the switching and fluorescence registration strategy used, these superresolution techniques can be categorized into coordinate-stochastic and coordinate-targeted approaches (2). The latter group of methods, comprising the so-called RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] (1, 3–7) approaches, have been realized using patterns of switch-off light with one or more zero-intensity points or lines, to single out target point (zero-dimensional) or line (1D) coordinates in space where the fluorophores are allowed to assume the on state. The RESOLFT idea can also be implemented in the inverse mode, by using switch-on light and confining the off state. In any case, probing the presence of molecules in new sets of points or lines at every scanning step produces images.Owing to the nature of the on and off states involved––first excited electronic and ground state––stimulated emission depletion (STED) (3) and saturated structured illumination microscopy (SSIM) (8), which both qualify as variants of the RESOLFT principle, typically apply light intensities in the range of MW/cm² and above. Especially when imaging sensitive samples where photoinduced changes must be avoided, RESOLFT is preferably realized with fluorophores which lead to the same factor of resolution improvement at much lower intensities of state-switching light. Reversibly switchable fluorescent proteins (RSFPs) are highly suitable for this purpose (4–7, 9), as transitions between their metastable on and off states require 5 orders of magnitude lower threshold intensities than STED/SSIM to guarantee switch-off. Suitable spectral properties, relatively fast millisecond switching kinetics, and high photostability of recently developed yellow-green-emitting RSFPs like rsEGFP (5), rsEGFP2 (7), and rsEGFP(N205S) (10) compared with early RSFPs have indeed enabled RESOLFT nanoscopy in living cells and tissues. To date, RSFP-based RESOLFT has achieved resolution improvements by factors of 4–5 in rsEGFP2-labeled samples (7). To further reduce the imaging time, massive parallelization of scanning has been reported (10). However, the diffraction-limited axial resolution and lack of background suppression restrict applications to thin samples.Imaging applications typically require careful tuning of imaging parameters including speed, contrast, photosensitivity, and spatial resolution, depending on the information that is sought. Light-sheet fluorescence microscopy (LSFM) (11–15) stands out by its ability to balance most of these parameters for 3D imaging of living specimens. Recently reenacted as the selective plane illumination microscope (13), this microscopy mode has sparked increasing interest notably because of its short acquisition times in 3D imaging and low phototoxicity in living specimens. It excites fluorophores only in a thin diffraction-limited slice of the sample, perpendicular to the direction of fluorescence detection. The LS is generated by a cylindrical lens which focuses an expanded laser beam in only one direction onto the specimen or into the back-focal plane of an illumination objective. Alternatively, a single beam is quickly moved as a “virtual” LS (16) across a specimen section.In such conventional LSFM imaging, the lateral resolution is determined by the numerical aperture (N.A.) of the detection objective (17), whereas axial resolution is given by the LS thickness, provided the latter is thinner than the axial extent of the point-spread function describing the imaging process from the focal plane of the detecting lens to the camera. In a previous study, the axial resolution of LSFM was pushed to the diffraction limit by using the full aperture of the illumination objective with Gaussian beams; this was carried out for practically useful combinations of N.A. (e.g., 0.8 for both illumination and detection objectives) permissible in light of the geometrical constraints given by the objective lens dimensions (18). High-N.A. illumination comes with short Rayleigh ranges of Gaussian beams, which inherently limit the field of view (FOV) along the direction of illumination. Scanned Bessel beams for diffraction-limited excitation with a virtual LS (19–21) typically offer larger FOVs (22), but side lobes broaden the scanned LS in the axial direction and contribute to phototoxicity outside of the focal plane of detection (20). A more complex approach has used Bessel-beam excitation in combination with structured illumination to obtain near-isotropic (but still diffraction-limited) resolution as measured on fluorescent beads (20), albeit at the cost of acquisition time and reduced contrast due to fluorescence generated by the side lobes. In different work, axial resolution has also been improved about fourfold by acquiring two complementary orthogonal views of the sample using two alternating LSs, followed by computationally fusing image information with a deconvolution incorporating both views (23). LS approaches have also helped suppress out-of-focus background for single-molecule imaging in biological situations (e.g., in ref. 24), including at superresolution (25–27).Slight axial resolution improvement beyond the diffraction barrier has been demonstrated by overlapping a Gaussian excitation LS with a STED LS featuring a zero-intensity plane (28). Due to scattering and possibly additional aberrations caused by the wavelength difference between excitation and STED light, the maximal achievable resolution in biological specimens was severely limited. This was the case even in fixed samples. A successful application of LS-STED to living cells or organisms has not been reported. The relatively high average STED laser power required for high resolution gains calls for developing a coordinate-targeted superresolution LS approach with low-power operation, meaning a concept that does not solely rely on changing the way the light is directed to––or collected from––the sample, but a concept that harnesses an “on–off” transition for improved feature separation.     

Inhibition of 5-aminolevulinic acid-induced DNA damage by melatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, quercetin or resveratrol

Porphyrias are defined as either inborn or acquired diseases related to enzymatic deficiencies in the heme biosynthetic pathway. Lead poisoning, hereditary tyrosinemia, and acute intermittent porphyria (AIP) are characterized by the absence of photosensitivity and the accumulation of 5-aminolevulinic acid (ALA) together with its increased urinary excretion. The main clinical manifestations of AIP are intermittent attacks of abdominal pain, neuromuscular weaknesses and neuropsychiatry alterations, and also an association with primary liver cancer, in which may be involved the oxidative potential of ALA which is able to cause DNA damage. The use of antioxidants in the treatment of ALA-induced oxidative stress is not well established. In the current work, we show the antioxidant efficacy of several compounds including melatonin, quercetin, resveratrol and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), a melatonin oxidation product, in terms of their ability to limit DNA damage induced by ALA/Fe2+ in an in vitro system. Damage was measured by plasmid DNA strand breaks and detection of 8-oxo, 7-8-dihydro,2'-deoxyguanosine (8-oxodGuo) by high-performance liquid chromatography coupled with electrochemical detection. All compounds tested showed a dose-dependent protective action against free radical damage. These results could be the first step toward studies of the possible use of these antioxidants in oxidative stress promoted by ALA or other pro-oxidants.     

Intracranial hemorrhage following bone marrow transplantation: an autopsy study of 58 patients

Autopsy files of 180 patients were reviewed, who died after BMT between July 1987 and June 1998 and 58 (32.2%) cases, who had experienced intracranial hemorrhage (ICH) were selected. Age, sex, underlying disease, preparatory regimens, immunoprophylaxis, chronic and acute GVHD, survival of the patients and localization and size of hemorrhages were evaluated. There were 33 males and 25 females, with a mean age of 23.4 years. The main underlying disorders for which BMT was performed included SAA (n = 21), CML (n = 13) and AML (n = 10). Forty patients were found to have intraparenchymal hemorrhage, 35 had subarachnoid hemorrhage and eight patients had subdural hemorrhage. In 16 cases the CNS hemorrhage was so extensive that it was considered to be the main cause of death. There was no significant statistical difference concerning sex (P = 0.217), age (P = 0.296), underlying disease (P= 0.352), preparatory regimens (P = 0.07), immunoprophylaxis (P = 0.914), chronic and acute graft-versus-host disease (P = 0.107 and P = 0.631, respectively) and survival (P = 0.701) when comparing patients with or without ICH. However, the number of cases in which the CNS was defined as the main cause of death was higher among patients with ICH than in patients without ICH (n = 16 vs 15) (P = 0.011). We conclude that ICH is common and has a significant mortality rate following BMT.