Venus Diamond Research Articles

Toothbrush Abrasion of Resin Composites with Different Filler Concepts

ABSTRACT Purpose To investigate the effect of tooth brushing wear with and without calcium carbonate slurry on four commercial resin composites based on different filler concepts. Materials and methods One nanofiller composite MI FIL (MFI, GC), one conventional hybrid type Venus (VEN) and two nanohybrid composites Venus Diamond (VED) and Venus Pearl (VEP) all from Heraeus Kulzer were examined. Forty beam-shaped specimens (12 × 3 × 3 mm) from each product were prepared and subdivided in two equal groups for pregrinding on SiC paper #600 and #4000 respectively. Ten specimens of each pre-ground group were subjected to toothbrush abrasion with calcium carbonate slurry, and 10 to toothbrushing with water only. The samples were submitted to five subsequent runs of 10,000 brushing strokes. Depth of wear and surface roughness (Ra) were measured with a profilometer after each 10 k strokes. Specimens after 50 k strokes were assessed by SEM. Additionally, the KHN (0.25 N/15 s) and the degree of conversion (DC) were determined. Data analysis was done by linear regression and ANOVA followed by Tukey's post-hoc test (p ≤ 0.05). Results Toothbrushing with abrasive slurry produced significantly different wear depths: VEN > MIF > VEP > VED. Linear relationships between depth of wear and number of cycles (r2 ≥ 0.94) were established for each material. Pregrinding with SiC #4000 resulted in less wear than pregrinding with #600. Ra figures were much higher for VED than for the other materials tested. MIF and VEN were uniformly abraded, whereas the largest glass fillers in VED protruded from the surroundings and the prepolymer particles in VEP were deeper abraded than the bulk of the material. Toothbrushing with water only revealed not measurable wear. Roughness Ra was practically unchanged when compared with the preground samples before challenging with toothbrushes. Ranking by KHN was: MIF < VEN, VEP < VED, by DC: MIF < VEN < VEP < VED. Conclusion Filler concepts and monomer compositions affect wear and roughness of resin composites when tooth brushed with abrasive slurry. Toothbrushing without abrasive medium produced neither wear nor roughness. Careful polishing of resin composite restorations is an important determinant of wear and surface roughness. How to cite this article Suzuki T, Kyoizumi H, Araki Y, Finger WJ, Kanehira M. Toothbrush Abrasion of Resin Composites with Different Filler Concepts. World J Dent 2012;3(2):184-193.

Morphological Features of Composite Resin Surfaces after Two- and Three-Body Wear Simulation

ABSTRACT Purpose To investigate morphological surface features of different composite resins after 30,000 sliding wear cycles under two- and three-body wear action. Materials and methods The morphology of worn surfaces of four nanofiller containing composite resins, Filtek Supreme XT (FIL), MI Flow (MFL), Venus Diamond (VED) and Venus Pearl (VEP) were investigated and compared with three conventional composites as references, microfilled Durafill VS (DUR), microhybrid Filtek Z250 (Z250) and hybrid-type Clearfil AP-X (APX). Plane surfaces of the polymerized and water-saturated materials (n = 5) were tested in a custom-built pin-on-disk wear machine fitted with a zirconia ball, 4 mm in diameter, serving as the antagonist ‘cusp’ and loading the specimen at 15° angulation for 3.7 mm long sliding paths (50 N load, 1.2 Hz, 30,000 cycles) either in water, simulating two-body wear, or in slurries of PMMA beads or poppy seed, simulating three-body wear. Random samples of each material were selected and sputter-coated with gold for inspection of the wear patterns using scanning electron microscopy. Results Under two-body wear action all materials showed cracking as indicator of fatigue. MFL and VEP with prepolymer particles were least affected. Similarly, surfaces after three-body wearing with PMMA bead slurry revealed crack formation for five of the composites tested. The micro-hybrid Z250 and the nanofilled FIL displayed compressed and shallow delaminated areas. With poppy seed slurry as the third-body medium DUR was deeply destructed. Also the nanohybrid VED with a small fraction of up to 20 ƒÝm large ground glass fillers revealed deep cracks, whereas small delamination areas characterized the hybrid composite APX. Z250 as well as FIL, MFL and VEP were smoothly abraded without showing signs of cracking or delamination. Conclusion Composite resin surfaces, worn under two-body sliding showed mainly crack formation as an expression of fatigue. Similarly, three-body abrasion with a PMMA bead slurry revealed surface cracks to various extent and delamination, which is also an expression of fatigue related damage. With fine-ground poppy seed slurry only the microfilled composite with large prepolymer particles showed catastrophic failure. In all other cases the small poppy seed fragments in the slurry abraded the surfaces, removing polymer or fine particle loaded matrix uniformly. Supposedly, poppy seed slurry is a suitable third-body medium, simulating occlusal wear produced by food, rich in fibers or grain. How to cite this article Koottathape N, Takahashi H, Iwasaki N, Kanehira M, Finger WJ. Morphological Features of Composite Resin Surfaces after Two- and Three-Body Wear Simulation. World J Dent 2012;3(3):221-228.

Atomic force microscopy nanoindentation of a dental restorative midifill composite

Objectives We investigated the elastic properties of one dental restoration resin composite of common use, Venus Diamond, at submicrometer spatial resolution. Methods We performed both nanoindentation experiments with atomic force microscopy, and microindentation experiments with a traditional indenter setup. We also used scanning electron microscopy and energy dispersive X-rays spectroscopy to better understand the correlation between properties and microscopic structure and composition. Results With atomic force microscopy we obtained quantitative evaluation of the elastic modulus (10.8 ± 4.3 GPa), in agreement with the microindentation value (reduced modulus of 12.7 ± 2.0 GPa), and by microindentation we also obtained an hardness value (460 ± 109 MPa) compatible in turn with the nominal value provided by the material manufacturer ( H ∼ 578 MPa). The nanoindentation also revealed that no relevant difference in elasticity appears between the 5 and 10 μm diameter filler particles and the surrounding areas, showing an excellent uniformity of the composite. In support of this finding, compositional uniformity of the material was also observed by X-rays spectroscopy. We conclude that the composite contains prepolymerized particles. Significance We demonstrate that, in addition to reliable quantitative analysis, the high resolution and two-dimensional mapping capability of atomic force microscopy allows for advanced insights into the microstructure of the composite that are not accessible via traditional microindentation.

Surface morphology and mechanical properties of new-generation flowable resin composites for dental restoration

Objectives The purpose of this study was to characterize the surface morphology and the elastic properties of four dental restorative flowable composites currently on the market (Venus Diamond Flow, Vertise Flow, Filtex Supreme XT Flow, Surefil SDR Flow). Additionally, one adhesive system (Adhese One F) and one non-flowable composite (Venus Diamond) have also been characterized as the control materials. Methods Surface morphology was studied by both scanning electron and atomic force microscopy, and the elastic modulus and the hardness measured by instrumented indentation. Grain analysis was performed on the microscopic images, and statistical analysis was carried out on the results of the nanoindentation measurements. Results It was observed that Vertise, Filtek XT and Surefil SDR exhibit stiffness similar to the non-flowable Venus Diamond, whereas Venus Diamond Flow presents itself as the more compliant flowable composite, with Adhese showing intermediate stiffness. Grain analysis of the images confirmed the general rule that the mechanical properties improve with increasing filler loading, with the notable exception of Vertise Flow that shows modulus and hardness as high as 9.1 ± 0.6 and 0.43 ± 0.03 GPa, respectively, for an estimated loading of only ∼40% by volume. Significance Whereas generally flowable composites are confirmed not to possess sufficiently strong mechanical properties for bulk restorations, exceptions can eventually be found upon appropriate laboratory screening, as presently seems to be the case for Vertise Flow. However, real practice in actual restorations and respective clinical evaluation are required for final assessment of the suggested results.

Marginal quality of flowable 4-mm base vs. conventionally layered resin composite

Objective This study evaluated marginal integrity of bonded posterior resin composite fillings to enamel and dentine with and without 4 mm flowable base, before and after thermo-mechanical loading (TML). Methods 80 MOD cavities with one proximal box beneath the CEJ were prepared in extracted human third molars. Direct resin composite restorations (SDR with CeramX mono, Tetric EvoCeram, Filtek Supreme XT, and Venus Diamond or the respective resin composites alone) were bonded with system immanent adhesives XP Bond, Xeno V, Syntac, Adper Prompt L-Pop, and iBond self-etch. Before and after thermomechanical loading (100,000 × 50 N, 2500 thermocycles between 5 and 55 °C), marginal gaps were analysed using SEM of epoxy resin replicas. Results were analysed with Kruskal–Wallis and Mann–Whitney U-tests ( p < 0.05). After thermomechanical loading, specimens were cut longitudinally in order to investigate internal dentine adaptation by epoxy replicas under a SEM (200× magnification). Results In enamel, high percentages of gap-free margins were initially identified for all adhesives. After TML, etch-and-rinse adhesives performed better than self-etch adhesives ( p < 0.05). Also in dentine, initially high percentages of gap-free margins were found for all adhesives. After TML, etch-and-rinse adhesives again performed better than self-etch adhesives for both marginal and internal adaptation ( p < 0.05). The presence of a 4 mm layer of SDR had no negative influence on results in any group ( p > 0.05). Conclusions SDR as 4 mm bulk fill dentine replacement showed an good performance with the material combinations under investigation.

Contraction stress, elastic modulus, and degree of conversion of three flowable composites

The aim of this study was to measure the contraction stress of three flowable resin composites and to correlate the stress with the elastic modulus and the degree of conversion. One low-shrinkage (Venus Diamond Flow) and two conventional (Tetric EvoFlow and X-Flow) flowable composites were polymerized for 40s with a light-emitting diode (LED) curing unit. Contraction force was continuously recorded for 300s using a stress-analyser, and stress values were calculated at 40s and at 300s. The maximum stress rate was also calculated for each specimen. The elastic modulus of each composite was assayed using a biaxial flexural test, and degree of conversion was analysed with Raman spectroscopy. X-Flow exhibited higher stress values than the other tested materials. Venus Diamond Flow showed the lowest stress values at 40s and at 300s, and the lowest maximum stress rate. Stress values were correlated with elastic modulus but not with degree of conversion, which was comparable among all tested materials.

Factors influencing marginal cavity adaptation of nanofiller containing resin composite restorations

Objectives The aim of this study was to investigate the effects of polymerization contraction, shrinkage stress and Young's modulus of nanofiller containing resin composites on early marginal adaptation of restorations in cavities. Methods Six nanofiller containing and two reference resin composites were studied. Marginal gap widths of restorations in cylindrical 4.2 mm wide and 1.5 mm deep dentin cavities, non-bonded or bonded with a self-etch adhesive, and in Teflon cavities of same dimensions were determined 15 min after irradiation ( n = 8). Polymerization shrinkage strains were measured using the bonded-disk ( n = 8) and a strain gage method ( n = 8). For determination of contraction stress the composites ( n = 10) were bonded to and cured in Araldit molds using a photoelastic method. Flexural moduli of the restoratives were studied according to ISO specification 4049 ( n = 5). Statistical analysis was performed with one- and two-way ANOVA, Kruskal–Wallis ANOVA test and post hoc tests ( p < 0.05). Results Only two nanofiller composites (Kalore, GC, Japan) and Venus Diamond (Heraeus Kulzer, Germany) showed consistently gap-free margins in bonded dentin cavities. The mean gap widths in non-bonded and in Teflon cavities were 6.1–12.8 and 14.1–25.5 μm, and linearly correlated ( r 2 < 0.85). Significant linear relationships were observed between strain, stress and marginal gap widths in non-bonded and Teflon cavities ( p < 0.01). Flexural moduli (15 min) were between 1.66 and 8.63 GPa. Significance Marginal cavity adaptation of restorations in bonded dentin cavities reflects complex interactions between adhesive bonding on the one hand, and polymerization contraction strain, stress and elastic modulus, on the other.

Polymerization stress, shrinkage and elastic modulus of current low-shrinkage restorative composites

Objective To compare currently available low-shrinkage composites with others regarding polymerization stress, volumetric shrinkage (total and post-gel), shrinkage rate and elastic modulus. Methods Seven BisGMA-based composites (Durafill/DU, Filtek Z250/FZ, Heliomolar/HM, Aelite LS Posterior/AP, Point 4/P4, Filtek Supreme/SU, ELS/EL), a silorane-based (Filtek LS, LS), a urethane-based (Venus Diamond, VD) and one based on a dimethacrylate-derivative of dimer acid (N′Durance, ND) were tested. Polymerization stress was determined in 1-mm high specimens inserted between two PMMA rods attached to a universal testing machine. Total volumetric shrinkage was measured using a mercury dilatometer. Maximum shrinkage rate was used as a parameter of the reaction speed. Post-gel shrinkage was measured using strain-gages. Elastic modulus was obtained by three-point bending. Data were submitted to one-way ANOVA/Tukey test ( p = 0.05), except for elastic modulus (Kruskal–Wallis). Results Composites ranked differently for total and post-gel shrinkage. Among the materials considered as “low-shrinkage” by the respective manufacturers, LS, EL and VD presented low post-gel shrinkage, while AP and ND presented relatively high values. Polymerization stress showed a strong correlation with post-gel shrinkage except for LS, which presented high stress. Elastic modulus and shrinkage rate showed weak relationships with polymerization stress. Significance Not all low-shrinkage composites demonstrated reduced polymerization shrinkage. Also, in order to effectively reduce polymerization stress, a low post-gel shrinkage must be associated to a relatively low elastic modulus.

Surface Roughness of Commercial Composites after Different Polishing Protocols: An Analysis with Atomic Force Microscopy

Background and Aims:Polishing may increase the surface roughness of composites, with a possible effect on bacterial growth and material properties. This preliminary in vitro study evaluates the effect of three different polishing systems (PoGo polishers, Enhance, Venus Supra) on six direct resin composites (Gradia Direct, Venus, Venus Diamond, Enamel Plus HFO, Tetric Evoceram, Filtek Supreme XT). Materials and Methods:For each composite, 12 square specimens were prepared: 9 specimens were polished, three for each different method, while three specimens were used as controls. Surface roughness was determined with AFM by measuring Root Mean Square (RMS) of average height.Results:PoGo polisher determined a significantly rougher surface, versus controls, in 5 out of 6 composites evaluated. Some significant differences from unpolished controls were observed also for Enhance polishing. Polishing with Venus Supra did not result in any significant difference in surface roughness versus controls. No differences were observed between different polishing systems.Conclusions:These preliminary results suggest that Venus Supra polishing system could determine a smoother composite surface if compared to the other polishing systems tested. On this basis, we are conducting an in vivo study to evaluate bacterial colonization on some combinations of composites and polishing protocols.

Contraction stress of low-shrinkage composite materials assessed with different testing systems

Objectives The contraction stress of a silorane-based material and a new low-shrinkage nanohybrid composite were compared to three conventional dimethacrylate-based resin composites using two different measuring systems. It was hypothesized that the silorane-based material and the low-shrinkage nanohybrid composite would exhibit lower contraction stress than dimethacrylate-based composites irrespective of measuring system. Methods The materials tested were Filtek Silorane LS (3M ESPE), Venus Diamond (Heraeus Kulzer), Tetric EvoCeram (Ivoclar Vivadent), Quixfil (Dentsply DeTrey), and Filtek Z250 (3M ESPE). Shrinkage stress was assessed using a stress–strain analyzer consisting of two opposing attachments, one connected to a load sensor and the other fixed to the device, or a system fixed to a universal testing machine with an extensometer as a feedback system. All specimens were light-cured with 20 J/cm 2; the contraction force (N) generated during polymerization was continuously recorded for 300 s. Contraction stress (MPa) was calculated at both 40 s and 300 s. Data were statistically analyzed by three-way ANOVA and Tukey's post hoc test ( α = 0.05). Results Venus Diamond exhibited the lowest stress under both experimental conditions. Stress values scored as follows: Venus Diamond < Tetric EvoCeram < Filtek Silorane LS < Quixfil < Filtek Z250 ( p < 0.05). Stress values measured with the stress–strain analyzer were significantly lower than those measured with the universal testing machine with feedback. Significance The hypothesis was partially rejected because only Venus Diamond exhibited the lowest stress values among the tested materials. Contraction stress was higher for all composites when measured in a test system with a feedback. This study confirms that simply reducing the shrinkage does not ensure reduced stress development in composites.

Resistance of nanofill and nanohybrid resin composites to toothbrush abrasion with calcium carbonate slurry

The aim of this study was to investigate the wear of four nanofilled resin composites using simulated toothbrushing for 50,000 cycles with calcium carbonate slurry. The depth of abrasion and roughness (Ra) were measured after each 10,000 brushing cycle. The surface texture of the worn samples was examined by SEM.The wear depths of the nanofill Filtek Supreme XT (FIL), the nanohybrides Grandio (GRA), Tetric EvoCeram (TET), and Venus Diamond (VED) increased linearly with numbers of brushing cycles or approximately 80, 12, 600, and 60 mum, respectively after 50,000 strokes. Surface roughness showed virtually no change between 10,000 and 50,000 brushing cycles; the ranking order was TET < FIL < GRA < VED. FIL showed rather uniform abrasion with nanoclusters protruding from the surface. TET was very smoothly abraded without signs of debonding of the prepolymerized particles, whereas GRA and VED showed pronounced wear of the matrix polymer surrounding larger glass filler particles.