Composite Resin Research Articles

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 < 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.

A Comparison of the Shear Bond Strength between a Luting Composite Resin and Both Machinable and Printable Ceramic–Glass Polymer Materials

This study aims to compare the shear bond strength (SBS) and Weibull characteristics between a luting composite resin and both printable and two different machinable ceramic–glass polymer materials. A total of 36 substrates were prepared, with 12 in each group. Printable substrates (12 mm × 12 mm × 2 mm) were printed by using permanent crown resin (3D-PR). Machinable substrates were obtained from Cerasmart 270 (CS) and Vita Enamic (VE) blocks (2 mm in thickness). The bonding surfaces of substrates were polished and airborne abraded (50 µm Al2O3). A self-adhesive luting composite resin (RelyX U200, 3M ESPE, St. Paul, MN, USA, SLC) was applied on substrates with the help of a cylindrical (Ø3 × 3 mm) mold. The SBS test was conducted using a universal test machine. The SBSs of three materials were compared using a one-way analysis of variance (ANOVA) (α = 0.05). The Weibull modulus was calculated for each material. The Kruskal–Wallis and chi-square tests were carried out for the failure mode analysis. There was no significant difference between the SBSs of the three materials (p = 0.129). The Weibull modulus was 3.76 for the 3D-PR, 4.22 for the CS, and 6.52 for the VE group. Statistical analysis showed no significant difference between the failure modes of the groups (p = 0.986). Mixed-failure fractures were predominantly observed in all three groups. The results show that the SBS of the SLC to printable 3D-PR is comparable to that of CS and VE material. Failure modes of printable 3D-PR show similar results with two different machinable ceramic–glass polymers.

Use of amazonian fruits in dental bleaching

Natural products stand out for their chemical diversity, thus plants are important candidates for screening new bioactive compounds. This study evaluated the effect of plant extracts combined with 16% carbamide peroxide (PC16%) on tooth whitening. Bovine teeth and composite resin blocks were randomly assigned to pigmentation and whitening protocols. For pigmentation, they were immersed in diluted coffee (14 days), and whitening was performed by mixing 1g of plant extract from each species and 0.5mL of PC16% (9 days). The extracts were prepared from fruits of species occurring in the Amazon biome: Myrciaria dubia (Myrtaceae), Bactris gasipaes (Arecaceae), Euterpe oleracea (Arecaceae), Theobroma grandiflorum (Malvaceae), and Paullinia cupana (Sapindaceae). PC16% was used alone as control, and a group without whitening was also included. Color analysis was performed using ΔE2000, ΔE1976, and WhiteIndex through an EasyShade Advanced 4.0 spectrophotometer before and after the protocols. The pH of the extracts at a concentration of 10% and micrographs after whitening were analyzed. Data were analyzed by one-dimensional ANOVA and Tukey's post-hoc test. Pigmentation showed significance only for bovine teeth (p 0.05). The pH of the pupunha and guaraná-de-maués extracts approached that of PC16%. Micrographs show that only the cupuaçu group had no surface alteration. Further research is needed to investigate variation factors, particularly given the study's limitations.

Improved interfacial properties of carbon fiber reinforced epoxy resin composite by in‐situ self‐assembled mental‐phenolic networks

AbstractThe chemical modification of carbon fiber surface often uses toxic reagents and harsh reaction conditions, while the preparation process of metal‐phenol networks (MPNs) is simple, rapid, non‐toxic and harmless, which provides a direction for alleviating environmental problems. In this study, tannic acid (TA) was coordinated with Fe3+ to form MPNs, which was coated on the surface of carbon fibers through π‐π interaction. The results indicated that oxygen functionalities on the surface of the MPN coating can facilitate better adhesion between the carbon fiber and the epoxy resin, when the molar ratio of TA to Fe3+ is 1:3 and the pH is 4, the interlaminar shear strength (ILSS) performance of the composite material reaches its optimal level. In addition, a green and non‐destructive method is provided for the surface modification of carbon fiber, which can effectively optimize the interfacial properties of carbon fiber reinforced polymer (CFRP) composites.

Effect of Silane-Containing Adhesives on Repair Bond Strength between Fresh and Aged Composite Materials-A Pilot Study.

This study investigated the effects of different surface treatments and a silane-containing adhesive on the repair bond strength between fresh and aged resin composites. A total of 140 composite specimens were prepared and aged for 24 h or 4 months. Each group was subdivided into seven subgroups (n = 10) depending on the surface treatment (no surface treatment (NT), sandblasting (SAND), or Sof-lex coarse disc (DISC)) in combination with the use of the silane-containing adhesive ScotchBond Universal Plus (SBU) or an adhesive without silane Prime&Bond Universal (P&B). The same composite was used for the repair as for the primary specimen. Specimens were dark stored in distilled water at 37 °C for 28 days. Shear bond strength was tested at a crosshead speed of 0.5 mm/min. The Kruskal-Wallis test with Bonferroni's post-hoc adjustment (α = 0.05) and the Mann-Whitney U-test were used for the statistical analysis. The results are shown as the median with the interquartile range. The highest bond strength (MPa) was achieved after 24 h in the DISC+P&B (20.39(16.85-28.83)). In the fresh 24 h group, the SAND+P&B (12.25(8.28-15.05)) and DISC+SBU (18.37(15.16-21.29)) were statistically similar. In the 4-month groups, both adhesives and surface treatments performed similarly. The NT, SAND, and DISC groups without adhesives had the lowest bond strength. In the repair of fresh or aged composite, the silane-containing adhesive SBU was not superior to the adhesive without the silane (P&B).

An In Vitro Comparative Analysis of the Shear Bond Value of Sixth, Seventh and Eight Generation Dentin Bonding Agents

ABSTRACT Objective: This study evaluates the shear bond strength (SBS) of 6th, 7th, and 8th generation dentin bonding agents. Materials and Methods: Thirty extracted premolars were divided into three groups of 10. Group A used a 6th generation bonding agent, Group B a 7th generation bonding agent, and Group C a 8th generation bonding agent. Each tooth was fixed in acrylic resin, sectioned to expose dentin, treated with the respective bonding agent, and built up with composite resin. SBS was assessed by universal testing machine. Results: Highest shear bond value was illustrated by the 8th generation bonding agent, with subsequent values progressively lower for the 7th and 6th generation bonding agents. Conclusion: The 8th generation bonding agents exhibit superior shear bond strength, suggesting enhanced dental restoration durability. Further clinical validation is recommended.

Structural strain and crack monitoring based on the fluorescence response of graphene quantum dots

Graphene quantum dots (GQDs), a novel nanomaterial, offer new avenues for structural health monitoring owing to the remarkable fluorescence response. In this study, the GQDs-epoxy resin composites were fabricated and applied to structural surface. Tests including tension, compression, bending, and fatigue were conducted to explore the fluorescence response of composites to structural strain and cracks. Results show that composites exhibited a heightened fluorescence sensitivity to structural strain. During the tensile tests of coated steel specimens, the fluorescence intensity of composites exhibited positive and negative correlation responses with increasing strain. Whereas in the compression test of coated concrete specimens, solely increased fluorescence intensity with rising strain was observed. Composites demonstrated excellent crack characterization on concrete and steel structures, whether penetrating or developing cracks. The fluorescence response of composites to cracks was based on the fluorescence enhancement at the crack site, and fluorescence intensity was approximately inversely proportional to crack width.

Comparative Strength Study of Indirect Permanent Restorations: 3D-Printed, Milled, and Conventional Dental Composites.

Background/Objectives: Limited research has been performed to assess the strength of resin-bonded 3D-printed restorations. Based on that, this study investigates the impact of different manufacturing methods on the fracture load of indirect composite restorations (ICRs) following an aging process. Methods: Three manufacturing techniques-conventional (CRC), milled (MRC), and printed (PRC)-were evaluated using 60 specimens, each with a diameter of 10 mm and a thickness of 1.0 mm. Sandblasting with Al2O3 particles was employed to optimize the bonding process, significantly influencing surface roughness parameters (Ra, Rz, RSm). All specimens were bonded to the dentin analog using composite resin cement and subjected to either 10,000 thermocycles (TC) or storage (ST) at 37 °C in distilled water. Fracture load assessments were performed using a universal testing machine. A finite element analysis was conducted to assess stress distribution. Results: Two-way ANOVA results indicated that the manufacturing method significantly affected mean fracture load values (p < 0.001), with PRC showing the highest mean fracture load (4185 ± 914 N), followed by MRC (2495 ± 941 N) and CRC (599 ± 292 N). The aging protocol did not have a significant impact on fracture load. Conclusions: This study revealed that 3D-printed resin composite exhibited comparable strength to milled resin composite when adhesively cemented, suggesting it is a promising option for indirect composite restorations based on its mechanical performance. However, further research is needed to evaluate its bond strength and optimal surface treatment methods to prevent early debonding.

Effects of different beverages on the color stability and fluorescence of resin composites: in situ study.

To evaluate the color change (ΔE) and fluorescence (FL) of resin composites after the consumption of beverages. One hundred and sixty disc-shaped specimens (6 × 2mm) of Filtek Z350 XT (FZX) and Forma (FOR) resin composites were randomized for use in devices by five volunteers who ingested 100ml daily of red wine (RW), beer (BE), energy drink (ED) and water (WT) over 15 days. The data were collected from digital photographs and analyzed using the CIE-Lab and RGB scales to obtain ΔE and FL and statistics via two-way ANOVA (for ΔE) and ANOVA for repeated measures (for FL), α = 0.05. The highest ΔE values were obtained for FZX and FOR in the RW (ΔE = 10.5 for FZX and ΔE = 9.90 for FOR) and BE (ΔE = 6.3 for FZX and ΔE = 6.1 for FOR) drinks. For FL, there were different levels of change between the composites, with a much more significant reduction in FL intensity with RW. Beverages have the potential to stain the composites evaluated, especially alcoholic beverages. Before carrying out an esthetic treatment with resin composites, it is ideal to investigate the types of drinks consumed by patients, for greater predictability of treatment.

Comparative analysis of different filling materials in deciduous teeth

Dental caries in pediatric patients presents a significant challenge in maintaining oral health, making the choice of filling materials for deciduous teeth crucial for long-term success. Various restorative materials, including composite resins, glass ionomer cements (GICs), and resin-modified glass ionomers (RMGICs), have been used, each with distinct properties regarding durability, biocompatibility, and aesthetic outcomes. Composite resins are well-regarded for their ability to closely match the natural color of teeth, making them ideal for anterior restorations. However, they are technique-sensitive and may not provide sufficient durability in posterior regions subjected to high stress. Glass ionomer cements, known for their ease of placement and fluoride release, offer functional benefits in high-caries-risk patients, despite their lower aesthetic quality and susceptibility to wear over time. Resin-modified glass ionomers attempt to combine the strengths of both composites and GICs by improving durability and aesthetics while maintaining the fluoride-releasing property. The safety and biocompatibility of these materials also play a pivotal role in pediatric dentistry. While composite resins may release small amounts of bisphenol A (BPA), which has raised concerns about its potential health risks, GICs and RMGICs are generally considered safer due to their simpler chemical composition and fluoride release. In terms of functional longevity, composite resins offer better wear resistance compared to GICs, though resin-modified glass ionomers provide a compromise with improved strength and ease of use. Ultimately, the choice of restorative material should consider the specific clinical circumstances, including the child’s caries risk, tooth location, and the balance between aesthetic and functional needs. No single material is universally ideal for all cases, and a tailored approach is necessary to optimize outcomes in pediatric dental restorations.

The effectiveness of direct versus indirect restoration techniques following canal therapy

The restoration of endodontically treated teeth is a critical aspect of dental practice, with the choice between direct and indirect restoration techniques being central to optimizing clinical outcomes. Direct restorations, such as composite resins, offer advantages in terms of cost, time efficiency, and preservation of tooth structure. However, their long-term performance, particularly in posterior teeth, may be compromised by issues such as marginal leakage, wear, and discoloration. Indirect restorations, including crowns, onlays, and inlays, provide enhanced durability, fracture resistance, and aesthetic outcomes, particularly for teeth that have undergone significant structural loss. These restorations, often made from ceramics or metals, offer superior longevity but come with higher costs and longer treatment times. The aesthetic performance of restorations plays a significant role in patient satisfaction. While direct restorations allow for immediate aesthetic adjustments and are generally more affordable, they may suffer from discoloration and wear over time. Indirect restorations, particularly porcelain-based options, offer better color stability and natural appearance, making them a preferred choice for patients with high aesthetic demands. Cost-effectiveness is another critical factor influencing clinical decision-making. While direct restorations are more affordable initially, their long-term cost-effectiveness may be compromised by the need for repairs or replacements. Indirect restorations, despite their higher upfront cost, often prove to be more economical in the long run due to their durability and reduced need for maintenance. The decision between direct and indirect restoration techniques should be individualized, considering factors such as tooth location, the extent of damage, aesthetic requirements, and financial constraints. A comprehensive evaluation of these factors, along with clear communication with the patient, is essential for achieving optimal clinical outcomes. Indirect restorations generally offer better long-term performance, particularly for heavily compromised teeth, while direct restorations remain a viable option for cases where cost and time efficiency are prioritized.

Long-term success of inlay and onlay procedures in dental repairs

Inlays and onlays are vital restorative techniques in dentistry, offering a conservative alternative to full crowns while preserving more of the natural tooth structure. These restorations, typically made from ceramic or composite resin materials, provide both aesthetic and functional benefits and are increasingly favored for their durability and longevity. In contrast to direct restorations, inlays and onlays are fabricated outside the mouth, allowing for greater precision and a more customized fit. The clinical success of these restorations largely depends on factors such as material choice, bonding technique, and patient-related variables like oral hygiene and habits. Ceramic materials are particularly noted for their resistance to wear and their ability to closely mimic the natural appearance of teeth, making them an attractive option for both patients and clinicians. Composite resins, while slightly less durable, offer a cost-effective alternative with satisfactory long-term results. Proper bonding techniques and high-quality materials are essential for ensuring the durability of inlays and onlays, with many restorations lasting over a decade. Patient-related factors also play a significant role in the success of inlays and onlays. Effective oral hygiene, regular dental check-ups, and the avoidance of habits like bruxism are essential for maintaining the integrity of these restorations over time. Despite the challenges and technical demands associated with their placement, inlays and onlays are highly successful when properly executed, offering patients a durable, aesthetically pleasing solution for dental repairs. The discussion of this review focuses on the critical elements that influence the long-term success of inlays and onlays, including material selection, clinical technique, and patient management, highlighting their effectiveness as a restorative option in modern dentistry.

In Vitro Fracture Strength of Primary Canine Teeth Reinforced With Prefabricated and Customized Fiber-Reinforced Post Systems.

The demand for esthetics has increased in today's worldand most parents prefer to preserve their children's primary anterior teeth until their natural exfoliation. However, an intracanal post is required to provide retention for reconstruction of severely damaged anterior teeth due to caries or trauma. Various materials and methods may be used for the fabrication of intracanal posts. This study assessed the fracture strength and fracture mode of primary canine teeth reconstructed with prefabricated and customized polyethylene and glass fiber posts. This in vitro study evaluated 60 extracted primary canine teeth in four groups (n = 15). After pulpectomy and post space preparation with 4 mm depth, composite resin post, prefabricated glass fiber post (Whitepost), customized glass fiber post (Interlig), or customized polyethylene fiber post (Ribbond) were placed in the root canals to provide retention, and the tooth crown was restored with bulk-fill composite resin. The fracture strength was then measured in a universal testing machine. The fracture mode was also evaluated visually. The mean fracture strength was 22.45 ± 5.06, 33.10 ± 8.5, 30.20 ± 7.33, and 32.61 ± 5.73 N/mm2 in the composite resin post, Whitepost, Interlig, and Ribbond groups, respectively. The fracture strength was significantly lower in the composite group than in the remaining three groups (p = 0.000). No other significant differences were found (p > 0.05).Also, no significant difference was observed among the study groups in the fracture mode (p = 0.241). The composite resin post yielded a significantly lower fracture strength than the prefabricated and customized glass and polyethylene fiber posts, but the fracture mode was not significantly different among the four groups.

Interfacial properties and mechanical performance of hybrid graphene/carbon fibre composites

The interaction zone between the matrix and the reinforcing component within carbon fibre (CF) composites plays a crucial role in influencing their performance characteristics, as extensively documented in scientific literature. Building on this fundamental knowledge, this research focuses to the investigation of the interface of fibrous composites and the effect of the incorporation of graphene nanoplatelets (GNPs) into the epoxy matrix. Through the utilization of laser Raman spectroscopy, a significant increase of over 60 % in interfacial strength with just a 2 % weight fraction of GNPs, as expressed by the enhanced shear-lag parameter observed in single fibre model composites, has been observed on model composites indicating a stronger interfacial interaction between the matrix and fibres. The effect of the incorporation of GNPs on CF-graphene interaction has been also investigated on a macroscopic level. Hybrid carbon fibre epoxy resin composite produced, by the introduction of GNPs into the polymer matrix. A series of mechanical tests were conducted, including extensive tensile testing of epoxy/graphene nanocomposite films, thorough examination of bending characteristics, and meticulous measurement of interlaminar shear strength for hybrid GNP/carbon fibre composites. These evaluations provided a clearer understanding of how the GNP integration affects the interface parameters that govern the mechanical behaviour of both the resin and carbon fibre composites.

Comparison of Water Sorption and Water Solubility Properties of Current Restorative Materials with Different Contents.

This study aimed to investigate and compare water sorption and solubility properties of current restorative materials with different contents. Alkasite, self-adhesive restorative material (Cention N, Ivoclar Vivadent AG, Schaan, Liechtenstein), bulk-fill glass hybrid restorative material (EQUIA Forte HT, GC Corp., Tokyo, Japan), nanohybrid universal composite material (OptiShade, Kerr Dental, United States), and bulk-fill composite material (Filtek One Bulk Fill Restorative, 3M ESPE, St. Paul, Minnesota, United States) were used. Samples (n = 6) were prepared (2 × 10 mm) according to the ISO 4049 standards. Water sorption and solubility values were calculated according to the ISO 4049 standards. One-way ANOVA, Tukey's post-hoc, Tamhane's T2 post-hoc, Pearson's correlation, and independent samples t-tests were used for statistical analysis (p < 0.05). Group EQUIA Forte HT significantly showed the highest water sorption values (57.278 ± 3.174), while Group Filtek One Bulk Fill Restorative exhibited the lowest (4.429 ± 0.174; p < 0.05). The water sorption values for Group Cention N were 5.000 ± 0.542. Group EQUIA Forte HT significantly had the lowest water solubility values (-99.799 ± 1.909), while Group Cention N (-2.966 ± 0.402) significantly exhibited the highest (p < 0.05). There was no significant correlation between water sorption and solubility values for each material (p > 0.05). The bulk-fill nano-filled composite resin material was successful in terms of water sorption while the bulk-fill glass hybrid restorative system in terms of water solubility. Alkasite can be recommended to be used as a base material due to its high solubility feature. Monomer, filler type, and amount had an impact on the water sorption and solubility properties of the tested materials.

Dual-Functional TiO2/SiO2@Poly(Hexadecyl Methacrylate-co-Butyl Methacrylate-co-Methyl Acrylate) Composites: Nanointegrated Enhancements in Oil Absorption and High-Efficiency Emulsion Interface Demulsification

Our research described in this report introduces a multifunctional composite resin, TiO2/SiO2@poly(hexadecyl methacrylate-co-butyl methacrylate-co-methyl acrylate), synthesized to enhance oil absorption and demulsification for oily wastewater treatment. By incorporating hydrophobically modified nano-titanium dioxide (nano-TiO2) and nano-silicon dioxide (nano-SiO2) into a polyacrylate resin through suspension polymerization, we aimed to overcome the limitations of traditional oil absorbent resins. The resin’s formulation included hexadecyl methacrylate, butyl methacrylate, and methyl acrylate. Characterization was conducted through measurements of contact angle, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller surface area analyses. The study meticulously optimized the chemical synthesis conditions, focusing on the amount of monomer, initiator and crosslinker, which are crucial for the polymerization reaction. Additionally, the physical parameters, such as the particle size and quantity of the nano-materials, were carefully controlled to achieve the desired material properties. The inclusion of nano-TiO2 and nano-SiO2 significantly enriched the resin’s porous structure, boosting its oil absorption ratios for oil in various solvents, notably enhancing stability and recyclability. The resin exhibited superior oil absorption capacities (e.g. 54.7 g/g for trichloromethane) and improved emulsion separation efficiency (e.g. 98.10% for trichloromethane emulsions), marking a substantial advancement in materials for environmental remediation applications.

Assessing the Aesthetic Performance of CAD/CAM Provisional Restorative Materials: A Spectrophotometric Analysis.

Achieving color match between natural teeth and restorative materials is crucial in dentistry. Factors such as the light source, brightness, and opacity influence tooth color, determined by light absorption and scattering within the material. Advances in CAD/CAM systems have enhanced prosthodontic treatments, particularly with new temporary materials, but data on their color stability and masking ability remains limited. However, data on the color stability and masking ability of these CAD/CAM materials is limited. Telio® CAD-Temp and VITA CAD-Temp® blocks were cut into slices and polished. Composite resin specimens were prepared using a custom-designed metal resin former and light-cured. Samples were paired randomly and assigned to experimental groups based on base type and thickness (n = 30). Samples were stored in a controlled environment for 24 h before color evaluation using an EasyShade® V spectrophotometer. Color difference (ΔE) was calculated using L*, a*, and b* values. Statistical analyses included the Shapiro-Wilk test, Levene's test, and three-way ANOVA, with post-hoc comparisons using the Bonferroni method (α = 0.05). ΔE was classified according to perceptibility (PT = 1.2) and acceptability (AT = 2.7) values.

The Impact of Modeling Liquids on Surface Roughness and Color Properties of Bulkfill Resin Composites After Simulated Tooth Brushing: An in Vitro Study. Part I.

To evaluate the effect of different modeling agents on color changes, surface roughness, and translucency parameters over time in Bulkfill resin composites. Sixty specimens were prepared using three Bulkfill resin composites (Tetric N-Ceram Bulkfill, Filtek One Bulkfill and Opus Bulkfill) and three modeling agents (Wetting Resin, Optibond FL and Ambar APS). All specimens were subjected to a simulated tooth-brushing (Baseline, 50.000 cycles, 100.000 cycles), and surface roughness was measured at each interval. Surface topography was evaluated. The translucency parameter and color changes were assessed after 24-h, 7-, 14- and 30-day immersion in water, wine, and coffee. Data was analyzed using ANOVA and Bonferroni test. All specimens increased roughness after simulated tooth-brushing (p < 0.05). Wetting Resin decreased roughness on Tetric N-Ceram Bulkfill (p < 0.05). The translucency parameter remained unaltered for all groups. All groups changed color after 30-days of immersion in wine and coffee (p < 0.05). Ambar APS and Wetting Resin on Tetric N-Ceram Bulkfill showed higher color changes when immersed in coffee (p < 0.05). The use of modeling agents does not jeopardize translucency properties but may affect surface roughness and color properties of Bulkfill resin composites depending on their composition. The findings of this study suggest that surface roughness and color properties are affected by the differences in the composition between modeling agents and Bulkfill resins composites.

Is use of flowable resin composite an option for occluso-proximal restorations in primary teeth? A fracture strength analysis.

Use of flowable resin composites for ocluso-proximal restorations in primary molars could improve cervical adaptation, and reduce the failure risk. To investigate the fracture strength of occluso-proximal restorations in primary teeth using different flowable resin composites (as an intermediate layer or entire cavity) and a conventional resin composite (incremental technique). Two standardized occluso-proximal cavities were prepared on mesial and distal surfaces of 50 sound primary molars. The teeth were randomly assigned into five groups (n = 10): 2 mm Filtek Bulk Fill Flow + Z350 XT; 4 mm Filtek Bulk Fill Flow; 2 mm Z350 XT Flow + Z350 XT; 4 mm Z350 XT Flow; and Z350 XT inserted by incremental technique. All restored teeth were subjected to cariogenic challenge and then submitted to fracture strength test. The failure pattern of each specimen was categorized as reparable or irreparable/need for replacement based on the World Dental Federation (FDI) criteria. Fracture strength means were submitted to one-way ANOVA and Tukey's post hoc tests. Failure pattern was analyzed descriptively. There was no statistically significant difference on fracture strength among groups (p = .48). A similar distribution of reparable (35%-40%) and irreparable (60%-65%) failures was observed among groups. Based on a laboratorial setting, the use of different flowable resin composites (as an intermediate layer or entire cavity) may be an option to restore occluso-proximal cavities in primary molars.

Comprehensive Evaluation of Long-Term Dentin Bond Strength, Water Sorption, Solubility, and Degree of Conversion of Self-Adhesive Resin Composites.

To evaluate the long-term microtensile bond strength (µTBS) to dentin, water sorption (WSP) and solubility (WSL), and degree of conversion (DC) of self-adhesive resin composites (SACs). The mid-coronal dentin of human molars was exposed, and teeth were randomly assigned to five groups according to the SACs (n &#61; 10): 1. FIT SA F03 (FIT); 2. Experimental (EXP); 3. Fusio Liquid Dentin (FLD); 4. Vertise Flow (VER); 5. Constic (CON). The µTBS was evaluated after 24 hours (24 h) and 6 months (6 m) storage. A scanning electron microscope examined failure modes and resin-dentin interfaces. The WSP and WSL (n &#61; 5) were evaluated following ISO 4049:2019 specifications, and DC (n &#61; 3) was measured using Raman spectroscopy. The statistical analyses were performed accepting a significance level of p &#61; 0.05. FIT, EXP, and FLD produced significantly higher µTBS median values than VER and CON after 24 h and 6 m (p 0.05). After 6m, the µTBS median of FIT and EXP significantly decreased (p 0.05), while FLD, VER, and CON showed no significant difference (p > 0.05). FLD and CON exhibited lower WSP than FIT, EXP, and VER (p 0.05). FLD presented the lowest (p 0.05), and VER revealed the highest WSL (p 0.05). FIT and EXP showed the highest (p 0.05), and VER demonstrated the lowest DC (p 0.05). Following the present study's design, SACs' bonding performance and physical properties remained restricted. Therefore, the application should be considered cautiously, and further clinical trials are necessary to evaluate their long-term performance.