Papers by Author: Anna Maria Visco

Abstract: In order to rebuild the decayed teeth it’s necessary to re-establish the elastic properties of lost dental tissues, replacing them with restorative materials. A not corrected reconstructive method in the dental implant could reduce the mechanical performance causing its progressive premature failure. In this work composite materials, based on quartz fibers posts and adhesive resins, were employed with the aim to restore damaged teeth. Two groups of extracted teeth were rebuilt with two different techniques. In the first group of samples (A) the fiber quartz post and the adhesive resins were simply located into the dental implant and then cured by a light source. In the second group (B) the post and the resin were in situ preformed and then photo-cured; the pre-formed post was then cemented to the tooth with the same procedure of the group A. The two different types of dental restorations were mechanically characterized with a pull-out test with an universal testing machine (Lloyd LR10K). The experimental results showed that the B group samples have an higher mechanical strength than the A group samples, evidencing a better interface adhesion between post– adhesive–tooth. The difference of means of pull out stress data was statistically confirmed by the ANOVA method.

Abstract: Damond-like (DLC) films can be produced by Pulsed Laser Deposition (PLD) technique. Different pulsed lasers can be employed to generate hot carbon plasma, to deposit and/or to implant energetic carbon atoms and molecules on substrates. A Nd:Yag laser radiation with ns pulse duration, about 1010 W/cm2intensity and 30 Hz repetition rate, can be employed to produce in vacuum thin carbon films with properties similar to graphite and diamond. The films were deposited on SiO2 substrates, placed at different distances and angles from the target. The PLDgenerated plasma can be controlled “in situ” by mass quadrupole spectroscopy and time-of-flight tehniques. “Ex situ” investigations were performed on the deposited films by using the Scanning Electron Microscopy (SEM) and Raman spectroscopy. Deposited films show evidence of carbon nanostructures, which find a growing variety of applications in medicine and bio-enegineering fields. Diamond-like carbon (DLC) shows low friction, high atomic density, hard but flexible structure, chemical inertia, wear, diffusion and corrosion resistance and highly bio and hemocompatible properties.

Abstract: A Nd:YAG laser is employed to ablate different materials useful in the bio-medical field. The laser source operates in the IR (1064 nm), VIS (532 nm) and UV (355 nm) regions with a pulse duration of 3-9 ns, a pulse energy of 3-300 mJ, a spot size of 1 mm2 and a repetition rate of 1- 30 Hz. Target material of interest are Titanium, Carbon, Hydroxyapatite (HA) and Polyethylene (PE). Laser irradiation occurs in vacuum, where hot plasma is generated, and thin films are deposited on near substrates. Generally, substrates of silicon, titanium, titanium-alloys and polymers were employed. Biocompatible thin films are investigated with different surface techniques, such as IR spectroscopy, Raman spectroscopy, XRD analysis and SEM investigations. Depending of the kind of possible application, films require special properties concerning the grain size, porosity, uniformity, wetting, hardness, adhesion, crystallinity and composition. The obtained results will be presented and discussed with particular regard to HA..