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Biomedical subjects

G Gambarini

Publications and source records attributed to G Gambarini.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rationale for the use of low-torque endodontic motors in root canal instrumentation.

Fracture of nickel-titanium rotary files is an iatrogenic error which can seriously jeopardize root canal therapy. If a high-torque motor is used, the instrument-specific limit-torque (fracture limit) is often exceeded, thus increasing the risk of intracanal failure. A possible solution to this problem is to use a low-torque endodontic motor which operates below these values. If the torque is set just below the limit of elasticity for each instrument, the risk of fracture is likely to be markedly reduced. The purpose of this paper was to discuss mechanical properties of NiTi rotary instruments, the rationale for selecting low torque values, and to use clinically a new endodontic motor (step-motor) which operates below the limit of elasticity of each rotary file. The step-motor was found to be helpful in reducing the risk of instrument fracture. Irreversible material damage (plastic deformation) and instrument fracture were rarely seen. Low-torque instrumentation also increased tactile sense and, consequently, mental awareness of rotary instrumentation.

Computer Systems↗
PubMed1999

Shaping and cleaning the root canal system: a scanning electron microscopic evaluation of a new instrumentation and irrigation technique.

The purpose of the present scanning electron microscopic study was to investigate the efficacy of a combination of EDTA, NaOCl, and surface-active irrigating solutions during and after root canal preparation with ProFile nickel-titanium rotary instruments. Thirty canals were divided into three groups, instrumented and irrigated as follows: 5% NaOCl and a final flush with 17% EDTA were used for group A; group B specimens were irrigated using 17% EDTA, followed 15 s later by 1% TRITON X-100 (tensioactive agent) and then by 5% NaOCl; and group C specimens were irrigated with the same combination, but once shaping procedures were completed the irrigating sequence was repeated three times. After scanning electron microscopic evaluation, group C specimens exhibited the most effective debridement of the root canals. Results showed that tensioactive agent contributed to enhanced debridement. Cleaning was significantly improved once shaping procedures were completed.

Chi-Square Distribution↗
PubMed1998

Chemical stability of heated sodium hypochlorite endodontic irrigants.

Several previous studies have investigated the advantage of temperature on tissue-dissolving and antimicrobial properties of sodium hypochlorite. However, it is known that the chemical stability of sodium hypochlorite is adversely affected by exposure to high temperature. The purpose of this study was to investigate the effect of heating sodium hypochlorite to 50 degrees C on the stability of the solution. An iodometric titration test was used to evaluate the decomposition rates of heated and nonheated solutions over 30 days. Results showed that all specimens exhibited a minimal, gradual degradation versus time. However, no statistically significant difference (p < 0.05) was noted between the two groups. After 30 days, both heated and non-heated solutions maintained high available chlorine content and pH values consistent with excellent tissue-dissolving and antibacterial properties.

Analysis of Variance↗
PubMed1996

Sealing ability of a new hydroxyapatite-containing endodontic sealer using lateral condensation and thermatic compaction of gutta-percha, in vitro.

A new sealer that contains hydroxyapatite has been developed; the additive is assumed to influence apical healing, but it may also affect the sealing ability of the cement because of its composite structure. The purpose of this study was to evaluate the sealing ability of Bioseal and to compare it with that of another zinc oxide-eugenol sealer (Pulp Canal Sealer), using a lateral condensation technique and thermatic compaction of gutta-percha. The study was conducted on 42 straight roots, prepared to apical size 35 to 40 and randomly separated into four groups. After obturation, the roots were suspended for 1 wk in methylene blue and sectioned transversely for measuring penetration of the dye. In the roots filled with Bioseal, the mean penetration was 1.1 mm for lateral condensation and 1.5 mm for thermatic compaction. In the Pulp Canal Sealer groups, the values were 1.4 mm for both. The difference was not significant at the 5% level (Mann-Whitney U test), indicating that the additive did not adversely affect the sealing properties.

Dental Leakage↗
PubMed1995

Proton activation analysis of stable isotopes for a molybdenum biokinetics study in humans.

Molybdenum is a trace element essential to life. Nevertheless, little information is available on its metabolism in humans. A methodology based on stable isotope administration that combines compartmental analysis, simultaneous use of two tracers, and proton nuclear activation (PNA) is presented. A four-compartment metabolic model was adopted. The compartments are stomach, small intestine, transfer compartment, and unquantified tissue pool. The employment of two different stable isotopes of the element under investigation as tracers was made possible by PNA. Optimization of the technique for molybdenum determination in plasma led to the choice of 95Mo and 96Mo as tracers. Their concentrations in plasma can be determined measuring the disintegration gamma lines of the corresponding technetium radioisotopes produced via (p,n) reaction. In the adopted experimental conditions, a minimum detectable concentration of 2 ng isotope/ml plasma was attained. A kinetics study was performed on two healthy volunteers. To both subjects one tracer was orally administered, and the other intravenously injected. Venous blood samples were withdrawn at different postinjection times and the concentrations for both isotopes determined. The model parameters describing molybdenum kinetics were obtained for the two individuals. Total absorbed fraction was found to be 0.84 +/- 0.03 and 0.86 +/- 0.07, respectively.

Activation Analysis↗
PubMed1994

Dose-response curve slope improvement and result reproducibility of ferrous-sulphate-doped gels analysed by NMR imaging.

Ferrous sulphate gel analysed by relaxation time measurements with NMR imaging is considered a useful dosimeter for 3D determinations of absorbed dose. A protocol for the gel preparation with agarose SeaPlaque that leads to a dosimeter with very high dose sensitivity is described. The dose-response curve slope is about 0.2 s(-1) Gy(-1) and the G factor turns out to be approximately 185 ions per 100 eV of absorbed energy. A method for making the measurements and analysing the results that brings about good result reproducibility is suggested. A thorough experimental study of the dependence of the dosimeter response on the elapsed time from preparation to irradiation and from irradiation to NMR measurement has revealed good reproducibility. The above characteristic of the gel system is very interesting, because it shows the possibility of utilizing the dosimeter for absolute dose determinations with satisfactory reliability.

Dose-Response Relationship, Radiation↗
PubMed1993

Response to a single oral test of molybdenum stable isotopes for absorption studies in humans.

Two volunteer subjects were given orally enriched solutions of Mo-95 and Mo-96 respectively. Blood samples were drawn at various times following the tracer administration. The Mo-95 and Mo-96 content in plasma samples was determined by proton nuclear activation and the response to the single oral test of enriched stable molybdenum isotopes was determined. Assuming a simple two-open-compartment model where the first compartment is the gastrointestinal tract and the other is the plasma, an indicative value of the fractional intestinal absorption for the two subjects is given. The feasibility of direct quantitative measurements of Mo intestinal absorption by the double-tracer technique, using stable tracers, is evidenced.

Administration, Oral↗
PubMed1993

[Preformed round-section NiTi arch wires: the mechanical and clinical aspects].

The authors emphasize the need to set up several products proposed by the manufacturers. Regarding to orthodontic wires, a suitable evaluation of their mechanical properties to fit them for clinical use is needed. After a short outline of the mechanical properties of the wires on the market, the authors focus their attention on the NiTi Japanese alloy superelastic wires. Therefore, an evaluation of the failure aspect of NiTi preformed arch wires with round section of 0.018" of diameter is reported. The tested wires underwent to clinical use as first arch wires, and were evaluated after 8 weeks from the beginning of the therapy, when they have shown failure at the control in the 8th week. After having cleansed and prepared the specimens, their failure zones have been observed by the SEM. The failure aspect was evaluated to check the reasons that produced it, basing on its surface characteristics. The aspect of the surface of the failure and the absence of permanent deformations showed that it is a fragile failure. The fragile failure occurs when materials are not able to tolerate plastic deformations and, typically concerning NiTi alloys constituent the tested wires, it joins the superelastic behaviour and the high wire resilience. It means that this wire is able to produce constant, continuous and light forces for a given stress range, and, furthermore, it is able to absorb energy without permanent deformations. Since 1971 NiTi wires have been on the market but without superelastic and crystallographic shape memory properties possessed by the wires produced by Furukawa El. Co. in 1978.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Alloys↗
PubMed1992

[A clinical study of the efficacy and tolerance of nimesulide compared to flurbiprofen and sodium diclofenac in the prevention and treatment of postoperative pain and inflammatory symptoms in dentistry].

The efficacy and tolerability of a new pharmaceutical formulation of a non-steroid anti-inflammatory drug, nimesulide were studied in a double blind study in comparison with flurbiprofen and diclofenac sodium, in 150 patients suffering from postsurgical pain-inflammatory symptoms. The three drugs, administered in a dose of one suppository twice a day for 10 days, showed marked anti-inflammatory, analgesic and antipyretic activity and produced a significant, progressive improvement in the typical symptoms of the inflammatory state. Nimesulide evidenced the greatest speed and duration of therapeutic action. Assessment on the efficacy and tolerability as expressed separately by the physician and the patients were positive in almost all cases of the three treatments.

Adolescent↗
PubMed1991

[Morphological characteristics of spreaders].

Different kinds of spreaders can be used in the lateral condensation technique. Selection of condensation instruments must not be empirical because the quality of the filling partly depends on the compatibility between the spreader and the prepared root canal. The shape of the instrument should allow for easy insertion to the proper length without any interference. On these bases the Authors evaluated and compared the morphology of some spreaders, and gave data and directions how to rationally use these instruments in clinical practice.

Dental Instruments↗
PubMed1984

[Early mother-child relations in relation to the desire for children. Significance of care conditions for the emotional conditioning of the female].

100 women have been asked using a psychologic open-answer-questionnaire containing items regarding the woman's distinctive features, her pregnancy delivery, puerperium and breastfeeding. Mainly there is a positive relationship to the growing fetus in cases of unwanted pregnancy, too. The highest degree of motivation is reached in the moment of the first contact between mother and newborn.

Attitude↗
PubMedDate not supplied

Discrimination of various contributions to the absorbed dose in BNCT: Fricke-gel imaging and intercomparison with other experimental results.

A method is described for the 3D measurements of absorbed dose in a ferrous sulphate gel phantom, exposed in the thermal column of a nuclear reactor. The method, studied for Boron Neutron Capture Therapy (BNCT) purposes, allows absorbed dose imaging and profiling, with the separation of different contributions coming from different secondary radiations, generated from thermal neutrons. In fact, the biological effectiveness of the different radiations is different. Tests with conventional dosimeters were performed too.

Boron Neutron Capture Therapy↗
PubMedDate not supplied

Dependence of TLD thermoluminescence yield on absorbed dose in a thermal neutron field.

The emission from 6LiF and 7LiF thermoluminescence dosimeters (TLDs) exposed to the mixed field of thermal neutrons and gamma-rays of the thermal facility of a TRIGA MARK II nuclear reactor has been investigated for various thermal neutron fluences of the order of magnitude of those utilised in radiotherapy, with the purpose of investigating the reliability of TLD readouts in such radiation fields and of giving some information for better obtainment of the absorbed dose values. The emission after exposure in this mixed field is compared with the emission after gamma-rays only. The glow curves have been deconvoluted into gaussian peaks, and the differences in the characteristics of the peaks observed for the two radiation fields, having different linear energy transfers, and for different doses are shown. Irreversible radiation damage in dosimeters having high sensitivity to thermal neutrons is also reported, showing a memory effect of the previous thermal neutron irradiation history which is not restored by anneal treatment.

Fluorides↗
PubMedDate not supplied

Phantom dosimeters examined by NMR analysis: a promising technique for 3-D determinations of absorbed dose.

Fricke-infused agarose gels examined by nuclear magnetic resonance (NMR) analysis are inspected, and their response to gamma-rays, thermal neutrons and protons, at radiotherapy dose levels, is examined. The gel composition is chosen with attention to the tissue equivalence for the radiation fields of interest; this problem is crucial, in particular, for thermal neutrons. The feasibility of three-dimensional determination of absorbed dose in Fricke-gel phantoms is investigated, and the possibility of employing the technique in conformal therapies, such as boron neutron capture therapy (BNCT) and proton therapy, is tested. Isodose curve determination in a cylindrical gel phantom exposed to thermal neutrons is presented. A method for depth-dose profiling in tissue exposed to protons is described, and some results are reported which show that the depth-dose data are determinable with millimetric precision. Results obtained with a spectrophotometer from gel augmented with a metal indicator are reported and discussed also. These results show the possibility of obtaining a very sensitive dosimetry technique consisting of spectrophotometric analysis of such a Fricke-gel.

Absorption↗
PubMedDate not supplied

An iron metabolism study in humans by means of stable tracers.

An investigation of iron metabolism in a female patient volunteer by administration of stable iron isotopes as tracers was performed. The applied methodology had already been tested in rabbits in comparison with radioactive tracer technique. The subject under study was given 58Fe solution intravenously and about 45 min later 57Fe solution orally. Ten blood samples were drawn at different times within 522 min from injection. Single iron isotopes content in plasma samples was determined by proton nuclear activation. A Compton suppressor system was utilized to improve the detector limits. The characteristic parameters of iron plasma clearance and of iron intestinal absorption were determined.

Activation Analysis↗