Experimental Dental Composites Research Articles

Enhancing the Antimicrobial Properties of Experimental Resin-Based Dental Composites through the Addition of Quaternary Ammonium Salts

Secondary caries is one of the main reasons for dental filling replacement. There is a need to obtain dental restorative material that is able to act against caries-inducing microorganisms. This study explores the antimicrobial properties of cetyltrimethylammonium bromide (CTAB) or dimethyldioctadecylammonium bromide (DODAB)-modified photo-cured experimental dental composites against Escherichia coli, Streptococcus mutans, and Candida albicans. The antimicrobial activity against Escherichia coli, Streptococcus mutans, and Candida albicans was assessed by using an Accuri C6 flow cytofluorimeter, and then analyzed using BD CSampler software (1.0.264). Bacterial/yeast surface colonization was carried out by using an GX71 inverted-optics fluorescence microscope equipped with a DP 73 digital camera. For bactericidal surface analysis of each sample type, simultaneous standardization was performed using a positive control (live cells) and a negative control (dead cells). A positive correlation between the increasing concentration of CTAB or DODAB and the dead cell ratio of Escherichia coli, Streptococcus mutans, and Candida albicans was revealed. In particular, CTAB at a 2.0 wt% concentration exhibits superior efficiency against pathogens (65.0% dead cells of Escherichia coli, 73.9% dead cells of Streptococcus mutans, and 23.9% dead cells of Candida albicans after 60 min). However, Candida albicans is more resistant to used salts than bacteria. A CTAB- or DODAB-modified experimental dental composite exhibits antimicrobial potential against Escherichia coli, Streptococcus mutans, and Candida albicans after 10 and 60 min of incubation, and the antimicrobial efficiency increases with the wt% of QAS in the tested material.

Formulation and Characterization of New Experimental Dental Composites with Zirconium Filling in Different Forms.

Short glass fibers are generally used in posterior dental restorations to enhance the mechanical properties and improve the material microstructure. Two resin-based composites (S0 and SF) were formulated and characterized to investigate the influence of zirconium in their characteristics and properties. The organic part of the investigated materials was the same (BisGMA, TEGDMA, and a photochemical polymerization system), and in the inorganic part, besides quart, glassA, and hydroxylapatite with Zn, sample S0 contained strontium glass with zirconium and sample SF contained fiber powder of chopped zirconium. The samples were characterized by the degree of conversion (DC), mechanical properties, water sorption (WS), scanning electron microscopy (SEM), atomic force microscopy (AFM) before and after the WS test, and antimicrobial properties. The results obtained were subjected to one-way ANOVA and Tukey's statistical tests. Both samples had a high DC. Regarding the mechanical properties, both samples were very similar, except DTS, which was higher for the composite without fibers. After 14 days, the WS value of the SF sample was lower than that of the S0 sample. Water caused significant changes in the topography of the SF sample, but thanks to its antimicrobial properties and the diffusion phenomenon, SF had a more pronounced antimicrobial effect. This study shows that the addition of appropriate amounts of Sr-Zr-glass powder gives the material in which it is added similar properties to material containing chopped zirconium glass fiber powder. According to the antimicrobial test results, resin composites containing experimental zirconia fillings can be considered in future in vitro clinical studies for posterior reconstructions with significantly improved mechanical properties.

The effect of quaternary ammonium polyethylenimine nanoparticles on bacterial adherence, cytotoxicity, and physical and mechanical properties of experimental dental composites

A significant problem related to the functioning of resin-based composites for dental fillings is secondary or recurrent caries, which is the reason for the need for repeated treatment. The cross-linked quaternary ammonium polyethylenimine nanoparticles (QA-PEI-NPs) have been shown to be a promising antibacterial agent against different bacteria, including cariogenic ones. However, little is known about the properties of dental dimethacrylate polymer-based composites enriched with QA-PEI-NPs. This research was carried out on experimental composites based on bis-GMA/UDMA/TEGDMA matrix enriched with 0.5, 1, 1.5, 2 and 3 (wt%) QA-PEI-NPs and reinforced with two glass fillers. The cured composites were tested for their adherence of Streptococcus Mutans bacteria, cell viability (MTT assay) with 48 h and 10-days extracts , degree of conversion (DC), water sorption (WSO), and solubility (WSL), water contact angle (CA), flexural modulus (E), flexural strength (FS), compressive strength (CS), and Vickers microhardness (HV). The investigated materials have shown a complete reduction in bacteria adherence and satisfactory biocompatibility. The QA-PEI-NPs additive has no effect on the DC, VH, and E values. QA-PEI-NPs increased the CA (a favorable change), the WSO and WSL (unfavorable changes) and decreased flexural strength, and compressive strength (unfavorable changes). The changes mentioned were insignificant and acceptable for most composites, excluding the highest antibacterial filler content. Probably the reason for the deterioration of some properties was low compatibility between filler particles and the matrix; therefore, it is worth extending the research by surface modification of QA-PEI-NPs to achieve the optimum performance characteristics.

Evaluation of physical/mechanical properties of an experimental dental composite modified with a zirconium-based metal-organic framework (MOF) as an innovative dental filler.

This study aimed to modify an experimental dental composite using a synthesized nano-structured methacrylated zirconium-based MOF to enhance physical/mechanical properties. The previously known Uio-66-NH2 MOF was first synthesized and post-modified with Glycidyl Methacrylate (GMA). Fourier Transform Infrared (FTIR) Spectroscopy and CHNS analysis confirmed the post-modification reaction. The prepared filler was investigated by XRD, BET, SEM-EDS, and TEM. The experimental composite was prepared by mixing 60% wt. of resin matrix with 40% wt. of fillers, including silanized silica (SS) or Uio-66-NH-Me (UM). The experimental composites' depth of cure (DPC) was investigated in five groups (G1=40% SS, G2=30%SS+10%UM, G3=20%SS+20%UM, G4=10%SS+30%UM, G5=40%UM). Then flexural strength(FS), Elastic Modulus(EM), solubility(S), water sorption(WS), degree of conversion(DC), polymerization shrinkage(PS), and polymerization stress(PSR) of the groups with DPC of more than 1mm were investigated. Finally, the cytotoxicity of composites was studied. The groups with more than 20% wt. UM, filler (G4, G5) had lesser than 1mm DPC. Therefore, we investigated three groups' physical and mechanical properties with lower than 20% UM filler (G1-G3). Within these groups, G3 has a higher FS, EM (P<0.05), and lower WS and S (P<0.05). DC dropped in G2 and G3 compared to G1 (p<0.05), but there was no significant difference between G2 and G3 (P=0.594). This new filler is an innovative coupling-agent free filler and can be part of dental filler technology itself. It can also introduce a new group of dental fillers based on MOFs, but it still needs a complete investigation to be widely used.

Effect of monomer composition and filler fraction on surface microhardness and depth of cure of experimental resin composites.

This study evaluated microhardness profiles and calculated depths of cure at 80% of the surface microhardness of experimental dental resin composites having different base monomer compositions and different filler fractions. Composites were prepared using four different base monomers (bisphenol A-glycidyl methacrylate [Bis-GMA], urethane dimethacrylate [UDMA], ethoxylated bisphenol-A dimethacrylate [Bis-EMA], and Fit-852) with triethylene glycol dimethacrylate (TEGDMA) used as a co-monomer at three filler:resin matrix weight percent fractions (50:50, 60:40, and 70:30). Uncured material was placed in 3D printed molds and light cured for 40 s from the top surface only. Knoop microhardness was measured at the top of the specimen, and at every 0.5mm up to 4mm in depth. Microhardness at the surface increased in all experimental composites as the filler fraction increased. When comparing base monomers, microhardness was the highest in UDMA-based composites, while Bis-GMA-based composites showed the lowest values. When comparing depth of cure as a function of base monomer type, both Bis-GMA and Bis-EMA showed significantly lower values than UDMA or Fit-852. Composites having 50wt% filler showed a significantly higher depth of cure than those with 60 and 70wt% filler. Base monomer and filler fraction significantly influence microhardness and depth of cure in these experimental composites.

Using Copper-Doped Mesoporous Bioactive Glass Nanospheres to Impart Anti-Bacterial Properties to Dental Composites.

Experimental dental resin composites containing copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were developed to impart anti-bacterial properties. Increasing amounts of Cu-MBGN (0, 1, 5 and 10 wt%) were added to the BisGMA/TEGDMA resin matrix containing micro- and nano-fillers of inert glass, keeping the resin/filler ratio constant. Surface micromorphology and elemental analysis were performed to evaluate the homogeneous distribution of filler particles. The study investigated the effects of Cu-MBGN on the degree of conversion, polymerization shrinkage, porosity, ion release and anti-bacterial activity on S. mutans and A. naeslundii. Experimental materials containing Cu-MBGN showed a dose-dependent Cu release with an initial burst and a further increase after 28 days. The composite containing 10% Cu-MBGN had the best anti-bacterial effect on S. mutans, as evidenced by the lowest adherence of free-floating bacteria and biofilm formation. In contrast, the 45S5-containing materials had the highest S. mutans adherence. Ca release was highest in the bioactive control containing 15% 45S5, which correlated with the highest number of open porosities on the surface. Polymerization shrinkage was similar for all tested materials, ranging from 3.8 to 4.2%, while the degree of conversion was lower for Cu-MBGN materials. Cu-MBGN composites showed better anti-bacterial properties than composites with 45S5 BG.

Impact of Copper-Doped Mesoporous Bioactive Glass Nanospheres on the Polymerisation Kinetics and Shrinkage Stress of Dental Resin Composites.

We embedded copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) with antibacterial and ion-releasing properties into experimental dental composites and investigated the effect of Cu-MBGN on the polymerisation properties. We prepared seven composites with a BisGMA/TEGDMA (60/40) matrix and 65 wt.% total filler content, added Cu-MBGN or a combination of Cu-MBGN and silanised silica to the silanised barium glass base, and examined nine parameters: light transmittance, degree of conversion (DC), maximum polymerisation rate (Rmax), time to reach Rmax, linear shrinkage, shrinkage stress (PSS), maximum PSS rate, time to reach maximum PSS rate, and depth of cure. Cu-MBGN without silica accelerated polymerisation, reduced light transmission, and had the highest DC (58.8 ± 0.9%) and Rmax (9.8 ± 0.2%/s), but lower shrinkage (3 ± 0.05%) and similar PSS (0.89 ± 0.07 MPa) versus the inert reference (0.83 ± 0.13 MPa). Combined Cu-MBGN and silica slowed the Rmax and achieved a similar DC but resulted in higher shrinkage. However, using a combined 5 wt.% Cu-MBGN and silica, the PSS resembled that of the inert reference. The synergistic action of 5 wt.% Cu-MBGN and silanised silica in combination with silanised barium glass resulted in a material with the highest likelihood for dental applications in future.

An Evaluation of the Hydrolytic Stability of Selected Experimental Dental Matrices and Composites.

Materials with potential use as dental restoration should be evaluated in an aggressive environment. Such accelerated aging is widely used in other industries and allows the assessment of service life. In the presented study, three neat resins (UDMA/Bis-GMA/TEGDMA 70/10/20 wt.%, UDMA/Bis-GMA/TEGDMA 40/40/20 wt.% and UDMA/Bis-EMA/TEGDMA 40/40/20 wt.%) and three composites based on these matrices were tested before and after aging protocols (I-7500 cycles, 5 °C and 55 °C, water and 7 days, 60 °C, 0.1 M NaOH; II-5 days, 55 °C, water and 7 days, 60 °C, 0.1 M NaOH). Flexural strength (FS), diametral tensile strength (DTS) and hardness (HV) were determined. Applied aging protocols resulted in a decrease in the value of the FS, DTS and HV. Larger changes were noticed for the neat resins. Materials in which the content of bis-GMA was lower or substituted by bis-EMA showed better resistance to degradation. The choice of mixtures with monomers characterized by lower sorption values may favorably affect hydrolytic stability. It was shown that for composites there was a drastic decrease in hardness, which suggests a more superficial effect of the used protocols. However, degradation of the surface layer can result in a growing problem over time given that the mastication processes are an inherent element in the oral environment.

Antimicrobial Effects of Propolis Incorporated Dental Composite Resin

Aim/Objective: The aim of this in-vitro study is to assess the antibacterial activity of a propolis-modified experimental dental composite resin in terms of reducing and preventing recurrent caries, usually caused by Streptococcus mutans. Materials and methods: Control group specimens were made using the 70/30 (filler/resin) method without the use of EPE. Group 1 specimens were made by mixing 12% EPE with 30% resin in experimental dental composite resin. The experimental dental composite was created by adding 16%EPE and 20% EPE to Group 2 and Group 3, respectively. Antibacterial testing was carried out in the inhibition zone using the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC). Surface roughness was assessed using scanning electron microscopy. Results: The results were evaluated using one-way ANOVA and Tukey's high significant difference test (HSD). The EPE displayed antibacterial action against S.mutans, according to the findings. The inhibitory zone of 20% EPE integrated dental composite resin was 2.2mm to 2.5mm. Inhibition zones ranging from 1.2mm to 1.8mm were found in 12% and 16% of the samples, respectively. The results of the minimum inhibitory concentration showed that 20% had stronger antibacterial activity than 12 and 16 %. Scanning electron microscopy research revealed that 20% of EPE samples had decreased surface roughness. Conclusion: The experimental dental composite showed antibacterial activity against S.mutans. Antibacterial activity is increased by increasing the proportion of EPE in the experimental composite. Due to its dark color appearance it is recommended for usage as a lining material under restorative materials. Keywords: Streptococcus mutans, Secondary Caries, Antibacterial activity, Propolis, Ethanolic extract of Propolis, Dental Composite Resin

POLYMERIZATION SHRINKAGE, DEGREE OF CONVERSION, DEPTH OF CURE, AND HEAT GENERATION OF NOVEL EXPERIMENTAL AND COMMERCIAL COMPOSITE

Objective:&#x0D; To compare and characterise commercial and control composites. By characterising these composites, target properties for new experimental dental composites can be outlined.&#x0D; Materials and Methods:&#x0D; Three commercial, and two experimental composites were compared and investigated. The composition of commercial materials were provided from published literature and manufacturer’s information. The changes in intensity of spectral peaks that were involved in free radical addition polymerization were used to determine the degree of conversion using FTIR (n=6). The samples were prepared in 1 mm, and 4 mm thickness and cured for 40 s from top. Depth of cure, Polymerization shrinkage and heat generation were determined using conversion data, and equations.&#x0D; Results:&#x0D; The conversion for Gradia, and Z250 were significantly lower than the flowable Vertise flow, and experimental composites C-HEMA, and C-4 META in both 1 mm, and 4 mm depth. The shrinkage, and heat generation values suggests opposite trends to conversion. With the highest shrinkage, and heat generation associated with Vertise flow. Depths of cure of all materials were in the range of 2.28 to 2.49 mm at 20 s, and 40 s cure.&#x0D; Conclusion:&#x0D; The experimental composite with added monomers had the potential to compete with commercially available composites, without compromising the properties.

Correction: Investigation of alumina doped 45S5 glass as a bioactive filler for experimental dental composites

Correction: Investigation of alumina doped 45S5 glass as a bioactive filler for experimental dental composites

Polymerization kinetics of experimental resin composites functionalized with conventional (45S5) and a customized low-sodium fluoride-containing bioactive glass

This study aimed to investigate polymerization kinetics and curing light transmittance of two series of experimental dental resin composites filled with 0–40 wt% of either 45S5 bioactive glass (BG) or a customized low-Na F-containing BG. Polymerization kinetics in 0.1-mm and 2-mm thick layers were investigated through real-time degree of conversion measurements using a Fourier transform infrared (FTIR) spectrometer. FTIR spectra were continuously collected at a rate of 2 s−1 during light-curing (1340 mW/cm2). Light transmittance through 2-mm thick composite specimens was measured using a UV–Vis spectrometer at a rate of 20 s−1. Unlike BG 45S5, which led to a dose-dependent reduction in the rate and extent of polymerization, the customized low-Na F-containing BG showed a negligible influence on polymerization. The reduction in light transmittance of experimental composites due to the addition of the low-Na F-containing BG did not translate into impaired polymerization kinetics. Additionally, the comparison of polymerization kinetics between 0.1-mm and 2-mm thick layers revealed that polymerization inhibition identified for BG 45S5 was not mediated by an impaired light transmittance, indicating a direct effect of BG 45S5 on polymerization reaction. A customized low-Na F-containing BG showed favourable behaviour for being used as a functional filler in light-curing dental resin composites.

Amorphous biogenic silica production and utilization in experimental dental composites: Effect of silica gel formation pH on silica and composite properties

AbstractThe purpose of this present study was to synthesize biogenic silica from rice hull ash (RHA) and investigate the effect of silica gel formation pH on the properties of silica powders and light‐cured experimental dental composites (EDCs) prepared using biogenic silica powders. Silica extracted from RHA and silica powders with different properties were obtained by the gelation of silicate solutions at pH 4, 7, and 9. Silica samples were characterized using inductively coupled plasma/optical emission spectrometry, X‐ray diffraction spectroscopy, Fourier‐transform infrared spectroscopy, scanning electron microscopy, laser particle sizer, and N2 adsorption analysis. Silanated silica powders were mixed with organic matrix (bisphenol A‐glycidyl methacrylate 50 wt%—2‐hydroxyethyl methacrylate 50 wt%) and EDC obtained were subjected to Vickers hardness, three‐point bending, and degree of conversion (DC) tests. EDC paste prepared with the inclusion of silica powder produced from pH 9 gel (9SiO2) could not be cured. EDC prepared with silica produced from pH 4 gel (4SiO2) had higher flexural strength than composite prepared with silica produced from pH 7 gel (7SiO2) at the same wt%. EDCs prepared using 9SiO2 showed significantly lower DC compared to EDCs prepared with 4SiO2 and 7SiO2. These observations reveal that EDC properties are susceptible to silica gel formation pH just as the obtained biogenic silica properties are. Furthermore, this study indicates the importance of optical properties of filler designed for light‐cured dental composites. Biogenic silica powders obtained from RHA may be low‐cost alternatives to current amorphous silica fillers depending on the production conditions.

Mechanical and Optical Properties of the Experimental and Commercial Dental Composites: A Systematic Review

Highly demand of aesthetic needed made dental composites become a major role as dental restorations. Minimal invasive of sound tissue and the ability to mimic the original teeth also have the recommendation to choose dental composites. The developments of dental composites mostly focus on filler systems to improve mainly in the mechanical and optical properties due to the esthetic aspect of dental care recently has become increasing importance. According to the component of dental composites, the fillers had a big role to determine the properties of dental composite. Many kinds of fillers have been utilized to improve the properties. Two kinds of dental composites had been known based on their fabrication procedure; i.e. experimental and commercial. The experimental dental composites had been produced by the researcher on their formula to obtain good properties while commercial dental composites were made by many manufacturers which have each brand that has each product of excellence, especially in mechanical and optical properties. The aim of this review focused on the mechanical and optical properties of experimental dental composites and commercial dental composites including describes many factors that affect those properties.

Experimental Dental Composites Containing a Novel Methacrylate-Functionalized Calcium Phosphate Component: Evaluation of Bioactivity and Physical Properties.

The aim of this study was to synthesize and characterize a novel methacrylate-functionalized calcium phosphate (MCP) to be used as a bioactive compound for innovative dental composites. The characterization was accomplished by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The incorporation of MCP as a bioactive filler in esthetic dental composite formulations and the ability of MCP containing dental composites to promote the precipitation of hydroxyapatite (HAp) on the surfaces of those dental composites was explored. The translucency parameter, depth of cure, degree of conversion, ion release profile, and other physical properties of the composites were studied with respect to the amount of MCP added to the composites. Composite with 3 wt.% MCP showed the highest flexural strength and translucency compared to the control composite and composites with 6 wt.% and 20 wt.% MCP. The progress of the surface precipitation of hydroxyapatite on the MCP containing dental composites was studied by systematically increasing the MCP content in the composite and the time of specimen storage in Dulbecco’s phosphate-buffered solution with calcium and magnesium. The results suggested that good bioactivity properties are exhibited by MCP containing composites. A direct correlation between the percentage of MCP in a composite formulation, the amount of time the specimen was stored in PBS, and the deposition of hydroxyapatite on the composite’s surface was observed.

Modified POSS nano-structures as novel co-initiator-crosslinker: Synthesis and characterization

ObjectiveTo synthesize an amine-modified polyhedral oligomeric silsesquioxane (POSS) nano-structure as a novel co-initiator-crosslinker (co-Ini-Linker) and to determine the effect of the co-Ini-linker on the physical and mechanical behavior of an experimental dental composite. MethodsThe amine-methacrylate POSS nano-structures (AMA-POSS) were chemically synthesized by anchoring a tertiary amine functionality on the methacrylate POSS (MA-POSS) branches. Three types of AMA-POSS, having different amine branches in their structures, were synthesized through the Aza Michael reaction. The chemical structure of AMA-POSSs were evaluated by1H-NMR spectroscopy. Afterward, the AMA-POSS was incorporated into a dental resin system composed of Bis-GMA, TEGDMA, and photo-initiator. Three resin systems with different AMA-POSS types were then prepared, and their properties were compared with a resin containing DMAEMA as a conventional co-initiator. The degree of conversion evaluated by FTIR spectroscopy and the shrinkage kinetics of the resins were determined through the bonded-disk technique. The flexural properties of the photopolymerized resins were also investigated. The distribution of nano-structures in the matrix resin was analyzed using EDX analysis. ResultsThe modified POSS structure and the number of amine branches were confirmed with1H-NMR spectroscopy. The resin containing 8 amine branches (P8) showed the same degree of conversion (DC%) as the resin containing DMAEMA (P > 0.05). Decreasing the amine branches in the POSS structure, however, revealed an increasing trend in DC%. The resin containing P8 showed the lowest shrinkage strain. By incorporating AMA-POSS into the resin system, the water sorption significantly decreased (P < 0.05). The flexural strength and modulus increased by adding P3 into the resin system (P < 0.05). EDX Si-map revealed that the co-Ini-linker was well dispersed in the resin matrix. SignificanceThe synthesized novel amine-methacrylate POSS nanostructures not only act as an amine co-initiator but also work as a reinforcing filler and a cross-linking agent.

Incorporation of Copper-Doped Mesoporous Bioactive Glass Nanospheres in Experimental Dental Composites: Chemical and Mechanical Characterization.

Experimental dental resin composites incorporating copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were designed to impart antibacterial and remineralizing properties. The study evaluated the influence of Cu-MBGN on the mechanical properties and photopolymerization of resin composites. Cu-MBGN were synthesized using a microemulsion-assisted sol–gel method. Increasing amounts of Cu-MBGN (0, 1, 5, and 10 wt %) were added to the organic polymer matrix with inert glass micro- and nanofillers while maintaining a constant resin/filler ratio. Six tests were performed: X-ray diffraction, scanning electron microscopy, flexural strength (FS), flexural modulus (FM), Vickers microhardness (MH), and degree of conversion (DC). FS and MH of Cu-MBGN composites with silica fillers showed no deterioration with aging, with statistically similar results at 1 and 28 days. FM was not influenced by the addition of Cu-MBGN but was reduced for all tested materials after 28 days. The specimens with 1 and 5% Cu-MBGN had the highest FS, FM, MH, and DC values at 28 days, while controls with 45S5 bioactive glass had the lowest FM, FS, and MH. DC was high for all materials (83.7–93.0%). Cu-MBGN composites with silica have a potential for clinical implementation due to high DC and good mechanical properties with adequate resistance to aging.

Investigation of alumina doped 45S5 glass as a bioactive filler for experimental dental composites

AbstractThis study aimed to investigate the effects of inclusion of Al2O3‐doped bioactive glass (BG) and silane treatment on physical properties and bioactivity behavior of resin‐based experimental dental composites (EDCs). Melt‐derived 45S5 BG and alumina doped 45S5 BG were prepared and incorporated into EDCs with and without silanization. EDCs prepared were subjected to three‐point bending, microhardness, water sorption (WS), solubility (S), and bioactivity tests. Using non‐silanized Al2O3‐doped BG in EDCs resulted in improved flexural strength (FS), flexural modulus (FM), and microhardness and decreased bioactivity compared to EDCs containing non‐silanized BG. There was no significant difference (p &lt; 0.05) between WS and S results of non‐silanized glass containing EDCs. Using silanized BG and Al2O3‐doped BG resulted in improved FS and FM, decreased WS, S, and bioactivity. Addition of Al2O3‐doped BG as a possible bioactive filler to EDCs improved mechanical performance while slightly decreasing bioactivity compared to BG containing EDCs.

Development of Chlorhexidine Loaded Halloysite Nanotube Based Experimental Resin Composite with Enhanced Physico-Mechanical and Biological Properties for Dental Applications

Objective: The objective of this study was to explore the effect of Chlorhexidine-loaded Halloysite nanotubes (HNT/CHX) fillers (diverse mass fractions from 1 to 10 wt.%) on physicochemical, morphological and biological properties of newly developed experimental dental resin composite, in order to compare with the properties of composites composed of conventional glass fillers. Methods: The dental resin composites were prepared by incorporating various proportions of HNT/CHX. Six different groups of specimens: control group and five groups composed of varied mass fractions of HNT/CHX (e.g., 1.0, 2.5, 5.0, 7.5 and 10 wt.%) as fillers in each group were fabricated. Mechanical properties of the composites were monitored, using UTM. The degree of conversion of dental resin composites and their depth of cure were also evaluated. Antimicrobial properties of dental composites were studied in vitro by applying agar diffusion test on strain Streptococcus mutans and cytotoxicity were studied using NIH-3T3 cell line. Results: The incorporation of varied mass fractions (1.0 to 5.0 wt.%) of HNT/CHX in dental resins composites enhanced mechanical properties considerably with significant antibacterial activity. The slight decrease in curing depth and degree of conversion values of composites indicates its durability. No cytotoxicity was noticed on NIH-3T3 cell lines. Significance: Consistent distribution of HNT/CHX as a filler into dental composites could substantially improve not only mechanical properties but also biological properties of dental composites.

Inverse gas chromatography in the examination of surface properties of experimental dental composites

Properties of the surface layer of materials determine their suitability for some special applications, affecting the value of adhesion between bonding materials. In the case of dental fillings, the high value of adhesion to tooth tissue is important and determines their durability and tightness. The surface properties of dental methacrylic resin with the addition of various zeolite fillers were examined using inverse gas chromatography (IGC). The dispersive and specific component of the surface energy, acceptor – donor properties were determined from IGC experiments. The effect of the addition of zeolite filler on the surface energy values of the examined dental composites was investigated. It has been shown that using IGC it is possible to determine parameters describing the adhesion between materials, expressed by the value of the work of adhesion. Different values of the work of adhesion were observed according to the type of tooth tissue (dentin or enamel).