PubMed Health⌕ Search

Biomedical subjects

E Rapisarda

Publications and source records attributed to E Rapisarda.

At least 19 recordsLinked to original sources
PubMed2001

Wear of nickel-titanium endodontic instruments evaluated by scanning electron microscopy: effect of ion implantation.

The present work analyzes possible increases in resistance to wear of nickel-titanium endodontic instruments that have undergone a process of ionic implantation. ProFile .04 taper #25 instruments were subjected to ionic implantation with bands of nitrogen ions of 250 KeV, currents in the order of 10 microA/cm2, and doses of 2 x 10(17) ions/ cm2. The instruments were used to make preparations in acrylic endodontic training blocks. Scanning electron microscopic investigations showed that after 60 s of work inside the endodontic training blocks nonionic implanted control instruments showed small modifications in their blades, and their tips showed the first signs of wear. After 240 s the control instruments showed consistent signs of wear and frequent changes to their surfaces. After 240 s of use the ionic-implanted instruments did not present any significant changes in the micromorphology of their surfaces. The implanted instruments did not manifest the typical signs of wear and did not show the surface changes that quickly affect the working life of untreated endodontic instruments manufactured from nickel-titanium.

Dental Instruments↗
PubMed2001

Defects in GT rotary instruments after use: an SEM study.

Used rotary nickel-titanium instruments require frequent replacement. This laboratory study evaluated defects of GT Rotary instruments before and after usage. The instruments were fixed into custom-made holders and photographed in an SEM at x 260 to x 12,000 magnification at preset points. Instrument sizes 20 with 1.0, 0.8, and 0.6 taper and instrument sizes 35 with 1.2 taper were used in 12 canals. The used instruments were cleaned and then reexamined in an SEM as before. The presence of 11 types of conditions was scored from the pre- and postusage photographs. No instruments fracturing or plastic deformation was observed during the test. The presence of debris, pitting, and scraping changed significantly. Imperfections were found on used GT Rotary instruments and the presence of defects (pitting, scraping, and blunt-cutting edges) increased in all of the instruments. The behavior of GT Rotary instruments with usage seems to be different, compared with that found in other instruments.

Dental High-Speed Technique↗
PubMed2000

The effect of surface treatments of nickel-titanium files on wear and cutting efficiency.

OBJECTIVES: This study was designed to verify whether nitridation treatment of the cutting surfaces resulted in surface or subsurface changes that produced an increase in the resistance to wear in nickel titanium (NiTi) endodontic files. STUDY DESIGN: Some experimental samples were exposed to ionic implantation by using 150 keV of nitrogen ions and doses of 1 x 10(17) ions per cm(2). Other samples were exposed to thermal nitridation processes performed for 480 minutes at 500 degrees C temperature. Control samples were not exposed to any process. The chemical composition of the surface layers of each sample was determined by means of x-ray photoelectron spectroscopy. The cutting efficiency was tested on an endotraining bloc. RESULTS: The experimental instruments showed in-depth distributions of chemical composition that were different from those seen in the control group; thermal-nitridated instruments demonstrated a surface ratio of nickel to titanium of 0.5. Implanted samples had a higher N/Ti ratio (1.2); this ratio may be due to the presence of a layer of titanium nitride. Samples in the experimental groups showed an increase in cutting ability as compared with the controls. CONCLUSIONS: Thermal nitridation and nitrogen-ionic implantation treatment of nickel-titanium files produced a higher wear resistance and an increased cutting capacity.

Dental Alloys↗
PubMed1999

Effect of sterilization on the cutting efficiency of rotary nickel-titanium endodontic files.

OBJECTIVE: Nickel-titanium instruments that offer greater flexibility than instruments made of other metallic materials have been developed. This study evaluated the behavior in vitro of nickel-titanium rotary instruments under repeated sterilization cycles. STUDY DESIGN: To investigate changes in cutting ability and superficial alterations, 36 ProFile instruments, 18 with a taper of .04 and 18 with a taper of .06, were exposed to different sterilization cycles. Samples were divided into 3 groups of 12 files each. The 12 group A samples were exposed to 14 cycles of sterilization for 30 minutes; the 12 group B samples were exposed to 7 cycles of sterilization for 30 minutes; the 12 group C samples were not sterilized and served as a control group. Chemical compositions of the near surface layers of samples of each group were determined by means of Auger spectroscopy. RESULTS: The instruments that underwent the greatest number of sterilizations (group A) showed in-depth distributions of chemical composition that were different from those seen in the control group; this was the result of greater amounts of titanium oxide on the surfaces of the sterilized instruments. The files of group A showed a decrease in cutting efficiency in comparison with those of the control group. CONCLUSIONS: On the basis of this research on nickel-titanium files, we determined that repeated sterilizations under autoclave alter the superficial structure of such instruments.

Dental Instruments↗
PubMed1999

[Comparison of different finishing methods for composites and compomers. Profilometric analysis].

BACKGROUND: Reconstructions with aesthetical materials neither finished nor polished can be extremely irregular and wrinkled. For this reason they represent an ideal basis for the growing of pigmentation which come from food remainings and the nestle of bacteria on the plaque. The finishing of aesthetical materials is a fundamental step in conservative dentistry. The finishing session regarding the aesthetical restorations should be considered and planned at the moment of their insertion in the prepared hollows. The finishing should not be considered an option, but the conclusion of all the conservative treatment. Purpose of the search is to examine and assess, through a technical equipment measuring the superficial wrinkledness of the materials, the action of 4 systems of finishing and polishing on two aesthetical materials widely used in the daily practice by dental surgeons: a compomer (Compoglass, Vivadent) and a composite (Spectrum, Dentsply). METHODS: For each of these two materials some little slabs model have been prepared, choosing the universal colour in the colorimetric scale. The two types of filling materials have been compared with 4 systems of finishing and polishing: Sof-Lex Pop-on (3M), Enhance system (Dentsply), Hawe Micro Disc (Howe Neos), Heawe Gommini Polisher (Heawe Neos). The total working time did not overcome 1 minute. The little slabs have been obtained, pressing the resin between two slides used in microscopy. In the hope to guarantee in the different samples, a uniform thickness, we have used a technical device. On each covering slide we have put a weight of 0.5 kg for 5 minutes. The thickness of the little slabs obtained was 2 mm. Thus, pressed between the two slides, the aesthetical material has been photopolymerized according to the time suggested by Manufacturing Industries. The sizes concerning the wrinkledness of samples subjected to different treatments have been carried out using a pointed profilometer with high sensitivity. (Tencor-P10). This instrument used in the National Laboratory of Catania, called INFN, is able to graphitize the wrinkledness of a surface "survbeying" it with a diamond ultramicrometric point. RESULTS: All tested systems gradually produce the upper layers of the materials less suitable to resist the assault of plaque bacteria as time passed. The 3M coarse and medium grain Disks are very abrasive and for this reason the surface of the materials is ill-shaped. Those disks with fine and extra fine grain, smooth the tracks left by previous disks. As they have been always used according to their decreasing granulometry, the disks are used only for removing small composite pieces in excess and to improve micromorphology of the restauration. The "Gommini" are less abrasive than Disks. In a few minutes and often with only one step they produce a much regular and polished fillings surface. CONCLUSIONS: The "Gommini" have a preference when the last photopolymerization has left a regular layer, with a very good micromorphology. Actually, "Gommini" do not remove much material, but they continue to smooth the outline of the reconstruction. Disks are not classified as being of first quality in the finishing of composites and compomers.

Composite Resins↗
PubMed1998

[The role of cell adhesion molecules in the formation of periapical granulomas].

Cell adhesion molecules (CAMs) are cell surface proteins involved in the binding of cells, usually leukocytes, to each other, to endothelial cells, or to extracellular matrix. Specific signals produced in response to wounding and infection control the expression and activation of certain of these adhesion molecules. The interactions and responses then initiated by binding of these CAMs to their receptors/ligands play important roles in the mediation of the inflammatory and immune reactions that consult one line of the body's defense against these insults. Most of the CAMs characterized so far fall into three general families of proteins: the immunoglobulin (Ig) superfamily, the integrin family, or the selectine family. Recent studies have indicated that selectins (E,L,P) are implicated in cell trafficking, an important aspect of inflammation-related process. Regulation of white blood cell trafficking from the blood vascular compartment to regions of pathogenic exposure is one of the most important functions of the immune system. The distinct phases of leukocyte migration include: rolling, activation, firm adhesion, transendothelial migration and subendothelial migration. The selectins have been implicated in the first step of this cascade. An inflammatory response is first evoked in the pulpal tissue in an attempt to neutralize the injurious agent and to dispose of damaged tissue and cells. The pulpal vessels dilate and blood flow to the tooth increases. At the same time, permeability of the vessels increases allowing leakage of fluid and leukocytes into the tissue.

Cell Adhesion Molecules↗
PubMed1998

[SEM (Scanning Electron Microscopy) study of the deterioration of ProFile .04 and .06].

BACKGROUND: The ProFile are endodontic instruments made by a special nickel-titanium alloy. They have to work on constant rotation at a speed of 350 revolutions per minute. The purpose of the study is to assess, through SEM research, a possible deterioration of different ProFile conicity. METHODS: Sixteen dental elements pulled out for period dental reasons have been used as samples to assess the progressive deterioration of .04 and .06 ProFile conicity. Eight molars and eight premolars with a total of 36 radicular canals were examined. The types of ProFile tested were 8: they were respectively 4 with .04 conicity and 4 with .06 conicity. Before being used, all instruments are previously studied through SEM. The tested ProFile with .04 conicity had a diameter of 15, 25, 30 and 45. Those with .06 conicity had a diameter of 20, 25, 30 and 35. Each tested ProFile was introduced inside a radicular canal and was turned for 180 seconds with a constant rotation of 200 revolutions per minute. After this first step, the alterations produced by the instrument could be observed through SEM. Afterwards, the same ProFile has worked again inside another radicular canal with the same time and the same number of turns, before being observed again through SEM. We have continued using this method up to the break of the instrument. RESULTS: The instruments with .04 conicity and smaller diameter are subject to a faster deterioration, more visible at the point. After a working time of 180 seconds all the instruments have their distinct morphological alterations: after other 180 seconds it is possible to often observer an alteration to the pitch of the instrument. The breaking times are related to the diameter and conicity of ProFile tested. CONCLUSIONS: Endodontic nickel-titanium instruments, even if they represent a progress in the field of canal preparation, undergo some alterations in their shape if they are put under inevitable mechanical stress. The damages can be: break at the top of the instrument and loss of cutting abilities at the turns level.

Bicuspid↗
PubMed1991

Effects of Nd-Yag laser vitreolysis on lens and vitreous prostaglandins in the rabbit eye.

This study concerns the quantitative modifications of the prostaglandins, PGF alpha e PGE2, in the vitreous and in the lens following the application of Nd-Yag Laser. Five minutes after the Yag-laser treatment, an increase of PGF1 alpha concentration of PGE2 decreased in the lens and increased in the vitreous. These changes, similar to those occurring in the aqueous humor, may be related to the activation of specific enzymatic pathways of prostaglandin synthesis.

Analysis of Variance↗
PubMed1990

[Shape memory alloys for orthodontic use studied with electron beams].

Shape memory alloys, which have the ability to be deformed into a temporary shape and then returned to its original shape giving useful elastic forces, are used in orthodontics field as shaped archs and springs. Their characteristics offer high potentiality to produce new orthodontics devices and to use in implantology. Using different analysis techniques with focussed electron beams, Authors have investigated on the superficial topography, alloy structural composition and on the absorbed elements of superficial layers of Nitinol orthodontics archs. SEM analysis have shown a compact and finished surface. PIXE analysis has quantized the atomic alloy composition in 55% and 45% on nickel and titanium, respectively. Auger spectroscopy and ion sputtering technique have shown that in surface of new archs oxygen and carbon are present up to about 300 A depth.

Alloys↗
PubMed1989

[Boron in dental hard tissues studied by 11B(p,alpha)8Be nuclear reaction].

Boron's low atomic number and low concentration make its measurement in hard dental tissues difficult. Using nuclear reaction, the 11B(p,alpha)8Be*, enamel, dentine and radicular cement of 18 dental elements, ten healthy and eight decayed teeth, both permanent and deciduous were studied. The highest Boron concentrations were found in the two most superficial microns of the vestibular enamel in non-decayed incisors, particularly deciduous ones. Premolar and molar teeth showed lower Boron concentrations than frontal ones, decayed teeth revealed hardly any Boron. In confirmation of the prevailing exogenous contribution of this karyostatic trace element, on average, Boron concentrations were 2.5 times as high as dentine and 10 times as high as cement.

Boron↗
PubMed1987

Analgesic activity of a synthetic analogue of eel-calcitonin and its effect on the spontaneous activity of brainstem neurons in the rat.

Intracerebroventricular (i.c.v.) injection of (Asul,7)eel-calcitonin, a synthetic analogue of eel-calcitonin, at doses of 3 or 6 IU/rat, (but not at 1.5 IU/rat) determined analgesic activity, in male rats, as evaluated by the 'hot-plate' test. Also electrophysiological studies carried out on 13 neurons belonging to the nucleus raphe magnus (NRM) showed that i.c.v. administration of the same doses of (Asul,7)eel-calcitonin increased the spontaneous cellular firing rate. No modification of the discharge frequency was observed when 1.5 IU/rat (Asul,7)eel-calcitonin was used. Authors suggest that the analgesic activity induced by i.c.v. injection of (Asul,7)eel-calcitonin is due, at least in part, to mechanisms affecting NRM neurons.

Action Potentials↗
PubMed1987

Inhibition of gastric secretion and stress-induced ulcers by intravenous Asu(1,7)eel-calcitonin independent of vasopressin.

The effects of different doses of Asu(1,7) eel-calcitonin, peripherally injected, on gastric secretion were studied in conscious Brattleboro rats, which are genetically deficient in vasopressin. Moreover, we evaluated the activity of this analogue on gastric ulcer formation by restraint stress. We found that 5 IU/kg Asu(1,7) eel-calcitonin decreased gastric secretion and inhibited the development of stress-induced ulcers in Brattleboro rats. These data suggest that vasopressin does not play a role in the gastrointestinal activity of Asu(1,7) eel-calcitonin.

Animals↗
PubMed1986

Effects of salmon calcitonin on plasma renin activity and systolic blood pressure in the rat.

Salmon calcitonin, centrally injected, increased plasma renin activity and blood pressure in rats. It is possible that the peptide through an action on the central serotonergic tone stimulated plasma renin activity with subsequent enhancement of blood pressure. Conversely, peripheral administration of the peptide increased plasma renin activity but did not cause changes in blood pressure. Probably, the enhancement of renin may be a physiological response to the renal activity of calcitonin; however, this activity does not seem to involve urinary prostaglandins.

Animals↗