IN VITRO EVALUATION OF THE INFLUENCE OF CONTRACTION STRENGTH IN POLYMERIZATION OF RESTAURATIVE COMPOSITES ON ADHESIVE CAPACITY OF ADAPTION SYSTEMS

Modern Restorative Dentistry today successfully capitalizes on the advances in the rapid evolution of adhesive systems, both in terms of materials and application techniques. Current patient requirements for aesthetics of restorations, as well as the development of adhesive techniques, have imposed composite diacrilic resins (DRCs) as selective materials for direct composite restorations. The contraction of polymerization as well as the stress of the polymerization contraction manifested inside the composite can compromise adhesion between the obturation and the dental tissue, with the appearance of the marginal microinfiltration phenomenon with all the known negative effects such as the occurrence of marginal stains, secondary caries and even pulp necrosis. Numerous studies on the adhesion of materials to dental structures have the objective of knowing and eliminating as far as possible the causes of degradation of the adhesive interface. In this note are also written the authors of this article, whose experimental results provide useful information regarding the influence and evaluation of the contraction stress on the polymerization of the restorative composites and different adhesive system

Testing the constructive strength of a container arranged as a mobile deposit of explosive materials

Today, due to the diversity of the conditions in which the blasting works are executed, they often require a special organization regarding the transportation and storage of the explosive goods near the blasting field. If for explosive storage arranged for long-term use such as those of the producers, there are detailed regulations regarding the constructive and security requirements that they must meet, for the temporary storage facilities, there are not enough details regarding the constructive requirements that they must comply with. One of the most important aspects taken into account when designing and arranging a mobile explosive depot is the limitation to the maximum of the dynamic action and the throw effect of pieces of material under the pression of an accidental detonation. The paper describes the results obtained after testing a container prototype designed for the storage of explosives. Following the tests performed and the evaluation of the dynamic effects of explosions inside and outside the container as well as the analysis of the measurement regarding the pressure generated by the detonation of explosive charges, it turned out that the construction and detonation behavior of the tested container complies with the purpose and safety requirements for setting up a mobile explosive depot

Acoustic zoning for the safe use of explosives in the open pit

Rockfall in open pit mining using explosives is the most method of operation. Also, in addition to the technical and economic advantages, this method of extraction produces effects that can have a negative impact in the area near the quarry. The effects of the blasting are such as seismic waves that produce vibrations, air overpressure (noise), rock throws and toxic gases. If the intensity and extent of these effects are not properly anticipated and assessed, serious consequences can occur to people, civil / industrial buildings, the environment, thus affecting the health of the population and the stability / integrity of buildings / slopes in the vicinity of mining operations. The paper describes methods to assess the noise produced by the detonation of explosives for civilian use when removing rocks in the quarry, with the aim of ensuring a degree of disturbance acceptable to the population as well as for the protection of civil / industrial objectives in the area of mining. The obtained results are extracted from a research study carried out for the opening in operation of a new mining deposit, applying calculations and theoretical interpretations having as reference the conditions established for the development of the blasting works

Computerized simulations and modelling for evaluation of ballistic and security parameters of explosives for civil use

Explosives are chemical compounds - substances or mixtures of substances that have a large amount of energy and which under the influence of external actions decompose suddenly, violently with the release of heat and the formation of gases capable of performing a mechanical work. Due to their specific characteristics, these products are used, both in the civil field and in industry, for the execution of works such as: extraction from the massif, in mines or quarries of useful rocks, execution of mining works (galleries) for opening and preparing deposits for exploitation, tunnels, wells, road constructions, railways, canals, demolition of foundations / civil / industrial buildings that have become unusable, geophysical-seism metric surveys, etc. Research in the field of use of explosives for civil use in various industrial and civil applications requires in-depth knowledge of areas such as the phenomenology of explosion, the behaviour of materials in shock waves, the dynamics of structures, seismic engineering, etc. The design of these types of processes requires the consideration, with a relative approximation, of the degree of danger due to the design of fragments resulting from detonation, vibrations, pressures, tensions created in the space affected by the explosion, generation of explosion gases, etc. legislation in force, being an important indicator regarding the classification, handling, storage and transport in the assessment and management of the risks related to these operations. The paper presents a series of computer simulations, both of the ballistic parameter regarding the working capacity of the explosives, and of the security parameter regarding the impact sensitivity

Забезпечення сейсмічного захисту наземних об'єктів на кар'єрах, що видобувають вапняк та гіпс

The paper highlights the research undertaken at three limestone and gypsum quarries belonging to a large cement producer in Romania, in order to evaluate the seismic protection of civil and industrial objectives located near the exploitation perimeters. In this regard, the results obtained from the tests on the determination of seismic parameters are presented, in order to assess the seismic effect generated by the blasting works on civil and industrial objectives located in the vicinity of exploitation areas.У статті висвітлено дослідження, проведене на трьох кар’єрах вапняку та гіпсу, що належать великому виробнику цементу в Румунії, з метою оцінки сейсмічного захисту цивільних та промислових об’єктів, розташованих поблизу периметрів експлуатації. У зв'язку з цим представлені результати, отримані в результаті випробувань з визначення сейсмічних параметрів, з метою оцінки сейсмічного ефекту, що виникає підривними роботами на цивільні та промислові об'єкти, розташовані в районі експлуатаційних зон

Cuspal Deflection and Adhesive Interface Integrity of Low Shrinking Posterior Composite Restorations

Kad je riječ o restaurativnim zahvatima u distalnom području trenuačno su u svim istraživanjima u središtu pozornosti nisko-kontrahirajući kompoziti. U vezi s tim obećavaju materijali dobiveni siloranskim kemijskim postupkom s prstenastim monomerima i kondenzabilni dimetakrilati s visokim postotkom punila. Materijali i metode: Na ekstrahiranim gornjim premolarima (n=10) promatran je otklon kvržica nakon svjetlosne polimerizacije transduserom s razlikovanjem direktne struje (DCDT-om) uz čuvanje adhezivne veze elektronskim mikroskopom (SEM-om) i dvama restorativnim sustavima. To su Filtek™ Silorane/Silorane System Adhesive (3M ESPE) i Premise™ Packable /OptiBond FL (KERR). Podaci su analizirani dvostranim t-testom. Rezultati: Vrijednost p< 0,05 postavljena je kao statistički značajna granica. Filtek™ Silorane može smanjiti otklon kvržica uzrokovan polimerizacijskom kontrakcijom, ali sumnja se može li se održati adhezivna veza. Zaključak: Premise™ Packable pokazao je veći otklon kvržica tijekom polimerizacije, ali i bolju adhezivnu vezu.Low shrinking resin composites are in the focus of research in posterior resin composite restoratives. In this context, the silorane-chemistry, incorporating ring-opening monomers and highly filled packable dimethacrylates seem to be most promising. Material and Methods: The goal of this study was to investigate cuspal deflection after light-curing in extracted upper premolars (n=10), using direct current differential transducers (DCDT), and adhesive interface integrity by scanning electron microscopy (SEM) evaluation, of two restorative systems: 1) Filtek™ Silorane/ Silorane System Adhesive (3M ESPE); 2) Premise™ Packable /OptiBond FL (KERR). Data were analysed using a two-tailed t-test. Results: A p-value < 0.05 was considered statistically significant. Filtek™ Silorane may reduce cuspal deflection associated to the polymerization process, but there is concern regarding durability of adhesive interface integrity. Conclusions: Premise™ Packable showed higher cuspal deflection and complete integrity of adhesive interface

Otklon kvržica i postojanost adhezivne veze kod restauracija s nisko-kontrahirajućim kompozitom u distalnom području Cuspal Deflection and Adhesive Interface Integrity of Low Shrinking Posterior Composite Restorations

Sažetak Kad je riječ o restaurativnim zahvatima u distalnom području trenuačno su u svim istraživanjima u središtu pozornosti nisko-kontrahirajući kompoziti. U vezi s tim obećavaju materijali dobiveni siloranskim kemijskim postupkom s prstenastim monomerima i kondenzabilni dimetakrilati s visokim postotkom punila. Materijali i metode: Na ekstrahiranim gornjim premolarima (n=10) promatran je otklon kvržica nakon svjetlosne polimerizacije transduserom s razlikovanjem direktne struje (DCDT-om) uz čuvanje adhezivne veze elektronskim mikroskopom (SEM-om) i dvama restorativnim sustavima. To su Filtek™ Silorane/Silorane System Adhesive (3M ESPE) i Premise™ Packable /OptiBond FL (KERR). Podaci su analizirani dvostranim t-testom. rezultati: Vrijednost p&lt; 0,05 postavljena je kao statistički značajna granica. Filtek™ Silorane može smanjiti otklon kvržica uzrokovan polimerizacijskom kontrakcijom, ali sumnja se može li se održati adhezivna veza. zaključak: Premise™ Packable pokazao je veći otklon kvržica tijekom polimerizacije, ali i bolju adhezivnu vezu. Ključne riječi kompozitne smole, polimeri; adhezivi, pretkutnjaci Većina smolastih kompozita (RBCs-a) koji se upotrebljavaju u reataurativnoj dentalnoj medicini imaju zajedničku osnovu -polimeriziraju slobodne radikale metakrilata. Taj postupak mijenja volumen materijala, što omogućuje napetost na spoju restauracija-zub poznatu pod nazivom &quot;polimerizacijski stres zbog kontrakcije&quot; (1). Takav stres nastaje u kompozitnoj masi te se prenosi na adhezivnu vezu (2) i zubnu površinu, što stvara otklon kvržica (3) te pukotine u okolnoj caklini i dentinu (4). Sve to pacijent doživljava kao postoperativnu preosjetljivost (5). Polimerizacijski stres može kompromitirati vezu zuba i restauracije te završiti bakterijskim mikrocurenjem (6) i na kraju rubnim obojenjem, sekundarnim karijesom, upalom zubne pulpe i nekrozom (7)

[Monnaie : Bronze, Ilici, Espagne]

Appartient à l’ensemble documentaire : MonnGr

[Monnaie : Bronze, Ilici, Espagne]

Appartient à l’ensemble documentaire : MonnGr