1,359 research outputs found
Calcifying odontogenic cyst associated with compound odontoma: A study on undemineralized material
In a minority of cases of calcifying odontogenic cyst (COC) it is possible to observe the formation of dental hard tissues in the cyst wall. The use of undemineralized sections has allowed an evaluation of the mineralized tissues normally lost with the use of demineralizing agents. All the dental hard tissues presented a high degree of morpho- and histodifferentiation. The histochemical staining for calcium salts (von Kossa) showed the presence of areas of low mineralization in the portion of the lesion, where the tissue maturation was not complete. In conclusion the appearance of the dental hard tissues in this case of compound odontoma arising in the cyst wall of a COC is similar to that already described in compound odontoma not associated with COC.Il est possible d’observer la formation de tissus dentaires durs dans la paroi d’une minorité de cas de kystes odontogènes calcifiants (KOC). L’utilisation de coupes de tissus non déminéralisés a permis une évaluation des tissus minéralisés qui sont habituellement perdus après décalcification. Tous les tissus dentaires durs présentent un degré important de morpho- en d’histodifférenciation. La coloration histochimique des sels calcaires (von Kossa) montre la présence de territoires de faible minéralisation dans les régions dans lesquelles la maturation tissulaire est incomplète.En conclusion, l’apparence des tissus dentaires durs dans ce cas d’odontome composé développé dans la paroi d’un kyste odontogène calcifié est semblable à celle déjà décrite dans les odontomes composés non associé à un KOC
Randomised study for the 1-year crestal bone maintenance around modified diameter implants with different loading protocols: a radiographic evaluation.
This study evaluated by standardised digitised
periapical radiography the crestal bone maintenance around
modified diameter internal hex implants with variable thread
design and narrow neck loaded with different procedures.
Forty implants were placed in 25 patients. Twenty implants
were conventionally loaded, 20 ones immediately loaded.
Radiographs were taken with a customised bite record and
processed with software. Measurements of bone from the
fixture–abutment junction to mesial and distal marginal bone
levels were made. Student’s t test statistical analysis was
adopted. Baseline data were variable; at 1-year follow-up,
there were no significant differences for marginal bone loss
between immediately and conventionally loaded maxillary
implants (p=0.1031), whilst there were slight significant
differences between immediately and conventionally loaded
implants in the mandible (p=0.0141). Crestal bone maintenance
around conventionally and immediately loaded
modified diameter implants was similar, with slight
significant differences in mandible where a lower marginal
bone loss was observed
Split crest technique for implant treatment of agenesis of the upper lateral incisors: results of a randomized pilot histological and clinical study at 24-month follow-up
Agenesis of lateral incisors, besides the functional issues, represents a great esthetic drawback. The selection of an appropriate treatment is a complex decision, which should consider the stability of the clinical outcomes over time. The aim of the present study was a histological and clinical comparison of two-stage split crest technique (SCT), with bone chips alone or mixed with porcine bone in patients affected by unilateral and bilateral agenesis of the upper lateral incisors. Eleven patients were enrolled, and randomly assigned to receive a treatment with autologous bone chips (group 1) or autologous bone chips mixed 1:1 to porcine-derived xenogenic bone (group 2). After a 2-month healing period, implants were placed and biopsies harvested for histomorphometrical evaluation. Clinical assessment, according to ICOI PISA health scale, and radiographic marginal bone loss evaluation at 12- and 24-month follow-ups were conducted. The histomorphometry showed significantly greater new bone formation (p > 0.0229) in group 2. At 12- and 24-month follow-ups, all the evaluated implants, regardless of the group they were allocated, could be categorized as "success" in the ICOI Pisa Health Scale for Dental Implants, and did not show significant difference in crestal bone loss. To the best of our knowledge, these are the first histological and clinical outcomes indicating that the use of bone chips mixed 1:1 to porcine bone in SCT could be a promising technique for the rehabilitation of patients with agenesis of the upper lateral incisors, although studies with a larger number of patients and implants, and a longer follow up are needed
The use of ESEM-EDX as an innovative tool to analyze the mineral structure of peri-implant human bone
This study aimed to investigate the mineralization and chemical composition of the bone-implant interface and peri-implant tissues on human histological samples using an environmental scanning electron microscope as well as energy-dispersive x-ray spectroscopy (ESEM-EDX) as an innovative method. Eight unloaded implants with marginal bone tissue were retrieved after four months from eight patients and were histologically processed and analyzed. Histological samples were observed under optical microscopy (OM) to identify the microarchitecture of the sample and bone morphology. Then, all samples were observed under ESEM-EDX from the coronal to the most apical portion of the implant at 500x magnification. A region of interest with bone tissue of size 750
7 500 microns was selected to correspond to the first coronal and the last apical thread (ROI). EDX microanalysis was used to assess the elemental composition of the bone tissue along the thread interface and the ROI. Atomic percentages of Ca, P, N, and Ti, and the Ca/N, P/N and Ca/P ratios were measured in the ROI. Four major bone mineralization areas were identified based on the different chemical composition and ratios of the ROI. Area 1: A well-defined area with low Ca/N, P/N, and Ca/P was identified as low-density bone. Area 2: A defined area with higher Ca/N, P/N, and Ca/P, identified as new bone tissue, or bone remodeling areas. Area 3: A well-defined area with high Ca/N, /P/N, and Ca/P ratios, identified as bone tissue or bone chips. Area 4: An area with high Ca/N, P/N, and Ca/P ratios, which was identified as mature old cortical bone. Bone Area 2 was the most represented area along the bone-implant interface, while Bone Area 4 was identified only at sites approximately 1.5 mm from the interface. All areas were identified around implant biopsies, creating a mosaic-shaped distribution with well-defined borders. ESEM-EDX in combination with OM allowed to perform a microchemical analysis and offered new important information on the organic and inorganic content of the bone tissue around implants
Prompt dipole radiation in fusion reactions
The prompt gamma ray emission was investigated in the 16A MeV energy region
by means of the 36,40Ar+96,92Zr fusion reactions leading to a compound nucleus
in the vicinity of 132Ce. We show that the prompt radiation, which appears to
be still effective at such a high beam energy, has an angular distribution
pattern consistent with a dipole oscillation along the symmetry axis of the
dinuclear system. The data are compared with calculations based on a collective
bremsstrahlung analysis of the reaction dynamics
The Dynamical Dipole Mode in Dissipative Heavy Ion Collisions
We study the effect of a direct Giant Dipole Resonance () excitation in
intermediate dinuclear systems with exotic shape and charge distributions
formed in charge asymmetric fusion entrance channels. A related enhancement of
the gamma yield in the evaporation cascade of the fused nucleus is
expected. The dynamical origin of such extra strength will show up in a
characteristic anisotropy of the dipole gamma-emission. A fully microscopic
analysis of the fusion dynamics is performed with quantitative predictions of
the photon yield based on a dynamics- statistics coupling model. In
particular we focus our attention on the energy and mass dependence of the
effect.
We suggest a series of new experiments, in particular some optimal entrance
channel conditions. We stress the importance of using the new available
radioactive beams.Comment: 20 pages (Latex), 14 Postscript figure
Strong enhancement of extremely energetic proton production in central heavy ion collisions at intermediate energy
The energetic proton emission has been investigated as a function of the
reaction centrality for the system 58Ni + 58Ni at 30A MeV. Extremely energetic
protons (EpNN > 130 MeV) were measured and their multiplicity is found to
increase almost quadratically with the number of participant nucleons thus
indicating the onset of a mechanism beyond one and two-body dynamics.Comment: 5 pages, 2 figures, submitted to Physical Review Letter
Measuring diffuse neutrino fluxes with IceCube
In this paper the sensitivity of a future kilometer-sized neutrino detector
to detect and measure the diffuse flux of high energy neutrinos is evaluated.
Event rates in established detection channels, such as muon events from charged
current muon neutrino interactions or cascade events from electron neutrino and
tau neutrino interactions, are calculated using a detailed Monte Carlo
simulation. Neutrino fluxes as expected from prompt charm decay in the
atmosphere or from astrophysical sources such as Active Galactic Nuclei are
modeled assuming power laws. The ability to measure the normalization and slope
of these spectra is then analyzed.
It is found that the cascade channel generally has a high sensitivity for the
detection and characterization of the diffuse flux, when compared to what is
expected for the upgoing- and downgoing-muon channels. A flux at the level of
the Waxman-Bahcall upper bound should be detectable in all channels separately
while a combination of the information of the different channels will allow
detection of a flux more than one order of magnitude lower. Neutrinos from the
prompt decay of charmed mesons in the atmosphere should be detectable in future
measurements for all but the lowest predictions.Comment: 12 pages, 3 figure
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