Composite Resin Groups Research Articles

Fracture Resistance of Class II MOD Cavities Restored by Direct and Indirect Techniques and Different Materials Combination.

This study aimed to evaluate the fracture resistance of class II MOD cavities restored using different techniques and materials. Sixty extracted maxillary molars were selected and standardized class II MOD cavities were prepared using a custom-made paralleling device. The specimens were divided into four groups based on the restoration technique used: Group 1 (direct resin composite), Group 2 (short-fiber-reinforced composite resin), Group 3 (composite polyethylene fiber reinforcement), and Group 4 (CAD/CAM resin inlays). Fracture resistance was assessed for each group after thermocycling aging for 10,000 cycles. The mode of fracture was assigned to five types using Burke's classification. To compare the fracture force among the tested materials, a paired sample t-test was performed. The significance level for each test was set at p < 0.05. Significant differences in fracture resistance were observed among the different restoration techniques. CAD/CAM inlays (2166 ± 615 N), short-fiber-reinforced composite resin (2471 ± 761 N), and composite polyethylene fiber reinforcement (1923 ± 492 N) showed superior fracture resistance compared to the group restored with direct resin composite (1242 ± 436 N). The conventional resin composite group exhibited the lowest mean fracture resistance. The choice of restoration material plays a critical role in the clinical survival of large MOD cavities. CAD/CAM inlays and fiber-reinforced composites offer improved fracture resistance, which is essential for long-term success in extensive restorations.

Effect of Laser and Conventional Office Bleaching and Polishing on the Color Change of Stained Nanohybrid and Microhybrid Composite Resin.

The present study investigated the effects of laser and conventional in-office bleaching, and polishing on the color of stained composite resin. A microhybrid composite (Clearfil AP-X) and a nanohybrid composite (Grandio) were selected. Twenty-four discs (2 × 10 mm) for each composite were prepared. The samples were immersed in coffee solution (25 g of coffee in 250 mL water) for seven days. Then the samples were divided into three groups (n = 8) and the stains were removed using bleaching (with Opalescence Xtra Boost), diode laser irradiation with Heydent material and a Sof-Lex polishing kit. The L ∗a ∗b ∗ color parameters were determined using a spectrophotometer before and after immersion and after stain removal procedures, and the overall color changes (ΔE) were calculated. The data were analyzed with two-way analysis of variance. In the Clearfil composite resin group, the mean ΔE compared to the baseline using in-office bleaching, laser irradiation, and Sof-Lex polishing kit were 3.31, 3.35, and 4.93, respectively. These values with the Grandio composite resin were 3.31, 6.35, and 4.57, respectively. The highest capacity to remove stains was related to the conventional in-office bleaching method. Grandio composite resin underwent more color changes than Clearfil composite resin significantly (P-value < 0.05). Both composite resins exhibited color changes after immersion in the discoloring solution. However, after staining-removing procedures, the ΔE values decreased. Decreases in the ΔE values were not sufficient to restore the color to that before immersion in the discoloring solution with any stain-removing methods.

Effect of push-out bond strength of a conventional and a bulk-fill composite resin as a biotechnological technique to root dentin of primary anterior teeth

This study aimed to compare the push-out bond strength of a bulk-fill and a conventional composite resin to root dentin of primary anterior teeth using a 7th-generation dentin bonding agent. This in vitro study evaluated 24 primary anterior teeth randomly divided into two groups: Filtek P60 conventional and Filtek bulk-fill composite resins. Single Bond Universal adhesive was used for bonding. After filling the coronal part of the canal with composite resin, the teeth were mounted in acrylic resin and sliced to obtain a 1-mm-thick section of each root. Next, the sections underwent the push-out bond strength test. After determining the push-out bond strength, the failure mode was determined under a light microscope at ×40 magnification. The data were analyzed with two-way ANOVA and t-test. The mean push-out bond strength was 13.37±4.40 MPa in the conventional and 5.40±2.91 MPa in the bulk-fill composite resin groups. This difference was statistically significant (P=0.001). In the conventional group, 50% of failures were cohesive in the traditional combined resin group, while in the bulk-fill composite resin group, 75% of losses were mixed. Filtek P60 conventional composite resin and Single Bond Universal 7th-generation bonding agent were determined as appropriate for fabricating intracanal composite posts in primary anterior teeth. Keywords: Push-out, Bond strength, Bulk-fill composite resin, Root dentin, Primary anterior teeth.

Micro shear bond strength of mineral trioxide aggregate to different innovative dental restorative materials.

The objective of this in vitro study was to investigate the micro shear bond strength (µSBS) of mineral trioxide aggregate to four different restorative materials. Sixty mineral trioxide aggregate (MTA) samples were randomly assigned into four experimental groups based on the restorative materials used: nanohybrid resin composite as a control, giomer, alkasite and ormocer. µSBS samples were prepared for each group (n = 15). These samples were then submitted to a µSBS test (crosshead speed, 0.5 mm/min). The resulting data were statistically analyzed by one-way analysis of variance (ANOVA), Levene, and Bonferroni tests (α = 0.05). The bond strength of the alkasite group was statistically significantly higher than all the tested groups (p<0.05), while there were no significant differences between the nanohybrid resin composite, giomer, or ormocer groups (p > 0.05). Within the limitations of this study, alkasite restorative material could be a promising material when placed over MTA.

Effect of immediate dentin sealing on load-bearing capacity under accelerated fatigue of thin occlusal veneers made of CAD-CAM glass-ceramic and resin composite material.

The objective of this study was to assess the influence of immediate dentin sealing (IDS) on the fatigue behavior of laminate occlusal veneers fabricated with CAD/CAM lithium disilicate ceramic and resin composite. Forty sound human molars were prepared and randomly divided into 4 groups (n=10): RC-IDS+(IDS and resin composite occlusal laminate veneer); RC-IDS- (resin composite occlusal laminate veneer without IDS); LD-IDS+(IDS and lithium disilicate laminate veneer); LD-IDS- (lithium disilicate occlusal laminate veneer without IDS). The restorations were obtained using a digital workflow. After surface conditioning and bonding, thermocycling and accelerated fatigue tests (20Hz, 5000 cycles with an initial load of 300N, step-size of 100N for 10,000 cycles, up to 1000N, and then a step-size of 50N until failure) were conducted. Fatigue data were recorded for both outcomes (crack or fracture) and statistically analyzed. Fractographic and adhesive interface analysis were conducted. The indirect resin composite groups showed better fatigue behavior compared to lithium disilicate. IDS only had a positive effect for the survival of resin composite restorations for the 'fracture' outcome. Evident presence of micro-gaps at the adhesive interface in the LD-IDS- group could be noted. Immediate dentin sealing improved fatigue resistance behavior of resin composite occlusal veneers. However, this effect was not observed in lithium disilicate veneers.

Surface grafting of Poly (ether ether ketone) on silica particles as novel filler for dental composites: Physico-chemical characterization

This study aimed to describe the fabrication of a novel dental composite by surface modification of silica fillers with polyether ether ketone (PEEK) and assess surface coverage of fillers and the effect of different concentration of modified fillers on degree of conversion, flexural strength, polymerization shrinkage, water sorption and solubility, viscosity and thermal expansion of the formulated composites. In this experimental study, aminosilane derivative of PEEK was synthesized and grafted to the silica filler surface, then evaluated using a fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). Silica-PEEK fillers were then mixed with Bis-GMA/TEGDMA resin base in 10, 30, and 50 wt%. The most relevant physico-chemical properties were evaluated and compared with a control composite resin group containing conventional 3-(methacryloxypropyl) trimethoxysilane (γ-MPS) modified fillers. Data were analyzed by ANOVA and Tukey’s HSD test. (α = 5%). The experimental composite with 30% modified fillers showed highest flexural strength and degree of conversion (DC) ( p &lt; 0.05), and comparable polymerization shrinkage and viscosity to the control composites ( p &gt; 0.05). After thermocycling, the composite with 30% modified fillers showed the lowest solubility and water sorption ( p &lt; 0.05). Surface modification of silica fillers with PEEK polymer significantly increases the resistance of the filler–matrix interface to hydrolysis. The above mentioned intervention can improve mechanical properties of the composite and may be considered as a promising protocol to reduce the failure of dental composites.

In Vitro Color Stability Evaluation of Three Polished and Unpolished Nanohybrid Resin Composites Immersed in a 0.12% Chlorhexidine-Based Mouthwash at Different Times.

The use of chlorhexidine-based mouthwashes on resin composites with rough surfaces can cause discoloration which compromises the esthetic of patients. The present study aimed to evaluate the in vitro color stability of Forma (Ultradent Products, Inc., South Jordan), Tetric N-Ceram (Ivoclar Vivadent, Schaan, Liechtenstein) and Filtek Z350XT (3M, ESPE, St. Paul, MN, USA) resin composites, with and without polishing, after being immersed in a 0.12% chlorhexidine (CHX)-based mouthwash at different times. The present in vitro experimental and longitudinal study used 96 nanohybrid resin composite blocks (Forma, Tetric N-Ceram and Filtek Z350XT) 8 mm in diameter and 2 mm thick, evenly distributed. Each resin composite group was divided into two subgroups (n = 16) with and without polishing and then immersed in a 0.12% CHX-based mouthwash for 7, 14, 21 and 28 days. Color measurements were performed with a calibrated digital spectrophotometer. Nonparametric tests were used to compare independent (Mann-Whitney U and Kruskal-Wallis) and related (Friedman) measures. In addition, the Bonferroni post hoc correction was used considering a significance level of p < 0.05. All polished and unpolished resin composites presented color variation < 3.3 when immersed for up to 14 days in 0.12% CHX-based mouthwash. The polished resin composite with the lowest color variation (ΔE) values over time was Forma, and the one with the highest values was Tetric N-Ceram. When comparing the color variation (ΔE) over time, it was observed that the three resin composites, with and without polishing, presented a significant change (p < 0.001), although these changes in color variation (ΔE) were evident from 14 days between each color acquisition (p < 0.05). The unpolished Forma and Filtek Z350XT resin composites showed significantly more color variation than the same polished ones at all times when immersed in a 0.12% CHX-based mouthwash for 30 s daily. In addition, every 14 days, all three resin composites with and without polishing showed a significant color change, while, every 7 days, color stability was maintained. All the resin composites showed clinically acceptable color stability when exposed for up to 14 days to the above-mentioned mouthwash.

Effect of acidic media on flexural strength and fatigue of CAD-CAM dental materials.

To investigate the effect of acidic media, including beverages and gastric fluids on flexural strength and fatigue of CAD-CAM materials. Four CAD-CAM materials (high-translucency zirconia (Ceramill Zolid HT+), lithium disilicate (IPS e-max CAD), hybrid ceramic (Vita Enamic), and nanohybrid resin composite (Grandio Blocs) were prepared and immersed in one of five media (gastric HCl, white wine, Coca-Cola, orange juice, and artificial saliva) in an incubator (37℃, 24h). Surface topography and roughness were obtained using a scanning electron microscope (SEM) and a stylus contact profilometer, respectively. Initial 3-point flexural strength was measured for half of the bars (n=20/gp) using a universal testing machine (0.5mm/min). The other bars underwent 106 cyclic fatigue loadings before measurement of residual 3-point flexural strength. Data were statistically analyzed (two-way and three-way ANOVA, Tukey's post-hoc, p<0.05). Weibull distributions were plotted for reliability analysis. Zirconia bars has the highest initial flexural strengths followed by lithium disilicate, while resin composite and hybrid ceramic groups had the lowest strength regardless of the erosive medium. Cyclic fatigue significantly reduced initial flexural strengths for all materials except for hybrid ceramic and resin composite. Weibull moduli were the highest for zirconia, lithium disilicate and resin composite and lowest for hybrid ceramic. Erosive media significantly changed surface roughness of CAD-CAM materials except for zirconia and resin composite without jeopardizing the flexural strength of the CAD-CAM materials. Despite the higher flexural strengths for zirconia and lithium disilicate, resin composite and hybrid ceramic were more resistant to cyclic fatigue.

The Effect of Food-Simulating Liquids on Surface Features of Single-Shade Universal Composites: An In Vitro Study.

This study aimed to investigate the microhardness, surface roughness, and field emission scanning electron microscopes (FE-SEM) images of three different single-shade composites (Essentia Universal, Omnichroma, and Vittra APS Unique) in food simulation liquids such as ethanol, citric acid, and distilled water. Three single-shade universal composites were selected for this study. For each composite resin group, 92 samples (5-mm diameter and 2-mm depth) were prepared in plexiglass molds (N = 276). Then, samples were separated into four groups randomly consisting of 23 samples each (10 for hardness, 10 for roughness, and 3 for FE-SEM analysis). Three groups were immersed in food-simulating liquids (FSL)-citric acid (0.02N), distilled water, and 75% ethanol stored in a glass at 37°C for the next 7 days to simulate a wet oral environment. Control samples were stored in an opaque-light-proof box at room temperature. After the conditioning period, roughness and microhardness were measured, and FE-SEM analysis was performed. For statistical analysis, the two-way analysis of variance and Tukey honestly significant difference tests were used to evaluate roughness and microhardness (P < 0.05). There was a statistically significant difference between the composites in terms of roughness and hardness averages (P = 0.001; P < 0.05). Omnichroma showed the most surface changes in ethanol storage, whereas Vittra Unique showed the most surface changes in citric acid storage such as Essentia. FSL that mimic various oral environments affect single-shade universal resin composite restorations.

Evaluation of Effect of Screw Access Filling Materials on the Retention of Cement-Retained Implant Supported Crowns with Surface Modified Abutments – An In Vitro Study

Background Inadequate data regarding advantages of screw access filling materials and its interaction with the luting agent for improving retention in clinical scenarios with minimal abutment height.Objectives To evaluate the effect of three different screw access filling materials on the retention of cement-retained implant supported crowns with sandblasted abutments when zinc phosphate is used as the luting agent.Methods Thirty Bioline straight dental implant abutments sandblasted and reduced to a height of 5 mm were attached to their corresponding analogs. Thirty Direct Metal Laser Sintering DMLS copings were fabricated. The samples were divided into three groups of ten each and filled with three different screw access filling materials Group A ndash Composite Resin Group B - Cavit and Group C ndash Teflon Tape. All the copings were cemented with zinc phosphate and stored in artificial saliva for 14 days at 37degC. Tensile testing was done in a universal testing machine at a cross-head speed of 5 mmmin. The data collected was subjected to One-way ANOVA test to determine the difference between groups.Results Although the mean uniaxial retentive force was found to be highest for Group B 804 N followed by Group A 690 N and Group C 668 N the results of the One-way ANOVA test showed no statistically significant difference in uniaxial retentive force between the three groups.Conclusion The retention of cement-retained implant supported crowns may not be affected by the screw access filling materials when zinc phosphate is used as the luting agent on sandblasted abutments.

Water Sorption, Solubility and Color Stability of Different Bulk-Fill Restorative Materials

Objectives: The aim of this study was to evaluate the color stability, water sorption and solubility of recent bulk-fill restorative materials. Materials and Methods: Seventy disc shaped specimens (height:1mm, diameter:15mm) were prepared with a micro-hybrid composite resin (Z250; Filtek Z250, 3M ESPE), two resin-based bulk-fill (Filtek One Bulk Fill, 3M ESPE and EBF; Estelite Bulk-Fill Flow, Tokuyama Dental), glass ionomer-based restorative (Equia FF; Equia Forte Fil, GC Dental), self-cure and light-cure alkasite (CN; Cention N, Ivoclar Vivadent) and indirect composite resin (Gradia P; Gradia Plus, GC Dental) (n=10). Baseline color measurements were performed and mass of the samples (m1) were noted. Color measurements were repeated after 24 h and 28 days immersion of the specimens in water. After the 28-days immersion, mass was noted as m2. Specimens were kept in desiccators and final mass (m3) were recorded. The color change (ΔE00) water absorption (WSP) and water solubility (WSL) of the specimens were calculated. Results: After 28-days immersion, Gradia P showed significantly lower water sorption than EBF and Equia FF groups (p&amp;lt;0.05). Light-cured and self-cured CN groups showed similar sorption with resin composite groups (p&amp;gt;0.05). The lowest solubility was observed in Z250and Gradia P. The lowest (ΔE00) was observed in self-cured CN group (p&amp;lt;0.05) and Gradia P showed the highest ΔE00. Conclusions: Light-cured and self-cured CN groups demonstrated similar sorption to the conventional composite resin and indirect composite resin. Self-cured CN demonstrated higher water solubility than composite resins. Restorative materials showed moderately unacceptable color change after 28-day immersion in distilled water.

THE EFFECT OF NON-DENTAL GLASS FIBER COMBINATION ON FLEXURAL STRENGTH OF PREPOLYMERIZED FIBER-REINFORCED COMPOSITE

Background: Fiber reinforced composite is a combination of composite resin and fiber. Fiber in FRC serves as a reinforcement to be resistant to fractures. One of the fibers used in FRC is dental glass fiber because it can increase mechanical strength. Dental glass fiber is very limited and expensive while glass fiber which available in the market is non dental glass. This material has mechanical properties almost same as dental e-glass fiber used in dentistry, so it can be used as an alternative material FRC. The aim of this study was to identify the effect of flexural strength of non dental glass fiber to prepolymerized fiber reinforced composites. Method: This study used true experimental design with 16 samples. The samples were divided into two groups according to prepolymerized composite resin groups without fiber and prepolymerized composite resins with the addition of non dental glass fiber. Data analysis in this study used the normality test with the Sapiro-Wilk test, levene test and independent t-test. Result: The results were statistically analyzed, the average flexural strength of prepolymerized composite resin without fiber is 36.60 MPa and prepolymerized composite resin with the addition of non dental glass fiber which is 54.26 MPa. Based on the normality test and the levene test values (p&gt; 0.05) and independent t-test values (p &lt;0.05) were obtained. Conclusion: The conclusion obtained that there is an effect of the addition of non dental glass fiber to the flexural strength of prepolymerized fiber reinforced composite.

Is the Metallic Color of Stainless Steel Crown Satisfying for Cooperative Children and their Parents? a Preliminary Study.

Currently, the demand for tooth-colored restorations in children and young adults is increasing. Stainless steel crown (SSC) is the most common restoration for decayed primary molars. Given the dark metallic color of SSC, the esthetic appearance of this restoration is poor and subsequently their acceptance is still a matter of debate. This study was conducted to evaluate the effect of restoration's color on children's daily living conditions and compare the clinical and radiographic success rates of composite resins with SSC in primary molars. This clinical trial study was performed on 70 primary molars in 44 healthy 4- to 7-year-old children. The children were randomly divided into two groups restored with SSC and restored with composite resin. Two researcher-made questionnaires were used to assess the children's satisfaction concerning the appearance and color of restoration. The data were analyzed with SPSS 20 using chi-squared, Fisher's, and Mann-Whitney U tests. The significance level was set at p< 0.05. Children's satisfaction with restoration color in the treatment session was 75% in the SSC group and 85% in the composite resin group. However, the difference was not statistically significant (p= 0.246). After one year of follow-up, the satisfaction rate decreased to 69% in the SSC group and increased to 90.6% in the composite resin group, with a significant difference (p< 0.001). Moreover, the frequency of clinical success was 95% in the SSC group and 96.7% in the composite resin group, with no statistically significant difference (p= 0.749). The frequency of radiographic success was 87.5% in the SSC group and 100% in the composite resin group; this difference was not significant (p= 0.061). The results verified that restoration color was not important for cooperative children in the treatment session. However, after one year, children who received composite resin restorations were pointedly more satisfied than those who were treated with SSC restorations.

Evaluation of Microleakage of a New Bioactive Material for Restoration of Posterior Teeth: An In Vitro Radioactive Model

Hybrid bioactive composite resins combine the benefits of glass ionomer cements with composite resins. Its self-adhesiveness is achieved through functional polyacrylic acids and carboxylic groups, hybridizing the smear layer and establishing ionic interactions between calcium and dentin. These materials are defined as having good aesthetics, moisture tolerance, durability, simplicity in technique and handling and are able to maintain a low microfiltration rate while releasing calcium, phosphate and fluorine. The aim of the present study was to evaluate microleakage in restorations using Surefill One™ bioactive resin. The null hypothesis is that this type of resin does not obtain a lower microleakage rate when compared to other materials. An in vitro study was carried out using thirty-six premolars and molars extracted for orthodontic reasons. Identical preparations were thus performed in all of them (Class V with 4 mm mesio-distal, 3 mm occluso-gingival and 3 mm in depth) and divided into different experimental groups: one positive control, one negative control and two tests with bioactive composite resin and conventional composite resin (Surefill One™ and Spectra™ ST HV, respectively). Through quantitative techniques using nuclear medicine, it was possible to evaluate microleakage through the use of a radioactive isotope, technetium. Radioactivity emitted by the specimens was detected by a gamma camera. The different groups were compared using the Kruskal–Wallis test and the Games–Howell test for multiple comparisons. The results of the experimental study point to statistically significant differences between the test groups (p = 0.002) with increased microleakage in the bioactive composite resin group. Based on the present microleakage study, it was possible to conclude that the bioactive composite resin (Surefill One™) does not reduce the microleakage rate when compared to a conventional nanohybrid composite resin (Spectra™ ST HV). However, Surefill One™ can be used in temporary restorations, primary teeth and in cases of tissue remineralization, thus avoiding more invasive procedures.

Comparison of the effect of preheating on the flexural strength of giomer and nanohybrid composite resin.

Background. Considering the increased use of preheating and novel resin-based materials to restore teeth, the present study investigated the impact of preheating on the flexural strength of a giomer and compared it with a nanohybrid composite resin. Methods. Two restorative materials (Beautifil II giomer and Alpha III nanohybrid composite resin) were used. Thirty rod-shaped samples (adding up to 60 samples) were prepared from the materials above and divided into two subgroups: with and without preheating (n=15). Before sample preparation, the giomer and nanohybrid composite resin tubes were preheated at 68ºC for 15 minutes in the preheating subgroups. In the subgroups without preheating, the tubes were kept in a room at 25ºC. Then the flexural strength was compared between the two groups with two-way ANOVA at a significance level of P<0.05. Results. The results showed significantly higher flexural strength in the preheated subgroups than in the non-preheated subgroups (P<0.001). In addition, the mean flexural strength values were significantly higher in the giomer groups than in the nanohybrid composite resin groups (P<0.001). Conclusion. Preheating increased the studied materials' flexural strengths significantly. The flexural strength of the giomer restorative material was higher than that of the nanohybrid composite resin, irrespective of preheating.

Comparative analysis of effect of fruit juices on surface roughness of bulk fill and flowable composite material.

Resin-based composites have been widely used to reconstruct anterior and posterior teeth, as dentistry has progressed and there has been an increasing interest in the creation of suitable materials to replace damaged tooth tissue. The aim of the study is to compare the effect of fruit juices on the surface roughness of bulk fill and flowable composite restorative material. A total of 8 bulk fill composite and flowable composite resin disc samples were made. These eight samples were tested for surface roughness following immersion in three juices which were pineapple juice, lime juice, orange juice, and distilled water as the control group. They were immersed at room temperature for 7 days. Surface roughness was evaluated by the Mitutoyo SJ-310 contact profilometer. It showed that there was a decrease in the Ra value of flowable composite when compared to bulk fill composite. Rq and Rz values were more for the flowable composite resin group. Flowable composite resin samples had more surface roughness than bulk fill dental composite restorative material after exposure to pineapple, lime, and orange juices.

Appropriate Immediate Dentin Sealing to Improve the Bonding of CAD/CAM Ceramic Crown Restorations.

This study aimed to use quantitative and qualitative evaluations based on micro-tensile bond strength (μTBS) to clarify the appropriate immediate dentin sealing (IDS) approach for improving the bonding of CAD/CAM ceramic crown restorations. Forty-eight extracted human molars were prepared to obtain standardized abutment specimens and divided into three groups: no IDS (group C: control), IDS performed by a single application of an all-in-one adhesive system (group A), and IDS performed by the combined application of an adhesive system and a flowable resin composite (group F). All specimens were restored with a ceramic crown fabricated by a chair-side CAD/CAM system and were divided into no-stress and stressed groups. After cyclic loading (78.5 N; total, 3 × 105 cycles; 90 cycles/min) on the specimens in the stressed group, all specimens were sectioned. The μTBS values for the occlusal and mesioaxial walls were measured (n = 16) and analyzed statistically. The quantitative bonding performance of groups A and F were superior to that of group C, regardless of the cyclic loading and abutment wall conditions. Group F showed the maximum bond strength and the highest bond durability in the qualitative bonding performance even under the cyclic loading condition simulating clinical mastication.

The Effects of Selected Mouthwashes on the Surface Microhardness of a Single-shade Universal Resin Composite: In Vitro Study

Aim: To investigate the effects of selected alcohol-free mouthwashes with different formulations (zinc-hydroxyapatite, hydrogen peroxide, and sodium fluoride) on the surface microhardness of a single-shade universal resin composite. Materials and Methods: Forty disc-shaped specimens (8 × 2 mm) from the universal resin composite (Omnichroma®), and a nano-hybrid composite (Tetric® N-Ceram) were prepared. After polymerization, baseline surface microhardness values were recorded using Vickers microhardness tester. The samples from each material were randomly assigned to 4 groups ( n = 10) and immersed in 20 ml of the mouthwashes: Biorepair®, Listerine®, Colgate® Optic White, and distilled water (control). The samples were kept in the immersion solutions for 24 hours, and post-immersion microhardness values were recorded. Data were analyzed with one-way ANOVA and paired sample t-tests at p &lt; .05. Results: Significant reduction in microhardness was observed in all resin composite groups after immersion in the mouthwashes compared to baseline values ( p &lt; .0001). The highest microhardness reduction in Omnichroma® group was observed after immersion in Colgate® Optic White; and Tetric® N-Ceram group after immersion in Listerine® mouthwash. For both materials, the least reduction in microhardness was observed after immersion in Biorepair®. Microhardness values for Omnichroma were significantly higher than Tetric® N-Ceram ( p &lt; .0001). However, Omnichroma exhibited a significantly greater reduction in microhardness after immersion in the tested mouthwashes. Conclusion: In vitro simulated use of the investigated mouthwashes negatively affected the surface microhardness of both tested resin composites. The observed effects were both mouthwash and material dependent.

Effect of Polishing Systems on the Color and Surface Properties of Resin Composites in the Process of Accelerated Artificial Aging

Objective: This study aimed to investigate the effects of polishing system on the color stability, surface roughness, and hardness of resin composites in the presence and absence of accelerated artificial aging (AAA). Methods: Six resin composites (Universal Restorative 200, G-Aenial Anterior, Ceram-X Duo, Admira, IPS Empress Direct, Clearfil Majesty Esthetic) were evaluated. Thirty disc-shaped samples were prepared for each composite group. Resin composite groups were divided into three subgroups: control (Mylar strip), disc (Optidisc), and rubber (Dimanto) (n=10). Color change (ΔE00) was calculated using the CIEDE 2000 formula. Before and after AAA, the surface roughness (Ra, μm) and hardness (VHN) values were measured. Data were analysed using ANOVA, the Bonferroni test, and Pearson correlation (p

The Microhardness and Surface Roughness Assessment of Bulk-Fill Resin Composites Treated with and without the Application of an Oxygen-Inhibited Layer and a Polishing System: An In Vitro Study.

The aim of this study was to assess the microhardness and surface roughness of bulk-fill resin composites treated with and without the application of an oxygen-inhibited layer (OIL) and a polishing system. This in vitro experimental study consisted of 72 resin composite blocks divided into three groups: Tetric N-Ceram Bulk Fill, Opus Bulk Fill APS, and Filtek Bulk Fill. Each resin composite group was further divided into two subgroups: with and without OIL control. Subsequently, surface roughness and microhardness were measured before and after polishing. A t-test was used to compare independent and related measures. For the intergroup comparison of variation before and after polishing, the Kruskal–Wallis test with Bonferroni post hoc was used considering a significance level of p < 0.05. When comparing surface roughness, significant differences were observed between Opus Bulk Fill resin composite with and without OIL control (p = 0.003) before polishing. The same occurred when comparing Tetric N-Ceram resin composite with and without OIL control (p = 0.039) after polishing. In addition, the surface roughness of Filtek Bulk Fill, Opus Bulk Fill, and Tetric N-Ceram Bulk Fill resin composites, with and without OIL control, decreased significantly after polishing (p < 0.001), while surface microhardness significantly increased (p < 0.05), with the exception of Opus Bulk Fill resin with OIL control (p = 0.413). In conclusion, OIL control and polishing significantly improved the surface roughness and surface microhardness of Filtek Bulk Fill and Tetric N-Ceram Bulk Fill resin composites. However, in the case of Opus Bulk Fill resin composite, only its surface roughness was significantly improved.