Muonic atom spectroscopy with microgram target material

Muonic atom spectroscopy-the measurement of the x rays emitted during the formation process of a muonic atom-has a long standing history in probing the shape and size of nuclei. In fact, almost all stable elements have been subject to muonic atom spectroscopy measurements and the absolute charge radii extracted from these measurements typically offer the highest accuracy available. However, so far only targets of at least a few hundred milligram could be used as it required to stop a muon beam directly in the target to form the muonic atom. We have developed a new method relying on repeated transfer reactions taking place inside a 100 bar hydrogen gas cell with an admixture of 0.25% deuterium that allows us to drastically reduce the amount of target material needed while still offering an adequate efficiency. Detailed simulations of the transfer reactions match the measured data, suggesting good understanding of the processes taking place inside the gas mixture. As a proof of principle we demonstrate the method with a measurement of the 2p-1s muonic x rays from a 5  μ g gold target.

Competition between Allowed and First-Forbidden β Decay: The Case of ^{208}Hg→^{208}Tl

The β decay of ^{208}Hg into the one-proton hole, one neutron-particle _{81}^{208}Tl_{127} nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z<82 quadrant of neutron-rich nuclei. While both negative and positive parity states with spin 0 and 1 are expected within the Q_{β} window, only three negative parity states are populated directly in the β decay. The data provide a unique test of the competition between allowed Gamow-Teller and Fermi, and first-forbidden β decays, essential for the understanding of the nucleosynthesis of heavy nuclei in the rapid neutron capture process. Furthermore, the observation of the parity changing 0^{+}→0^{-}β decay where the daughter state is core excited is unique, and can provide information on mesonic corrections of effective operators.

Colorimetric study about the stratification's effect on colour perception of resin composites

To evaluate the influence of a different order of dentin and enamel layers on stratification appearance of different resin composites. 144 Dentin (D) and Enamel (E) composite samples (Clearfil Majesty ES-2 Premium, Brilliant EverGlow, Estelite Asteria), 1 mm thick, were divided into 12 configurations for each composite, with Enamel-Dentin-Dentin-Enamel (EDDE) assumed as target. The colour specification was conducted using a spectrophotometer, elaborating the results with the CIE L*a*b* colour coordinates and calculating the colour difference in terms of [Formula: see text] quantity. A value of this last major of 3.3 was considered not clinically acceptable. Moreover, data were analyzed using two-way analysis of variance and Tukey post hoc test (P < 0.05). For Clearfil Majesty ES-2 Premium and Brilliant EverGlow, six configurations showed [Formula: see text] > 3.3 compared to gold standard EDDE. [Formula: see text] was influenced especially by b* and L* coordinates (P < 0.05). EDED showed no visual difference (0 < [Formula: see text] < 1.1) for both composites. For Estelite Asteria, two configurations reported [Formula: see text] > 3.3 compared to EDDE. In particular, the L* coordinate influenced [Formula: see text] results (P < 0.05). EDDD was the best configuration (0 < [Formula: see text] < 1.1). Within the limits of a vitro study, Brilliant EG showed more dependence from order and thickness of stratification (resulting more similar to Clearfil Majesty ES-2 Premium); therefore, it could be indicated for more complex aesthetic restorations. Estelite Asteria seems to be able to balance small differences in thickness of dentin and enamel layers, and consequently, it is more indicated to different clinical situations.

Nuclear structure with radioactive muonic atoms

Muonic atoms have been used to extract the most accurate nuclear charge radii based on the detection of X-rays from the muonic cascades. Most stable and a few unstable isotopes have been investigated with muonic atom spectroscopy techniques. A new research project recently started at the Paul Scherrer Institut aims to extend the highresolution muonic atom spectroscopy for the precise determination of nuclear charge radii and other nuclear structure properties of radioactive isotopes. The challenge to combine the high-energy muon beam with small quantity of stopping mass is being addressed by developing the concept of stopping the muon in a high-density, a high-pressure hydrogen cell and subsequent transfer of the muon to the element of interest. Status and perspectives of the project will be presented.

Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation

Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85  MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.

Carbon fragmentation measurements and validation of the Geant4 nuclear reaction models for hadrontherapy

Nuclear fragmentation measurements are necessary when using heavy-ion beams in hadrontherapy to predict the effects of the ion nuclear interactions within the human body. Moreover, they are also fundamental to validate and improve the Monte Carlo codes for their use in planning tumor treatments. Nowadays, a very limited set of carbon fragmentation cross sections are being measured, and in particular, to our knowledge, no double-differential fragmentation cross sections at intermediate energies are available in the literature. In this work, we have measured the double-differential cross sections and the angular distributions of the secondary fragments produced in the (12)C fragmentation at 62 A MeV on a thin carbon target. The experimental data have been used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before. In particular, we have compared the experimental data with the predictions of two Geant4 nuclear reaction models: the Binary Light Ions Cascade and the Quantum Molecular Dynamic. From the comparison, it has been observed that the Binary Light Ions Cascade approximates the angular distributions of the fragment production cross sections better than the Quantum Molecular Dynamic model. However, the discrepancies observed between the experimental data and the Monte Carlo simulations lead to the conclusion that the prediction capability of both models needs to be improved at intermediate energies.

Cyclic fatigue resistance of two reciprocating nickel-titanium instruments after immersion in sodium hypochlorite

AIM

To assess resistance to cyclic fatigue of reciprocating nickel-titanium ( NiTi ) files (Reciproc and WaveOne) after immersion in NaOCl solution over several time periods.

METHODOLOGY

A total of 90 new Reciproc R25 and WaveOne Primary were tested. The 45 files of the same brand were randomly assigned to three groups (n = 15) and submitted to the following immersion protocol in 5% NaOCl at 37 °C for 16 mm: no immersion (control), 1 or 5 min dynamically. The dynamic immersion and the following cyclic fatigue tests were performed using the appropriate preset reciprocation modes ('RECIPROC ALL' or 'WAVEONE ALL') in a specially designed endodontic motor. Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. The artificial canal was manufactured reproducing the instrument's size and taper. Data were analysed by 2-way analyses of variance.

RESULTS

Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl . Reciproc R25 was associated with a higher cyclic fatigue resistance in all groups compared to WaveOne Primary (P < 0.0001).

CONCLUSIONS

Reciprocating dynamic immersion in NaOCl for 1 or 5 min did not reduce the cyclic fatigue resistance of NiTi files significantly. However, the type of reciprocating instrument influenced cyclic fatigue resistance with Reciproc R25 being more resistant than WaveOne Primary.

Image-based point spread function implementation in a fully 3D OSEM reconstruction algorithm for PET

The interest in positron emission tomography (PET) and particularly in hybrid integrated PET/CT systems has significantly increased in the last few years due to the improved quality of the obtained images. Nevertheless, one of the most important limits of the PET imaging technique is still its poor spatial resolution due to several physical factors originating both at the emission (e.g. positron range, photon non-collinearity) and at detection levels (e.g. scatter inside the scintillating crystals, finite dimensions of the crystals and depth of interaction). To improve the spatial resolution of the images, a possible way consists of measuring the point spread function (PSF) of the system and then accounting for it inside the reconstruction algorithm. In this work, the system response of the GE Discovery STE operating in 3D mode has been characterized by acquiring (22)Na point sources in different positions of the scanner field of view. An image-based model of the PSF was then obtained by fitting asymmetric two-dimensional Gaussians on the (22)Na images reconstructed with small pixel sizes. The PSF was then incorporated, at the image level, in a three-dimensional ordered subset maximum likelihood expectation maximization (OS-MLEM) reconstruction algorithm. A qualitative and quantitative validation of the algorithm accounting for the PSF has been performed on phantom and clinical data, showing improved spatial resolution, higher contrast and lower noise compared with the corresponding images obtained using the standard OS-MLEM algorithm.

Isotopic dependence of the nuclear caloric curve

The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of (124)Sn and radioactive beams of (124)La and (107)Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects (DeltaT approximately 0.6 MeV) appear for residue production near the onset of multifragmentation.

Experimental evidence of (2)He decay from (18)Ne excited states

Two-proton decay from (18)Ne excited states has been studied by complete kinematical reconstruction of the decay products. The (18)Ne nucleus has been produced as a radioactive beam by (20)Ne primary projectile fragmentation at 45 AMeV incident energy on a Be target. The (18)Ne at 33 AMeV incident energy has been excited via Coulomb excitation on a (nat)Pb target. The obtained results unambiguously show that the 6.15 MeV (18)Ne state two-proton decay proceeds through a (2)He diproton resonance (31%) and democratic or virtual sequential decay (69%). The quoted branching ratio has been deduced from relative angle and momentum correlations of the emitted proton pairs.

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.

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.

[The vertical root fracture]

Remembering the epidemiology and the possible etiologies of vertical root fractures, the authors distinguish between fractures that occur in vital teeth and vertical fractures of endodontically treated roots. They discuss predisposing factors, onset modality and follow-up. They describe the symptomatology and the few radiographic pathognomonic signs. They show the importance, prognostic and therapeutic purposes, of an exact differential diagnosis as regards periodontal problems. On the basis of personal experience and the literature they believe that the one certain resolutive therapy is extraction in the case of monorooted teeth and the root amputation of the fractured root in case of plurirooted teeth with a good periodontal supporting bone. They conclude by stressing the importance of a preventive global approach to reduce, among other things, the incidence of these unusual conditions that are difficult to diagnose, present no clear signs, and have an unfavourable prognosis.

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.

[Thermoelastic analysis of nickel-titanium endodontic files]

BACKGROUND

Technological progress in the endodontic field has allowed the creation of innovative nickel-titanium endodontic instruments, made with a superelastic alloy with a reduced modulus of elasticity. The elastic properties of the NiTi alloy can undergo significant variations in connection with mechanical movements and cyclic fatigue induced on the instruments caused by their repeated usage, especially in canals which are anatomically difficult to shape. The state of tension of the instrument determines a deformation of the geometry of the files and, therefore, a modification in their properties. Similarly to mechanical stress, thermal treatments can influence the properties of the alloy. The aim of the study is to subject the NiTi alloy to repeated thermomechanical cycles, examining the influence of the mechanical and thermal stress on the temperature at the beginning and end of the martensite transformation, on the increase of recovery of deformation during the cooling phase and on the change in the internal structure of the material.

METHODS

The instruments (30 ProFile Maillefer) were subdivided into 5 groups: Group I, composed of 6 new ProFiles submitted to 14 sterilization cycles in an autoclave for 30 minutes each; Group II, formed by 6 unused ProFiles subjected to one sterilization cycle in an autoclave; Group III made up of 6 new ProFiles used as controls; Group IV made up of 6 ProFiles submitted to clinical use on endodontic simulators in plexiglas for a total time of 240 seconds; Group V consisting of 6 ProFiles used on endodontic simulators for a total time of 480 seconds. All the above mentioned samples were tested using a thermomechanic dynamic analyzer (DMTA) produced by Rheometric Scientific.

RESULTS

The files from Group III (control) show an elastic deformation curve typical of nickel-titanium instruments. The samples from Groups IV and V subjected to sequential use on endodontic simulators evidenced modifications in their elastic behaviour compared to the control instruments. The operative use caused modifications in the original properties of the alloy, with a reduction in elasticity proportional to the number of uses. The instruments that underwent 14 cycles of sterilization in the autoclave (I group) present dynamic analysis curves which are different compared to the new unsterilized ProFiles. After 14 cycles there is a modification in the response of the instruments to thermodynamic stress.

CONCLUSIONS

Both the samples undergoing repeated mechanical stress on Plexiglas endodontic simulators and those sterilized in the autoclave at thermodynamic analysis show significant modification in modulus of elasti- city. The different taper does not influence the experimental results, there not being any significant differences found in the elastic behaviour between ProFiles.

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.

[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.

[Evaluation of two root canal preparation and obturation methods: the Mc Spadden method and the use of ProFile-Thermafil]

BACKGROUND

In endodontic field different instruments and techniques have been suggested for the preparation and filling or radicular bent canals. The purpose of this study is to compare two different cleaning and canal filling methods: preparation and filling technique, according to Mc Spadden's method, instrument technique and the closing of the canal system according to ProFile-Thermafil method.

METHODS

In this study ten molars divided into two groups of five elements each were used. The five molars of the first group were prepared according to the "crown-down" technique with nickel-titanium instruments by NT Engine Files Quantec 2000 series. The 18 canals found out in the five molars have been filled with Pac Mac and gutta-percha preheated. The five molars of the second group have 17 radicular canals which, firstly, have been cleaned with ProFile .04 and .06 taper fitted to a manipulator at 220 revolutions per minute and then filled by Thermafil n. 30 with plastic carrier. All ten molars were X-rayed first, during and after the treatment. All teeth were soaked into polymerised resin, dissected into three different points and observed through Optical Microscope.

RESULTS

Both cleaning techniques succeed in being efficient in bent canals. The instruments made by Mc Spadden highlight a greater preservation of canal dentine than the ProFile. In samples of the first group there is an excellent adaptation of multiphase gutta-percha to the canal walls and a correct relationship between the filling material and the apical foramen. In filling with Thermafil the adaptation of gutta-percha inside the radicular canal shows outstanding differences in relation to sections taken into account. Actually, while in portion of the crown the filling can be considered satisfactory towards the canal walls, in apical sections there is a decrease in the quantity of gutta-percha step by step, while a contact of plastic carrier with dentine walls is highlighted.

CONCLUSIONS

Wheter in the shaping or in the canal filling phase, the two methods are efficient and conservative towards dental structure at the same time. These methods, have an outstanding reduction in dental weakening and in times of the endodontic treatment performance.

[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.

[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.

[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.

[Sonic and ultrasonic instruments for endodontics. 2. Operative sequence and clinical advantages]

The authors describe the differential characteristics between sonic and ultrasonic endodontic devices: the former type is pneumatic and uses the air coning from the odontoiatric chair that gives to the endodontic instrument only a lateral way of swinging. The latter type changes the ultrasonic activity coming from piezoeletric phenomena into swinging mechanical energy (operating at 25 KHz). The authors specify the characteristics of endodontic instruments and explain their operating ways, demonstrating that reaming by endosonic instruments increases effects of hypochlorite. They also describe the operating train, pausing on the opportunity that the root canal should be manually probed, measured and reamed up to a diameter that gives sufficient space to the file vibration. They conclude listing the advantages that gives the correct use of sonic and ultrasonic devices; they also augur that with their use endodontics could have a greater diffusion.

[Indications for the use of fibrobronchoscopy in oral surgery]

Fibrobronchoscopy, first used in pneumology with a diagnostic and therapeutic purpose, has been recently used in the therapy of "difficult intubations". After trismus, complex fracture, serious maxillofacial malformations and wide neoplasia, classic nose--orotracheal intubation through direct laryngoscopy may turn out difficulty. Some years ago blind intubation was used, which was stressing for the operator and very dangerous for the patient. In the most serious cases, tracheotomy was used. Thanks to flexible fibroscopes of suitable lenght and reduced diameter, nosetracheal intubations guided by fibroscope can be carried out today. Remembering the indications about fibrobronchoscope use in oral surgery, the Authors describe tre method they have used. They also underline the facility of this technique which allows to carry out a sure and not traumatic intubation without resorting to lisive medicines without producing lacerations or tumefactions in laryngotracheal mucosa.

[Sonic and ultrasonic instruments for endodontics. 1. Overview]

Remembering at the common aim for every endodontic treatment, the authors underline that is basal to clean and shape the root canal. The authors describe technical and anatomical handicaps existing in this stage and discriminate between traditional instruments and endosonic instruments. They also remember the advantages of ultrasonic joined with mechanical smoothing of the canal; after they make clear some concepts of wave physics to clarify the terms utilized in this study. Moreover they discriminate endosonic sets in sonic and ultrasonic devices. The authors conclude their study thinking that the endosonic way in endodontics is the synthesis of physical, chemical and biological effects.

[Oral surgery and histologic reports: the incidence of various diseases in eastern Sicily]

According to the histological exams executed from January 1975 to June 1988, the authors assessed the frequency in the years, in the sex and in the decades and of the pathology surgery executed. For simplicity of graphic representation, the authors subdivided the pathologies in nine groups: phlogistic trial, cysts, epulis, leukoplakia and precancerous lesion, epithelial tumor, connectival tumor, vascular tumor and osseous tumor. With the voice "other" we consider some neoplasies which are not numerous and which are not differently classificable. According to the present statistics numerous operations are excluded like dysodontiasis, dental embedding, fractures, supernumerary teeth and so on. The authors ascertained on elevated frequency of cysts and of osteitis of maxillary bone caused by an inadequate and late treatment of the cavity. During the passing of the years the incidence of phlogistic trial is particularly reduced while the cysts presented a notable increase. Comparison of leukoplakia was exceptional while among the tumors predominate the epithelial tumors one. According to the presented information the Authors come to an end hoping a more preventive sensibility of people and dentistries.

[Structural modifications induced by ionic implantation on functional surfaces of prosthetic attachments]

Authors present the results on N+ ion implantation of an inox steel matrix set. They show the main utilization of prothesis attachments and their actual classification in prothesis field. The bombarded surfaces show a resistance increase to oxide-reduction processes respect to non implanted ones. Using the SEM technique to different magnifications, Authors demonstrate that the ion implantation increase the material hardness and the wear resistance of treated surfaces. The modifications, that not involve the matrix volume but only the superficial layers, produce an increase in attachment duration and affidability. Authors conclude valuing the possible application on this new technique for material treatment in Dentistry field.

[Therapeutic choices in myeloma]

After having considered the elements which can rightly address to a precox diagnosis of the multiple myeloma, the AA. analyse the principal laboratory exams. Then, they refer about different therapeutic certificates underlining that the obtained results by the Prof. Reizenstein and Mathè teams are nearly corresponding. They discuss about the compositions and posologies of the most present therapeutic certificates underlining the importance of a precox diagnosis.

[Ionic implantation in the dental field]

Authors present the physics bases and the experimental equipment to obtain ion implant in metals. This new technique is already used in orthopaedic field to increase the metal surface quality as adherence and biocompatibility. In Dentistry field this technique can be employed to increase the surface hardness, the resistance to corrosion processes and the resistance to wear of implanted prosthesis.

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.