Fill Resin Composites Research Articles

Effect of hydroelectrolytic beverages on the roughness and microhardness of bulk fill resin composites

Aim: This study aimed to assess the effects of a hydroelectrolytic beverage on the surface roughness and microhardness of different bulk fill resin composites. Methods: Sixty resin composite samples were prepared and divided into three groups: FiltekTM Z350 (C), FiltekTM One Bulk Fill (BF-F), and Opus Bulk Fill APS (BF-O). These were further subdivided to analyze two beverage groups: GatoradeTM Lemon (GL) and distilled water (control). Surface roughness (Ra), surface microhardness (KHN), and scanning electron microscopy (SEM) results were evaluated (n=10). The data were subjected to two-way ANOVA (for roughness) or three-way ANOVA (for microhardness), followed by Tukey’s post hoc test (α=0.05). Results: The C group exhibited higher microhardness than the BF-F and BF-O groups, regardless of the solution used. A reduction in microhardness was observed in all groups when comparing initial and final time points. SEM images revealed variations in the size, amount, and arrangement of particles among the different resin composites. Conclusion: The study concluded that the microhardness of different bulk fill resin composites decreases when exposed to either the hydroelectrolytic beverage or distilled water. However, the type of immersion liquid did not influence the surface roughness of the evaluated composite resins.

Supercritical CO2-Stable Cementing Materials Based on Vinyl Ester Resin for Maintaining Wellbore Integrity.

Ensuring long-term wellbore integrity is critical for carbon dioxide geological storage. Ordinary Portland cement (PC) is usually used for wellbore primary cementing and plug operation, and set cement is easily corroded by acidic fluids, such as carbon dioxide, in underground high-temperature and high-pressure (HTHP) environments, resulting in a decrease in the mechanical properties and an increase in permeability. In order to achieve long-term wellbore integrity in a CO2-rich environment This study introduces materials such as thermosetting vinyl ester resin (TSR), filler composite resin (FCR), and low-cost resin cement (RC). Corrosion experiments were conducted using four materials in 28 days under supercritical carbon dioxide gas and water phase conditions of 60 °C and 10 MPa. The samples were characterized through mechanical property testing machines, core permeability measuring instruments, FTIR, XRD, and SEM. The results proved that after corrosion, PC mechanical properties decreased, the permeability increased, and the microscopic composition and morphology changed greatly. Penetrating corrosion occurs in the sample in the gas phase environment, and propulsive corrosion from outside to inside occurs in the water phase environment. However, TSR, FCR, and RC materials all maintain excellent resistance to carbon dioxide corrosion in gas and water environments. They have higher compressive strength and extremely low permeability compared to ordinary Portland cement. These three materials' compressive strengths can be maintained around 131, 99, and 58 MPa, and permeability can be stabilized at <6 × 10-7, <6 × 10-7, and 0.16 mD levels. In summary, the above three materials all show better performance than ordinary Portland cement and are promising alternative materials that can be used in primary cementing and plug operations of carbon dioxide geological storage wells.

Restoring with flowables: An injection moulding technique – A report of two cases

This case report showcases the conservative management of aesthetic anterior restorations for patients seeking to enhance their smiles using the highly filled flowable composite resin injectable moulding technique. This efficient method resulted in optimal, aesthetically pleasing outcomes, leading to high patient and dentist satisfaction. Direct veneers made from injectable flowable resin composites provide a minimally invasive treatment option, given that the case selection criteria are appropriately followed. Furthermore, this approach can be viewed as a more cost-effective alternative. However, additional follow-ups are essential to thoroughly assess the clinical longevity of both the restorations and the materials utilised.

Clinical performance of polyethylenefiber reinforced resin composite restorations in endodontically treated teeth: (a randomized controlled clinical trial)

AimThe purpose of this study was to evaluate the performance of polyethylene fiber reinforced resin composite fillings compared to bulk fill resin composite fillings in endodontically treated teeth over a two-year monitoring period.MethodA total of 240 individuals with endodontically treated lower molars and a moderate amount of tooth structure were divided into two equal groups of 120 each. One group received polyethylene fiber reinforced bulk fill resin composite restorations while the other group received only bulk fill resin composite restorations, both applied as per manufacturer guidelines. Two proficient experienced blinded assessors assessed the restorations using modified USPHS criteria at baseline, 6, 12, and 24 months.Statistical analysis usedData analysis involved the utilization of Mann-Whitney U, Friedman’s test, and Nemenyi post hoc test, with age data being displayed as mean and standard deviation. The significance level was established as p < 0.05, and R software was utilized for statistical analysis.ResultsThere were no notable distinctions in any parameters or scores between the intervention and comparator groups at various time points. Alpha scores were present for retention, gross fracture, and secondary caries at all follow up intervals.ConclusionBoth direct resin composite restorations reinforced with polyethylene fibers and direct bulk fill resin composite restorations placed in endodontically treated molars with moderate remaining tooth structure demonstrated satisfactory clinical outcomes during a 24-month follow-up period.Clinical relevanceBulk fill resin composites directly placed in endodontically treated molars with moderate remaining tooth structure showed promise as a treatment option over a two-year period.Clinical trial registration(06-01-2022) on https://ClinicalTrials.gov with the ID (NCT05180903).

24 Months clinical prospective of proximal restorations with repeated preheating bulk fill composite up to ten cycles: randomized controlled trial

This study aimed to clinically evaluate the performance of non-preheated bulk fill resin composite in class II cavities versus one, five and ten-time preheating cycles at 68 °C. Eighty-four recruited participants were randomly allocated into four groups (21 patients per group). One posterior Bulk-fill proximal restoration was performed for each participant according to the preheating cycles where in group I; teeth were restored with non-heated resin composite, group II: One preheating cycle of composite syringe was performed prior restoration, and group III: five preheating cycles while for group IV: Ten preheating cycles were performed. These restorations were clinically evaluated at 6, 12, 18 and 24 months. Statistical analysis was performed using one way ANOVA, with set p-value < 0.05. The results revealed that there was perfect agreement between both observers and observations WK (95% CI) [0.908 (0.780:1.000)] and [0.940 (0.824:1.000)], respectively. All restorations showed acceptable clinical performance with alpha and bravo scores. No replacement was required for any restoration. No statistically significant differences were detected between the control and intervention groups across all parameters during the various evaluation stages. It could be concluded that the clinical performance of ten cycles of repeated preheated bulk fill resin composite was equivalent to that of non-preheating resin composites after 24 months follow-up period, with great improvement in manipulation. Preheating of resin composite could be performed up to ten cycles prior to placement without any clinical adverse consequences on the performance of the restoration.

The Effect of Micromechanical Surface Preparation and Adhesive Surface Modification Strategies on Resin-Matrix Ceramic Repair Bond Strength Using Universal Adhesive Containing Silane Agent

Abstract Objectives This research assesses the effect of the different micromechanical surface preparations and chemically adhesive surface modification strategies applied to resin-matrix ceramics (Shofu Block HC) repaired using resin composites. Materials and Methods Eighty resin-matrix ceramics were conducted and designed into eight groups of 10 specimens and surface treated with (1) micromechanical preparation with sandblast (SB) or hydrofluoric acid (HF), and (2) chemically adhesive techniques with HC primer (HC) and/or silane (Si) and/or conventional adhesive (AD) or universal adhesive (UA) designing are as follows: group 1, SB + HC; group 2, SB + HC + AD; group 3, SB + HC + Si + AD; group 4, SB + HC + UA; group 5, HF + HC; group 6, HF + HC + AD; group 7, HF + HC + Si + AD; and group 8, HF + HC + UA. An ultradent model was put on the specimen center, then filled resin composite. Mechanical testing instrument was used to determine the samples' microshear bond strength (MSBS). To inspect failure modes, a stereomicroscope was used for observing the debonded surfaces. Statistical Analysis To assess the data, a one-way analysis of variance was employed, and the significant level (p &lt; 0.05) was established with Tukey's test. Results Group 3 (29.29 ± 2.58 MPa) and group 4 (28.34 ± 1.26 MPa) demonstrated the two maximum MSBS values. The minimum MSBS (10.02 ± 3.31 MPa) was discovered by group 5. Nevertheless, group 2's MSBS values (22.78 ± 2.44 MPa) differed significantly from the values for groups 3 and 4. All the fractured samples in groups 1, 5, 6, 7, and 8 had an adhesive failure pattern. Furthermore, group 3 presented the greatest mixed failures (40%). Conclusion The SB is the most effective protocol for producing micromechanical retention. The application of HC primer and Si agent prior to the adhesive agent is the best chemical adhesive strategy for sandblasted resin-matrix ceramic surfaces. Additionally, the application of HC primer before the use of UA containing acid-resistant Si is the best alternative chemical adhesive strategy for improving the MSBS.

Effect of carbamide peroxide treatment on the ion release of different dental restorative materials

BackgroundTo predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials.MethodsIn this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer’s instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05).ResultsIt was determined that the amount of ions release from the restorative materials decreased over time (p < 0.05). According to the results of the Mann-Whitney U test, there was no difference between the bleaching and control groups in most of the restorative materials (p > 0.05).ConclusionWithin the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials.

BASE SURFACE TEMPERATURE OF BULK FILL RESIN COMPOSITE WITH DIFFERENT THICKNESS

Background: The material thickness is one factor that influences the polymerization of resin composites. Bulk fill resin composite is an efficient dental resin composite restoration material because it can be cured to a thickness of up to 4-5 mm. The thickness of the material can also affect the temperature rise, while maintaining the temperature is very important because a significant increase can damage the pulp. Purpose: This research aimed to analyze the base surface temperature of bulk fill resin composite with different thicknesses. Methods: Thirty bulk fill resin composite samples with a diameter of 5 mm were divided into three groups with different thicknesses, namely group I (3 mm), group II (4 mm), and group III (5 mm). Each group of samples was cured using an LED Light Curing Unit for 20 seconds, and carried out simultaneously with the measurement of the base surface temperature using a type-K digital thermocouple. Data analyzed using One Way ANOVA and LSD post hoc tests. Results: The mean and standard deviation of the base surface temperature of bulk fill resin composite in groups I, II, and III, respectively, is 37.56 ± 1.06oC, group II 36.89 ± 1.23oC, and group III 36.00 ± 1.2 oC. It showed significantly different between the groups (p&lt;0,05). Conclusion: The thicker the bulk fill resin composite, the lower the base surface temperature.

Repair bond strength of aged non methacrylate ORMOCER based bulk fill resin composite. An in-vitro study.

Repair bond strength of aged non methacrylate ORMOCER based bulk fill resin composite. An in-vitro study.

Comparison of the Effect of Adhesive Protocols and Light Curing Units on the Repair Bond Strength of Bulk Fill Composite Resins

Background: The aim of this study is to compare the shear bond strength (SBS) after the repair of a microhybrid composite resin (CR) with three different bulk fill CRs using a 2nd and 3rd generation light-emitting diode (LED) light curing units and a universal adhesive with different application protocols. Methods: 120 acrylic blocks, each with an open surface and a depth of 2 mm and a diameter of 6 mm, were filled with a microhybrid CR (Filtek Z250) and cured with an LED for 20 seconds. The samples were roughened for 5 seconds with a diamond fissure bur under water cooling and then subjected to 5,000 thermal cycles. A universal adhesive was applied to the prepared samples using two different protocols (total etch and self-etch), and samples were then filled with bulk fill CRs. Each bulk fill CR group was polymerized with 2nd and 3rd generation LED to form subgroups (n=10). The SBS values were recorded in MPa using a universal testing device. Results: The highest SBS values were obtained for the X-tra Fil group in total etch mode with polymerization using 3rd generation LED, while the lowest SBS values were found for Filtek One Bulk Fill group in self-etch mode with polymerization using the 3rd generation LED. In all groups, total etch mode yielded higher SBS values compared to self-etch mode. Conclusion: Different adhesive protocols and LCUs were found to affect the SBS values of bulk fill CRs during repair.

Effect of Polywave and Monowave Light Curing Units on the Microtensile Bond Strength and Failure Types of Different Bulk-Fill Resin Composites: An in vitro Study.

This study aimed to evaluate the effects of polywave and monowave light-emitting diode curing units on the microtensile bond strength and failure types of three bulk-fill resin composites. This in vitro experimental study was performed on 180 microbars obtained from human third molars and were distributed into 12 groups according to the type of bulk-fill resin composite and the light-curing unit. Third molars were restored using Filtek One Bulk Fill Restorative, Tetric® N-Ceram Bulk Fill, and Opus Bulk Fill resin composites was light-cured with Elipar Deep Cure L and Valo in three modes: standard, high power, and extra power. Subsequently, microtensile analysis was carried out with a universal testing machine and the type of failure with an optical stereomicroscope. For statistical analysis, the Kruskal-Wallis H-test was used, with the Bonferroni post hoc test and Fisher's exact test, considering a significance of p<0.05. There were significant differences in the microtensile bond strength between the Filtek One Bulk Fill restorative and Opus Bulk-Fill (p = 0.042) when light was cured with the polywave unit at standard power. On the other hand, the Filtek One Bulk Fill Restorative and Opus Bulk Fill resins showed significant differences in microtensile bond strength when light was cured with the monowave unit compared with the polywave unit (p<0.05). The presence of alternative photoinitiator systems that are more reactive than camphorquinone produced higher microtensile bond strength in Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins when light-cured with a high and standard polywave unit, respectively, compared to Filtek One Bulk Fill resins. Finally, Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins had the highest percentage of mixed failures, while Filtek One Bulk Fill resin had adhesive failures, which was related to its lower microtensile bond strength.

Dental Service Cost Analysis Using Time-Driven Activity-Based Costing

This research has the objective to analyze dental service costs of the case study dental clinic using Time-Driven Activity-Based Costing (TDABC). The study was conducted in teaching clinic where dental services were provided by undergraduate-level dentistry students under the supervision of the teachers of Dentistry Faculty, and where there were also dental assistants on hand to provide service support. The research studied only five treatment procedures with a maximum frequency of service use, cumulatively totaling 80%, according to the Pareto principle. The research started from studying various activities in the processes of providing each category of dentistry service. Then, the dental service costs using TDABC were analyzed by estimating from two key parameters: the capacity cost rate and the time taken for each activity of the treatment procedure. The study found that Sealant Compounds, Tooth Extraction, Preventive Resin Restoration, Composite Fillings and Stainless Steel Crown had treatment costs of 623, 594, 669, 642 and 761 Thai Baht/treatment respectively. This research enabled the case study dental clinic to identify its costs for each treatment procedure, and also calculate profit and loss by comparison with income from service users. These data could also be used to determine more appropriate service charges for each category of treatment.

Comparison of Three Different Orthodontic Adhesives Bonded to Metallic and Ceramic Brackets: SEM and SEM/EDX Analysis (In Vitro Study).

To compare three different orthodontic adhesives (Transbond XT Light Cure Adhesive, Heliosit Orthodontic, Fuji Ortho LC) bonded to two types of orthodontic brackets: ceramic brackets (Fascination Roth 0.22) and metallic brackets (Topic Roth 0.22, Dentaurum). The study was performed on 18 human teeth (6 for each adhesive). The prepared teeth were divided into three groups according to the examination time. Subsequently, they were observed after 1, 2 and 3 weeks following bonding. After the experimental procedure, the teeth samples were cut in half along the longitudinal axis in the vestibulo-oral direction, fixed with conductive carbon cement, placed in a high-vacuum evaporator and then coated with carbon. One half of each sample was observed under a Field-emission gun scanning electron microscope (FEG-SEM Hitachi SU 8030, Japan), while on the second half of the samples qualitative (X-ray line-scans) and semi-quantitative point X-ray energy dispersive analyses (EDX) were performed with Thermo Noran (USA) NSS System 7, equipped with Ultra Dry detector (30 mm2 window). Transbond XT had an ideal bond with the enamel and the bracket base, with rare presence of microgaps and cracks in the enamel. Heliosit Orthodontic demonstrated a better bond relationship with the bracket base than the enamel, whereas in the latter the presence of microgaps in the bond was observed. The microphotographs of Fuji Ortho LC demonstrated many cracks inside the adhesive, and some of them continued to move forward into the enamel surface. Therefore, an impression of a very solid bond relationship with the enamel exists, with cracks being present in the enamel surface and never at the enamel-adhesive interface. Microgaps also appeared at the bracket-adhesive interface. Transbond XT is a highly filled composite resin and is an ideal orthodontic adhesive in each aspect examined, with an ideal enamel-adhesive and bracket-adhesive interface. Heliosit Orthodontic provides better bracket-adhesive interface compared to the enamel. Fuji Ortho LC as a solid resin-modified GIC provides a better enamel-adhesive interface, compared to the bracket base.

Evaluation of Microvoid and Microleakage Potential of Bulk-Fill Resin Composites in MOD Restorations

Background: Polymerization shrinkage and microvoid formation has been a significant problem giving way to resin composite failure. The aim of this study was to evaluate the microvoid potential and microleakage of two bulk-fill and a microhybrid resin composite applied with different adhesive materials. Materials and Methods: MOD cavities were prepared in 60 endodontically treated maxillary premolars. The teeth were divided into six different groups (n = 10) according to adhesive systems (Gluma (Kulzer), OptiBond FL (Kerr) and resin composite materials EverX Posterior (GC) and Filtek One Bulk Fill (3M ESPE). An aging procedure with 5000 cycles of thermal cycling was applied. All teeth were individually scanned with micro-computed tomography. A Shapiro–Wilk test, two-way MANOVA, and Bonferroni analysis were used for statistical tests. Results: Self-etch groups showed more microleakage than total-etch groups. Minimum microleakage was observed in Filtek One Bulk Fill groups, whereas G-aenial Posterior groups showed maximum microleakage. Conclusions: Filtek One Bulk Fill (3M ESPE) resin composite was found to be more effective in reducing microvoid formation in MOD cavities when applied with total-etch adhesive systems. However, EverX Posterior (GC) and G-aenial Posterior (GC) showed less microvoid formation with self-etch adhesive systems.

Color and surface roughness alterations of bulk-fill resin composites submitted to simulated toothbrushing with whitening dentifrices

Aim: To evaluate the surface roughness and color stability of bulk-fill resin composites after simulated toothbrushing with whitening dentifrices. The radioactive/relative dentin abrasion (RDA) and radioactive/relative enamel abrasion (REA) of dentifrices were also assessed. Methods: Specimens (n=10) of Tetric N Ceram Bulk Fill (TNCB), Filtek One Bulk Fill (FOB) resin composites, and Z100(Control) were prepared using a cylindrical Teflon matrix. Surface roughness (Ra, μm) was assessed by a roughness meter and the color evaluations (ΔEab , ΔE00 , WID ) were performed using a digital spectrophotometer based on the CIELAB system. Three measurements were performed per sample, before and after simulated toothbrushing with 3D Oral-B White Perfection (3DW) and Black is White (BW) dentifrices. The abrasivity (REA and RDA values) of the used dentifrices was also determined by the Hefferren abrasivity test. Results: The Ra values increased significantly in all resin composites after 3DW and BW toothbrushing. The acceptable threshold color varied among resin composites, and TNCB and Z100 presented the highest ΔEab and ΔE00 for BW dentifrice. The 3DW dentifrice was significantly more abrasive than BW dentifrice on enamel and dentin. Conclusions: simulated toothbrushing with tested whitening dentifrices increased the surface roughness at acceptable levels. The Tetric N Ceram Bulk-fill and Z100 composite showed the highest color alteration in BW. 3D White Perfection dentifrice was more abrasive on dentin and enamel than Black is White.

Optimizing fracture resistance of endodontically treated maxillary premolars restored with preheated thermos-viscous composite post-thermocycling, a comparative study. Part I

PurposeThis research aimed to investigate fracture resistance of endodontically treated maxillary premolars restored using preheated thermo-viscous and fiber-reinforced bulk fill resin composite, in vitro.MethodologySixty sound human maxillary premolars were selected and divided randomly into 6 groups of ten teeth each (n = 10). Group 1; is the positive control with sound unprepared teeth (P), Group 2; is the negative control in which Mesio-occluso-distal (MOD) cavities were left unrestored (N), Group 3; includes the teeth restored by incremental packing with conventional nanohybrid composite (ChP), Group 4; includes teeth restored with short fiber reinforced bulk fill composite (EF), Group 5; includes teeth restored with preheated thermo-viscous bulk fill composite (VB), and Group 6; includes teeth restored using packable bulk fill composite (XF) Tested restorative materials were bonded with a universal adhesive in self-etch mode. Teeth were kept in distilled water for 24 h at 37 °C proceeded by thermocycling (5- 55 °C, 1200×). Teeth were then exposed to compressive load till fracture at a crosshead speed of 1 mm/min. One-way ANOVA followed by Tukey post-hoc test was implemented to compare between more than two groups in non-related samples. The significance level was established at α = 0.05 for both tests.ResultsIntact teeth significantly recorded the highest fracture resistance values among all groups. A significant difference was recorded among all the tested groups, with the EF recording the highest values, followed by the VB group then the XF group and ChP that recorded the lowest data. Negative control premolars significantly recorded the lowest fracture.ConclusionsAfter thermocycling, endodontically treated maxillary premolars restored with pre-heated thermos-viscous composite did not exhibit an increase in fracture resistance. Notably, our findings indicate that short fiber-reinforced composite demonstrated significantly higher fracture resistance compared to other types of composites assessed in this study. This suggests the potential superiority of short fiber-reinforced composite in enhancing the overall structural integrity of endodontically treated teeth subjected to occlusal forces.

Effect of duration and infection control barriers of light curing unit on hardness of Bulk Fill composite resin.

This study aimed to investigate the impact of the duration of light curing unit (LCU) usage and the use of infection control barriers on the hardness of Bulk Fill composite resin after curing. The hypotheses were that extended usage of the LCU would not reduces its output power and resin hardness, and that the presence of polyethylene film barriers exacerbates the reduction in resin hardness. Based on the absence or presence of polyethylene film (PE) and the number of layers used, a 3M LED curing light (EliparTM DeepCure-S; 3M ESPE, St Paul, MN, USA) was divided into three groups: PE0, PE1, and PE3. The curing light was used 30 times daily for 20 s per exposure, at frequencies of 0, 6, and 12 months. Maximum output power tests were conducted for each group of curing lights. Custom-made plastic modules were used to stack Bulk Fill composite resin (Filtek Bulk Fill Posterior Restorative; 3M ESPE) to a thickness of 4 mm. Each group of curing lights was used to cure the modules in a direct contact manner for 20 s. Vickers hardness measurements were taken at the top and bottom surfaces of the resin specimens using a digital microhardness tester. A one-way or two-way ANOVA analyzed the power of LCUs, Vickers hardness of Bulk Fill composite resin, and hardness decrease percentage across groups. Pairwise comparisons used the Tukey test (α = 0.05). As the duration of usage increased, both the power of the curing light and the hardness of the resin significantly decreased. Significant differences were observed in power and resin hardness among the PE0, PE1, and PE3 groups. When the duration of usage was 6 months or less, only multi-layered PE films led to a significant increase in the percentage decrease of hardness of cured resin from top to bottom. However, at 12 months, both single-layer and multi-layered PE films resulted in a significant increase in the percentage decrease of hardness of cured resin from top to bottom. The output power of the light curing unit decreases with prolonged usage, thereby failing to meet the curing requirements of Bulk Fill composite resin. The use of single-layer PE as an infection control barrier is recommended.

Pre-heating decreases micro-leakage of bulk fill composite resins in dentin margins of class II cavities: an in-vitro study

Pre-heating decreases micro-leakage of bulk fill composite resins in dentin margins of class II cavities: an in-vitro study

Grau de radiopacidade de resinas compostas Bulk Fill

ABSTRACT Objective: To verify and compare the radiopacity of four composite resins available in the national market and analyze their compliance with International Standards Organization 4049 guidelines. Methods: Five specimens of each Bulk Fill composite resin were prepared, and radiographs were taken alongside an aluminum step wedge using a digital imaging system. The images were processed using software capable of measuring mean grey values (MGVs), which were then converted to millimeters of aluminum. Statistical analysis was performed (P 0.05). Results: The four tested composite resins showed radiopacity values higher than those of enamel and dentin, standing out the Tetric N-Ceram- Ivoclar Vivadent (11.05 mmAl). All samples are in accord with the ISO 4049 radiopacity standard. The resin Opus Bulk Fill and Tetric N-Ceram were compared to each other, revealing statistically significant differences (p0,05). Conclusion: All materials demonstrated radiopacity values higher than those of dentin and enamel. All samples are in accordance with the International Organization for Standardization 4049 guidelines. More studies should be conducted with the composite resins used in this study due to the limited research involving these specific resins.

Influence of Light-Curing Time and Increment Thickness on the Properties of Bulk Fill Composite Resins With Distinct Application Systems.

The objective of this study was to evaluate the influence of light-curing time and increment thickness on the microhardness and degree of conversion (DC) of bulk fill composite resins with different application systems. Translucency parameter (TP) was also measured. Specimens of resin composites were prepared in a circular matrix using a single increment with different thicknesses (2, 4, and 6 mm) and light-cured with distinct times (10, 20, and 40 s). The materials tested (n = 5 pergroup) were Filtek One (FO) bulk fill, Tetric N-Ceram (TC) bulk fill, SonicFill 3 (SF), VisCalor (VC) bulk. After 24 h, Knoop microhardness (KN) was measured, and the bottom/top ratio (B/Tratio) was calculated. The DC was measured using Fourier transformed infrared (FTIR) spectroscopy. The TP was assessed in additional specimens with 1 mm thick (n = 5). The data were statistically analyzed with analysis of variance (ANOVA) and Tukey's tests (5%). Significant differences were observed for all factors, for both B/Tratio and DC (p < 0.05). The higher increment thickness and the lower curing times resulted in lower B/Tratio and DC means. The VC and TC resins exhibited the overall higher B/Tratio, and the highest TP. SF presented the lowest values of B/Tratio and DC, with compromised polymerization at 6 mm depth. TP (means ± SD) were FO (12.85 ± 1.0)1, SF (15.62 ± 0.73)2, TC (20.32 ± 0.49)3, and VC (20.53 ± 0.73)3. We concluded that the greater the thickness of the increment, the lower the DC. Higher light curing times resulted on increased DC of the tested composites. The higher translucent materials VC and TC showed the greater B/Tratio; and FO resin exhibited the higher DC values.