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)

Raman Spectroscopy as Spectral Tool for Assessing the Degree of Conversion after Curing of Two Resin-Based Materials Used in Restorative Dentistry

(1) Background: The treatment of dental cavities and restoration of tooth shape requires specialized materials with specific clinical properties, including being easy to model, light-cured, having a natural color, reduced shrinkage, a hardness similar to hydroxyapatite, and no leakage. The dimensional stability of resin composite materials is affected by polymerization shrinkage, degree of conversion (number of π carbon bonds converted into σ ones), thermal contraction and expansion, and interactions with an aqueous environment. (2) Methods: The materials used in our investigation were two composite resins with similar polymer matrices, but different filler (micro/nano filler). To evaluate the properties of samples, we employed the pycnometer technique (pycnometer from Paul Marienfeld Gmbh, Lauda-Königshofen, Germany), RAMAN spectroscopy technique (MiniRam Equipment from B&W Tek Inc., Plainsboro Township, NJ, USA; 785 nm laser source), SEM and EDX (FEI Inspect S.). (3) Results: The size of the filler plays an important role in the polymerization: for the pycnometric results, the larger particle filler (Sample 1) seems to undergo a rapid polymerization during the 45 s curing, while the nanoparticle filer (Sample 2) needs additional curing time to fully polymerize. This is related to a much larger porosity, as proved by SEM images. The lower degree of conversion, as obtained by Raman spectroscopy, in the same geometry means that the same volume is probed for both samples, but Sample 1 is more porous, which means less amount of polymer is probed for Sample 1. (4) Conclusions: For the two composites, we obtained a degree of conversion of 59% for Sample 1 and 93% for Sample 2, after 45 s of curing

Performance Assessment of Three Similar Dental Restorative Composite Materials via Raman Spectroscopy Supported by Complementary Methods Such as Hardness and Density Measurements

(1) Background: A widespread problem in oral health is cavities produced by cariogenic bacteria that consume fermentable carbohydrates and lower pH to 5.5–6.5, thus extracting Ca2+ and phosphate ions (PO43−) from teeth. Dental restorative materials based on polymers are used to fill the gaps in damaged teeth, but their properties are different from those of dental enamel. Therefore, a question is raised about the similarity between dental composites and natural teeth in terms of density and hardness. (2) Methods: We have used Raman spectroscopy and density and microhardness measurements to compare physical characteristics of several restorative dental composites at different polymerization intervals. (3) Results: XRVHerculite®, Optishade®, and VertiseFlow® showed the very different characteristics of the physical properties following four polymerization intervals. Of the three composites, OptiShade showed the highest polymerization rate. (4) Conclusions: Only fully polymerized composites can be used in teeth restoring, because incomplete polymerization would result in cracks, pitting, and lead finally to failure