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Popular media now often present 3D printing as a widely employed technology for the production of dental prostheses. This article aims to show, based on factual information, to what extent 3D printing can be used in dental laboratories and dental practices at present. It attempts to present a rational evaluation of todays´ applications of 3D printing technology in the context of dental restorations. In addition, the article discusses future perspectives and examines the ongoing viability of traditional dental laboratory services and manufacturing processes. It also shows which expertise is needed for the digital additive manufacturing of dental restorations.
Introduction: The treatment of carious lesions is one of the most fundamental competencies in daily dental practice. However, many commercially available training models lack in reality regarding the simulation of pathologies such as carious lesions. 3D printed models could provide a more realistic simulation. This study provides an exemplary description of the fabrication of 3D printed dental models with carious lesions and assesses their educational value compared to commercially available models in conservative dentistry.
Materials and Methods: A single-stage, controlled cohort study was conducted within the context of a curricular course. A stereolithographic model was obtained from an intraoral scan and then printed using fused deposition modelling. These models were first piloted by experts and then implemented and compared against commercial models in a conservative dentistry course. Experts and students evaluated both models using a validated questionnaire. Additionally, a cost analysis for both models was carried out.
Results: Thirteen dentists and twenty-seven 5th year dental students participated in the study. The 3D printed models were rated significantly more realistic in many test areas. In particular, the different tactility and the distinction in colour was rated positively in the 3D printed models. At 28.29€ (compared to 112.36€), the 3D printed models were exceptionally cost-efficient.
Conclusions: 3D printed dental models present a more realistic and cost-efficient alternative to commercial models in the undergraduate training of conservative dentistry.
This study deals with 3D laser investigation on the border between the human lymph node T-zone and germinal centre. Only a few T-cells specific for antigen selected B-cells are allowed to enter germinal centres. This selection process is guided by sinus structures, chemokine gradients and inherent motility of the lymphoid cells. We measured gaps and wall-like structures manually, using IMARIS, a 3D image software for analysis and interpretation of microscopy datasets. In this paper, we describe alpha-actin positive and semipermeable walls and wall-like structures that may hinder T-cells and other cell types from entering germinal centres. Some clearly defined holes or gaps probably regulate lymphoid traffic between T- and B-cell areas. In lymphadenitis, the morphology of this border structure is clearly defined. However, in case of malignant lymphoma, the wall-like structure is disrupted. This has been demonstrated exemplarily in case of angioimmunoblastic T-cell lymphoma. We revealed significant differences of lengths of the wall-like structures in angioimmunoblastic T-cell lymphoma in comparison with wall-like structures in reactive tissue slices. The alterations of morphological structures lead to abnormal and less controlled T- and B-cell distributions probably preventing the immune defence against tumour cells and infectious agents by dysregulating immune homeostasis.
Rationale: Classic histology is the gold standard for vascular network imaging and analysis. The method however is laborious and prone to artefacts. Here, the suitability of ultramicroscopy (UM) and micro-computed tomography (CT) was studied to establish potential alternatives to histology.
Methods: The vasculature of murine organs (kidney, heart and atherosclerotic carotid arteries) was visualized using conventional 2D microscopy, 3D light sheet ultramicroscopy (UM) and micro-CT. Moreover, spheroid-based human endothelial cell vessel formation in mice was quantified. Fluorescently labeled Isolectin GS-IB4 A647 was used for in vivo labeling of vasculature for UM analysis, and analyses were performed ex vivo after sample preparation. For CT imaging, animals were perfused postmortem with radiopaque contrast agent.
Results: Using UM imaging, 3D vascular network information could be obtained in samples of animals receiving in vivo injection of the fluorescently labeled Isolectin GS-IB4. Resolution was sufficient to measure single endothelial cell integration into capillaries in the spheroid-based matrigel plug assay. Because of the selective staining of the endothelium, imaging of larger vessels yielded less favorable results. Using micro-CT or even nano-CT, imaging of capillaries was impossible due to insufficient X-ray absorption and thus insufficient signal-to-noise ratio. Identification of lumen in murine arteries using micro-CT was in contrast superior to UM.
Conclusion: UM and micro-CT are two complementary techniques. Whereas UM is ideal for imaging and especially quantifying capillary networks and arterioles, larger vascular structures are easier and faster to quantify and visualize using micro-CT. 3D information of both techniques is superior to 2D histology. UM and micro-CT together may open a new field of clinical pathology diagnosis.
Aims: The examination of histological sections is still the gold standard in diagnostic pathology. Important histopathological diagnostic criteria are nuclear shapes and chromatin distribution as well as nucleus-cytoplasm relation and immunohistochemical properties of surface and intracellular proteins. The aim of this investigation was to evaluate the benefits and drawbacks of three-dimensional imaging of CD30+ cells in classical Hodgkin Lymphoma (cHL) in comparison to CD30+ lymphoid cells in reactive lymphoid tissues.
Materials and results: Using immunoflourescence confocal microscopy and computer-based analysis, we compared CD30+ neoplastic cells in Nodular Sclerosis cHL (NScCHL), Mixed Cellularity cHL (MCcHL), with reactive CD30+ cells in Adenoids (AD) and Lymphadenitis (LAD). We confirmed that the percentage of CD30+ cell volume can be calculated. The amount in lymphadenitis was approx. 1.5%, in adenoids around 2%, in MCcHL up to 4,5% whereas the values for NScHL rose to more than 8% of the total cell cytoplasm. In addition, CD30+ tumour cells (HRS-cells) in cHL had larger volumes, and more protrusions compared to CD30+ reactive cells. Furthermore, the formation of large cell networks turned out to be a typical characteristic of NScHL.
Conclusion: In contrast to 2D histology, 3D laser scanning offers a visualisation of complete cells, their network interaction and spatial distribution in the tissue. The possibility to differentiate cells in regards to volume, surface, shape, and cluster formation enables a new view on further diagnostic and biological questions. 3D includes an increased amount of information as a basis of bioinformatical calculations.
Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) can show variable histological growth patterns and present remarkable overlap with T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL). Previous studies suggest that NLPHL histological variants represent progression forms of NLPHL and THRLBCL transformation in aggressive disease. Since molecular studies of both lymphomas are limited due to the low number of tumor cells, the present study aimed to learn if a better understanding of these lymphomas is possible via detailed measurements of nuclear and cell size features in 2D and 3D sections. Whereas no significant differences were visible in 2D analyses, a slightly increased nuclear volume and a significantly enlarged cell size were noted in 3D measurements of the tumor cells of THRLBCL in comparison to typical NLPHL cases. Interestingly, not only was the size of the tumor cells increased in THRLBCL but also the nuclear volume of concomitant T cells in the reactive infiltrate when compared with typical NLPHL. Particularly CD8+ T cells had frequent contacts to tumor cells of THRLBCL. However, the nuclear volume of B cells was comparable in all cases. These results clearly demonstrate that 3D tissue analyses are superior to conventional 2D analyses of histological sections. Furthermore, the results point to a strong activation of T cells in THRLBCL, representing a cytotoxic response against the tumor cells with unclear effectiveness, resulting in enhanced swelling of the tumor cell bodies and limiting proliferative potential. Further molecular studies combining 3D tissue analyses and molecular data will help to gain profound insight into these ill-defined cellular processes.
The Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) as well as the T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) are rare types of malignant lymphomas. Both NLPHL and THRLBCL are frequently observed in middle-aged men with THRLBCL presenting frequently with an advanced Ann-Arbor stage with B-symptoms and associated with more aggressive courses.3 However, due to the limited number of tumor cells in the tissue of both NLPHL and THRLBCL, limited numbers of studies have been conducted on these lymphomas and current results are mainly based on general molecular genetic studies.
In order to obtain a better understanding for these disease forms as well as possible changes in their nuclear and cytoplasmatic sizes, the following study relied on the comparison of the different NLPHL forms and THRLBCL in terms of nuclear size and nuclear volume. This was carried out using both 2D and 3D analysis. During the 2D analysis of nuclear size and nuclear volume no significant differences could be presented between those groups. However, the 3D analysis of NLPHL and THRLBCL pointed out a slightly enlarged nuclear volume in THRLBCL. Furthermore, the analysis indicated a significantly increased cytoplasmatic size of THRLBCL compared to NLPHL forms. Nevertheless, differences occurred not only between the tumor cells of both disease forms, but also the T cells presented a larger nuclear volume in THRLBCL. B cells, which were considered as the control group, did not demonstrate any significant differences between the different groups. The presented results suggest an increased activity of T cells in THRLBCL, which is most likely to be interpreted as a response against the surrounding tumor cells and probably limits the proliferation of the tumor cells. Based on these results, the importance of 3D analysis is also evident due to the fact that it is clearly superior to 2D analysis. For a better understanding of both disease forms, it is therefore recommended to use the 3D technique in combination with molecular genetic analysis in future research.