Micro-morphologic changes around biophysically-stimulated titanium implants in ovariectomized rats

<p>Abstract</p> <p>Background</p> <p>Osteoporosis may present a risk factor in achievement of osseointegration because of its impact on bone remodeling properties of skeletal phsiology. The purpose of this study was to evaluate micro-morphological changes in bone around titanium implants exposed to mechanical and electrical-energy in osteoporotic rats.</p> <p>Methods</p> <p>Fifteen 12-week old sprague-dowley rats were ovariectomized to develop osteoporosis. After 8 weeks of healing period, two titanium implants were bilaterally placed in the proximal metaphyses of tibia. The animals were randomly divided into a control group and biophysically-stimulated two test groups with five animals in each group. In the first test group, a pulsed electromagnetic field (PEMF) stimulation was administrated at a 0.2 mT 4 h/day, whereas the second group received low-magnitude high-frequency mechanical vibration (MECHVIB) at 50 Hz 14 min/day. Following completion of two week treatment period, all animals were sacrificed. Bone sites including implants were sectioned, removed <it>en bloc </it>and analyzed using a microCT unit. Relative bone volume and bone micro-structural parameters were evaluated for 144 μm wide peri-implant volume of interest (VOI).</p> <p>Results</p> <p>Mean relative bone volume in the peri-implant VOI around implants PEMF and MECHVIB was significantly higher than of those in control (<it>P </it>< .05). Differences in trabecular-thickness and -separation around implants in all groups were similar (<it>P </it>> .05) while the difference in trabecular-number among test and control groups was significant in all VOIs (<it>P </it>< .05).</p> <p>Conclusion</p> <p>Biophysical stimulation remarkably enhances bone volume around titanium implants placed in osteoporotic rats. Low-magnitude high-frequency MECHVIB is more effective than PEMF on bone healing in terms of relative bone volume.</p

Microcomputed tomographic analysis of bone reaction at insertion of orthodontic mini-implants in sheep.

PURPOSE: To evaluate the effects on bone of forced insertion of self-tapping orthodontic mini-implants and thus obtain biomechanical data to develop insertion protocols and optimize drills for implant site preparation. MATERIALS AND METHODS: After implant site preparation, 39 orthodontic mini-implants (OMI), 1.6 x 7.5 mm each, were inserted into the hard bone of sheep mandible; 24 were placed with a 1-mm bone drill and 15 were placed with a standard-diameter (1.2-mm) drill. Removal torque was measured immediately (group A) and 8 weeks after insertion (group B). Eight OMIs (group C) were removed from the mandible in block sections of appropriate size for microcomputed tomographic morphometric and morphologic analyses. RESULTS: All OMIs were placed without complications, with mean insertion torque of 17.625 (\ub1 1.71) Ncm (test groups) and 17.70 (\ub1 1.41) (control groups) and were stable at reentry. Group A implants showed a reduction in removal torque of 5.66%, while in group B, removal torque was reduced by 43.25%. In the control groups (ie, OMIs placed with a 1.2-mm drill), removal torque immediately after placement was reduced by 5.64%, and 8 weeks after insertion, removal torque had declined by 18.2%. Microcomputed tomographic bone morphometric analysis for both test and control groups showed that bone-implant contact was lower than expected in cortical bone 8 weeks after insertion. Morphologic analysis revealed cavities in the cortical bone close to the surface and microcalli in soft bone. Cavities in the cortical bone may have been caused by bone trauma during insertion. CONCLUSIONS: The use of a narrow drill for site preparation increased orthodontic screw insertion torque, but it also damaged the bone and decreased removal torque. Standard histologic examination may clarify whether cavities in hard bone are actually signs of bone resorption that results from the activation of remodeling

Microstructure of Titanium-Cement-Lithium Disilicate Interface in CAD-CAM Dental Implant Crowns: A Three-Dimensional Profilometric Analysis

Abstract Background Peri-implantitis is an infection of the implant surface caused by adhesion of bacteria that generate bone resorption and sometimes even consequent implant loss. Both screw-retained and cemented fixed implants are affected. Purpose The purpose of this study is to investigate the morphological defects at the cemented interface between titanium abutment and ceramic crown, comparing different adhesive cements used to fill the marginal gap. Materials and Methods Twelve computer-aided design\u2013computer-aided manufacturing dental crowns were cemented to titanium abutments using three different resin composite cements. Sealed margins were polished using grommets with descending diamond particle size. Three groups of four crowns each were made according to the cement used, namely RelyX Unicem (3\u2009M ESPE), Panavia F 2.0 (Kuraray), and NX3 (Nexus Kerr). Samples were analyzed using optical inspection, three-dimensional profilometry, and image analysis, including analysis of variance. Results Although RelyX showed significantly lower root mean square surface roughness (4.4\u2009\ub1\u20091.5\u2009\u3bcm) than that of NX3 (7.0\u2009\ub1\u20092.9\u2009\u3bcm), it showed no significant difference with Panavia (3.7\u2009\ub1\u20091.5\u2009\u3bcm). The marginal gap was significantly wider in Panavia (149\u2009\ub1\u2009108\u2009\u3bcm) as compared with NX3 (71\u2009\ub1\u200945\u2009\u3bcm) and Relyx (64\u2009\ub1\u200934\u2009\u3bcm). For all groups, homogeneous heights of both metal-cement and ceramic-cement gaps were observed. Moreover, all samples showed homogeneity of the margins and absence of instrumental bias, thus validating both procedure and materials. Conclusions When using the chosen polishing method, RelyX Unicem showed both low roughness and marginal width, and thus the smoothest and more continuous abutment-crown interlayer, promising a low probability of occurrence of peri-implantitis

A new method for oral cancer biomarkers detection with a non-invasive cyto-salivary sampling and rapid-highly sensitive ELISA immunoassay: a pilot study in humans

Introduction: Oral squamous cell carcinoma (OSCC) accounts for approximately 90% of oral malignancies and has a 5-year mortality rate close to 50%. A consistent part (70%) of all oral cancers is diagnosed at an advanced stage since available screening techniques are ineffective. Therefore, it would be urgent to improve them. The diagnostic gold standard is tissue biopsy with histological and immunohistochemical assessment. This method presents some limitations. Biopsy is invasive and the histopathological evaluation is semi-quantitative, and the absolute abundance of the target cannot be reliably determined. In addition, tissue is highly processed and may lead to loss of information of the natural state. The search for classical and new clinical biomarkers on fragments of tissue/cells collected with a cytobrush is a highly hopeful technique for early detection and diagnosis of OSCC, because of its non-invasive sampling and easy collection method. Methods: Here we analyzed cytobrush biopsies samples collected from the oral cavity of 15 patients with already diagnosed OSCC by applying an innovative high-sensitivity ELISA technique, in order to verify if this approach may provide useful information for detection, diagnosis, and prognosis of OSCC. To this end, we selected six biomarkers, already used in clinical practice for the diagnosis of OSCC (EGFR, Ki67, p53) or selected based on recent scientific and clinical data which indicate their presence or over-expression in cells undergoing transformation and their role as possible molecular targets in immunecheckpoints blockade therapies (PD-L1, HLA-E, B7-H6). Results: The selected tumor biomarkers were highly expressed in the tumor core, while were virtually negative in healthy tissue collected from the same patients. These differences were highly statistically significant and consistent with those obtained using the gold standard test clearly indicating that the proposed approach, i.e. analysis of biomarkers by a custom ELISA technique, is strongly reliable. Discussion: These preliminary data suggest that this non-invasive rapid phenotyping technique could be useful as a screening tool for phenotyping oral lesions and support clinical practice by precise indications on the characteristics of the lesion, also with a view to the application of new anti-tumor treatments, such as immunotherapy, aimed at OSCC patients

Identification of a novel cord blood NK cell subpopulation expressing functional programmed death receptor-1

BackgroundNatural Killer cells (NKs) represent the innate counterpart of TCR &amp; alpha;&amp; beta; lymphocytes and are characterized by a high anti-tumor and an anti-viral cytotoxic activity. Recently, it has been demonstrated that NKs can express PD-1 as an additional inhibitory receptor. Specifically, PD-1 was identified on a subpopulation of terminally differentiated NKs from healthy adults with previous HCMV infection. So far it is unknown whether PD-1 appears during NK-cell development and whether this process is directly or indirectly related to HCMV infection. MethodsIn this study, we analyzed the expression and function of PD-1 on Cord Blood derived NKs (CB-NKs) on a large cohort of newborns through multiparametric cytofluorimetric analysis. ResultsWe identified PD-1 on CB-NKs in more than of half the newborns analyzed. PD-1 was present on CD56(dim) NKs, and particularly abundant on CD56(neg) NKs, but only rarely present on CD56(bright) NKs. Importantly, unlike in adult healthy donors, in CB-NKs PD-1 is co-expressed not only with KIR, but also with NKG2A. PD-1 expression was independent of HCMV mother seropositivity and occurs in the absence of HCMV infection/reactivation during pregnancy. Notably, PD-1 expressed on CB-NKs was functional and mediated negative signals when triggered. ConclusionTo our understanding, this study is the first to report PD-1 expression on CB derived NKs and its features in perinatal conditions. These data may prove important in selecting the most suitable CB derived NK cell population for the development of different immunotherapeutic treatments

Letras, 1985, nº 14 (número completo)

Contenido: El aparente estilo sin estilo en “El gallego y su cuadrilla”, de Camilo José Cela / Norma Susana Alioto – Notas para una evaluación del pensamiento de Bakhtin en el “Rabelais” / Susana G. Artal – La India y sus caminos de liberación / Carmen Balzer -- ¿Usó el moly Odiseo? / Pablo A. Cavallero – La historia y la novela: “El banquete de Severo Arcángelo”, de Leopoldo Marechal / Graciela Maturo – Las Confesiones de San Agustín, obra concluída, según el análisis de estructura y estilo / Amalia S. Nocito – El texto del Poema de Mio Cid ante el proceso de la tradicionalidad oral y escrita / Germán Orduna – La conciencia moral en una novela de H. James / Rosa E. M. D. Penna – El mundo medieval en la poesía de Enrique Banchs / Lía Noemí Uriarte Rebaudi – La construcción condicional en español con + infinitivo / Hilda Albano Vázquez – Ensayo etnológico de “La tierra permanece”, de George Stewart // Pablo Wright – Nota – Reseñas bibliográfica