Dental Restorative Composites Research Articles

Characterization of SLA-printed ceramic composites for dental restorations

This study introduces a novel ceramic-composite resin specifically developed for stereolithography (SLA) 3D printing, aimed at enhancing dental restorations. The integration of advanced digital technologies in dentistry has shifted traditional methods towards more precise and efficient techniques such as computer-aided design/computer-aided manufacturing (CAD/CAM). However, these processes typically involve material waste due to their subtractive nature. Additive manufacturing, or 3D printing, particularly SLA, which uses ultraviolet light to cure photosensitive resins, presents a viable alternative with the potential for creating detailed, custom restorations with minimal waste. Our research focuses on formulating and evaluating a ceramic-composite resin that combines the benefits of light-cured materials with the mechanical robustness required for dental applications. We conducted comprehensive tests to assess the printability, mechanical properties and wear resistance of the developed material. The ceramic-composite resin demonstrated a tensile strength of approximately 73 MPa, significantly higher than the 42 MPa observed for traditional photopolymer resins. Additionally, the ceramic-composite resin showed ability to resist incidental friction and wear. This research could significantly impact the dental prosthetics field by providing a method for producing high-performance, patient-specific restorations efficiently and cost-effectively.

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<0,05). Conclusion: The thicker the bulk fill resin composite, the lower the base surface temperature.

Optimization and ranking of dental restorative composites by ENTROPY‐VIKOR and VIKOR‐MATLAB

AbstractResin‐based composites, now the most prevalent material for restorative dental treatments, are available in a multitude of types. Next‐generation composites are designed to be bio interactive, solving issues such as secondary caries and mechanical failures, thus prolonging the restoration lifespan. To facilitate the discrimination of the bio interactive composite's performance and the identification of the optimal composition, we tested the VIKOR method for multi‐criteria decision‐making analysis. This study encompassed 12 performance parameters and 5 experimental dental composites. We measured density, void content, water sorption, water solubility, polymerization shrinkage, depth of cure, degree of conversion, hardness, compressive strength, and surface roughness as performance parameters, and we tested a conventional BisGMA‐TEGDMA resin blend filled with yttria‐stabilized zirconia (20 wt.%) and tricalcium phosphate. The alignment between computational methods and MATLAB‐based calculations validated the robustness of the assessment, verifying the significance of the conclusions drawn from this comprehensive analysis. Both methods (ENTROPY‐VIKOR and VIKOR‐MATLAB) ranked TZC0 as the top composite. This research provided a comprehensive understanding of the complex relationship between material composition, performance attributes, and optimization strategies in dental restorative composites, offering valuable insights for future advancements in restorative dentistry.

Mechanical properties, cytotoxicity, and protein adsorption of three-dimensionally printable hybrid resin containing zwitterionic polymer and silicate-based composites for dental restorations

ObjectiveTo evaluate the mechanical and biological properties of three-dimensionally (3D) printable resins filled with 2-methacryloyloxyethyl phosphorylcholine (MPC) and silicate-based composites and compare with those of a commercially available 3D-printable resin for definitive restorations. MethodsA group of 3D-printable hybrid resins (HRs) filled with 6 wt% MPC and three different compositions of silicate-based composites (barium silicate to zirconium silicate ratios: 1.50:1 for HR1, 0.67:1 for HR2, and 0.25:1 for HR3) were prepared. The HR groups were compared with the commercially available unfilled 3D-printable resin (CR) marketed for definitive restorations in terms of flexural strength and modulus, fracture toughness, surface roughness, Vickers hardness, light transmittance (all, n = 15), cytotoxicity, and protein adsorption (both, n = 3). All data were analyzed by using non-parametric Kruskal–Wallis and Dunn's tests (α=0.05). ResultsThe HR groups had significantly higher flexural strength, modulus, fracture toughness, and hardness values than the CR (P < 0.001). HR3 had the highest surface roughness and light transmittance among the groups (P ≤ 0.006). None of tested resins showed cytotoxicity. Both HR2 and HR3 showed significantly lower protein adsorption than the CR, with a difference of approximately 60% (P ≤ 0.026). ConclusionBoth HR2 and HR3 exhibited superior mechanical properties (flexural strength, flexural modulus, fracture toughness, and Vickers hardness), light transmittance, and protein-repellent activity than the CR, with no impact on cytotoxicity. Clinical significanceThe MPC/silicate-based composite-filled resins may be a suitable alternative for definitive restorations, given their higher mechanical properties and promising biological properties to prevent microbial adhesion and subsequent biofilm formation, as well as their non-cytotoxic properties.

Performance Assessment of Three Similar Dental Restorative Composite Materials via Raman Spectroscopy Supported by Complementary Methods Such as Hardness and Density Measurements.

(1) Background: A widespread problem in oral health is cavities produced by cariogenic bacteria that consume fermentable carbohydrates and lower pH to 5.5-6.5, thus extracting Ca2+ and phosphate ions (PO43-) from teeth. Dental restorative materials based on polymers are used to fill the gaps in damaged teeth, but their properties are different from those of dental enamel. Therefore, a question is raised about the similarity between dental composites and natural teeth in terms of density and hardness. (2) Methods: We have used Raman spectroscopy and density and microhardness measurements to compare physical characteristics of several restorative dental composites at different polymerization intervals. (3) Results: XRVHerculite®, Optishade®, and VertiseFlow® showed the very different characteristics of the physical properties following four polymerization intervals. Of the three composites, OptiShade showed the highest polymerization rate. (4) Conclusions: Only fully polymerized composites can be used in teeth restoring, because incomplete polymerization would result in cracks, pitting, and lead finally to failure.

Assessment of Prevalence and Causative Factors for Replacement of Composite and Amalgam Restorations: An Observational Study

ABSTRACT Aim: This study intends to evaluate the frequency and causes of replacement for failed amalgam and composite dental restorations. Methodology: A cross-sectional study comprising female patients with failed permanent composite and amalgam restorations aged 15–60 years old was carried out at the dental clinics of Qassim University. Using a self-structured proforma, demographic data and causes for restoration failure were recorded. The effectiveness of the restorations was assessed by using the Ryge criteria after performing clinical and radiographic examinations. The Statistical Package for Social Science was used for the statistical analysis. Results: It is found that 84.6% of the 299 unsuccessful restorations examined were composite, and 15.4% were amalgam. The main reason for dental failure for both amalgam (95.6%) and composite (93.28%) restorations was secondary caries. Failure of amalgam restoration was largely caused by poor marginal adaptation. With varied incidences between amalgam and composite restorations, typical complaints included discomfort, sensitivity, pain, and food impaction with soreness. The main justification for replacement in amalgam restorations was sensitivity. Repair and replacement rates were similar for amalgam, composite, and mandibular/maxillary restorations. Moreover, 21.1% of individuals overall reported no symptoms, with 8.7% in the amalgam group and 23.3% in the composite group with significant differences (χ 2 = 34.28, P = 0.001). Conclusion: According to the current study, secondary caries was found to be the main reason for both amalgam and composite restoration failure. The main problems reported were sensitivity, discomfort, and pain with amalgam showing more sensitivity-related failures.

Comparison of volumetric loss and surface roughness of composite dental restorations obtained by additive and subtractive manufacturing methods

Statement of problemPermanent crown materials produced with new generation additive manufacturing and traditional subtractive manufacturing materials have not been compared in terms of wear resistance. PurposeThis study aims to compare the volumetric loss related to wear and resulting surface roughness after aging in a chewing simulator between resin nano ceramics produced with milling technique and permanent crown materials produced with three dimensional (3D) printing. Materials and methodsThree different hybrid composite-ceramic (HCC) (The three materials are GC: Cerasmart, VE: Vita Enamic, and GV: Grandio Voco.) and one 3D printed definitive crown resin (FormLabs Permanent Crown Resin) were investigated before aging (n:8), the surface roughness of all samples was measured with a profilometer, and 1 randomly selected sample from each subgroup was imaged with scanning electron microscope (SEM). 3D scans of each sample were obtained with a desktop scanner. Thermomechanical aging was performed using a chewing simulator. Four hundred thousand cycles were completed under a vertical occlusal force of 49 ± 0.7 N with a thermal cycle of 1.7 Hz 5–55° and with a dwell time of 120 s, mimicking 2 years of aging. The imaging procedures were repeated, and the change in surface roughness was evaluated. 3D images were also overlapped, and the volumetric loss was calculated with the relevant inspector software. The data obtained were analyzed by two-way ANOVA (p < 0.05). ResultThe results showed significant statistical differences for both parameters (p > 0.05). The highest volumetric loss was found in the GV group while the lowest volumetric loss was in the VE group. The highest surface roughness values were observed in the GV group, while the lowest values belonged to the VE one. ConclusionOf the restorative materials evaluated, the VE group is suitable for long-term restorations, whereas the GV one is suitable for medium-term restorations. It is promising in terms of 3D printing technologies that the 3D material gives comparable results with the GV group. Clinical i̇mplicationAdditive manufacturing techniques are a successful method that accelerates the manufacturing process. Permanent crown resins are promising alternatives to conventional production.

Fourier-transform infrared spectroscopic method for assessing sensitivity of light-curable dental restorative composites to ambient light – a pilot study

Fourier-transform infrared spectroscopic method for assessing sensitivity of light-curable dental restorative composites to ambient light – a pilot study

Mobile dental clinic for oral health services to underserved rural Indian communities.

Mobile dental vehicle (MDVs) can be adopted to address the oral healthcare needs of different populations. Therefore, it is of interest to evaluate mobile dental clinic program in providing oral health services to underserved rural communities. A 2 x 2.5 meter box trailer is used by the UN, and it can be carried by a vehicle with all-wheel drive for all types of weather. There was a small box trailer with its weather proof canvas cover extended, changing it into four dental operators and an integrated waiting and teaching space. Clinical examination, scaling, polishing, health education, individual and group teaching in dental hygiene, fluoride applications, fissure sealants, amalgam and composite restorations, extractions, and minor oral surgery were all supplied at no cost to the patients. In a longitudinal study of 3 years in underserved rural areas, a total of 6326 patients were provided different dental treatments. It was found that 93.3% patients did not undergo any dental treatment in the past.

Multi-response optimisation analysis of material properties in dental restorative composites under the influence of thermal and thermomechanical stimuli – A 3D finite element study

ObjectivesRestored teeth undergo more damage than intact teeth. Therefore, the scientific investigation of their mechanical and physical behaviour under varying oral conditions is vital. The current study is to numerically investigate the stresses on a class-II mesio-occluso-distal (MOD) restored molar due to thermal and thermomechanical stimuli with varying input properties such as coefficient of thermal expansion and elastic properties. This is performed to optimise the dental restoration material, thereby reducing the stresses and failure of the restoration. MethodsAn upper molar was scanned using μ-CT for segmenting and modelling the enamel and dentine. A class-II MOD cavity was then prepared on the model, after which non-manifold meshing was generated. The coefficient of thermal expansion (CTE) and elastic modulus (E) properties of the restoration were varied from 20 × 10−6 °C-1 to 55 × 10−6 °C-1 and 5 GPa–20 GPa, respectively. After the material properties and boundary conditions were set for the finite element (FE) analysis, the thermal and thermomechanical loading analyses were performed to demonstrate the influence of input parameters on the stress. The maximum values of principal stresses on the restoration-enamel junction and the restoration were evaluated. The results were statistically processed using analysis of variance, response surface methodology (RSM) and optimisation analysis to estimate the most optimum inputs for minimising principal stresses. ResultsThe study reveals that the location of principal stress occurs at the restoration-enamel junction (REJ) and the restoration changes based on the composite material value of E and CTE due to thermal and thermomechanical stimuli. The REJ showed higher principal stress than restoration during the application of both thermal and thermomechanical stimuli, making it more vulnerable to fracture and failure. Moreover, the study showed non-linear variations in the values and locations of principal stresses due to thermal and thermomechanical stimuli with the change in the property of the restoration composite used. Finally, this study derived an optimised restorative value for CTE and E due to the application of thermal and simultaneous thermal and mechanical stimuli. ConclusionThis study highlights the importance of choosing the suitable material properties of the restoration composite by dental clinicians to repair a large class MOD cavity. The findings from this study also suggest that the difference in the values of E and CTE in a dental restoration composite when compared with the enamel causes a lack of uniformity in mechanical and thermal properties, thereby forming stress concentrations at the interfaces. The study establishes two optimised CTE and E values for the MOD restoration composite as 25 × 10−6 °C-1 and 20 GPa and 37 × 10−6 °C-1 and 5 GPa, respectively.

Effect of saliva of patients with leukemia on surface hardness and roughness of enamel and dental composite resin during chemotherapy regimen: An – Invitro study

Background: Evaluate the surface roughness and hardness of tooth enamel and dental resin composite restoration immersed into saliva collected from leukemia patient. Objective: To evaluate the surface roughness and hardness of tooth enamel and dental resin composite restoration immersed on to saliva collected from 4 types of leukemia patient. Patients and Methods: 30 patients with 4 types of leukemia (Acute lymphoblastic leukemia ALL, Acute myeloid leukemia AML, Chronic lymphocytic leukemia CLL, and Chronic myeloid leukemia CML) were included for taking saliva separately. A total number of 50 enamel specimen and 50 of composite resin disk were prepared and randomly divided into 5 groups of enamel (1,2,3,4, and 5) and 5 groups of composite resin disk (A,B,C,D, and E), surface roughness and hardness were measured and data collected, group A and 1 were immersed in artificial saliva for 7 days as control, group B and 2 immersed into saliva collected from patient with ALL, group C and 3 immersed into saliva collected from patient with AML, group D and 4 immersed into saliva collected from patient with CLL and group E and 5 immersed into saliva collected from patient with CML all group for 7 days then surface roughness and hardness were measured data collected and analyzed and statistically significant regarded at p&lt;0.05. Results: In group A and 1 artificial saliva there were no significant effect on surface roughness and hardness of both enamel and composite resin disk, while surface roughness and hardness of enamel and composite resin significantly changed after immersing in saliva of ALL, AML, CLL, patients and surface roughness of composite resin highly significantly increased after immersing in saliva of CML patients. Conclusion: Saliva of ALL, AML, CLL, and CML seems to significantly changes in mechanical properties of enamel and composite, however saliva of CML highly significantly increase surface roughness of composite resin. Keywords: 4 types’ leukemia, chemotherapy, surface roughness and hardness, enamel, dental composite resin.

Effect of saliva of patients with leukemia on surface hardness and roughness of enamel and dental composite resin during chemotherapy regimen: An – Invitro study

Background: Evaluate the surface roughness and hardness of tooth enamel and dental resin composite restoration immersed into saliva collected from leukemia patient.&#x0D; Objective: To evaluate the surface roughness and hardness of tooth enamel and dental resin composite restoration immersed on to saliva collected from 4 types of leukemia patient.&#x0D; Patients and Methods: 30 patients with 4 types of leukemia (Acute lymphoblastic leukemia ALL, Acute myeloid leukemia AML, Chronic lymphocytic leukemia CLL, and Chronic myeloid leukemia CML) were included for taking saliva separately. A total number of 50 enamel specimen and 50 of composite resin disk were prepared and randomly divided into 5 groups of enamel (1,2,3,4, and 5) and 5 groups of composite resin disk (A,B,C,D, and E), surface roughness and hardness were measured and data collected, group A and 1 were immersed in artificial saliva for 7 days as control, group B and 2 immersed into saliva collected from patient with ALL, group C and 3 immersed into saliva collected from patient with AML, group D and 4 immersed into saliva collected from patient with CLL and group E and 5 immersed into saliva collected from patient with CML all group for 7 days then surface roughness and hardness were measured data collected and analyzed and statistically significant regarded at p&lt;0.05.&#x0D; Results: In group A and 1 artificial saliva there were no significant effect on surface roughness and hardness of both enamel and composite resin disk, while surface roughness and hardness of enamel and composite resin significantly changed after immersing in saliva of ALL, AML, CLL, patients and surface roughness of composite resin highly significantly increased after immersing in saliva of CML patients.&#x0D; Conclusion: Saliva of ALL, AML, CLL, and CML seems to significantly changes in mechanical properties of enamel and composite, however saliva of CML highly significantly increase surface roughness of composite resin.

The Influence of Adhesive Strategy, Type of Dental Composite, and Polishing Time on Marginal Gap Formation in Class I-like Cavities

Even after more than six decades of dental composite invention (1962), there is still controversial information about the time in which composite restorations should be polished in order to avoid marginal gap formation at the tooth–composite interface. The aim of the present study was to analyze the influence of adhesive strategy, the type of dental composite, and polishing time on marginal gap formation (%MG) at the tooth–composite interface. Class I-like cavities were hybridized with a universal adhesive system (Single Bond Universal) through two strategies: selective enamel etching (SEE) or self-etching mode (SEM). Cavities were filled with two types of dental composites: nanofilled (Z350) or bulk fill (Filtek One Bulk Fill—ONE), and polishing was performed immediately or delayed for 7 days (n = 5). %MG was evaluated by using a 3D laser confocal microscope. As flexural modulus (FM) and degree of conversion (DC%) are determinants of marginal integrity in dental composite restorations, these properties were evaluated for both composites. Data were analyzed by ANOVA and Tukey’s HSD test (α = 0.05). Cavities hybridized following the SEE strategy presented lower %MG (p &lt; 0.05). Z350 showed higher %MG than ONE (p &lt; 0.05). There was no difference in %MG between the polishing times when the SEE strategy was used (p &gt; 0.05). Z350 presented higher FM than ONE (p &lt; 0.05). DC% was found to be not significant (p &gt; 0.05). The results suggest that selective enamel etching (SEE) is a better strategy for producing less %MG in composite restorations with enamel margins irrespective of the time in which the restoration is polished.

Investigation of new light-cured composite dental materials by atomic absorption spectroscopy

The paper the study of new light-cured composite dental materials by atomic absorption spectroscopy are considered. High-quality aesthetics, durability, functionality and maximum preservation of hard dental tissues are the result of new adhesive preparation and improvement of the physico-chemical and optical properties of composites, therefore, the study of the optical properties of composites is relevant and promising. The article the objects under study, the appearance of the spectrophotometer, the optical scheme and the technical characteristics of the device are presented. In the study of restorative dental composites, different absorption capacity of materials was obtained. Maximum absorption in all composite materials in the wavelength range = 250…360 nm was detected.

Effect of mouthwashes on the microhardness of aesthetic composite restorative materials.

Mouthwashes are increasingly being used worldwide. However, these preparations are known to have a negative impact on composite resin dental restorations. In this study, we aim to evaluate the effect of mouthwashes on the microhardness of such restorations. Thirty specimens of Tetric N-Ceram composite were prepared. Each composite specimen was cured for 40 seconds and kept in saline solution for 24 hours at 37 °C. Baseline microhardness of each specimen was recorded using an Innovatest Vickers Micro Hardness Tester. Composite specimens were randomly placed in 20 mL of the selected mouthwashes (Colgate® Plax, Listerine® Teeth & Gum Defence, and Closeup® Antibacterial Mouthwash Cool Breeze) and stored in an incubator for 24 hours at 37 °C. Next, microhardness values were rechecked. pH measurements were recorded for each type of mouthwash using a digital pH meter. Due to the acidic nature of Colgate® and Listerine®, the microhardness of the restorations decreased with these mouthwashes; Listerine® caused the greatest decrease in microhardness and had the lowest pH reading (4.34). For Closeup®, with a neutral pH (7.02), no negative effect on microhardness was found; on the contrary, due to the presence of zinc in this latter mouthwash, an increase of the microhardness was found. We confirm the negative effect of acidic mouthwashes on the microhardness of composite dental restorations.

Current antibacterial agents in dental bonding systems: a comprehensive overview.

Dental caries is mainly caused by oral biofilm acid, and the most common dental restoration treatment is composite dental restorations. The main cause of failure is secondary caries adjacent to the restoration. Long-term survival of dental materials is improved by the presence of antibacterial agents, which selectively inhibit bacterial growth or survival. Chemical, natural and biomaterials have been studied for their antimicrobial activities and antibacterial bonding agents have been improved. Their usage has been increased to inhibit the growth of invading and residual bacteria in the oral cavity, as biofilm accumulation increases the risk of treatment failure. In this article, the success and applications of antibacterial agents are discussed in dental bonding systems.

Exploring the discoloration potential of Propolis extract and Morus nigra syrup on restorative dental composites: an in vitro study

Aim: The aim of this study was to analyse color stability of dental composites immersed in Propolis extract and Morus nigra syrup at in-vitro conditions simulating clinical usage time intervals and to explore the relationship between discoloration potential and phenolic contents. Material and Method: A total of 126 composite discs of nanohybrid (n=42), microfilled (n=42) and microhybrid (n=42) were prepared using a Teflon mold with a diameter/thickness of 6 mm/2 mm. After polishing procedures, composites were subdivided into three and immersed into %15 Propolis extract with total phenolic content=53 mg GAE/ml (B’eeo, İstanbul) and Morus nigra syrup with total phenolic content=25 mg GAE/100 g dw (Hünnap, İstanbul) and distilled water for 12 hours(T1) and 24 hours (T2) simulating 1-year and 2-year time spans respectively. Color measurements were performed by Vita easy Shade Compact (Vita Zahnfabrik, Bad Sackingen, Germany) prior to immersion and analysed by CIEDE2000 formula. Result: Between T0 and T2, minimum/maximum color change values (ΔE) of nanohybrid, microfilled and microhybrid composites immersed in Propolis and Morus nigra syrup were 1,24/5,29 and 0,97/2,65 respectively. Nanohybrid composite discs were discolored within clinically acceptable limits in all test solutions. Microfilled and microhybrid composite discs showed clinically unacceptable discoloration at T1 and T2 periods in Propolis extract solution. Conclusion: The phenolic and flavonoid components of herbal formulations can be considered as one of the major determinants in discoloring potential.

Enhanced effect of a novel bioactive glass-ceramic for dental application.

Dental caries is the most common chronic disease in humans, caused by the acid produced by the microflora in the mouth that dissolves the enamel minerals. Bioactive glass (BAG) has been used in various clinical applications due to its unique bioactive properties, such as bone graft substitutes and dental restorative composites. In this study, we introduce a novel bioactive glass-ceramic (NBGC) prepared through a sol-gel process under a water-free condition. The anti-demineralization and remineralization effects of NBGC were evaluated by comparing the measurements of bovine enamel surface morphology, surface roughness, surface micro-hardness, enamel elements, and mineral content before and after related treatments with a commercial BAG. The antibacterial effect was characterized by minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Results showed that NBGC had greater acid resistance and remineralization potential compared to commercial BAG. The fast formation of a hydroxy carbonate apatite (HCA) layer suggests efficient bioactivity. In addition to its antibacterial properties, NBGC shows promise as an ingredient in oral care products that can prevent demineralization and restore enamel.

Cytotoxicity and reactive oxygen species production induced by different co-monomer eluted from nanohybrid dental composites

BackgroundSafety issues for dental restorative composites are critical to material selection, but, limited information is available to dental practitioners. This study aimed to compare the chemical and biological characteristics of three nanohybrid dental composites by assessing filler particle analysis, monomer degree of conversion (DC), the composition of eluates, and cytotoxicity and reactive oxygen species (ROS) production in fibroblasts.MethodsThree nanohybrid composites (TN, Tetric N-Ceram; CX, Ceram X Sphere Tec One; and DN, DenFil NX) were used. The size distribution and morphology of the filler particles were analysed using scanning electron microscopy (n = 5). The DC was measured via micro-Raman spectroscopy (n = 5). For the component analysis, methanol eluates from the light-polymerised composites were evaluated by gas chromatography/mass spectrometry (n = 3). The eluates were prepared from the polymerised composites after 24 h in a cell culture medium. A live/dead assay (n = 9) and Water-Soluble Tetrazolium-1 assay (n = 9) were performed and compared with negative and positive controls. The ROS in composites were compared with NC. Statistical significance in differences was assessed using a t-test and ANOVA (α = 0.05).ResultsMorphological variations in different-sized fillers were observed in the composites. The DC values were not significantly different among the composites. The amounts of 2-hydroxyethyl methacrylate (HEMA) were higher in TN than DN (p = 0.0022) and triethylene glycol dimethacrylate (TEGDMA) in CX was higher than in others (p < 0.0001). The lowest cell viability was shown in CX (p < 0.0001) and the highest ROS formation was detected in TN (p < 0.0001).ConclusionsThree nanohybrid dental composites exhibited various compositions of filler sizes and resin components, resulting in different levels of cytotoxicity and ROS production. Chemical compositions of dental composites can be considered with their biological impact on safety issues in the intraoral use of dental restorative composites. CX with the highest TEGDMA showed the highest cytotoxicity induced by ROS accumulation. DN with lower TEGDMA and HEMA presented the highest cell viability.

Surface free energy and roughness of flowable dental composites

Purpose The surface properties like roughness, wettability and surface free energy are important for utility properties of traditional and flowable dental restorative composites, due to their role in plaque formation, discoloration, mechanical wear or adhesion and bonding. The goal of our work was to assess the surface free energy (SFE) and the surface roughness (Ra) of three commercial flowable dental composites: everX Flow (bulk), everX Flow (dentin) and Flow-Art. Methods Surface roughness, contact angle and surface free energy were determined for tested composites. Two surface states (control and roughened) were compared. Roughness was measured with the use of the 3D optical profilometer. The contact angle (CA) was determined through the sessile drop method with the use of four different probing liquids. This enabled to apply two surface free energy approaches (Owens–Wendt (O-W) and van Oss–Chaudhury–Good (LWAB)). Additionally, Zisman’s approach (γC) was used. Results The water contact angle values were similar for Flow-Art (67.56±1.49°) and everX Flow (bulk) (68.94±2.72°) compared to higher value for everX Flow (dentin) (74.39±2.05°). SFE was in the range from 43 to 50 mJ/m^2 for O-W and from 47 to 62 mJ/m2 for LWAB. The γC was from 37 to 45 mJ/m^2. Conclusions Roughening composites’ surface influenced on increasing the CA value. All approaches of surface free energy calculations provide useful data for predicting interactions between flowable composites and dental tissues. Tested composites showed good wetting for initial state of surface after polymerization. These influence on better adhesion of the material to the bonding system during dental restoration.