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Purpose To assess bone microarchitecture in maxillary sites grafted with autogenous or xenogenous grafts as well as to demonstrate the usefulness of micro CT in dental implant research. Materials and Methods Samples ( n = 12) consisting of titanium fixation screws covered by at least 0.5-1 mm of human bone were obtained from 17 sites grafted with autogenous or xenogenous materials and prepared for micro CT scanning and conventional histology. Bone histomorphometric parameters were evaluated in three distinct regions (graft region, transitional region, and native bone region). Three-dimensional (3D) bone-to-implant contact ( BIC) calculation was performed using micro CT data. Histological sections were used to calculate two-dimensional (2D) BIC percentages, which were compared with values obtained from 2D micro CT images. Results Histomorphometric parameters varied according to the type of graft used, but sites reconstructed with autogenous bone showed higher mean values in general. In autograft samples, indices for parameters such as Tb.Th and Tb.Sp were significantly different when the native bone region was compared to the graft region. While a higher mean 3D BIC was found in the native bone region for both graft materials, significant BIC differences were absent when graft types were compared. The 2D BIC percentages obtained from histological and micro CT images were similar. Conclusions Autografts outperformed the xenogenous material used in this study concerning the histomorphometric parameters assessed. While graft type did not seem to influence 3D BIC, the native bone region showed the highest BIC percentages when compared to the other regions in both graft groups. In addition, 2D BIC ratios were similar regardless of graft material or image source (histological sections x micro CT slices). Taken together, our findings suggest that micro CT is an effective tool for 2D and 3D histomorphometric and BIC assessments in dental implant research. [ABSTRACT FROM AUTHOR]

Objectives: To develop a novel 3D landmark reference system that is specific for mandibular midline cephalometric landmarks and to assess its repeatability and reproducibility. Methods: Cone-beam computed tomography (CBCT) scans (3D Accuitomo® 170) were performed on 26 dry human skulls. The CBCT data were exported into DICOM files and imported to Maxilim® software to create 3D surface models. Two observers identified five landmarks to create a specific mid-sagittal mandibular plane: two mandibular foramina, two molar landmarks and one interincisive landmark. On this mid-sagittal mandibular plane, four mandibular cephalometric landmarks were marked: Point B, Pogonion, Gnathion and Menton. All observations were repeated by the two observers after an interval of 4 weeks. The coordinates (x, y, z) of each landmark were exported, and statistical analyses were performed to evaluate inter- and intra-rater precision. Results: The intra-observer median precision in locating all landmarks ranged between 0.17 and 0.61 mm. The intra-observer repeatability was generally good with a precision under 1 mm in more than 50 per cent. The overall median inter-observer precision was 0.26-2.30 mm. The mandibular foramina showed the best inter-observer reproducibility. The general inter-observer reproducibility was moderate to good, except for Pogonion and Point B. Limitations: Dry human skulls may not represent anatomical conditions found in living patients, thus the system should be validated using patients' data. Conclusion: The novel reference system offered good precision and generally good to moderate repeatability and reproducibility for mandibular midline cephalometric landmark identification in three dimensions. These findings will be useful for further improvement of 3D cephalometric systems. [ABSTRACT FROM AUTHOR]

Objective: To report the incidence of trigeminal neuropathy seen among new patients in a referral center within a period of 1 year (2013). The cause of damage, method of management and treatment outcome was assessed after 1-year follow-up. Materials and Methods: The records of all new patients visiting the oral and maxillofacial unit of the University hospital of Leuven in 2013 were screened for a history of damage to branches of the trigeminal nerve. The selected records were examined and the duration of nerve damage, received treatment as well as the outcome of the neuropathy after treatment was noted after 1-year follow-up. Results: 56 patients (21 males, 35 females) from 7602 new patients had symptoms of damage to the trigeminal nerve branch. These symptoms persist in more than one-third of the patients [21/56 (37.5 %)] after 1-year follow-up. The least recovery is seen from oral surgery, implant placement, orthognathic surgery and tooth extraction. After 1 year 85 % (12/14) of neuropathic pain cases still have their symptoms as compared to 19 % (5/26) of patients with hypoesthesia. Conclusion: This study shows a low incidence of nerve damage among the new patients presenting in oral and maxillofacial surgery clinic (<1 %); however, one-third of patients who sustain nerve damage never recover fully. Early diagnosis of the cause of neuropathy is essential. There is a need to objectively assess all patients with symptoms of trigeminal nerve damage before, during and after treatment. [ABSTRACT FROM AUTHOR]

Objectives: An immunohistological study of an infected immature permanent human tooth after a regenerative endodontic procedure (REP) was conducted in order to determine the histologic outcome of this procedure. Besides observed signs of angiogenesis and neurogenesis, repair and/or regeneration of the pulp-dentin complex was also investigated. Materials and methods: A REP was performed on tooth 45 of a 10-year-old girl. Eleven months post-treatment, the tooth had to be removed for orthodontic reasons. The following investigations were performed: immunohistology and radiographic quantification of root development. After hematoxylin-eosin (HE) staining, the following immunomarkers were selected: neurofilament (NF), pan cytokeratin (PK), osteocalcin (OC), and CD34. Results: The REP resulted in clinical and radiographic healing of the periradicular lesion and quantifiable root development. The HE staining matches with the medical imaging post-REP: underneath the mineral trioxide aggregate a calcified bridge with cell inclusions, connective pulp-like tissue (PLT) with blood vessels, osteodentin against the root canal walls, on the root surface cementum (Ce), and periodontal ligament (PDL). The PDL was PK. The blood vessels in the PLT and PDL were CD34. The Ce, osteodentin, and stromal cells in the PLT were OC. The neurovascular bundles in the PLT were NF. Conclusions: Immunohistologically, REP of this infected immature permanent tooth resulted in an intracanalar connective tissue with a regulated physiology, but not pulp tissue. Clinical relevance: REP of an immature permanent infected tooth may heal the periapical infection and may result in a combination of regeneration and repair of the pulp-dentin complex. [ABSTRACT FROM AUTHOR]

Hydrogels have emerged as promising biomaterials for regenerative medicine. Despite major advances, tissue engineers have faced challenges in studying the complex dynamics of cell-mediated hydrogel remodelling. Second harmonic generation (SHG) microscopy has been a pivotal tool for non-invasive visualization of collagen type I hydrogels. By taking into account the typical polarization SHG effect, we recently proposed an alternative image correlation spectroscopy (ICS) model to quantify characteristics of randomly oriented collagen fibrils. However, fibril alignment is an important feature in many tissues that needs to be monitored for effective assembly of anisotropic tissue constructs. Here we extended our previous approach to include the orientation distribution of fibrils in cellular hydrogels and show the power of this model in two biologically relevant applications. Using a collagen hydrogel contraction assay, we were able to capture cell-induced hydrogel modifications at the microscopic scale and link these to changes in overall gel dimensions over time. After 24 h, the collagen density was about 3 times higher than the initial density, which was of the same order as the decrease in hydrogel area. We also showed that the orientation parameters recovered from our automated ICS model match values obtained from manual measurements. Furthermore, regions axial to cellular processes aligned at least 1.5 times faster compared with adjacent zones. Being able to capture minor temporal and spatial changes in hydrogel density and collagen fibril orientation, we demonstrated the sensitivity of this extended ICS model to deconstruct a complex environment and support its potential for tissue engineering research. Statement of significance It is generally accepted that looking beyond bulk hydrogel composition is key in understanding the mechanisms that influence the mechanical and biological properties of artificial tissues. In this manuscript, we performed label-free non-invasive imaging and extended a robust automated analysis method to characterize the microstructural organisation of cellular hydrogel systems. We underpin the sensitivity of this technique by capturing minor changes in collagen density and fibril orientation in biologically relevant systems over time. Therefore, we believe that this method is applicable in fundamental cell-matrix research and has high-throughput potential in screening arrays of hydrogel scaffolds, making it an interesting tool for future tissue engineering research. [ABSTRACT FROM AUTHOR]

Tumor infiltrating stem cells have been suggested as a vehicle for the delivery of a suicide gene towards otherwise difficult to treat tumors like glioma. We have used herpes simplex virus thymidine kinase expressing human multipotent adult progenitor cells in two brain tumor models (hU87 and Hs683) in immune-compromised mice. In order to determine the best time point for the administration of the codrug ganciclovir, the stem cell distribution and viability were monitored in vivo using bioluminescence (BLI) and magnetic resonance imaging (MRI). Treatment was assessed by in vivo BLI and MRI of the tumors. We were able to show that suicide gene therapy using HSV-tk expressing stem cells can be followed in vivo by MRI and BLI. This has the advantage that (1) outliers can be detected earlier, (2) GCV treatment can be initiated based on stem cell distribution rather than on empirical time points, and (3) a more thorough follow-up can be provided prior to and after treatment of these animals. In contrast to rodent stem cell and tumor models, treatment success was limited in our model using human cell lines. This was most likely due to the lack of immune components in the immune-compromised rodents. [ABSTRACT FROM AUTHOR]