Filtek Supreme XTE Research Articles

Cytotoxicity evaluation of dental and orthodontic light-cured composite resins.

IntroductionThe aim of this study was to determine the cytotoxicity of light‐cured composite resins (Clearfil ES‐2, Clearfil ES Flow, Filtek Supreme XTE, Grengloo, Blugloo, Transbond XT, and Transbond LR) then to assess leachable components in contact with human gingival fibroblasts (GFs) and to quantity detected bisphenol A (BPA).MethodsLight‐cured composite resin discs were immersed for 24 hours in gingival fibroblastic medium (n = 3 for each product) and in control medium (n = 2 for each product) contained in plate. Cytotoxicity of the products (n = 95) was determined by the measure of cell viability using MTT assay after reading the optical densities of the plates. The analysis of leachable components was done by gas phase chromatography and mass spectrometry (GC–MS) and detected BPA was quantified. The limit of quantification was 0.01 μg/mL. Statistical analyses were performed by using IBM SPSS Statistics 20 and Kruskal–Wallis and Mann–Whitney U‐tests were applied.ResultsCell viabilities were between 85 and 90%. Many chemical compounds including triethylene glycol dimethacrylate (TEGDMA) and BPA were identified. The average concentrations were 0.67 μg/mL ± 0.84 in the control medium and 0.73 μg/mL ± 1.05 in the fibroblastic medium. Filtek Supreme XTE presented the highest concentration of BPA with 2.16 μg/mL ± 0.65 and Clearfil ES Flow presented the lowest with 0.25 μg/mL ± 0.35. No BPA was detected with Transbond XT and Transbond LR. Clearfil ES Flow, Filtek Supreme XTE, Grengloo and Transbond LR presented residual TEGDMA.ConclusionsLight‐cured composite resins are slightly cytotoxic opposite GFs and release many components including BPA and TEGDMA. Clinical precautions should be taken to decrease the release of these monomers.

Wear, roughness and microhardness analyses of single increment restorative materials submitted to different challenges in vitro.

To evaluate the microhardness, roughness, profilometry and cross-sectional hardness of single increment materials submitted to different challenges. Thirty-six disks of each material, Filtek Supreme XTE (FT), Filtek One Bulk Fill (BK), Ketac Molar Easy Mix (KT) and Equia Forte + Coat (EQ) were immersed in saliva, pH cycling and Coke for 15days. Half of each surface was used as its own control. Superficial microhardness, roughness, perfilometry analysis were performed. All samples were sectioned, embedded in acrylic resins, polished and cross-sectional hardness were made. Data were analyzed by ANOVA and Tukey's test (p < 0.05). The KT presented superficial microhardness superior than EQ. However, in depth, EQ showed superior values. FT, KT suffered the effects of challenges on microhardness values. The highest roughness and wear values were found for KT. RC do not suffer wear. All materials suffered the effects of Coke and pH challenges in depths 10µm and 60µm. The single increment restorative material that suffered less action on its surface was the bulk-fill resin. The coat present in the hybrid ionomer was able to resist to the immersion actions. In addition, Coke was the most aggressive challenge.

Margin Integrity of Bulk-Fill Composite Restorations in Primary Teeth.

This in vitro study examined the margin integrity of sculptable and flowable bulk-fill resin composites in Class II cavities of primary molars. Standardized Class II cavities were prepared in human primary molars and restored with the following resin composite materials after application of a universal adhesive: a sculptable bulk-fill composite (Tetric EvoCeram Bulk Fill (TEC) or Admira Fusion x-tra (AFX)), a flowable bulk-fill composite (Venus Bulk Fill (VBF) or SDR), or a conventional composite (Filtek Supreme XTE (FS)). The bulk-fill materials were applied in 4 mm layers, while the conventional composite was applied in either 2 mm (FS2, positive control) or 4 mm layers (FS4, negative control). The specimens were exposed to thermo-mechanical loading (TML) in a computer-controlled masticator. A quantitative margin analysis was performed both before and after TML using scanning electron microscopy, and the percentage of continuous margins (margin integrity) was statistically analyzed (α = 0.05). All composites showed a significant decline in margin integrity after TML. AFX exhibited the significantly highest margin integrity of all materials after TML (97.5 ± 2.3%), followed by FS2 (79.2 ± 10.8%), TEC (73.0 ± 9.1%), and FS4 (71.3 ± 14.6%). SDR (43.6 ± 22.3%) and VBF (25.0 ± 8.5%) revealed the lowest margin integrity. In conclusion, the tested sculptable bulk-fill materials show similar or better margin integrity in primary molars than the conventional resin composite placed in 2 mm increments.

Detection of Bisphenol A in dental wastewater after grinding of dental resin composites

ObjectivesThis study evaluated the release of bisphenol A (BPA) in wastewater after grinding of resin composites and tested three filtration materials. MethodsThree resin composites (Ceram X, Filtek Supreme XTE and Core-X flow) were used. Samples (5mm×2mm, n=10) were prepared using a metal mold and were polymerized for 20s according to manufacturers’ instructions. A dental unit was disconnected from wastewater circulation and composite samples were ground under standardized procedures (200,000rpm; 90s). Wastewater was collected in glass bottles. Water samples were collected as control by performing the same procedure without grinding resin composite. All samples were stored at 7°C for 6 months to simulate storage. Then they were analyzed by HPLC–FLD. Three filtration materials (Zeosorb, Katalox Light and Catalytic Carbon) were used for water treatment to remove BPA. BPA-water solutions were prepared; corresponding to the highest amount released by the resin composites. These solutions were analyzed before and after filtration by HPLC–FLD and their efficacy (%) was calculated. ResultsBPA was detected in all composite solutions: Ceram X and Filtek Supreme XTE showed similar findings (p>0.05) which were significantly higher than the control (p<0.001) and Core-X flow (p=0.001). The efficacy of the filtration materials was: Katalox Light (5.09%)<Zeosorb (7.91%)<Catalytic Carbon (99.38%). Only Catalytic Carbon caused a clinically significant reduction of BPA (p<0.05). SignificanceBPA can be released in wastewater during dental procedures. This release seems to be material dependent. Among the filtration methods tested, Catalytic carbon seems to be effective for BPA reduction in water.

Particulate Production and Composite Dust during Routine Dental Procedures. A Systematic Review with Meta-Analyses.

Composite dust generation is most likely a continuous and daily procedure in dental practice settings. The aim of this systematic review was to identify, compile and evaluate existing evidence on interventions and composite material properties related to the production of aerosolized dust during routine dental procedures. Seven electronic databases were searched, with no limits, supplemented by a manual search, on 27 April 2020 for published and unpublished research. Eligibility criteria comprised of studies of any design, describing composite dust production related to the implementation of any procedure in dental practice. Study selection, data extraction and risk of bias (RoB) assessment was undertaken independently either in duplicate, or confirmed by a second reviewer. Random effects meta-analyses of standardized mean differences (SMD) with associated 95% confidence intervals (CIs) were employed where applicable. A total of 375 articles were initially identified, resulting in 13 articles being included in the qualitative synthesis, of which 5 contributed to meta-analyses overall. Risk of bias recordings ranged between low and high, pertaining to unclear/raising some concerns, in most cases. All types of composites, irrespective of the filler particles, released significant amounts of nano-sized particles after being ground, with potentially disruptive respiratory effects. Evidence supported increased % distribution of particles < 100 nm for nanocomposite Filtek Supreme XTE compared to both conventional hybrid Z100MP (SMD: 1.96, 95% CI: 0.85, 3.07; p-value; 0.001) and nano- hybrid Tetric EvoCeram (SMD: 1.62, 95% CI: 0.56, 2.68; p-value: 0.003). For cytotoxicity considerations of generated aerosolized particles, both nanocomposites Filtek Supreme XTE and nanohybrid GradiO revealed negative effects on bronchial epithelial cell viability, as represented by % formazan reduction at 330–400 μg/mL for 24 hours, with no recorded differences between them (SMD: 0.19; 95% CI: −0.17, 0.55; p-value: 0.30). Effective and more rigorous management of dental procedures potentially liable to the generation of considerable amounts of aerosolized composite dust should be prioritized in contemporary dental practice. In essence, protective measures for the clinician and the practices’ personnel should also be systematically promoted and additional interventions may be considered in view of the existing evidence.

Fear of the Relapse: Effect of Composite Type on Adhesion Efficacy of Upper and Lower Orthodontic Fixed Retainers: In Vitro Investigation and Randomized Clinical Trial.

The aim of this laboratory and clinical study is to determine the reliability of the flowable nanocomposite Filtek Supreme XTE (FL) for the adhesion of orthodontic retainers, compared to highly filled orthodontic resin Transbond XT (XT). Portions of a round section multistranded wire (Ortosmail Krugg) were bonded to 40 bovine incisors with Scotchbond Universal in total-etch modality. For group one (XT, 20 samples), the orthodontic resin was used, whereas in group two (FL, 20 samples), the flowable one. Specimens were placed into a universal testing machine which applied a shear force on retainers with a crosshead speed of one/minute. Shear bond strength (SBS) and adhesive remnant index (ARI) scores were calculated. In the clinical trial, 100 patients requiring a canine-to-canine palatal and lingual retainer were randomly divided into two groups, according to the resin used for bonding procedure: the orthodontic in group one (XT, 50 participants) and the flowable in group two (FL, 50 participants). Monthly visits were carried out over a 24-month follow up to assess any detachment occurring on teeth of both arches. All data were submitted to statistical analysis. In vitro, FL reported a significant lower mean SBS, whereas no significant differences in ARI were reported between the two groups which both showed a major frequency of scores “1” and “2”. At the end of the 24-month follow up, FL reported significantly higher failure rates in both arches besides a significantly lower survival rate starting from the sixth month after retainers bonding. According to the results assessed in vitro and clinically, XT would be preferable to FL when performing retainers bonding procedure.

Wear Properties of Different Additive Restorative Materials Used for Onlay/Overlay Posterior Restorations.

The purpose of this laboratory study was to compare the two-body wear resistance of different restorative materials commonly used for the indirect restoration of posterior teeth. The tested materials, based on ceramic (Imagine Press X, IPS e.max CAD, Milled Celtra Duo, Glaze-Fired Celtra Duo, Vita Mark II) and composite (Enamel Plus HRi, Enamel Plus HRi Bio-Function, Filtek Supreme XTE, Lava Ultimate), were compared with the wear properties of a type III gold alloy (Aurocast 8). Flat samples were prepared with a 6-mm thickness (n=10). Composite samples were tested after a heat polymerization cycle. All samples were exposed to a two-body wear test in a dual axis chewing simulator performing over 120,000 loading cycles. The opposing abrader cusps were fabricated from yttria-stabilized tetragonal zirconia polycrystal. The vertical substance loss (mm) and the volume loss (mm3) were recorded, as was the wear of the antagonist cusp (mm). Mean values were analyzed by one-way analysis of variance. Significant differences among materials were detected. The heat-cured resin-based composite material Enamel Plus Bio-Function and the type III gold alloy demonstrated similar mean values for wear depth and volumetric loss.

3D Interfacial Gap and Fracture Resistance of Endodontically Treated Premolars Restored with Fiber-reinforced Composites.

To evaluate interfacial gap and fracture resistance of endodontically treated maxillary premolars, restored with different glass-fiber reinforced materials. Eighty-four extracted intact premolars were endodontically treated and MOD cavities prepared. Specimens were divided into 7 groups (n = 12 for each) as follows: sound teeth (G1); no restoration (G2); direct composite restoration with fiber-reinforced composite (everX Posterior GC) (G3); direct composite restoration (Filtek Supreme XTE, 3M Oral Care; "FSXTE") (G4); a horizontal layer of high-viscosity flowable composite (G-ænial Flow, GC) was placed on the pulp chamber floor, 10 mm x 3 mm glass fibers (everStick NET, GC) were inserted into the cavity (G5); same procedure as in group 5 except the direct restoration was made incrementally with FSXTE (3M Oral Care) (G6); composite overlays were placed (G7). Specimens were scanned with micro-CT to evaluate 3D interfacial gaps before and after chewing simulation using Mimics software to calculate voids between restoration and tooth (dentin and enamel). These data (in mm3) were collected for statistical analysis. Thereafter, specimens were loaded to fracture using a universal testing machine. Maximum breaking loads were recorded in Newton (N). The data obtained were analyzed using two-way ANOVA and post-hoc Tukey's test (p < 0.05). ANOVA showed that horizontal glass-fiber insertions statistically significantly reduced interfacial gaps after chewing simulation. No differences in fracture resistance were found between Filtek Supreme XTE and everX Posterior; moreover, glass-fiber insertion did not significantly improve fracture resistance in either case. Composite overlays achieved significantly better fracture toughness than did direct restorations. For the direct restoration of endodontically treated premolars, the insertion of glass fibers into direct composite restorations was unable to guarantee a significant increase in the fracture resistance or a significant change in the fracture pattern. However, it significantly reduced interfacial gap volume after cycling fatigue.

Effect of Composite Age on the Repair Bond Strength after Different Mechanical Surface Pretreatments.

To investigate the reparability of aged and fresh resin composite after different mechanical surface pretreatments. Sixty composite specimens (Filtek Supreme XTE, 3M Oral Care) were either aged by thermal cycling (5000 cycles, 5-55°C) and six months of water storage, or immediately processed within 5 min after polymerization. Both aged and fresh specimens were either ground with fine (46-µm) or coarse (100-µm) diamond burs and then silanized or sandblasted with aluminum oxide (Al2O3) and silanized. In the negative control group, no mechanical surface pretreatment or silanization was performed. Specimens (n = 6 per group) were repaired with an adhesive (OptiBond FL, Kerr) and a resin composite (Filtek Supreme XTE). Directly adhered composite-to-composite increments served as the positive control group. After thermoycling, microtensile repair bond strength was assessed and statistically analyzed (α = 0.05). Aged composite surfaces revealed significantly lower repair bond strength than immediately repaired composite. The negative control group demonstrated the significantly lowest microtensile bond strength of all groups. No significant differences in repair bond strength were observed between the different mechanical pretreatments for both aged and fresh specimens. The repair bond strength of fresh composite pretreated with a fine diamond bur + Al2O3 + silane or a coarse diamond bur with/without Al2O3 + silane did not differ significantly from the positive control group. The age of the repaired composite has a greater influence on repair bond strength than does the type of composite surface pretreatment.

The Mechanical Performance of a Novel Self-Adhesive Restorative Material.

The development of a novel material requires a comprehensive pre-clinical assessment of clinical longevity before any market release. This study aimed to investigate the mechanical performance of a novel self-adhesive restorative material (ASAR MP4). Fracture strength (FS), flexural fatigue strength (FFS) and fracture toughness (KIc) were measured for the experimental material ASAR MP4 in self-cure (SC) and light-cure (LC) mode. ASAR MP4 was processed in capsules. Three direct resin composites (CeramX mono+, DentsplySirona; Heliomolar, IvoclarVivadent; Filtek Supreme XTE, 3M) and two glass-ionomer-cement (GIC) based materials (Equia Forte, GC; Fuji II LC, GC) were selected for comparison with ASAR MP4. FS specimens (n = 15) were tested in a 4-point bending configuration according to ISO 4049 and 9917. FFS specimens (n = 25) were additionally stressed for 104 loading cycles using the staircase approach. The single-edge-notch beam (SENB) configuration was selected for determining KIc according to ISO 13586. All specimens were stored for 14 days at 37°C. Data were analyzed using Weibull statistics (FS), ANOVA (FS, KIc), and the non-parametric Mann-Whitney U-test (FFS). The FS, FFS and KIc data of the ASAR MP4 material reveal a mechanical performance in the range of the successful permanent direct resin composites CeramX mono+ and Heliomolar. The results for ASAR MP4 in SC mode were superior to the LC mode. A fine-grained and pore-free microstructure was observed. Within the limitations of this study we conclude that the novel self-adhesive restorative material ASAR MP4 exhibits mechanical performance close to that of the resin composites Heliomolar and CeramX mono+, both indicated for permanent use in the load-bearing posterior region. Processing the material in either self-cure or light-cure mode led to superior performance over glass-ionomer cements.

The polymerization efficiency of a bulk-fill composite based on matrix-modification technology.

ObjectivesTo evaluate the polymerization efficiency of a matrix-modified bulk-fill composite, and compare it to a conventional composite which has a similar filler system. The degree of conversion (DC%) and monomer elution were measured over different storage periods. Additionally, fillers' content was examined.Materials and MethodsCylindrical specimens were prepared, in bulk and incrementally, from Filtek Bulk Fill (B) and Filtek Supreme XTE (S) composites using a Teflon mold, for each test (n = 6). Using attenuated total reflection method of Fourier transformation infrared spectroscopy, DC% was measured after 24 hours, 7 days, and 30 days. Using high-performance liquid chromatography, elution of hydroxyethyl methacrylate, triethylene glycol dimethacrylate, urethane dimethacrylate, and bisphenol-A glycidyl dimethacrylate was measured after 24 hours, 7 days and 30 days. Filler content was examined by scanning electron microscopy (SEM). Data were analyzed using 2-way mixed-model analysis of variance (α = 0.05).ResultsThere was no significant difference in DC% over different storage periods between B-bulk and S-incremental. Higher monomer elution was detected significantly from S than B. The elution quantity and rate varied significantly over storage periods and between different monomers. SEM images showed differences in fillers' sizes and agglomeration between both materials.ConclusionsMatrix-modified bulk-fill composites could be packed and cured in bulk with polymerization efficiency similar to conventional composites.

Cytotoxic and genotoxic potential of respirable fraction of composite dust on human bronchial cells

ObjectiveTo determine the cytotoxic and genotoxic potential of the respirable fraction of composite dust (<4 μm) on human bronchial epithelial cells. MethodsComposite sticks of three commercial dental composites (Filtek Supreme XTE, Grandio, Transbond XT) were ground in an enclosed plexiglass chamber with a rough dental bur (grain-size 100 μm) and the generated airborne respirable dust was collected in a personal cyclone on a teflon filter (pore size 5 μm). Immediately after particle collection, the dust was quantified gravimetrically and the particles were suspended in cell culturing medium. Next, human bronchial epithelial cells (16HBE14o-) were exposed to the suspensions (3 μg/ml–400 μg/ml). After 24 h, cell viability (WST-1 assay) and membrane integrity (LDH assay) were evaluated. Furthermore, the genotoxic effect of a sub-cytotoxic concentration (50 μg/ml) of composite dust was evaluated by the comet assay after 3 h exposure and cell cycle disturbances were analyzed by flow cytometry. Cellular uptake of particles was evaluated by transmission electronic microscope (TEM). ResultsFor all three tested composite materials, a decrease in metabolic activity of 10–35% was observed when the cells were exposed to the highest concentrations (100 μg/ml–400 μg/ml). Toxicity was partially linked to membrane disruption especially after 72 h exposure. All tested composites provoked a mild genotoxic effect after short-term exposure compared to the control groups. TEM revealed that respirable particles of all tested composites were taken up by the cells. SignificanceThe respirable fraction of composite dust only showed cytotoxic effects at the highest concentrations, whereas mild genotoxicity was observed after exposure to a sub-cytotoxic concentration.

Effect of a hydrophobic bonding resin on the 36-month performance of a universal adhesive-a randomized clinical trial.

To evaluate if the addition of a layer of a hydrophobic bonding resin to the recommended application sequence of a universal adhesive improves the respective clinical behavior in non-carious cervical lesions (NCCLs) after 36months. Scotchbond Universal Adhesive (SBU, 3M Oral Care) was applied in NCCLs of 39 subjects using four adhesion strategies: (1) three-step ER (etch-and-rinse), (2) two-step ER, (3) two-step SE (self-etch), and (4) one-step SE. An extra layer of a hydrophobic bonding resin was applied for strategies three-step ER and two-step SE. The same composite resin (Filtek Supreme XTE, 3M Oral Care) was used for all strategies. Restorations were evaluated at baseline and 18 and 36months using the modified United States Public Health Service (USPHS) criteria. Kruskal-Wallis, Mann-Whitney U, Friedman, and Wilcoxon non-parametric tests were computed. The cumulative failure rate was 8.6%. The 36-month retention rates were 100% for both 3-ER and 2-ER, 76.0% for 2-SE, and 86.2% for 1-SE. A lower retention rate was observed for two-step SE at 36months compared with both three-ER (p < 0.01) and two-ER (p < 0.01). Identical retention rates were measured for the two SE groups. When retention rate was compared at baseline versus 36months for each adhesion strategy, a significant decrease was observed for 2-SE. The restorations performed with 3-ER, 2-SE, and 1-SE had a significant deterioration in marginal discoloration at the 18-month recall. The 36-month clinical performance of Scotchbond Universal Adhesive improved for both etch-and-rinse strategies. Phosphoric acid etching is still recommended to provide retention to composite restorations in NCCLs.

Influences of Different Air-Inhibition Coatings on Monomer Release, Microhardness, and Color Stability of Two Composite Materials.

The aim of this study was to evaluate the effect of light-curing protocols on two modern resin composites using different air-inhibition coating strategies. This was accomplished by assessing the amount of monomer elution, surface microhardness, and composite discoloration in different storage conditions. A total of 120 specimens were prepared using Filtek Supreme XTE (3M ESPE, Seefeld, Germany) and CeramX Universal (Dentsply DeTrey, Konstanz, Germany). Specimens were light-cured in air as per manufacturer's instructions or in the absence of oxygen. This latter condition was achieved using three different approaches: (i) transparent polyester strip; (ii) glycerin; (iii) argon gas. Specimens were assessed for release of monomers, Vickers hardness, and discoloration after storage in different solutions. The results were analyzed with ANOVA one-way test followed by Student-Newman-Keuls test. Moreover, multiple comparisons of means were performed using the Student t-test (p<0.05). The amount of monomers released from the tested specimens was very low in all conditions. The presence of oxygen induced some decrease in microhardness. The highest discoloration values, for both materials, were obtained after ageing in red wine. In case finish and polish procedures are awkward to achieve in posteriors composite restoration, light-curing in the absence of oxygen should be considered, especially when performing composite restoration in esthetic areas.

Fluorescence of feldspathic ceramics: in vitro pilot study

Introduction: Ceramic veneers color is determined by the color and thickness of the ceramic, the cement and dental substrate color [1,2]. Changes in the thickness of feldspathic veneers, as well as the cement used, drastically influence the final color of the restoration [3]. Fluorescence is the optical property responsible for the perception of tooth vitality [4]. In a tooth, this optical property is mainly determined by dentin as it has more collagen (organic matter), which contains fluorescence-releasing amino acids, such as tryptophan, providing three times the fluorescence of enamel [5,6]. Aim of the study: Fluorescence emission evaluation of feldspathic ceramics using different cement colors as well as different ceramic thickness. Materials and methods: Feldspathic ceramic CEREC blocks (color A2) were cut with a manual microtome at a speed of 450 rpm with refrigeration to obtain 40 samples with a thickness of 0.5 and 0.8 mm. Filtek Supreme XTE Body composite resin discs with a thickness of 1mm [7] were produced using a resin frame. The discs were polymerized with a light-curing Elipar S10 Led. Surface treatment of the ceramic was carried out according to the manufacturer’s instructions. Ceramic samples were cemented to the composite resin discs with Relyx Veneer B0,5 / white or with Filtek Supreme XTE Body color A3 (previously heated in a resin oven). The cementation of the groups was done with a constant force of 50 Newtons for 60 seconds and polymerized for 40 seconds with Elipar S10 Led photopolymerizer. Fluorescence spectra were obtained on a SPEX Fluorolog2I2I spectrofluorometer at a wavelength of 380 nm and at room temperature. Results: An increase in thickness intensified the emission of fluorescence. The cementation material used in the study didn’t show statistically significant differences in fluorescence emission intensity when used in two different thicknesses (p = 0,378). Nonetheless, significant differences (p < 0.001) were found between the RelyX and Filtek group for each thickness. Discussion and conclusions: Fluorescence emission value is higher for the thicker group in the RelyX because this cementing material does not have components that add to the emission of fluorescence by the ceramic itself. The ceramic, having a greater thickness, presents a greater concentration of components that are able to emit fluorescence, which allows greater emission of fluorescence than the cementing material in use, such as in the study of Volpato et al. [8]. Like in the study by Pereira in 2015 the choice of different resin cements and ceramic thickness has to be taken into account when planning a case [9].

Flexural Properties and Elastic Modulus of Different Esthetic Restorative Materials: Evaluation after Exposure to Acidic Drink.

Background Acidic beverages, such as soft drinks, can produce erosion of resin composites. The purpose of the present study was to investigate mechanical properties of different esthetic restorative materials after exposure to acidic drink. Methods Nine different composites were tested: nanofilled (Filtek Supreme XTE, 3M ESPE), microfilled hybrid (G-ænial, GC Corporation), nanohybrid Ormocer (Admira Fusion, Voco), microfilled (Gradia Direct, GC Corporation), microfilled hybrid (Essentia, GC Corporation), nanoceramic (Ceram.X Universal, Dentsply De Trey), supranano spherical hybrid (Estelite Asteria, Tokuyama Dental Corporation), flowable microfilled hybrid (Gradia Direct Flo, GC Corporation), and bulk fill flowable (SureFil SDR flow, Dentsply De Trey). Thirty specimens of each esthetic restorative material were divided into 3 subgroups (n=10): specimens of subgroup 1 were used as control, specimens of subgroup 2 were immersed in 50 ml of Coca Cola for 1 week, and specimens of subgroup 3 were immersed in 50 ml of Coca Cola for 1 month. Flexural strength and elastic modulus were measured for each material with an Instron Universal Testing Machine. Data were submitted to statistical analysis. Results After distilled water immersion, nanofilled composite showed the highest value of both flexural strength and elastic modulus, but its flexural values decreased after acidic drink immersion. No significant differences were reported between distilled water and acidic drink immersion for all other materials tested both for flexural and for elastic modulus values. Conclusions Even if nanofilled composite showed highest results, acidic drink immersion significantly reduced flexural values.

Long-term elution of monomers from resin-based dental composites

ObjectiveTo bridge the gap between the current alarming literature on resin-based dental materials and the limited clinical observations, more precise knowledge on the actual quantity of released compounds should be acquired. The objective of this study was to quantify the long-term elution of various compounds from resin-based dental composites during one year. MethodsEight materials were investigated: G-aenial Anterior, G-aenial Posterior, Venus, Venus Pearl, Venus Diamond, Ceram X mono, Dyract and Filtek Supreme XTE. Cylindrical specimens (6 mm diameter, 2 mm thickness) were immersed in 1mL of three different extraction solutions (water, artificial saliva or ethanol) and stored in the dark at 37°C. Every week, the extraction solution was refreshed. The samples were analyzed using ultra-performance liquid chromatography-tandem mass spectrometry. ResultsBisEMA3, BisEMA6, BisEMA10, BisGMA, CQ, HEMA, TCD-DI-HEA, TEGDMA, and UDMA were quantified in the samples. Depending on the composite and the extraction solution, certain monomers (BisGMA, HEMA and UDMA) were able to continuously elute from the materials, up until 52 weeks after initial immersion. Monomer elution was clearly higher when ethanol was used as extraction solution. It could be demonstrated that the tested composites continued to release small quantities of monomers over longer periods when a continuous refreshing protocol is followed. SignificanceEven if monomer elution may not lead to a risk at short term, the potential long-term toxicity should be further investigated. Long-term elution and subsequent chronic exposure to monomers from resin-based dental materials should not be neglected when assessing the overall human health risks.

Comparison of micro-CT and conventional dye penetration for microleakage assessment after different aging conditions

AimThe aim of this study was to compare microleakage assessment by micro-tomography (micro-CT) and conventional microscopy in class V restorations after different aging treatments. MethodsClass V cavities were prepared in sound human molars and restored with composite (Filtek Supreme XTE) after application of a self-etch adhesive (Clearfil SE Bond). Sealing ability was evaluated by assessing silver nitrate penetration along enamel and dentin margins either by micro-CT or by conventional stereomicroscopy. Class V cavities were divided in three groups (each n = 5): control: no aging, thermocycling: 10,000 cycles, 5–55 °C; thermo-erosive cycling: thermocycling with concomitant storage in HCl (pH 2.1, 5 min, 6×/day, 8 days). Penetration of silver nitrate was quantified by micro-CT and stereomicroscopy (25-fold magnification). Data for silver penetration assessed by stereomicroscopy and micro-CT were checked for normality and analyzed by Pearson or Spearman correlations. Differences between the aging effects were analyzed by one-way ANOVA (enamel) or Kruskal-Wallis tests (dentin) (p< 0.05). ResultsFor enamel, the correlations between stereomicroscopy and micro-CT data were not significant. For dentin, silver penetration depths obtained by stereomicroscopy and by micro-CT were moderately correlated (r=0.54, p=0.039), while volume of silver penetration (micro-CT) was not significantly correlated with penetration depth of silver (stereomicroscopy). Thermo-erosive cycling mostly increased microleakage compared with the control group and restorations submitted to thermocycling. ConclusionsThermo-erosive aging increased the microleakage at enamel and dentin. The micro-CT analysis resulted in lower values of microleakage compared with the conventional stereomicroscope. Clinical significanceMicroleakage is often used to evaluate the interfacial integrity of adhesives with dental hard tissues. The micro-CT analysis underestimated the dye penetration compared with the assessments made by the conventional stereomicroscopy, leading to lower microleakage values.

Repair bond strength and nanoleakage of artificially aged CAD-CAM composite resin

Statement of problemThe polymerization of computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins during their manufacture enhances their physical properties and biocompatibility but might compromise their reparability. PurposeThe purpose of this in vitro study was to determine the microtensile bond strength and nanoleakage (NL) of aged LAVA Ultimate (LU) CAD-CAM composite resin after different repair protocols. Material and methodsFifty-eight LU miniblocks were prepared, thermocycled (10000 cycles, 5°C to 55°C), and assigned to 10 surface pretreatment and bonding protocols: (1) tribochemical silica coating (CoJet, CoJet Sand; 3M ESPE)+Scotchbond Universal Adhesive (SBU; 3M ESPE); (2) CoJet+silane (SI, ESPE Sil; 3M ESPE)+Adper Scotchbond 1 XT Adhesive (XT; 3M ESPE); (3) CoJet+10-methacryloyloxydecyl dihydrogen phosphate–based silane (MO; Monobond Plus; Ivoclar Vivadent AG)+XT; (4) CoJet+XT; (5) 30-μm alumina airborne-particle abrasion (AL)+SBU; (6) AL+SI+XT; (7) AL+MO+XT; (8) AL+XT; (9) no pretreatment+SBU; and (10) no pretreatment+XT. All blocks were repaired using the Filtek Supreme XTE (3M ESPE) composite resin. Stick-shaped specimens (0.9×0.9 mm) were obtained and submitted to microtensile bond strength (μTBS) and %NL testing after 24 hours. μTBS data were analyzed with 1-way ANOVA, followed by the Tukey post hoc test, and NL data with nonparametric Kruskal-Wallis and Dunn tests (α=.05). ResultsFor μTBS, CoJet, and AL pretreatments showed significantly higher mean μTBS, especially when used together with SBU. No pretreatment+XT yielded the lowest mean μTBS. For NL, marginal sealing improved significantly after the use of SBU regardless of the surface treatment. This improvement was only statistically different after tribochemical silica coating. ConclusionsAirborne-particle abrasion with alumina particles, silica coated or not, together with the application of SBU resulted in the highest mean μTBS. The lowest %NL was recorded when aged LU blocks were repaired using SBU.

Do collagen cross-linkers improve dentin’s bonding receptiveness?

ObjectivesDentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes. Methods60 molars were randomly divided in accordance with the three variables: cross-linker, adhesive and bonding mode (n=5). The cross-linkers glutaraldehyde (5wt%; GA), proanthocyanidin (6.5wt%; PA), or UVA-activated riboflavin (0.5wt%; RB), and distilled water (control) were applied on dentin for 60s after acid-etching (E&R) or before self-etching (SE). The 3-step E&R adhesive (3E&Ra) OptiBond FL (Kerr), the 2-step SE adhesive (2SEa) Clearfil SE Bond 2 (Kuraray Noritake) and the universal adhesives G-Premio Bond (GC) and Prime&Bond Active (Dentsply), the latter two employed in both E&R and SE modes, were applied following the respective manufacturer’s instructions. Composite buildups (8×8×8mm) were made using Filtek Supreme XTE (3M) prior to 1-week storage in artificial saliva. After the teeth were sectioned into mini-specimens (1.5×2.0×18mm), a single notch was prepared at the adhesive–dentin interface. Half of the specimens were immediately loaded until failure by 4-point bending to determine the mini-iFT, while the remaining specimen set was tested upon 6-month aging. Data were statistically analyzed with a linear model (p<0.05). ResultsNo significant decrease in mini-iFT was noted only for PA (p<0.05), while the mini-iFT decreased for both other cross-linkers and in quite a similar way as when solely water (Wa) was applied. SignificanceThe cross-linker proanthocyanidin (PA) applied in clinically relevant conditions was able to maintain a stable mini-iFT after 6-month aging. The incorporation of UVA-activated riboflavin (RB) and glutaraldehyde (GA) in the dentin-bonding protocol appeared not effective to improve the stability of adhesive–dentin interfaces.