Nanohybrid Composite Research Articles

Effect of 9.3 μm CO2 and 2.94 μm Er:YAG Laser vs. Bur Preparations on Marginal Adaptation in Enamel and Dentin of Mixed Class V Cavities Restored With Different Restorative Systems

This study aimed to compare marginal adaptation in enamel and dentin before and after aging of laser vs. bur-prepared mixed class V cavities restored by different restorative systems. Seventy two caries-free human molars were distributed to nine experimental groups; cavities were prepared using two different lasers: a handpiece -integrated 2.94 μm Er:YAG laser at 4.5 W, 300 mJ, and 0.75 W, 50 mJ with 15 Hz (LiteTouch, Light Instruments, Israel) and a novel CO2 laser at 12.95 W, 19.3 mJ, and 4.1 W, 6.11 mJ with 671 Hz (Solea 9.3 μm, Convergent Dental, USA). Cavities prepared with conventional diamond burs (Intensiv, Switzerland) in a red contra angle at high speed under maximal water cooling served as control. Cavities were prepared under simulation of dentinal fluid and restored using three different self-etching universal adhesives in combination with three nanohybrid composites, applied in two layers: Scotchbond Universal with Filtek Supreme XTE (3M, USA), G-Premio BOND with Essentia Universal (GC, Japan), and OptiBond Universal with Harmonize Universal (Kerr, USA). After restorations' polishing and simultaneous thermal (5–50°C, 2 min each) and mechanical loading (max. 49 N; 200,000 cycles), replicas of restoration margins were examined under SEM at × 200 magnification. Percentages of continuous margins (CMs) were quantified before and after the fatigue test and statistically compared (two-way ANOVA with Fisher's least significant difference [LSD] post hoc test). Significant differences were found in almost all groups between the results before and after the fatigue test, as well as between the different preparation tools and restorative materials (p < 0.05). Traditional bur preparations are confirmed as gold standard in enamel and dentin, as all three tested restorative systems provide results of marginal adaptation of more than 80% CM after loading. Er:YAG laser preparations can be equally effective in combination with SBU/Filtek Supreme XTE. CO2 laser ablation could not provide convincing results with the tested self-etching restorative systems. Marginal adaptation has been highly dependent on the substrate and showed impaired adhesion, especially in enamel. Scotchbond Universal/Filtek Supreme XTE showed the highest and most stable values of CM. The other two restorative systems were highly dependent on the preparation device of the substrate.

Electrical and thermal performances of epoxy-based micro–nano hybrid composites at different electric fields and temperatures

This paper investigates the electrical and thermal properties of pure epoxy resin (EP) and its micro–nano hybrid composites (20 wt% micro-AlN fillers with 1 wt% and 3 wt% nano-Al2O3 fillers; 50% micro-AlN with 3% nano-Al2O3 fillers) for power electronic packaging applications. Electrical properties such as space charge distribution, electrical conductivity and surface potential decay are measured. The thermal performance of the fabricated samples is estimated using thermal analysis devices. The hybrid composite consisting of 20 wt% micro-AlN and 1 wt% nano-Al2O3 fillers exhibits the least space charge accumulation, higher thermal conductivity and better thermal stability. However, the excessive addition adversely affects space charge and electrical conductivity properties. The micro–nano hybrid composites significantly exhibit higher electrical conductivity than pure EP. The microfiller addition from 20 wt% to 50 wt% significantly improves the thermal conductivity of the EP. The reduced space charge injection and accumulation in the hybrid micro–nano composites are attributed to the enhancement of the injection barrier and reduction of the charge carrier traps in these materials. A theoretical mechanism of the charge dynamics inside the samples under different test conditions is proposed to support the experimental results.

Simulation studies on nano-hybrid polymer composites as covered conductor for enhancing the insulation characteristics of low voltage and medium voltage applications

The development of cover conductors involving nano-hybrid polymers possessing high strength & good insulation properties would really help the electrical industry to avoid fatal accidents due to electrical shock and minimize electrical damage occurring due to short circuit in the event of tree/load falling on the bare overhead lines/conductors. The material selection and design are very essential parameters from the point of manufacturing, processing and application. The material characteristics dictate the mechanical as well as electrical performance in the field. For any material to have long life expectancy, compositions/constituents matter a lot with the combination of the basic raw materials. When any material such as overhead conductor is subjected to heavy electrical & mechanical loads, there is a likelihood of sag in the line and short circuit in the event of bare conductors resulting in fire. In such cases, the propagation of fire, fire retardancy, generation of smoke in addition to line protection are required to be considered from the point of life saving and system reliability. In this context, the electrical properties get affected due to varying loads acting on the conductor from time to time and depend on the season. As a part of remedial measures, cover conductor is best suited to meet the requirements. The design of the cover conductor shall be done in such a way that it meets the requirement of the prevailing standards. In the present work simulation studies will be performed using simulation software to study the behavior of electric field of nano based covered conductor and prove that these conductors will give better reliability and superior performance compared to the existing bare conductor. Further, the matrices and filler addition are envisaged are Acrylonitrile Butadiene Styrene (ABS)/Polytetrafluoroethylene (PTFE) of different combinations and nano-silica/nano-clay as fillers for the preparation of nano insulating covered conductor material.

Ultrasonication-mediated nitrogen-doped multiwalled carbon nanotubes involving carboxy methylcellulose composite for solid-state supercapacitor applications

In this study, a novel nanohybrid composite containing nitrogen-doped multiwalled carbon nanotubes/carboxymethylcellulose (N-MWCNT/CMC) was synthesized for supercapacitor applications. The synthesized composite materials were subjected to an ultrasonication-mediated solvothermal hydrothermal reaction. The synthesized nanohybrid composite electrode material was characterized using analytical methods to confirm its structure and morphology. The electrochemical properties of the composite electrode were investigated using cyclic voltammetry (CV), galvanic charge–discharge, and electrochemical impedance spectroscopy (EIS) using a 3 M KOH electrolyte. The fabricated composite material exhibited unique electrochemical properties by delivering a maximum specific capacitance of approximately 274 F g−1 at a current density of 2 A g−1. The composite electrode displayed high cycling stability of 96% after 4000 cycles at 2 A g−1, indicating that it is favorable for supercapacitor applications.

Giant Piezoresistive Effect of CdS@C Hybrid Nanobelts for Volatile Real-Time Sensor and Erasable Nonvolatile Memory to Stress.

Here, CdS@C nanohybrid composites, where CdS quantum dots (QDs) are uniformly embedded in carbon micro-/nanobelt matrixes, are synthesized via a combustion synthesis followed by a postvulcanization. In the nanohybrids, trap centers are effectively created by the introduction of QDs and moreover their barrier height and filling level can be effectively modulated through a coupling of externally loaded strain and bias. Thus, a single CdS@C micro-/nanobelt-based two-terminal device can exhibit an ultrahigh real-time response to compressive and tensile strains with a tremendous gauge factor of above 104, high sensitivity, and fast response and recovery. More importantly, the trapped charges can be mechanically excited by stress, and furthermore, the stress-triggered high-resistance state can be well-maintained at room temperature and a relatively low operation bias. However, it can be back to its initial low resistance state by loading a relatively large bias, showing a superior erasable stress memory function with a window of about 103. By an effective construction of trap centers in hybrid composites, not only can an ultrahigh performance of volatile real-time stress sensor be obtained under the synergism of external stress and electric field but also can an outstanding erasable nonvolatile stress memory be successfully realized.

Surface Analysis and Spectrophotometric Evaluation of Different Esthetic Restorative Materials Frequently Exposed to a Desensitizing Agent.

Background Patients with tooth sensitivity are frequently exposed to desensitizing agents on a regular basis. These agents might have an impact on the surface properties and color of existing oral restorations. Accordingly, this study aimed to investigate the color stability, surface microhardness, and surface roughness of resin-modified glass ionomer (RMGIC), amalgomer CR, nanohybrid, and bulk-fill resin composites restorative materials after frequent exposure to a desensitizing agent. Materials and Methods. One hundred and twenty specimens were prepared; 10 specimens for each restorative material were equally subdivided into control and desensitizing-agent-exposed groups in each test. Surface microhardness and surface roughness were evaluated using the Vickers microhardness tester and surface profilometer, respectively. The color change was measured by using a spectrophotometer using the CIE L∗a∗b∗ formula. Surface topography was analyzed using a scanning electron microscope (SEM). The collected data were analyzed with Student's t-test, one-way ANOVA, and Tukey post hoc tests for pairwise comparison at a level of significance of 0.05. Result The frequent use of a desensitizing agent significantly decreased surface hardness of RMGIC, amalgomer, and bulk-fill composite materials. However, nanohybrid composite exhibited a significant surface hardness increase. The surface roughness of RMGIC, amalgomer, and nanohybrid composite increased significantly. Meanwhile, the bulk-fill resin composite showed a nonsignificant decrease. Both RMGIC and amalgomer exhibited significantly higher values of color change in comparison to those of nanohybrid and bulk-fill composites. Conclusion The bulk-fill composite seems to be more resistant to discoloration and surface topographical changes than other tested materials on frequent exposure to the desensitizing agent. However, this exposure may pose a negative impact on its surface hardness. Bulk-fill resin composite may be the most suitable esthetic restorative in patients who frequently use desensitizing agents.

Effect Of Chemo-Mechanical Caries Removal On The Micro-Tensile Bond Strength Of Resin Composite Using Universal Adhesive To Caries Affected Dentine

Aim: to evaluate effect of chemo-mechanical caries removal on micro-tensile bond strength (µTBS) of composite using universal adhesive to caries affected dentine. Materials and methods: 64 permanent molars were used. 32 were sound and the other (32) were carious. Carious molars were divided into four groups as followed Group 1: caries was removed by Carisolv then universal adhesive was applied with etch and rinse approach followed nanohybrid composite to be tested with µTBS test after 24h. Group 2: as group (1) but tested after 3 months. Group 3: same as group (1) but using self-etch mode and tested after 24h. Group 4: as group (3) but tested after 3 months. Sound molars were divided into four groups according to bonding mode and according to the time of bond strength testing. Carisolv was applied according to manufacturer’s instructions. The universal adhesive used with both approaches following manufacturer’s recommendations. Nanohybrid composite was packed. For delayed groups specimens were stored in distilled water for 3 months. The specimens were cut to produce 1mm2 beam-shaped specimens for µTBS test. The fractured specimens were examined to determine mode of failure. Results: there was a statistically significant difference in µTBS values between different adhesive approaches at each storage time. Etch & Rinse approach yielded significantly highest µTBS mean values in both Caries affected dentin and sound dentin for both times. Conclusion: the etch and rinse approach is the indicated approach for bonding of the used universal adhesive to caries affected dentin especially after chemo-mechanical caries removal.

Surface roughness and gloss of polished nanofilled and nanohybrid resin composites

Background/purposeThere is limited literature on the polishability of new launched nanofilled and nanohybrid. The aim of this study is to evaluate the polishability of nanofilled and nanohybrid composites by measuring surface roughness and gloss values and explore the surface qualities of composite before and after polishing in vitro.Materials and methodsOne nanofilled resin composite, two nanohybrid resin composites and one microhybrid resin composite were selected. All specimens were light cured against celluloid matrix strips. Then surface roughness(Ra) and gloss(GU) values were tested as negative control. Specimens were roughened with a 600-grit silicon carbide paper for 30 s to serve as positive control and then polished with Sof-Lex polishing disk system. Mean Ra and GU values of each step were measured with a profilometer and a small-area glossmeter. The surface qualities were observed by scanning electron microscope.ResultsRa values of polished surfaces were significantly higher than negative control and lower than positive control(P < 0.05). All materials showed no significant difference on Ra values after polishing(P > 0.05). GU values of polished surfaces were significantly lower than negative control and higher than positive control(P < 0.05). After polishing the microhybrid resin composite showed lower GU values than nanofilled and nanohybrid resin composite groups. The SEM images showed surface textures and irregularities were corresponded to the results of surface roughness and gloss.ConclusionNo significant differences were noted on surface roughness among nanofilled, nanohybrid, and microhybrid composites after polishing with Sof-Lex disc system. Microhybrid composite presented lower gloss values than nanofilled and nanohybrid resin composites.

Effect of layer thickness on residual monomer release in polymerization of bulk-fill composites

The aim of the present study was to investigate and compare the quantity of residual monomers leached from the bulk-fill composites with different compositions polymerized at varying layer thickness. Three bulk-fill (X-tra-fil, Beautifil Bulk Restorative, Fill-Up) and a nanohybrid composite (Filtek Z550) were used for the study. The composite resin samples were prepared with a stainless steel mold. For each composite, two groups were constructed. The samples in the first group were prepared using the 2 + 2 mm layering technique. In the second group, the composite samples were applied as a 4 mm-thick one layer and polymerized. Then, each composite samples were kept in a 75% ethanol solution and residual monomers released from composite resins were analyzed with an HPLC device after 24hour and 1 month. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. Except the Fill-Up, all of residual monomer elution from the bulk-fill composites was significantly affected by the layer thickness (p &lt; 0.05). The greatest monomer release was detected at 1 month after polymerization as a single 4 mm layer for Beautifil Bulk Restorative. Fill-Up composite showed similar residual monomer release in polymerization at different layer thicknesses compared to other composite resins. In the 2 + 2 mm layering technique, the least monomer elution was detected in the Filtek Z550 composite group. While Bis-GMA was the most released monomer in X-tra fil composite, UDMA was the most released monomer in all other composite resins. During polymerization of the bulk-fill composite, the layer thickness of the composite applied may affect the amount of residual monomers released from the composite resins. Conventional composites may release less monomer than bulk-fill composites when used with layering.

Can the use of surface sealant on restorative materials prevent discoloration related to iron syrup supplements?

The purpose of this study was to evaluate the impact of surface sealants on the stain resistance of restorative materials exposed to iron syrups. Sixty specimens were prepared from each of three restorative materials-compomer (Dyract XP), a microhybrid composite (Filtek Z250), and a nanohybrid composite (G-aenial Anterior). Specimens were divided into three solution groups (n = 20) and immersed in two iron syrups (Ferrum and Ferro Sanol B) and distilled water. Two subgroups, sealed (BisCover ( +)) and unsealed (BisCover (-)), were established for each group (n = 10). Color changes between baseline and measurements at 4, 8, 24, 48, and 72h were calculated with CIEDE2000 (ΔE00) metrics. Data were analyzed with 4-factor mixed-design ANOVA. The first null hypothesis of this study that the use of surface sealant would not mitigate the restorative materials' susceptibility to staining was rejected: significant differences were found between BisCover ( +) and BisCover (-) groups in ΔE00 values for all restorative materials tested in Ferro Sanol B (p < 0.001) and Ferrum (p = 0.002) solutions. The ΔE00 values in the Ferro Sanol B/BisCover ( +) groups were significantly lower than in Ferrum/BisCover ( +) groups (p = 0.002), the second null hypothesis that different forms of iron syrups would not impact the staining resistance of restorative materials was rejected. ΔE00 values were different for each restorative materials tested, the third null hypothesis that the type of restorative material would not affect staining resistance was rejected. The application of surface sealant significantly improved the color stability of restorative materials. The content of iron syrups was also an important factor affecting color change. Nanohybrid composites seem to be more resistant to the staining effects of iron syrups.

Charge dynamics and thermal properties of epoxy based micro and nano hybrid composites at high temperatures

AbstractThis paper presents the effects of the filler type and testing temperature on the charge dynamics and thermal properties of the epoxy resin. The micro‐nano hybrid composites with different content of the micro and nano aluminum nitride (AlN) fillers are fabricated. The morphology of micro‐nano hybrid composites is characterized. Electrical testing and thermal analysis methods are adopted to analyze its electrical and thermal performance. The results show that the space charge accumulation is suppressed and the charge decay process is facilitated in the hybrid composites. The electrical performances of the hybrid composites are enhanced by the nano‐fillers. The apparent mobility and activation energy are decreased with nano‐AlN fillers in the composites at the high temperature. The glass transition temperature and thermal stability of the materials is improved with the nano‐AlN. A hypothetical mechanism is proposed to explain the charge carrier injection and transport of the composites at different temperatures.

The Effect of Different Polishing Systems on the Surface Roughness of Nanocomposites: Contact Profilometry and SEM Analyses.

The aim of this study was to evaluate the effects of different polishing systems on the surface roughness of different nanocomposite resins using various analysis methods. Three types of nanocomposite resins were investigated in this study: supra-nanohybrid (Estelite Asteria), nanohybrid (GrandioSo), and nanoceramic composite resins (Ceram-X Spheretec One). Forty-eight disc-shaped specimens (4 mm in diameter, 2 mm in thickness) were fabricated using a Teflon mold and divided into four groups according to the different polishing systems (n=12). All specimens were processed with one of the following methods: Mylar strip (control), one-step polishers (Opti1step), two-step polishers (Clearfil TwistDia), or multistep polishers (Sof-Lex XT Pop-on). The surface roughness (Ra, μm) was measured by contact profilometry (Mahr, Marsurf PS1) (n=10) and scanning electron microscopy (SEM) (Thermo Fisher Scientific, Phenom XL) at 400× magnification (n=2). The data were statistically analyzed using Kruskal-Wallis and Bonferroni correction tests (p<0.05). In addition, the surface morphology and elemental content were examined by SEM and energy dispersive x-ray spectroscopy (EDS) analyses. Under SEM evaluation, in terms of the polishing systems, there were no significant differences in the surface roughness for supra-nanohybrid composite resin (p>0.05). The multistep polishers created lower surface roughness than the one-step polishers for nanohybrid and nanoceramic composites. In terms of the composite resins, supra-nanohybrid composite exhibited lower surface roughness than nanohybrid composite for all polishing systems (p<0.05). The SEM observations confirmed the surface roughness measurements related to the surface morphology. One-step and two-step polishers created porosity on the surface of nanohybrid and nanoceramic composites. EDS analysis indicated the elemental composition of the particles in the porous zones was quite close to diamond abrasives and glass fillers.

Fabrication of rGO/Cuprous Oxide Nanocomposites for Gas Sensing

We report a simple fabrication of a gas sensor using a nanohybrid composite of reduced graphene oxide/cuprous oxide (rGO/Cu2O). The deoxidation of GO occurs meanwhile with the synthesis of Cu2O. The Cu2O component of the nanohybrid material has a linear morphology and a micron size, which is homogeneously mixed with rGO. The rGO/Cu2O gas sensor can effectively detect ppm level of NO2 gas, showing an outstanding reusability. Because rGO/Cu2O has a large specific surface area, it is more conducive to gas adsorption on its surface. Its good effect on detecting NO2 proves that the sensor has good commercial prospects.

Finite element analysis of V-shaped tooth defects filled with universal nanohybrid composite using incremental technique

The aim of the present paper is to study the stresses and strains in fillings of V-shaped tooth defects made of universal photo-cured nanohybrid composite (UPC) using incremental technique. Numerical modeling with FEA and microleakage test are performed. Inhomogeneous distribution of the equivalent Von Mises stresses after polymerization of the two UPC layers is found, as the maximal value after polymerization of the first layer is 1.5 times lower compared to that of second one. In the first layer, maximum stresses are concentrated on dentin surface in cervical region of the obturation border and in occlusal region of the obturation volume. In the second layer, maximum stresses are generated in cervical area of the obturation volume and on dentin surface occlusally along the obturation border. The displacement after polymerization of each layer is inhomogeneous, as its values are more than 2 times smaller compared to that in fillings of glass-ionomer cement and flowable composite. In the first layer, the displacement is maximal on surface in the cervical region, while in the second layer it is maximal on surface occlusal of the obturation. The adequacy of the model used is confirmed by the microleakage test results. It is proven that UPC is better choice for filling of V-shaped defects due to the lower microleakage.

Effects of Different Fiber-Reinforced Solutions on Fracture Strength and Pattern in Endodontically Treated Molars.

To evaluate the fracture strength of endodontically treated molars filled with different composite resins with vs without fiber reinforcement. A total of 60 intact mandibular molars were selected and endodontically treated. A standardized mesio-occlusal-distal cavity was prepared with cervical margins 1 mm above the cementoenamel junction and oral and buccal walls with 1.5-mm thickness. Universal adhesive was used in all specimens in etch-and-rinse mode. Specimens were divided into four groups (n = 15 each) according to restoration technique: group CSM = adhesive overlay with hybrid ceramic; group EXP = direct restoration with short fiber-reinforced composite; group ESU = direct restoration with nanohybrid composite; and group EST = direct restoration with nanohybrid composite reinforced with horizontal bidirectional glass fibers placed over the pulpal chamber floor. After 7 days of storage in water, samples were loaded until fracture using a universal testing machine. The maximum breaking loads were recorded in Newtons, and statistical analysis was then conducted with two-way ANOVA and post hoc Tukey test. Fragments were analyzed using scanning electron microscopy. Mean fracture resistance values were: CSM = 1,428.91 ± 316.90 N; EXP = 1,874.57 ± 299.47 N; ESU = 1,557.44 ± 355.65 N; and EST = 1,870.27 ± 145.11 N. The CSM and EXP groups showed the highest strength values when compared to the other groups. The variable fiber insertion did not significantly alter the fracture resistance. The origin of the fracture was always located on the occlusal surface, mainly in the major contact loading area. The use of fiber-reinforced composite showed great improvement in fracture resistance, similar to a cuspal coverage restoration. However, only short fiber-reinforced composites showed a favorable fracture pattern. Int J Prosthodont 2023;36:603-611.

Cost-effectiveness of glass hybrid versus composite in a multi-country randomized trial

ObjectivesWe assessed the cost-effectiveness of two amalgam alternatives, glass hybrid (GH) and composite (CO) in a multi-country randomized controlled split-mouth trial. MaterialsUniversity clinics in Croatia, Serbia, Italy and Turkey participated. Pairs of GH (EQUIA Forte, GC) and a nano-hybrid CO (TetricEvoCeram, IvoclarVivadent) were randomly placed in occlusal-proximal two-surfaced cavities in permanent molars of adults (n = 180/360 patients/molars). We used 3-years interim data for this evaluation. FDI-2 criteria were applied and teeth requiring repair, re-restoration, endodontic treatment or extraction recorded. Our outcome was the time until any or major complications (requiring endodontic treatment or extraction) occurred. Costs were calculated in US Dollar (USD) 2018, with the local currencies being converted using Purchasing Power Parities. To estimate initial and re-treatment costs, a payers’ perspective was taken and direct medical costs estimated from fee item catalogues. Incremental-cost-effectiveness ratios (ICER) were used to express the cost difference per gained or lost effectiveness. ResultsOverall costs were lower for GH than CO in Croatia, Turkey and Serbia, while this difference was minimal in Italy. GH tended to survive longer than CO in Croatia and Italy, and shorter in Serbia and Turkey; overall survival time was not significantly different (p = 0.67/log-rank). The cost-effectiveness differences indicated CO to be more expensive at limited (ICER: 268.5 USD/month without any complications) or no benefit at all (-186.2 USD/month without major complications). ConclusionsGH was less costly than CO both initially and over 3 years. Efficacy differences were extremely limited. Clinical significanceGiven their low initial costs and as efficacy between GH and CO did not differ significantly, GH had a high chance of being more cost-effective within this specific trial.

Twenty-Four-Month Clinical Comparison of Two Bulk-Fill and a Microhybrid Composite Restorations in Class II Cavities.

The aim of this study was to evaluate the clinical performance of two bulk-fill composite resins in Class II cavities for up to twenty-four months. In total 75 Class II restorations were made in 25 patients using two nanohybrid bulk-fill resin composites and a microhybrid composite. The restorations were evaluated at baseline and at 6, 12, and 24 months, using U.S. Public Health Service (USPHS) criteria. The restoration groups were compared using the Pearson chi-square test, and the Cochran Q-test was used to compare the changes across different time points within restorative materials (p⟨0.05). Two patients who did not attend the appointments were excluded from the study, so 23 patients were evaluated with a 92% recall rate; at the end of the two-year follow-up, 66 restorations were evaluated. Three restorations underwent endodontic treatment and were deemed failures. The overall success rate was 96%. There were statistically significant differences between the three restorative resins in terms of color match parameter (p⟨0.05). No differences were observed between the restorative resins in terms of other criteria (p⟩0.05). During the two-year follow-up period, the three composite resins showed similar clinical performance except for the color match parameter.

Bacterial Adhesion on Glass–Ionomer Cements and Micro/Nano Hybrid Composite Dental Surfaces

Dental restorations need to reproduce the aspect of the natural teeth of the patient, and must be non-toxic, biocompatible, and have good mechanical properties so that they can last for longer. The aim of this study was to determine the extent of bacterial adhesion of Streptococcus mutans on four different dental material surfaces, i.e., two glass–ionomer cements (Fuji conventional and Fuji hybrid) and two ceramic composites (Micro hybrid composite and Nano hybrid composite). To understand the bacterial adhesion on these four different dental materials, various surface properties were measured: roughness, contact angle, CIE color parameters and zeta potential. We found that the greatest adhesion extent was obtained for the Nano hybrid composite surface. The pronounced adhesion is the interplay between the relatively high roughness and hydrophilicity of the Nano hybrid composite surface. Color changes upon immersing ceramic composites in red wine and black tea proved that both beverages adhered to them. Black tea adhered more intensively than wine, and showed a higher inhibitory effect on the growth of Streptococcus mutans and Staphylococcus aureus.

In Vitro Effects of Fluoride, Hydroxyapatite, and Bromelain-Containing Toothpaste Types on Surface Roughness of Different Restorative Materials

Aim: To examine the effects of fluoride, hydroxyapatite, and bromelain-containing toothpaste types on the surface roughness of nanohybrid, nanofilled, flowable, and bulk-fill composites; conventional, light-curing, and low-viscosity glass ionomers; and compomers. Materials and Methods: A total of 160 specimens were fabricated using nanohybrid, nanofilled, flowable, and bulk-fill composites; conventional, light-curing, and low-viscosity glass ionomers; and compomers. Each material group was divided into four subgroups ( n = 5) as follows: Control (C), fluoride toothpaste (FT), bromelain toothpaste (BT), and hydroxyapatite toothpaste (HT). Surface roughness values of all specimens were examined using an optical profilometer and a scanning electron microscope at 500, 1,000, and 3,500 magnifications. Results: The highest average roughness value (Ra; µm) was obtained from the conventional glass ionomer material ( P &lt; .001). While the mean Ra value was 0.155±0.116 µm at baseline, it was 0.262±0.203 µm in the fluoride group, 0.237±0.192 µm in the hydroxyapatite group, 0.260±0.293 µm in the bromelain group, and 0.198± 0.187 µm in the control group ( P &lt; .001). Conclusion: We have found that brushing with various types of toothpaste containing fluoride, bromelain, and hydroxyapatite may not result in obtaining different surface roughness values from different types of restorative materials. Differences in surface roughness values of restorative materials may be found at different magnifications under scanning electron microscope.

THE ABILITY OF COFFEE TO STAIN NANOHYBRID COMPOSITE RESINS

INTRODUCTION: One of the main causes of composite replacement is its discoloration after prolonged exposure to the oral environment. In an effort to fulfill the patient esthetic desire, harmonize composite material have been introduced with limited studies regarding its esthetic properties and color stability.OBJECTIVES: To study the effect of coffee on the color stability of two nanohybrid composites with different monomers.MATERIALS AND METHODS: The resin composites tested were Venus diamond and Harmonize. A custom made disk-shaped mold (4mm thickness x 8 mm diameter) used to prepare 12 composite specimens. They were divided into 2 groups (n=6) according to the resin based composite that was used as follow: Group A restored with Urethane dimethacrylate based composite (Venus diamond, Heraeus Kulzer) and Group B restored with Bisphenol A diglycidil dimethacrylate based composite (Harmonize, Kerr). The specimens were finished using (Multi fluted tungsten carbide finishing bur for fifteen seconds) followed by polishing using (HiLuster, Kerr) polishing system. After that, the specimens were immersed in coffee solution for 7 days. Color difference ΔE was calculated before and after immersion of specimens for 48 hours and after 7 days using spectrophotometer (VITA easy shade).RESULTS: Mann Whitney U test showed significant difference in ΔE among composite restorative materials (p < 0.05). Venus diamond composite resin was found to be more stain-resistant than Harmonize composite resin after both 48 hours and 7 days.CONCLUSION: Different monomer compositions, immersion time and solution may have direct effect on the color stability of nanohybrid restorative materials.