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Influence of fillers on the water sorption of composites
Abstract
The main objectives of this work were to characterize the water sorption of dental composites in terms of water uptake, diffusion coefficients (D), and polymer content, and to study how these parameters are influenced by the nature of the filler and the presence of 4-META (4-methacryloxy ethyl trimellitic anhydride). Four anhydrous composites--(1) tribasic calcium phosphate (TCP 50%) and triethylene glycol dimethacrylate (TEGDM), (2) silanated lithium aluminum silicate (SS, 75%) and TEGDM, (3) barium sulfate [BaSO4 (70%) and poly(methyl methacrylate) (PMMA)], and (4) silane-coated barium glass (SBG) (75%)--and PMMA were employed in the water-sorption studies at 37 degrees C. The effect of 5% 4-META on the diffusion and uptake of water was studied at 37 degrees C. The data conformed approximately to Fick's laws of diffusion. The values of D were found to be significantly smaller with SS, suggesting an effective coupling. Polymer contents in the latter two composites were determined by incineration of the samples to constant weight. The uptake of water by the filled specimens was about two-fold that which would be expected on the basis of the PMMA content. These filled specimens took nearly twice as much water as unfilled PMMA. An additional amount of water is perhaps accommodated at the interface between the filler and PMMA matrix. The D values for water in filled specimens were considerably larger than those in the unfilled specimens. It appears that the filler-matrix interface provides paths of facile diffusion similar to grain boundary diffusion.
... Although the statistical analysis does not show any differences among the evaluated materials used, Natural Look composite presented the lowest final volume when compared to Z250 and Charisma. This could have happened because UDMA polymer absorb less water than BisGMA, due to its higher crosslinking ability [51][52][53]. Another factor that can explain these small differences could be the amount of filler in each material, as there is an inverse correlation with the degree of hygroscopic expansion and water sorption. ...
... As the filler volume increases, there is a decrease in the water sorption and consequently the hygroscopic expansion [42]. A study idealized the influence of the filler/matrix interface [53], where a poor bonding would provide a way of facilitating the water diffusion, then a material with high filler volume would accommodate the water volume in this region. ...
... In this wet condition, the initiation of the crack/flaw is then facilitated, requiring little effort, such as stresses generated after polymerization shrinkage. Consequently, the adhesion of the particles to the matrix can be destroyed by hydrolysis [52][53][54][55][56][57]. If the material is inhomogeneous and anisotropic, as almost all dental materials are, several sizes of defects can be present [58]. ...
To characterize the mechanical properties of different resin-composites for dental application. Methods: Thirteen universal dentin shade composites (n = 10) from different manufacturers were evaluated (4 Seasons, Grandio, Venus, Amelogen Plus, P90, Z350, Esthet-X, Amaris, Vita-l-escence, Natural-Look, Charisma, Z250 and Opallis). The polymerization shrinkage percentage was calculated using a video-image recording device (ACUVOL—Bisco Dental) and the hygroscopic expansion was measured after thermocycling aging in the same equipment. Equal volumes of material were used and, after 5 min of relaxation, baseline measurements were calculated with 18 J of energy delivered from the light-curing unit. Specimens were stored in a dry-dark environment for 24 h then thermocycled in distilled water (5–55 °C for 20,000 cycles) with volume measurement at each 5000 cycles. In addition, the pulse-excitatory method was applied to calculate the elastic modulus and Poisson ratio for each resin material and the degree of conversion was evaluated using Fourier transform infrared spectroscopy. Results: The ANOVA showed that all composite volumes were influenced by the number of cycles (α = 0.05). Volumes at 5 min post-polymerization (12.47 ± 0.08 cm3) were significantly lower than those at baseline (12.80 ± 0.09 cm3). With regard to the impact of aging, all resin materials showed a statistically significant increase in volume after 5000 cycles (13.04 ± 0.22 cm3). There was no statistical difference between volumes measured at the other cycle steps. The elastic modulus ranged from 22.15 to 10.06 GPa and the Poisson ratio from 0.54 to 0.22 with a significant difference between the evaluated materials (α = 0.05). The degree of conversion was higher than 60% for all evaluated resin composites.
... Workers have generally selected similar dimensions; 0.8-1.3 mm thickness x 20 mm diameter (Braden et al. 1976), 1 mm x 15 mm (Pearson 1979), 0.8 mm x 21 mm (Soderholm 1984), 1 mm x 20 mm , 1 mm x 14 mm (Kalachandra 1989) and 1 mm x 15 mm (Kildal and Ruyter 1997;Tanoue et al. 1998C). Clinically, the time taken for all the regions in the composite restoration to be permeated by water, will be more complex, since this is affected by temperature, shape and the varying thickness of the restoration. ...
... As mentioned previously, most fillers are protected with a silane coupling agent and large differences in water uptake and strength between proprietary composites made from methyl methacrylate were attributed to differences in the filler matrix bond as revealed by fractographic analysis (Beech and Brown 1972). Coupling agents are used in composites to improve mechanical properties (Kalachandra 1989). Conventionally a variety of silane compounds are used, but there is some concern about the long term solubility in aqueous environments. ...
... Conventionally a variety of silane compounds are used, but there is some concern about the long term solubility in aqueous environments. Further, it has been shown that some PMMA (Polymethyl-methacrylate) based composites accommodate additional water at the interface between filler particles and the matrix (Kalachandra 1989), other coupling agents such as 4-META (4 methacryloxy ethyl trimellitic anhydride) have been used on some filler types and lowered the water uptake . It is possible, therefore, that some breakdown at the filler- There appears to be a continuous release of elements from the filler particles and this shows no sign of decrease over at least the first year of service (Soderholm et al. 1996). ...
Composite resins, while popular on aesthetic grounds, have shown a number of problems including wear, shrinkage and long term degradation. Extra-oral polymerisation has been proposed as a means of reducing bulk polymerisation shrinkage whilst enhancing mechanical properties. However, there still exists a problem with shrinkage associated with the resin cement lute. There are problems obtaining measurement of the cement lute thickness, particularly over the whole fit surface of the restoration. The observed discrepancies between the cavity surface and the fit of the inlay are variable. This study investigates some physical properties of three inlay systems, and attempts to determine the effect of cavity configuration on the dimensional change of the inlay during polymerisation. The physical properties evaluated were flexural strength and hardness to confirm the effect of extra oral polymerisation on the composite. The water sorption and solubility were also determined. Linear shrinkage was measured in different dimensions to determine the effect of the constraining influence of a mould. The apparent cement lute thickness of the inlays in a stylized cavity was assessed using a laser scanning profilometer. An addition silicone impression rubber of similar viscosity to resin cement was used as the luting medium. The greatest shrinkage occurred in width rather than length. Highest values for shrinkage were observed in the system polymerised by heat and pressure. A high solubility value for the heat and light polymerising system (0.53%) was recorded which also showed the lowest water sorption (0.92%). The heat and pressure system had similar solubility values (0.51%), but high water sorption (1.54%). The flexural strength was found to decrease in all samples over a period of 6 months in aqueous solution, the greatest reduction occurring in the laboratory heat and light system. Surface hardness also decreased after 6 months immersion in water. In all cases substantial cement lute thickness was observed and this varied with the cavity configuration. The effect of cavity design on these materials is not clear.
... Filtek One Bulk Fill and Fitek Z250, as two of the most filled materials in our research, exhibited the highest water sorption for both polymerization methods. Although the high content of fillers slows down the diffusion of water, the type of fillers and the percentage of their silanization affect the final water sorption values, which have been considered in previous studies (35,36). Nano-fillers that tend to agglomerate and silane on their large surface easily hydrolyze when exposed to water. ...
... Filtek One Bulk Fill i Filtek Z250, kao dva najviše punjena materijala u našem istraživanju, pokazala su najveću apsorpciju vode tijekom oba načina polimerizacije. Iako visok udio punila usporava difuziju vode, vrsta punila i postotak njihove silanizacije utječe na konačne vrijednosti apsorpcije vode, što je razmatrano u prijašnjim istraživanjima (35,36). Nanopunila imaju tendenciju prema aglomeraciji i silan na njihovoj velikoj površini lako hidrolizira pri izlaganju vodi. ...
Objectives: The aim of the study was to examine the impact of rapid high-intensity polymerization on water sorption and solubility of a new generation of bulk-fill composite materials.
Material and methods: Five materials were tested: a conventional composite Filtek Z250 (3M, St. Paul, USA) and four bulk-fill composites, Filtek One Bulk Fill (3M), Tetric PowerFill (Ivoclar Vivadent, Schaan, Liechtenstein), Tetric PowerFlow (Ivoclar Vivadent), SDR Plus (Dentsply, Konstanz, Germany). Composite specimens with a 9-mm diameter and a 2-mm height (n = 6) were polymerized with a high-intensity curing unit (Bluephase® PowerCure, Ivoclar Vivadent). The control group was polymerized for a total of 40 s on both sides (1193 mW / cm2) and 3s group for 3 s on one side (3053 mW/cm2). Water sorption and solubility were measured by ISO 4049 method up to 30 days of immersion. The results were statistically analyzed using one-way ANOVA with Tukey post-hoc correction. Different polymerization protocols for the same material were compared by t-test (p <0.05).
Results: The 3s polymerization protocol increased the solubility of all materials. Filtek One Bulk Fill showed the highest water sorption and solubility values, and Tetric PowerFlow proved to be a stable material with low values of tested parameters. During immersion, a saturation of specimens was achieved in low-viscosity bulk-fill composites within two weeks, while in other materials it was not achieved within 30 days, or more, following the immersion.
Conclusions: Rapid polymerization caused an increase in solubility, which could affect the biocompatibility of the investigated materials not intended for the 3s curing. SDR Plus and Filtek One Bulk Fill should not be polymerized with rapid high-intensity curing due to increased solubility that exceeds ISO 4049:2009 limits.
... Besides, the monomers Bis-GMA, UDMA, and Bis-EMA are common for all of them, whereas β-allyl sulfone, PBPA, and DCP are specific for PFILL [9]. DCP has a cyclic aliphatic structure [39], which probably improves mechanical properties by providing rigidity to the polymer network. Besides, the addition-fragmentation chain-transfer mechanism also influences the mechanical properties of PFILL. ...
... Silane molecules, primarily if present in unbound form as found in filler particles having excessive silanization or particle agglomeration, easily hydrolyze upon exposure to water, thus creating diffusion pathways that facilitate further water sorption [54]. Previous research also considers the claim that a high proportion of fillers does not necessarily mean lower water sorption, but rather that this is determined by the properties of these fillers, i.e., whether they are unsilanized, prepolymerized, or agglomerated [39,50]. ...
This study evaluated the behavior of a new generation of bulk-fill resin composites after prolonged exposure to an aqueous environment and accelerated aging in ethanol. Six bulk-fill materials were tested (Tetric PowerFill, Filtek One Bulk Fill Restorative, Tetric EvoCeram Bulk Fill, Fill-Up!, Tetric PowerFlow, SDR Plus Bulk Fill Flowable) and compared to two conventional reference materials (Tetric EvoCeram and Tetric EvoFlow). Flexural strength, modulus, and Weibull parameters were examined at three time points: 1 day, 30 days, and 30 days followed by ethanol immersion. Degree of conversion after 30 days, water sorption, and solubility up to 90 days were also investigated. Filtek One Bulk Fill had the highest flexural strength and modulus among the tested materials, followed by Tetric PowerFill and SDR plus. Flexural strength and modulus of high-viscosity bulk-fill materials showed higher stability after accelerated aging in ethanol compared to their low-viscosity counterparts and reference materials. After 30 days, the degree of conversion was above 80% for all tested materials. Dual-cure material Fill-Up! was the best-cured material. The water sorption was highest for Fill-Up!, Filtek One Bulk Fill Restorative, and Tetric EvoFlow, while solubility was highest for Tetric EvoCeram. After aging in water and ethanol, new generation high-viscosity bulk-fill materials showed better mechanical properties than low-viscosity bulk-fill and conventional composites under extended light curing conditions.
... Besonders die kohäsive Festigkeit von Kompositen wird durch Wasseraufnahme in die Matrix verringert (Söderholm et al. 1984). Da es sich hierbei um Diffusionsprozesse handelt, scheint die ausreichend lange Wasserlagerung bei 37° C ein effizientes Verfahren darzustellen (Kalachandra 1989), wobei die größte Wasseraufnahme innerhalb der ersten 7 Tage ermittelt wurde (Örtengren et al. 2001). ...
... Basierend auf den Erkenntnissen von Kalachandra (1989) (Gordan 2009;Özcan et al. 2010;Opdam et al. 2012). ...
In-vitro Untersuchung der Verbundfestigkeit von Kompositreparaturen runder Prüfkörper im Zugversuch. Filtek Surpreme und Tetric EvoCeram wurden gestrahlt und/oder mit 37% Orthophosphorsäure geätzt und mit Scotchbond Universal oder Optibond FL gebonded. Strahlverfahren erhöhten die Verbundfestigkeit, die zusätzliche Ätzung von abgestrahlten Oberflächen beeinflusste die Verbundfestigkeit nicht.
... Fillers are incorporated into adhesive resins to increase bond strength and decrease degradation over time, as well as to improve or functionalize material properties. [2], [3], [4], [16] In this study, an experimental adhesive resin with N-ZnO particles was developed and its physico-mechanical properties were evaluated. The N-ZnO structure consists of needle-like arms extending in different directions [8] with a mean particle size of 40 nm and a specific surface area of 16 m2/g. ...
... It suggests that the increased amount of unreacted monomers did not negatively compromise the resistance to degradation. This finding could be explained by the fillers' low tendency to degradation when compared to resin matrix, [16] which could have overcome the lower degree of conversion due to an increased filler content. ...
Aim:
The aim of this study was to develop an experimental adhesive resin with nanoneedle-like zinc oxide (N-ZnO), an inorganic filler, that could avoid particle agglomeration and lead to a homogeneous stress distribution within the material and characterize it.
Materials and methods:
N-ZnO particles obtained by a thermal evaporation technique were characterized regarding size and surface area and added at 0 (control), 1, 2, 5, and 10 wt%, to an experimental adhesive resin. The following experimental adhesive resins' properties were assessed: radiopacity, contact angle to conditioned enamel and dentin, color, degree of conversion, flexural strength, resistance to degradation, and cytotoxicity. Statistical analysis was performed using one-way ANOVA and Tukey's post hoc test and paired Student's t-test.
Results:
Particles presented a mean particle size of 40 nm and a specific surface area of 16 m2/g. N-ZnO10%showed an increased radiopacity when compared to N-ZnO0%. Contact angles were significantly higher for N-ZnO10%at enamel and N-ZnO2%, N-ZnO5%, and N-ZnO10%at dentin. All groups showed color change when compared to N-ZnO0%. Higher the N-ZnO concentration, lower the degree of conversion. There were no significant differences between the groups for flexural strength and resistance to degradation. The addition of N-ZnO showed no difference in cytotoxicity when compared to positive control, N-ZnO0%, and all groups showed higher values than negative control.
Conclusions:
N-ZnO possibly exceeded potential limitations due to particles' agglomeration and improved the transference and distribution of stress within the material. It could be effectively used as a filler for adhesive resins.
... 7 Recent research has demonstrated that the addition of fillers in adhesives can improve their mechanical qualities while reducing water sorption and solubility. 8,9 Thus, it is extremely desirable to incorporate inorganic nanomaterials as fillers/particles to enhance the physicomechanical characteristics of bonding agents. In recent years, dental researchers have become interested in several materials, including graphene. ...
Background
Graphene is the thinnest, strongest, and stiffest imaginable material. The biocompatible property of graphene oxide can initiate and facilitate cell adhesion, proliferation, and differentiation of periodontal ligament, osteogenic, and oral epithelial cells. Furthermore, the antibiofilm and anti-adhesion properties of graphene oxide in the prevention of dental biofilm infections, dental caries, and dental erosion as well as for implant surface modification and as an anti-quorum sensing agent. Composites are the most often utilized materials for restoration in the field of dentistry due to adhesive resins' improved mechanical and cosmetic properties. To safeguard the dentin and prevent dental cavities, dentin adhesives are utilized to affix hydrophobic resin composites to hydrophilic dentin tissue.
Materials and Method
Dental adhesives have a harder time adhering to dentin because it contains more water and is less mineralized than enamel. This makes the method more sensitive.
Result
As a result, it was chosen to assess and contrast the impact of 5% Hydroxyapatite nanoparticles and 2% Graphene oxide nanoparticles, both separately and together, on the Micro tensile bond strength of 5th generation adhesive.
Conclusion
Graphene oxide is the most versatile form of Graphite in structural and functional configuration. Graphene oxide possesses extraordinary physical, chemical, optical, electrical and mechanical properties. Among the graphene family nanomaterials, the reduced form of Graphite adding the oxygenated functional group to the structure increases the surface area and therefore exhibits enviable excellent interaction ability with metal and ions as well as organic species. Graphene oxide in dentistry has provided outstanding results in antimicrobial action, regenerative dentistry, bone tissue engineering, drug delivery, physicochemical properties, enhancement of dental biomaterials and oral cancer treatment.
... When compared to other direct restoratives, such as conventional or resin-modified glass ionomer cements, dimethacrylate-based composites are considered relatively hydrophobic and impervious [6,15]. However, while silanization of the glass filler particles impedes the transit of fluids at the particle-polymer interface [12,20], solvent uptake occurs through the polymer network, as confirmed by a direct correlation between water sorption (WS) and monomer hydrophilicity [28,39] and an indirect correlation between WS and filler fraction [14]. ...
... 7 Recent research has demonstrated that the addition of fillers in adhesives can improve their mechanical qualities while reducing water sorption and solubility. 8,9 Thus, it is extremely desirable to incorporate inorganic nanomaterials as fillers/particles to enhance the physicomechanical characteristics of bonding agents. In recent years, dental researchers have become interested in several materials, including graphene. ...
Background Graphene is the thinnest, strongest, and stiffest imaginable material. The biocompatible property of graphene oxide can initiate and facilitate cell adhesion, proliferation, and differentiation of periodontal ligament, osteogenic, and oral epithelial cells. Furthermore, the antibiofilm and anti-adhesion properties of graphene oxide in the prevention of dental biofilm infections, dental caries, and dental erosion as well as for implant surface modification and as an anti-quorum sensing agent. Composites are the most often utilized materials for restoration in the field of dentistry due to adhesive resins' improved mechanical and cosmetic properties. To safeguard the dentin and prevent dental cavities, dentin adhesives are utilized to affix hydrophobic resin composites to hydrophilic dentin tissue. Materials and Method Dental adhesives have a harder time adhering to dentin because it contains more water and is less mineralized than enamel. This makes the method more sensitive. Result As a result, it was chosen to assess and contrast the impact of 5% Hydroxyapatite nanoparticles and 2% Graphene oxide nanoparticles, both separately and together, on the Micro tensile bond strength of 5th generation adhesive. Conclusion Graphene oxide is the most versatile form of Graphite in structural and functional configuration. Graphene oxide possesses extraordinary physical, chemical, optical, electrical and mechanical properties. Among the graphene family nanomaterials, the reduced form of Graphite adding the oxygenated functional group to the structure increases the surface area and therefore exhibits enviable excellent interaction ability with metal and ions as well as organic species. Graphene oxide in dentistry has provided outstanding results in antimicrobial action, regenerative dentistry, bone tissue engineering, drug delivery, physicochemical properties, enhancement of dental biomaterials and oral cancer treatment.
... Water uptake by filler specimens is almost twice that anticipated as compared to counterparts made of unfilled resin. 30 The absorption of water causes softening of the resin matrix, microcrack formation, resin degradation, and debonding of the filler-matrix interface. 26 The hydrophilicity of monomer in resin matrix increases water uptake; for example, triethylene glycol dimethacrylate (TEGDMA) had greater hydrophilicity than others. ...
This study examined the influence of cariogenic environments on the surface roughness of ion-releasing restorative materials (IRMs). Custom-made stainless steel molds with holes of 5 mm × 2mm were used to fabricate 60 disc-shaped specimens of each of the following materials: Activa Bioactive (AV), Beautifil Bulk Restorative (BB), Cention N (Bulk-fill) (CN), and Filtek Z350XT (FZ) (Control). Baseline surface roughness (Ra) measurements were obtained using an optical 3D measurement machine (Alicona Imaging GmbH, Graz, Austria). The specimens were then randomly divided into five subgroups (n=12) and exposed to 10 ml of the following mediums at 37°C: distilled water (DW), demineralization solution (DM), remineralization solution (RM), pH cycling (PC) and air (AR) (control). Ra measurements were again recorded after one week and one month, followed by statistical evaluations with two-way analysis of variance (ANOVA) to determine interactions between materials and mediums. One-way ANOVA and post hoc Games Howell tests were performed for intergroup comparisons at a significance level of 0.05. Mean Ra values ranged from 0.085 ± 0.004 (μm) to 0.198 ± 0.001 μm for the various material-medium combinations. All IRMs showed significant differences in Ra values after exposure to the aqueous mediums. The smoothest surfaces were observed in the AR for all materials. When comparing materials, AV presented the roughest surfaces for all mediums. All IRM materials showed increased surface roughness over time in all cariogenic environments but were below the threshold value for bacterial adhesion, except for AV 1-month post immersion with pH cycling. Therefore, besides AV, the surface roughness of IRMs did not deteriorate to an extent that it is clinically relevant.
... 7 Recent research has demonstrated that the addition of fillers in adhesives can improve their mechanical qualities while reducing water sorption and solubility. 8,9 Thus, it is extremely desirable to incorporate inorganic nanomaterials as fillers/particles to enhance the physicomechanical characteristics of bonding agents. In recent years, dental researchers have become interested in several materials, including graphene. ...
Graphene is the thinnest, strongest, and stiffest imaginable material. The biocompatible property of graphene oxide can initiate and facilitate cell adhesion, proliferation, and differentiation of periodontal ligament, osteogenic, and oral epithelial cells. Furthermore, the antibiofilm and anti-adhesion properties of graphene oxide in the prevention of dental biofilm infections, dental caries, and dental erosion as well as for implant surface modification and as an anti-quorum sensing agent.
Composites are the most often utilized materials for restoration in the field of dentistry due to adhesive resins' improved mechanical and cosmetic properties. To safeguard the dentin and prevent dental cavities, dentin adhesives are utilized to affix hydrophobic resin composites to hydrophilic dentin tissue. Dental adhesives have a harder time adhering to dentin because it contains more water and is less mineralized than enamel. This makes the method more sensitive. As a result, it was chosen to assess and contrast the impact of 5% Hydroxyapatite nanoparticles and 2% Graphene oxide nanoparticles, both separately and together, on the Micro tensile bond strength of 5th generation adhesive. Graphene oxide is the most versatile form of Graphite in structural and functional configuration. Graphene oxide possesses extraordinary physical, chemical, optical, electrical and mechanical properties. Among the graphene family nanomaterials, the reduced form of Graphite adding the oxygenated functional group to the structure increases the surface area and therefore exhibits enviable excellent interaction ability with metal and ions as well as organic species. Graphene oxide in dentistry has provided outstanding results in antimicrobial action, regenerative dentistry, bone tissue engineering, drug delivery, physicochemical properties, enhancement of dental biomaterials and oral cancer treatment.
... The rate of sorption of resin cement depends on filler content; that is, low-filler resins have increased water sorption [23]. Kalachandra et al. [24] reported that the nature and quality of fillers and matrix links is an important factor. ...
Background
Among the various mechanical and biological properties of luting cement, the most important are its resistance to disintegration, degradation, and stability in the oral cavity. The sorption and solubility of cement alter the mechanical properties by impeding the half-life of the filling. It also leads to variations in dimensions, discoloration, and margin breakage. It is, therefore, essential to choose a low-solubility cement since there is always an interaction between teeth and restorative margins. The aim of this study is to assess and compare the solubility and sorption values of three different luting cements in three liquid media.
Materials and methods
Three luting cements were used for the investigation. Disc-shaped specimens of the cement, which were of 10 mm diameter and 2 mm height, were prepared. The sample included a total of 126 disc-shaped specimens made up of three materials, glass ionomer cement (GIC), resin cement, and resin-modified GIC, which were used in three liquid media (14 of each material in each medium). Fourteen specimens of each material were placed in glass vials containing 20 ml of each medium: distilled water, artificial saliva, and carbonated water. The samples were then put in an incubator at 37 °C. The measurements and masses of the samples were documented on days one, three, seven, 14, 21, 28, and 35. The samples were taken out of the solution after five weeks and stored in a desiccator with calcium sulphate for another five weeks. The weight and dimensional changes were estimated on days one, three, seven, 14, 21, 28, and 35. The values of water sorption (WSO) and solubility (WSL) were estimated. To determine the mean and standard deviation of each cohort, descriptive statistics were employed. Utilizing the Shapiro-Wilkinson test, the normality was determined. An independent test was used to determine the difference between all pairs of groups, while one-way ANOVA, Dunn test, and post hoc analysis were used to establish the distinction between the three groups.
Results
One-way ANOVA showed that significant differences existed among the groups: resin cement showed the least sorption and solubility, resin-modified GIC showed the highest solubility in distilled water (0.40 ± 0.03), and GIC showed the highest solubility in both artificial saliva (0.36 ± 0.03) and carbonated water (0.04 ± 0.05).
Conclusion
Considering the experimental outcomes and the limitations of an in vitro investigation, it was concluded that in the complex setting of the oral environment, this selection procedure is crucial for maintaining mechanical strength and for the long lifespan of dental restorations.
... In order to increase durability of dentin adhesive bond, addition of inorganic fillers in adhesives is suggested to improve their interaction with the dentin surface and possibly minimizing dentinadhesive degradation [5][6][7] . Previous studies have shown that addition of fillers in adhesives can reduce water sorption and solubility, in addition to enhancing its mechanical properties [5][6][7][8][9] . Therefore, addition of inorganic nano-materials as fillers to improve the physical and mechanical properties of dentin adhesives is highly desirable. ...
... Dental adhesives based on nanomaterials with bioactive, antibacterial, and biocompatible properties have been studied; however, very few of them were marketed and became available for clinical applications [37,38]. It is claimed that the inclusion of nanomaterials in dental adhesives can reduce bacterial viability [39], improve mechanical properties and interfacial bonding [40], reduce polymerization shrinkage and water sorption, and inhibit enzymatic and chemical degradation [41][42][43][44][45]. ...
This study aimed to evaluate the incorporation of zirconia/silver phosphate nanoparticles to develop experimental dental adhesives and to measure their physical and mechanical properties. The nanoparticles were synthesized by the sonication method, and the phase purity, morphological pattern, and antibacterial properties with Staphylococcus aureus and Pseudomonas aeruginosa were assessed. The silanized nanoparticles were incorporated (0, 0.15, 0.25, and 0.5 wt.%) into the photoactivated dimethacrylate resins. The degree of conversion (DC) was assessed, followed by the micro-hardness and flexural strength/modulus test. Long-term color stability was investigated. The bond strength with the dentin surface was conducted on days 1 and 30. The transmission electron microscopy and X-ray diffractogram confirmed the nano-structure and phase purity of the particles. The nanoparticles showed antibacterial activities against both strains and inhibited biofilm formation. The DC range of the experimental groups was 55–66%. The micro-hardness and flexural strength increased with the concentration of nanoparticles in the resin. The 0.5 wt.% group showed significantly high micro-hardness values, whereas a non-significant difference was observed between the experimental groups for flexural strength. The bond strength was higher on day 1 than on day 30, and a significant difference was observed between the two periods. At day 30, the 0.5 wt.% showed significantly higher values compared to other groups. Long-term color stability was observed for all the samples. The experimental adhesives showed promising results and potential to be used for clinical applications. However, further investigations such as antibacterial, penetration depth, and cytocompatibility are required.
... 7 Recent research has demonstrated that addition of fillers in adhesives can improve their mechanical qualities while reducing water sorption and solubility. 8,9 Thus, it is extremely desirable to incorporate inorganic nanomaterials as fillers/particles to enhance the physicomechanical characteristics of bonding agents. In recent years, dental researchers have become interested in several materials, including graphene. ...
Graphene is the thinnest, strongest and stiffest imaginable material. The biocompatible property of graphene oxide can initiate and facilitate cell adhesion, proliferation and differentiation of periodontal ligament, osteogenic and oral epithelial cells. Furthermore, the antibiofilm and anti-adhesion properties of graphene oxide in prevention of dental biofilm infections, dental caries, dental erosion as well as for implant surface modification and as anti-quorum sensing agent.
Composites are most often utilised materials for restoration in the field of dentistry due to adhesive resins' improved mechanical and cosmetic properties. To safeguard the dentin and prevent dental cavities, dentin adhesives are utilised to affix hydrophobic resin composites to hydrophilic dentin tissue. Dental adhesives have a harder time adhering to dentin because it contains more water and is less mineralized than enamel. This makes the method more sensitive. As a result, it was chosen to assess and contrast the impact of 5% Hydroxyapatite nanoparticles and 2% Graphene oxide nanoparticles, both separately and together, on the Micro tensile bond strength of 5th generation adhesive. Graphene oxide is the most versatile form of Graphite in structural and functional configuration. Graphene oxide possess extraordinary physical, chemical, optical, electrical and mechanical properties. Among the graphene family nanomaterials, the reduced form of Graphite adding the oxygenated functional group to the structure increases the surface area and therefore exhibits enviable excellent interaction ability with metal and ions as well as organic species. Graphene oxide in dentistry has provided outstanding results in antimicrobial action, regenerative dentistry, bone tissue engineering, drug delivery, physicochemical property, enhancement of dental biomaterials and oral cancer treatment.
... Resistance of an orthodontic bonding system to degradation is essential for the success of orthodontic therapy. Addition of a small amount of nanofiller might enhance SEP longevity, as inorganic nanoparticles are less liable to degradation than the polymeric matrix [45]. Modifying nanofiller size, shape, composition, or amount can improve resin mechanical properties [40]. ...
Objectives
This study aimed to incorporate hydroxyapatite nanoparticles (nHA) or amorphous calcium phosphate nanoparticles (nACP) into a self-etch primer (SEP) to develop a simplified orthodontic bonding system with remineralizing and enamel preserving properties.
Materials and Methods
nHA and nACP were incorporated into a commercial SEP (Transbond™ plus) in 7% weight ratio and compared with the plain SEP as a control. Shear bond strengths (SBS), enamel damage, and adhesive remnant index (ARI) scores were evaluated at 24 h and post 5000 thermocycling. Field-emission scanning electron microscope (FESEM) was used to inspect the distribution of the nanoparticles in the experimental SEPs and evaluate the enamel surface integrity both before bracket bonding and post bracket debonding. Phase determination and remineralizing capability of the modified SEP were characterized by X-ray diffraction and Raman spectroscopy, respectively.
Results
The addition of nHA or nACP to the SEP significantly reduced the SBS, ARI, and enamel damage (p < 0.05) as compared to the control SEP; however, only nHA-SEP survived the thermocycling protocol and yielded acceptable SBS (13.38 MPa). Enamel remineralizing ability of the developed nHA-SEP was confirmed by both FESEM images and Raman phosphate map.
Conclusions
Incorporating nHA into SEP resulted in clinically acceptable bond strengths with remineralizing ability.
Clinical relevance
The newly developed nHA-SEP has unprecedented ability to simultaneously etch, prime, and remineralize the enamel in a single step leaving immaculate enamel surface with the potential of saving cost and time at the post-debonding step.
... In order to increase durability of dentin adhesive bond, addition of inorganic fillers in adhesives is suggested to improve their interaction with the dentin surface and possibly minimizing dentinadhesive degradation [5][6][7] . Previous studies have shown that addition of fillers in adhesives can reduce water sorption and solubility, in addition to enhancing its mechanical properties [5][6][7][8][9] . Therefore, addition of inorganic nano-materials as fillers to improve the physical and mechanical properties of dentin adhesives is highly desirable. ...
Objectives: This study assessed the antibacterial effect and the shear bond strength of self-etch adhesive after incorporating Graphene oxide nanoparticles. Materials and methods: Graphene oxide nanoparticles was synthetized and incorporated within a self-etch adhesive (Quadrant Uni-SE-Bond) with 0% control group (without Graphene) (group I), 2% (group II) and 5% (group III). The antibacterial effect was evaluated against S. Mutans using agar well diffusion method. 24 holes (n=8) with a diameter of 6-8 mm were performed and the inhibition zone was evaluated in millimeters after 24 hrs. For shear bond strength, 12 premolars were sectioned horizontally to expose dentin and to obtain 24 specimens for assessing the bond strength (n=8). Composite cylinders (2x2 mm) were bonded to the dentin and subjected to shear bond strength using universal testing machine. Results: The incorporation of Graphene oxide nanoparticles into self-etch adhesive showed a significantly dose-dependent antibacterial effect. On the other hand, the shear bond strength reported no significant difference between the three groups. Conclusion: Addition of Graphene oxide NP to self-etch adhesive produced an antibacterial effect without affecting the bond strength.
... More interfaces are created as a result of the dissolving, which can affect filler degradation. 36 A silica-filled composite may be said to degrade faster from a clinical perspective. ...
Objectives: The aim of this study is to investigate the effect of a high concentration hydrogen peroxide
bleaching agent on the surface roughness of four different composite resins.
Material and Methods: For this purpose, with the help of teflon molds, a total of 24 composite samples (10 x 4
mm) were prepared, with n = 6 for each composite group. The samples were placed in teflon molds in two
layers of 2mm and covered by transparent mylar strips at the top and bottom surfaces. The material was
compressed with finger pressure between 1mm thick glass plates. The tip of the light device was applied
directly from the transparent tape surface for the polymerization of the samples. Polymerization of the
samples was carried out using LED light device in each layer. After the samples were polished with finishing
discs, they were kept at 37°C for 24 hours in the distilled water. Surface roughness values (Ra) of all samples
were measured with a profilometer device. After the first measurements, a whitening agent containing 35%
hydrogen peroxide was applied to the surfaces, and surface roughness measurements were repeated after this
process. Data were analyzed statistically using analysis of variance (ANOVA) and Tukey tests.
Results: Profilometric evaluations showed a small increase in the surface roughness of all samples with a
bleaching agent. When the initial and treated measurements of the groups were compared, the difference
between the measurements was found statistically insignificant.
Conclusion: The office bleaching agent containing 35% hydrogen peroxide did not make any difference in the
roughness of the nanohybrid and microhybrid composite resins.
Keywords: Hydrogen Peroxide, Surface, Composite, Bleaching, Roughness
... More interfaces are created as a result of the dissolving, which might impact filler deterioration. 54 In light of all this information, the filler structure is considered to be of primary importance, although other factors, such as filler particle shape, the proportion and size of the largest fillers in composite resins, may play a role in the surface roughness caused by bleaching agents. 3 Based on data reported in previous studies 34,37 , surface polishing should not be the preferred treatment after bleaching, considering that extensive and irreversible deterioration may have occurred in composite restorations. ...
EFFECT OF HIGH CONCENTRATION PEROXIDE BLEACHING AGENTS ON THE SURFACE PROPERTIES OF COMPOSITE RESTORATIONS
... The diffusivity of the ethanol solution in dental composite specimens is greater than that of water in dental composites. (26,27) The solubility parameter describes the ease with which a molecule will penetrate and dissolve within another substance, and the solubility parameter of ethanol is closer to that for the dental composite 3x104 J 1/2 /m 3/2 , while the solubility parameter of water is about 4.8x104 J 1/2 /m 3/2 this value has been shown to fall beyond the solubility parameter ranges for Bis-GMA based composite and thus has little influence on matrix softening, while ethanol has greater permeability. (24) The results further confirmed earlier results by Lee et al, (3,28,29) they suggested that the materials were not very susceptible to chemical breakdown by artificial saliva which contains 90-95% water for up to 30 days of immersion, but a significant decrease in shear bond strength was noticed after exposure to 75% ethanol. ...
The effect of food simulants on the bond strength of orthodontic metal brackets bonded to enamel with light cured composite was studied. One hundred twenty extracted human premolars were selected and randomly divided into three equal groups each with 40 teeth, representing the adhesive bonding generation (5th, 6th and 7th). Each group was subdivided in to two subgroups which represented the storage media, which are distilled water (DW) and 75% aqueous ethanol (Food simulating solution-FSS). Then the storage media group was subdivided into two subgroups with 10 teeth each, representing two storage periods (1 day and 30 days). At the end of the storage period in the immersion media the brackets were debonded by an Instron universal testing machine to measure the shear bond strength. It was found immersion in the food simulants for 30 days significantly reduces the bond strength of light cured composite brackets.
... To counteract this loss of adhesive's bond strength, inorganic fillers are added to the adhesive that improves their dentin interaction and probably curtail the degradation of the adhesive [11]. Past studies have validated that nanofillers' incorporation in the adhesive reduces their solubility and improves their mechanical properties [12,13]. Accordingly, the inclusion of nano-inorganic fillers to enhance various properties of dentin adhesives is warranted. ...
The present study aimed to synthesize and equate the mechanical properties and dentin interaction of two adhesives; experimental adhesive (EA) and 5 wt.% reduced graphene oxide rGO) containing adhesive. Scanning electron microscopy (SEM)-Energy-dispersive X-ray spectroscopy (EDX), Micro-Raman spectroscopy, push-out bond strength test, and Fourier Transform Infrared (FTIR) spectroscopy were employed to study nano-bond strength, degree of conversion (DC), and adhesive-dentin interaction. The EA was prepared, and rGO particles were added to produce two adhesive groups, EA-rGO-0% (control) and rGO-5%. The canals of sixty roots were shaped and prepared, and fiber posts were cemented. The specimens were further alienated into groups based on the root canal disinfection technique, including 2.5% sodium hypochlorite (NaOCl), Photodynamic therapy (PDT), and ER-CR-YSGG laser (ECYL). The rGO nanoparticles were flake-shaped, and EDX confirmed the presence of carbon (C). Micro-Raman spectroscopy revealed distinct peaks for graphene. Push-out bond strength test demonstrated highest values for the EA-rGO-0% group after NaOCl and PDT conditioning whereas, rGO-5% showed higher values after ECYL conditioning. EA-rGO-0% presented greater DC than rGO-5% adhesive. The rGO-5% adhesive demonstrated comparable push-out bond strength and rheological properties to the controls. The rGO-5% demonstrated acceptable DC (although lower than control group), appropriate dentin interaction, and resin tag establishment.
... Color perception is directly connected to light scattering by particles in the composite resin and interfaces among them. This is one of the well documented weak points of composite materials [47]. ...
... It was reported that aging can change the translucency of the composites due to changes in scattering and absorption properties [33]. Previous studies reported that water from the bleaching agent is released during the bleaching procedures [29,34] and it is able to penetrate within the polymer chains and stay between the layers [27,35]. This process can induce hydrolytic degradation of the material [29,34,36], leading to filler-matrix interface debonding and changes in optical properties due to an altered pattern of light diffusion [32,33,36]. ...
... Color perception is directly connected to light scattering by particles in the composite resin and interfaces among them. This is one of the well documented weak points of composite materials [47]. ...
... They speculated that nano-filled composites take up more water due to the larger surface area to volume ratio of the fillers in nano-filled compared with those of -for example -the microhybrid composites. In 1988 already Kalachandra suggested that the filler-matrix interface provides paths of facile diffusion of water [97]. ...
The aim of this study was to evaluate the mechanical performance of resin composites after 10 or 40 s of light curing. Subsequently the influence of water absorption on the performance on the composite is examined. Specimen of dental resin composite (TetricEvoCeram, IvoclarVivadent) were produced in disc- and bar-shape and cured for either 10 s or 40 s. Afterwards they were stored in distilled water for 24 h, 14 or 60 d at 37°C and then weighed for water absorbance tests. Bar-shaped specimen were produced and stored similarly, with the 24 h probes, however, stored in dry conditions. To investigate initial flexural strength (FS) specimen un- derwent quasi-static loading and cyclic loading for flexural fatigue strength (FFS) under 4-point bending. It was determined that FS and FFS decreased with prolonged storage duration. 40 s polymerisation time improved mechanical performance espe- cially for short storage durations (24 h and 14 d). After 60 d only minimal improvements were observed. Mechanical properties of resin composites were impaired by increasing storage duration but improved by prolonged curing time. The performance of composite fillings positively increases with pro- longed polymerisation time, even though water absorption reverses this effect in the long run.
... This may explain the results of △E ab , since conventional resin has these monomers in its composition, corroborating the findings of Mansouri and Zidan. 34 The results presented values above the limit of 2.7, 22,23 which is considered clinically acceptable. 22 However, the color change obtained by the CIEDE2000 formula (ΔE 00 ) is better correlated with visual perception than the CIELAB. ...
The aim of this in vitro study was to evaluate the color stability of a bulk-fill (Filtek One Bulk Fill, 3M ESPE) and a conventional (Filtek Z350 XT, 3M ESPE) composite resin light-cured at different distances, before and after being submitted to staining with a coffee solution. Sixty specimens of each composite resin were prepared and light-cured at distances of 0, 2 and 4 mm, using a LED light-curing unit (Valo, Ultradent). The specimens were separated (n = 10) for immersion in either distilled water or coffee solution (10 minutes a day for 8 days) to stimulate staining. Color evaluations were performed before and after immersion in the solutions, according to CIELab (△Eab), CIEDE2000 (△E00) and the Whiteness Index for Dentistry (△WID). Kruskal Wallis and Dunn tests, Mann-Whitney tests and Wilcoxon test were applied (α = 5 %). The a* value for conventional composite resin showed a significant increase after immersion in coffee and distilled water (p < 0.05). Both composite resins showed greater b* values when immersed in coffee than in distilled water, with no significant difference among the light-activation distances (p > 0.05). There was no significant difference for L* among the light-activation distances; both resins showed significant decrease in L* after immersion in coffee (p < 0.05). Color change (△Eab, △E00) and difference in whiteness (△WID) were higher for conventional resin when immersed in the coffee solution at all the light-activation distances. Conventional composite resin presented a higher staining value than bulk-fill composite resin, regardless of the light-activation distance.
... Söderholm und Roberts (1990) Füllstoffmatrix-Grenzflächen (Ferracane et al., 1995). Über Defekte entlang der Grenzflächen des Füllkörpers kann das Wasser ins Komposit eindringen (Kalachandra, 1989;Mortier et al., 2005). Die Wasseraufnahme führt zu einem Volumenanstieg und zur vermehrten Trennung der Füllfaser von der Matrix, die wiederum zum Anstieg der Oberflächenrauheit beiträgt (Drummond, 2005;2008). ...
Das Ziel der vorliegenden In-vitro-Studie war es, den Einfluss verschiedener Lösungsmittel auf die Oberflächenrauheit dentaler Komposite zu untersuchen. Die Oberflächenrauheit der Komposite wurde mit einem Laserprofilometer gemessen.
Dafür wurden drei Kompositmaterialien, ein Nanohybrid (Filtek™ Supreme XT), ein Ormocer (Ceram X™) und ein Siloran (Filtek™ Silorane) in vier verschiedenen Lösungsmitteln (Ethanol 75 %, Aceton, Speichel und isotonische Kochsalzlösung) gelagert. Jedes Komposit wurde auf einem Trägermaterial befestigt und in den vier Lösungsmittel eingelegt. Pro Lösungsmittel wurden 18 Proben angefertigt. Somit wurden insgesamt 216 Proben hergestellt. Die Proben wurden in Flaschen bei Raumtemperatur gelagert und zur Messung der Oberflächenrauheit jeweils nach 24 Stunden, sieben Tagen und 28 Tagen aus den Gefäßen genommen. Direkt nach der Messung wurden die Gefäße mit frischer Einlagelösung gefüllt. Rauheitsveränderungen wurden mittels Laserprofilometer und in drei Parametern Ra, Rt-Ry und Rz gemessen. Aceton musste aufgrund der zu starker Aggressivität auf das Trägermaterial beim weiteren Verlauf der Studie ausgeschlossen werden.
Die Rauheit von Filtek™ Silorane hat sich über sie gesammte Lagerungszeit von 28 Tage nicht signifikant verändert (p>0,05). Bei Ceram X™ trat nur in den Parametern Rt-Ry und Rz eine signifikante Veränderung auf (p<0,05). Bei Filtek™ Supreme XT wurde eine Veränderung der Rauheit in allen Lösungen festgestellt, wobei diese in Ethanol am größten war. Damit zeigt Filtek™ Silorane mit keinerler signifikante Veränderungen in der vorliegenden Versuchsreihe die wenigestens Oberflächenveränderung nach Einlage in Lösungsmitteln.
Fazit: Die Lösungsmittel dieser Studie konnten eine Veränderung der Oberflächenrauheit bei den Kompositen erzielen. Diese Veränderung ist sowohl abhängig vom Lösungsmittel als auch dem verwendeten Komposit.
... This was also illustrated by Kalachandra (1989) in the case of PMMA filled with barium-based particles (Table 7.11). The detrimental effects of the interface can be partially attenuated by the use of proper coupling agents (such as 4-methacryloxyethyl trimellitic anhydride). ...
... Ethanol has dissolving feature similar to Bis-GMA and this may farther improve its seepage into the composite leading to farther destruction (25) . The diffusion properties of the ethanol solution in dental composite specimens is much more than that of water (26) . ...
Objective: To investigate the effect of using different food simulant materials on the shear bond strength (SBS) of orthodontic bracket after Icon application. DESIGHN: Laboratory study. SETTING: Pediatric dentistry, Orthodontics & Prevention dentistry department, Dentistry College, Kufa University & department of materials, Technology university. Methods: Metal brackets were bonded to 48 extracted premolars and were randomly arrange for three categories with 16 teeth for each, revealing the storage solutions, which were distilled water, 50% aqueous ethanol (alcoholic food), and corn oil (fatty food). Then each category was split for two subgroups, with 8 teeth describing Icon application, all specimens are immersed in their corresponding food simulants for 30 days. After the completed proposed time, the specimens were debonded by using an Instron apparatus to test the SBS. Results: Results showed significantly diminished the bond strength of orthodontic adhesive after holding the specimens for 30 days in the food simulants specially ethanol (highest for 50% ethanol, less for corn oil & least for D.W). Icon categories showed higher SBS rather than non-Icon categories. Conclusion: Application of Icon on enamel will increase the bond strength & the food simulating agents especially food and rinses containing ethanol could influence the orthodontic bond strength which causes bond failure so that the clinicians should inform their patients concerning their possible adverse effects and complications.
... Adhesives with inorganic fillers presented improved chemical and mechanical properties [1,2,9]. In addition, their presence within the resin matrix can reduce degradation over time, leading to a longer-lasting material when bonded to the dental substrate [4,25]. ...
The aim of the present study was to formulate dental adhesives with different concentrations of LiNbO3 and to evaluate their physicochemical and antibacterial properties. A dental adhesive was formulated using methacrylate monomers and photoinitiators and used as a control filler-free group. Subsequently, three experimental adhesives doped with LiNbO3 at different concentrations (1 wt.%, 2 wt.%, and 5 wt.%) were also formulated. All the experimental adhesives were assessed to evaluate the degree of conversion (DC), softening in solvent, immediate and long-term microtensile bond-strength (μ-TBS), radiopacity, ultimate tensile strength, and antibacterial activity. The incorporation of 1 wt.% of LiNbO3 had no negative effect on the DC of the adhesive resin compared to the control group (p > 0.05). We observed a decrease in the percentage of softening in solvent in the group LiNbO3 at 1 wt.% (p < 0.05). The addition of LiNbO3 increased the radiopacity at a concentration above 2 wt.%, and there was also an increase in cohesive strength (p < 0.05). The immediate μ-TBS increased for LiNbO3 at 5 wt.% (p < 0.05), and there was no statistical difference for the other groups compared to the control (p > 0.05). After six months, the group with 5 wt.% still presented the highest μ-TBS (p < 0.05). The adhesives showed no antimicrobial activity (p > 0.05). LiNbO3 was successfully incorporated in dental adhesives, increasing the radiopacity and their resistance to degradation. Although LiNbO3 offered no antibacterial properties, the reliability of LiNbO3 incorporation in the adhesive encourages new tests to better investigate the antimicrobial action of LiNbO3 through temperature variation.
... Recent innovative approaches in remineralizing the hybrid layer may improve the resistance of hybrid layers to different types of degradations overtime, and have an important role in caries prevention (1) . Codex Recently, nanoparticles have been used in the formulation of restorative composite systems (2) . Nanoparticles have very small size which enables them to penetrate with the adhesive resin matrix into the dentinal tubules resulting in a composite adhesive layer with improved characteristic (3,4) . ...
... 27 As the inorganic filler content decreases, the interface between fillers and matrix tends to become larger, providing paths for easy water diffusion. 18 This may have increased water sorption by the composite, which reached adhesive and nanometric spaces located inside the hybrid layer, making adhesive polymers act as semi-permeable membranes even after polymerization, thus increasing silver uptake. 36 It was reported that even in the absence of gaps, silver ions could penetrate the hybrid layer in microporosity zones. ...
Purpose:
To evaluate the bond strength (BS), nanoleakage, and marginal adaptation (MA) of three bulk-fill and one conventional composite, submitted or not to mechanical and thermal cycling.
Materials and methods:
Ninety-six molars were selected and 4-mm-deep class I cavities were prepared and restored. Half of the teeth were submitted to mechanical and thermal cycling (MTC). Teeth were divided into 8 groups (n = 12), according to the composite used - Filtek Z350 XT (Z350), Tetric N-Ceram Bulk Fill (TET), Filtek Bulk Fill Posterior Restorative (FBF) and SonicFill (SF) - and aging, submitted or not to MTC. Fifty-six teeth (n = 7) were used for bond-strength testing, which was performed on stick-shaped specimens obtained from the restored area. Two sticks per tooth were selected to assess nanoleakage. For MA analysis, 40 teeth (n = 5) were sectioned parallel and perpendicular to the occlusal surface and resin-based replicas from the obtained surfaces were prepared. Fracture pattern, nanoleakage, and MA were evaluated using SEM. Quantitative analysis of nanoleakage and MA were performed with ImageJ software. Data obtained were submitted to two-way ANOVA and Tukey's test (ɑ = 0.05).
Results:
TET presented good MA and higher values of BS when compared to SF. Z350 and FBF presented poorer MA and lower BS, which was statically similar to the other groups. SF obtained the best MA values. Regarding nanoleakage, the highest values were obtained for TET, which differed significantly from the other groups, which presented similar results among themselves. Aging by MTC solely affected MA.
Conclusion:
Bulk-fill composites presented similar performance to the conventional nanocomposite and remained stable when aged.
... This was also illustrated by Kalachandra (1989) in the case of PMMA filled with barium-based particles (Table 7.11). The detrimental effects of the interface can be partially attenuated by the use of proper coupling agents (such as 4-methacryloxyethyl trimellitic anhydride). ...
This chapter reviews several cases of methacrylate-based polymers used for medical applications. The main chemicals and fillers used for elaborating biomaterials are presented, together with the main synthesis reactions. Their properties are recalled and discussed using the well-established structure–properties relationships of polymer physicochemistry. Last, the main degradation mechanisms are recalled, together with their consequences on the engineering properties of polymethacrylates, in order to predict the long-term in vivo behavior of such complex materials.
... In addition to the diffusion through polymeric matrix, water sorption can take place by flowing along the filler/matrix interface 35) . In conventional composites with silanized glass fillers, this occurs as the composite ages and siloxane bonds are hydrolyzed 36) , while in experimental bioactive composites with a high amount of hydrophilic unsilanized filler (up to 40 wt%), the interfacial path of diffusion exists from the beginning of immersion 37,38) . As the water sorption advances, micro-cracks are formed at the filler/matrix interface, facilitating further water sorption and degradation of the composite structure 39) . ...
The aim of this study was to evaluate water sorption and solubility of two series of experimental composites containing amorphous calcium phosphate (ACP) or bioactive glass (BG). Water sorption and solubility were measured for up to 287 days. The surface precipitation of calcium phosphates was evaluated by scanning electron microscopy. The ACP-series showed higher water sorption (223–568 µg/mm³) than the BG-series (40–232 µg/mm³). In contrast, the ACP-series had generally lower solubility (37–106 µg/mm³) than the BG-series (1–506 µg/mm³). The constant specimen mass for the ACP-series was attained after 14 days of water immersion, while the mass decrease due to long-term solubility in the BG-series lasted beyond 287 days. Calcium phosphates precipitated in composites with the BG filler loading of 10 wt% or more, as well as in all of the ACP-containing composites. The experimental composite series showed water sorption and solubility considerably higher than commercial materials.
... Because of its bioactivity and remineralization capability, it is also used as filler in adhesive resins (Collares et al., 2012;Labella, Braden, & Deb, 1994;Sadat-Shojai, Atai, Nodehi, & Khanlar, 2010). By adding HA filler to the adhesive resins, degradation of hybrid layer could be reduced and the bonding strength may be increased (Kalachandra, 1989;Van Landuyt et al., 2007). ...
The purpose of this study was to evaluate the micro‐tensile bond strength (μTBS) of dentin bonding agents containing different ratios of nano‐sized hydroxyapatite fillers (HA). X‐ray diffraction analysis was used for characterization, and scanning electron microscope (SEM) analysis was used to determine the HA particle size after that HA were mixed a bonding agents without filler. Dentin bonding agents were divided into four groups according to addition of different ratios of nano‐sized hydroxyapatite fillers as 2% HA, 5% HA, 7% HA, and no‐filler control group. The teeth (n = 32) were sectioned with a low‐speed diamond blade under water cooling to expose the mid‐coronal dentin. Following the bonding application, restorations were applied incrementally. Each tooth was cut on the x and y axis, and each specimen was fixed to a testing device and stressed until failure occurred. The debonded specimens were examined under 250× magnification without a coating layer at 2.00 kV using a SEM to determine failure patterns. μTBS data were analyzed using a anova and Tukey's post hoc test. The failure mode data were analyzed using the Chi‐Square test. The maximum mean value of μTBS was in the 7% HA group, while the minimum mean value of μTBS was observed in the control group. 7% HA group was statistically significant and higher than other groups while there were no significant differences between the control, 2% HA, and 5% HA groups. According to SEM analysis, fracture analysis revealed that the mixed fracture type was seen more often than the other fracture types. The particle size and amount of HA fillers added to the adhesive resin seem to affect the success of the bond strength to the dentin. Adding different ratio nano‐sized HA fillers to the adhesive resin contributed positively to the immediate μTBS values in the dentin.
... It was reported that aging can change the translucency of the composites due to changes in scattering and absorption properties [33]. Previous studies reported that water from the bleaching agent is released during the bleaching procedures [29,34] and it is able to penetrate within the polymer chains and stay between the layers [27,35]. This process can induce hydrolytic degradation of the material [29,34,36], leading to filler-matrix interface debonding and changes in optical properties due to an altered pattern of light diffusion [32,33,36]. ...
Objectives: To evaluate the effect of bleaching on colour, gloss, translucency, and microhardness of two types of resin composites (Charisma Classic and Filtek Z350 XT), previously aged.
Materials and methods: Forty specimens of each material were artificially aged for 300 hours (UV-accelerated aging). Specimens were then treated with 35% hydrogen peroxide (Whiteness HP) in four 15-minutes sessions, totaling one hour of bleaching. Colour coordinates CIE L*a*b* and parameters of translucency (PT) were measured using a spectrophotometer (CM2600d – Konica Minolta), surface gloss readings were performed with a glossmeter (Novo-Curve – Rhopoint TM), and microhardness was assessed using a hardness device (FM-700, Future-Tech). Measurements have been performed after artificial aging as well as after the first and last bleaching protocol. Data were analyzed by two-way ANOVA and two-way repeated measures ANOVA, followed by Tukey’s test (5%).
Results: The bleaching procedures of aged resin composites decreased the gloss and increased the translucency, but did not alter colour and microhardness.
Conclusion: Bleaching procedures should be used carefully when resin composite restorations are present.
... Enhancement in the properties of materials has been an area of research for a long time. Addition of llers, to the neat materials is an e cient method to enhance their properties [9][10][11][12]. Di erent types of llers are used to enhance properties of polymers. ...
Hydrogenated-Nitrile-Butadiene-Rubber (HNBR) is known for its good physical strength. It is a widely used rubber in electrical insulation and other high performance applications. Performance of HNBR is affected in high temperature and an aggressive fluid environment. Adding silica to HNBR may overcome this problem. In order to investigate the effect of fluids and temperature on HNBR/silica composites we prepared multiple composites of HNBR with 8.3, 16.7, 33.4, 50 and 66.7 phr of silica (SiO 2 ) by two roll compounding method. Swelling index and thermo gravimetric analyses were performed. Calculations of swelling indexes were performed at different time periods with ethanol, toluene and water. For thermo gravimetric analysis (TGA), thermo grams of samples were obtained and % char yields at 550 °C were analyzed for all samples. Improvements with the addition of silica were recorded up to a great extent in both analyses. Swelling index decreased with the addition of silica as compared to neat HNBR and reached an optimum position with 50 phr silica loading in ethanol, 8.3 phr in water and 66.7 phr in toluene. Moreover, the HNBR composite with 66.7 phr of silica was found to be the highest thermally stable sample and lost less than 60% of weight at 550 °C in comparison to neat HNBR in which 80% of weight loss occurred at 550 °C.
... 36 The present study shows a higher color stability of a nanofilled alteration because color perception has a direct relation with scattering. 2 That means that the interface between the organic matrix and filler particles is the most sensitive region to suffer hydrolytic degradation through water sorption. 37 Therefore, the light scattering through the interface might suffer more interference in wider particles. 2 The positive results obtained in composites light activated with higher irradiances might be explained by the composite higher DC, which leads to lower water uptake and absorption. ...
Objective
The aim of this study was to evaluate the color stability of two resin‐based composites photo‐activated by two light curing units (LCU) with different irradiances.
Materials and Methods
Hundred disc‐shaped specimens (2‐mm thick) of a nanofilled (FZ‐ FiltekTM Z350 XT, 3M ESPE) and a microhybrid (ED—Empress® Direct, Ivoclar Vivadent) composites were photo‐activated with two LCU: Valo® Cordless, Ultradent (VA—1800 mW/cm²) or Radii‐cal, SDI (RA—900 mW/cm²). Samples (n = 5) were immersed during 12 days in distilled water (WT), orange juice (OJ), red wine (RW), coffee (CF), or Brazilian tea (BT). CIELAB coordinates were obtained using a spectrophotometer (Easyshade 4.0, Vita Zahnfabrik) before (T0) and after (T1) immersion. CIEDE2000 color difference (ΔE00) and whiteness index for dentistry (WID) were calculated. Data was analyzed by two‐way ANOVA and Tukey's test (α = 0.05%).
Results
FZ light‐activated by VA showed higher L* and WID values (T0) and lower ΔE00 values after immersion in WT, OJ, and RW. However, there was no effect of both factors on ΔE00 when samples were immersed in BT and CF. ED light‐activated by RA showed significant higher C* values (p ≤ .05).
Conclusions
The nanofilled composite photo‐activated with higher irradiance showed greater L* and WID values and better color stability. However, all samples immersed in colored beverages showed ΔE00 values above the acceptability threshold.
Clinical Significance
Initial color of resin‐based composites can change after immersion in staining beverages. However, the best color stability was obtained by the nanocomposite photo‐activated by a light‐curing unit of higher irradiance.
Retinitis pigmentosa is an inherited disorder caused by mutation in numerous different genes, leading to loss of photoreceptors. Currently, there is no approved therapy for the recovery or suppression of the progression of this disease. In this study, we investigated a device offering sustained transscleral delivery of unoprostone isopropyl, which is a potent neuroprotective agent through big potassium channel regulation. The sustained unoprostone-release device is composed of photopolymerized poly(ethyleneglycol) dimetacrylates. It consists of a microfabricated reservoir, drug formulation, and controlled release cover, which were fabricated using three-dimensional-printed molds. In this chapter, we summarize the physicochemical properties, in vivo efficacy and safety of this unoprostone-release device. The goal is to initiate a clinical trial of this device in patients with retinitis pigmentosa.
Diş hekimliğinde dijital teknolojilerin yaygınlaşması ile birlikte hareketli protezlerin bilgisayar destekli üretimi için polimetilmetakrilat (PMMA) ve polietereterketon (PEEK) blok kaide materyalleri kullanılmaktadır. Bu materyallerin su emilimi ve çözünürlük gibi fiziksel özelliklerinin geleneksel yöntemle ısı ile polimerize edilen PMMA’dan daha üstün olduğu öne sürülmektedir. Bu çalışmada, blok PMMA, Titanyum dioksit (TiO2) içerikli PEEK kaide materyallerinin ve PEEK’in veneerlenmesinde kullanılan bir indirekt laboratuvar kompozit rezininin su emilimi ve suda çözünürlük değerlerinin ısı ile polimerize olan PMMA ile karşılaştırılması amaçlanmıştır. Blok PMMA, TiO2 içerikli PEEK, indirekt kompozit rezini ve ısı ile polimerize olan akrilikten 10×2 mm disk şeklinde örnekler hazırlanmıştır (n=40). Örnekler hassas terazide tartıldıktan sonra 7 gün süreyle distile suda 37oC’de saklanmıştır. Daha sonra hassas terazide tartılarak su emilimi oranı hesaplanmıştır. Çözünürlük ise örnekler tamamen kurutulduktan sonra tekrar tartılarak hesaplanmıştır. Su emilimi ve çözünürlük verileri Kruskal-Wallis ve post-hoc Tukey testleri ile analiz edilmiştir (p=0.05). Blok PMMA (%1.372), indirekt kompozit rezine (%0.389) ve PEEK’e (%0.212) göre daha fazla su emilimi gösterirken; ısı ile polimerize olan PMMA örnekler (%1.329) ise PEEK’e göre daha fazla su emilimi göstermiştir (p0.05). Isı ile polimerize olan PMMA, en yüksek suda çözünürlüğü göstermiştir. PEEK örnekler blok PMMA’ya (p=0.003) ve ısı ile polimerize olan PMMA’ya (p=0.000) göre daha az suda çözünürlük göstermiştir. İndirekt kompoziti, blok PMMA’ya (p=0,011) ve ısı ile polimerize olan akriliğe göre (p=0.000) daha az çözünürlük göstermiştir. Su emilimi ve çözünürlüğün hareketli protezlerde akrilik kaidenin mekanik özelliklerini, mikroorganizma tutulumunu, renklenmesini olumsuz yönde etkilediği bilinmektedir. Bu çalışmanın sonuçlarına göre TiO2 içerikli PEEK ve yüzeyinin dişeti renginde veneerlenmesinde kullanılan indirekt kompozit rezinin kaide materyali olarak kullanıldığında her iki PMMA materyalden daha az su emilimi ve çözünürlük göstermesi biyolojik, mekanik ve estetik özellikler bakımından uzun vadede hareketli protezler için yarar sağlayabilir.
While dental composite long-term aging has already been studied in the past, no data exist about the early aging while it might be detrimental regarding the composites' longevity. This study aims to better understand the effects of early water exposure on dental composites. Dental resin composites with different fillers ratio were subjected to water exposure during 24h, 1 week, or 1 month. After photopolymerization, the samples were stored different conditions, whether in wet or dry condition (W, D, respectively) and in wet conditions after a first 24h storage in dry conditions (DW). Three-point bending tests were performed to measure the flexural modulus. The samples were then subjected to a sorption/desorption protocol. While the matrix alone did not undergo any mechanical degradation with exposure time, the composites matrices presented a decrease in elastic modulus. This decrease was the highest for the matrix with non-silanized fillers. Interestingly, the DW condition was detrimental for all the samples. Regarding the sample with non-silanized fillers in DW for 1 month presented an elastic modulus lower than the matrix alone. These results were assigned to the sorption capacity of the polymer matrix, suggesting that the diffusion mechanisms and the nature of water molecules are determinant in the composite degradation. This study showed that dental composite early degradation mechanisms after water exposure are involved in the polymer matrix post-polymerization process as soon as after 24h. Such mechanisms are detrimental in terms of the dental composite efficiency and have to be understood.
The aim was to synthesize and characterize an adhesive incorporating HA and GO nanoparticles. Techniques including scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), micro-tensile bond strength (µTBS), and micro-Raman spectroscopy were employed to investigate bond durability, presence of nanoparticles inside adhesive, and dentin interaction. Control experimental adhesive (CEA) was synthesized with 5 wt% HA. GO particles were fabricated and added to CEA at 0.5 wt% (HA-GO-0.5%) and 2 wt% GO (HA-GO-2%). Teeth were prepared to produce bonded specimens using the three adhesive bonding agents for assessment of µTBS, with and without thermocycling (TC). The adhesives were applied twice on the dentin with a micro-brush followed by air thinning and photo-polymerization. The HA and GO nanoparticles demonstrated uniform dispersion inside adhesive. Resin tags with varying depths were observed on SEM micrographs. The EDX mapping revealed the presence of carbon (C), calcium (Ca), and phosphorus (P) in the two GO adhesives. For both TC and NTC samples, HA-GO-2% had higher µTBS and durability, followed by HA-GO-0.5%. The representative micro-Raman spectra demonstrated D and G bands for nano-GO particles containing adhesives. HA-GO-2% group demonstrated uniform diffusion in adhesive, higher µTBS, adequate durability, and comparable resin tag development to controls.
Glass-ionomer cement (GIG) has become widely accepted as a restorative material due to its bonding ability and sustained release of fluoride. The cement is, however, sensitive to moisture imbalance and lacks toughness. Recently, resin-modified glass-ionomer cements (RMGIC) have been introduced. These materials contain monomeric species, such as 2-hydroxyethyl methacrylate (HEMA) in addition to the components of the conventional glass-ionomer cements. Disadvantages of RMGICs include a relatively high contraction and exotherm on polymerisation. HEMA is known to be cytotoxic, leading to problems of biocompatibility, and polyHEMA swells on exposure to water, leading to dimensional instability of the cements. Addressing these problems is important in the development of the RMGICs. Using alternative monomers to replace or reduce the amount of HEMA used in the current RMGIC formulations would be appropriate. This study was divided into two parts. Initially certain properties such as water sorption, micro-hardness, flexural strength and polymerisation exotherm of commercially available RMGICs were evaluated. Long-term storage of RMGICs in aqueous solutions resulted in their high water uptakes and solubilities and large volumetric expansions. However, the surface hardness and strengths of the restorative grade RMGICs were not affected on storage in distilled water. When the materials were immersed in artificial saliva, significantly higher water uptake were obtained; the equilibrium water uptake were not reached after 20 months. As a consequence, plastic behaviour and reduced surface hardness were observed. The RMGICs also produced high exotherm during polymerisation. The second part of the study investigated the use of an experimental resin as an alternative to HEMA. The experimental resin has the advantage of low toxicity to the pulp and relatively low polymerisation shrinkage. This study compared the polymerisations of the resin and HEMA, and of mixtures of these two monomers with other dimethacrylates such as bis-GMA and UDMA. The experimental cements formulated with these resins were evaluated using similar tests to those performed in the first part and their properties were compared with those of the commercial materials. Strength and hardness of the experimental cements were higher than those using HEMA. These two parameters of all the cements increased over a period up to 30 days. Polymerisation exotherm of the cements formulated using the experimental resin combinations were similar but water sorption, solubility and volumetric expansion of these cements was lower than those of cements formulated using HEMA. This implies a higher degree of conversion of the experimental resins when compared to the HEMA model system.
In this study, the amount of water sorption, flexural strength, flexural elastic modulus, fluidity, contact angle and inorganic filler content of five commercial low-viscosity resin composites were evaluated, and the surface of each cured composite was observed by scanning electron microscopy (SEM). The amount of water sorption varied from 4.9 to 23.0μg/mm³ with the product. Flexural strength also varied in the range of 160〜200 MPa with the product. Composites with a higher filler content showed a greater flexural elastic modulus. The fluidity of composite paste increased with a decrease in the apparent contact angle of the paste. Although 10〜15μm irregular-shaped fillers and spherical fillers under 1μm in diameter were found on SEM observation, the particle size of fillers differed with the product. It was suggested that the fluidity was influenced by the matrix resin monomer.
L'étanchéité à l'interface, le retrait de polymérisation, le taux de conversion, la contrainte de polymérisation et l'influence du facteur C, l'absorption d'eau et la solubilité de trois résines composites de restauration photopolymérisables ont été évalués in vitro. Une résine condensable (Filtek P60), une résine fluide (Filtek Flow) et leur adhésif (Scotchbond 1) et un ormocer et son adhésif (Admira & Admira Bond) ont été utilisés, la polymérisation s'est faite à l'aide d'une lampe LED selon deux modes continus de 20s et 40s et selon un mode exponentiel de 20s. L'étanchéité a été évaluée selon la pénétration d'un colorant (ISO 11405) ainsi qu'en MEB, la technique de la déflection de la lame de verre a été utilisée pour déterminer le retrait de polymérisation, la contrainte de polymérisation a été déterminée à l'aide d'une machine de traction, le taux de conversion a été mesuré en spectroscopie infrarouge à transformée de Fourier, l'absorption/ solubilité a été mesurée selon la méthode ISO 4049. L'étanchéité est significativement supérieure pour tous les matériaux à l'interface amélaire par rapport à l'interface cémentaire. Les retraits de polymérisation sont significativement différents pour tous les matériaux. Le mode de polymérisation affecte significativement les cinétiques de contraction. Les taux de conversion et les contraintes de polymérisation sont significativement différents pour tous les matériaux sans influence du mode de polymérisation. La diminution du facteur C entraine une diminution des contraintes et de leurs cinétiques. D'importantes différences d'absorption/ solubilité ont été mises en évidence entre les matériaux.
Since their introduction, composite resin filling materials have replaced direct filling resins and the silicate cements as the materials of choice for anterior restorations where aesthetics are of the primary importance. These materials have met with wide acceptance in spite of several performance shortcomings. It has been reported that many of the commercial composite resin materials exhibit some leakage at the margins of the restoration (1–4) and gross surface disintegration (5). Many investigators have attempted to trace these problems to some basic properties of the system, such as water sorption and polymerization shrinkage (6). Due to the complex nature of this system, the results of these investigations have not been conclusive.
Integral absorption of bulk water in melamine-formaldehyde (1:2 mole ratio) resins has been studied. Diffusion is non-Fickian but can be quantitatively described by an equation incorporating a stress relaxation rate factor. This stress relaxation is irreversible and leads to structural degradation of the thermoset resin. The activation energy for diffusion of bulk water in the unfilled polymer is 143 ± 8 kJ mol−1 and 59 ± 4 kJ mol−1 in a cellulose-filled polymer (68% resin). The cellulose filler does not significantly alter the flexural properties of the resin nor does it prevent stress crazing, but it does reduce gross structural deterioration. A sharp ‘advancing front’ moving with has been observed. When two such fronts meet in the centre of the sample, the diffusion mechanism is altered.
Following Di Benedetto it is proposed that noncrystalline polymer regions possess an approximate semicrystalline order with chain bundles that are locally parallel along distances of several nanometers. Packing with on-average four nearest neighbors is assumed. A spherical molecule may move through such a substrate in two distinct ways: (a) along the axis of a “tube” formed by locally parallel chains or (b) perpendicular to this axis by two polymer chains separating sufficiently to permit passage of the molecule. The first process is relatively fast, generally requires little activation energy, and determines the effective jump length in diffusion. The second is responsible for the activation energy of diffusion, which is taken as the minimum energy necessary to produce a symmetrical chain separation which allows transfer of a molecule. This is calculated as a function of the penetrant diameter d and parameters Γ and β which characterize the interchain cohesion and chain stiffness, respectively. Γ is estimated from the polymer density and cohesive energy density by suitably linearizing a relation given by Di Benedetto for the potential between two polymer chains approximated as infinite strings of Lennard-Jones force centers. β is shown to be approximately obtainable from the polymer chain backbone geometry and bond rotation potentials. An expression for the diffusion coefficient D is developed which contains only one disposable parameter, the effective jump length.
Sheets of polymethyl methacrylate were weighed periodically in water and, after surface mopping, in air. A case was made for dual mode sorption kinetics with 40–60% of the water accommodated in microvoids and the remainder taken up by swelling. The kinetics of sorption departed from Fick's laws in ways which appeared to be mutually inconsistent. For example, the value of the diffusion coefficient appeared to increase not only in the course of sorption but also in desorption. This inconsistency was interpreted as an artifact due to a retarded swelling component of dual mode kinetics.
Plasticized poly(methyl methacrylate) was made by γ-irradiation of mixtures of monomer and various phthalates. Samples were immersed in water and uptake and diffusion coefficients determined. More reliance was placed on determinations made in desorption because these did not involve complications due to loss of components by dissolution. As expected, plasticizers reduced water uptake simply due to their more hydrophobic nature. An additional reduction was attributed to the filling, by plasticizer, of microvoids which otherwise would have been able to accommodate water. The diffusion coefficient of water increased with plasticizer content and there was an indication that this increase was greater above the glass transition temperature.
We synthesized 4-methacryloxyethyl trimellite acid (4-MET) and anhydride (4-META), and tried them as a reactive comonomer for adhesives to bovine enamel. In the case of non-etched enamel, tensile adhesive strength was 40-50 Kg/cm2 after one day immersion in 37 degrees C water, but it decreased below 10 Kg/cm2 after a month immersion in 37 degrees C water. It could be concluded that this adhesion was not sufficient for practical usage. Then we applied this method to an etched enamel. After a series of experiments we concluded that it was necessary to etch bovine enamel surface with 30% citric acid for practical usage. Adhesion of some dental alloys with a PMMA rod was also studied and adhesive strength in Co-Cr alloy was over 150 Kg/cm2 either after one month immersion in 37 degrees C water or 60 times thermal cycles between 4 degrees C and 60 degrees C.
An investigation of the long term water sorption and solubility of four composites has been carried out. The findings show that all materials rapidly absorb water and at the same time there is a loss of material at a slower rate. Considerable variation in results is observed in the latter stages of the experiment. The possible causes of the variations are discussed.
Properties of commercial and a series of experimental pit and fissure sealants, based on Bis-GMA were determined using rapid test procedures. By proper selection of monomeric diluent and addition of a photocrosslinking agent, the characteristics of sealant formulations can be varied widely.
It was hoped that it might be possible to establish some standard or starting point which could be used by future investigators to judge adequate levels of radiopacity of radiopaque denture-base materials. Aluminum and copper were used to define a suitable radiopacity scale. The scale was represented by two sets of specimens--one of regular outline and uniform thickness, the other of irregular shape and tapering thickness. Radiographs of the chest and abdominal regions of a cadaver were exposed, with the specimens placed on the film side and then on the opposite side of the cadaver. The results showed that it was more difficult to locate the beveled irregular specimens, that there was little difference between the chest and the abdomen with respect to ease of locating the same objects, and that the closer an object is to the film the easier it is to locate. For 95 per cent observability, an object should have a level of radiopacity at least equal to that produced by 0.20 mm. of copper.
The uptake of water by composite filling materials seems to be a diffusion-controlled process; the magnitudes of the diffusion coefficients obtained are consistent with the uptake base through the resin matrix. The diffusion coefficients measured show the diffusion coefficient to decrease with increasing water concentration, which accounts for the protracted nature of the attainment of equilibrium uptake. Diffusion coefficients are generally lower in these composites based on difunctional methacrylates, compared with methyl methacrylate, presumably because of the highly cross-linked nature of the former.
Polymethacrylate networks were made by copolymerization of a range of compositions of bis-GMA and triethylene glycol dimethacrylate (TEGDM). Polymerization was initiated both by heating with benzoyl peroxide or by photopolymerization (lambda greater than 400 nm) using camphoroquinone as sensitizer. The uptake of water increased from 3 to 6% as the proportion of TEGDM increased from 0 to 1.0. Intermediate compositions took up less water than would be predicted from the law of mixtures. Volumetric changes were determined and clinical significance discussed. A copolymer prepared by photopolymerization took up more water as the temperature was increased from 24-60 degrees C. In this range, values of the diffusion coefficient (D) conformed to the Arrhenius equation, D = Do exp (-E/RT), giving E = 42-46 kJ/mol and Do = 0.13 cm2 s-1.
Pastes were made by spatulating a hydroxyapatite powder into triethylene glycol dimethacrylate (TEGDMA) that contained benzoyl peroxide. For comparison, similar pastes included 5 wt-% 4-methacryloxyethyl trimellitic anhydride (4-META) in the TEGDMA. Composites were made by heating at 120 degrees C under pressure. Inclusion of 4-META reduced the rate of diffusion of water by about one-third, at 27 degrees C. Also after thermal cycling in water, inclusion of 4-META decreased the fractional drop in compressive strength by about one-half. Examination of fracture surfaces indicated that inclusion of 4-META improved the wetting of filler particles and gave more coherent composites. All these findings are consistent with the view that 4-META acts as a coupling agent.
Four composite resins were used in various aspects of this study in which their physical and mechanical properties were determined. Polymerization contraction, thermal dimensional change, indentation resistance and recovery, compressive properties, and tensile strength were among the properties evaluated. Water sorption and solubility were tested also. In a test for surface roughness, the effects of 15 finishing procedures on one composite resin were evaluated. Smoother finishes were obtained with use of white Arkansas stones and silicon carbide disks; use of green or diamond stones is recommended for removal of gross excesses which are away from the enamel margin.
Physical properties were determied for radiopaque composite denture base materials consisting of poly (methyl methacrylate) as thematrix and 30, 40, and 50% by weight fo a singlane-treated barum fluoride-containing glass powder as the reinforcing filler. Specimens without glass were include for comparision.
All of the materials met the requirements of Amerrican ental Association Specification No. 12 for Denture Base Polymer except that t6he material containing 50% glass had less deflection than the minimum required at the 5000-gm load in transverse testing.
There was little or no difference among thematerials with respect to hardness, in denation resistance, water sorption, color stability, and resistance to drop impact.
Addition of glass of the 30% level decreased the transevers strenght while 50% means with no glass. In general, the addition of glass increased the time to reach only slight effect on densities, and Young's, bulk, shear, and flexural moduli, had only slight effect on solubility and decreased the cold-cure repairability and the coefficient of linear thermal expanision.
The solubility of the glass power was aboutfour times that of powdered porcelain teeth after 24 hr, and totaled 0.55% afeter 5 days.
Particles of a lithium aluminum silicate, which had been treated with a silane coupling agent, were centrifuged either in an adduct of bisphenol-A/glycidyl methacrylate (Bis-GMA) or in a mixture of Bis--GMA and methyl methacrylate. Polymerization was effected by heating with 2,5-dimethyl-hexane-2,5-dihydroperoxide. Flexural strength passed through an optimum value with increasing loading of the silicate. Inclusion of 4-methacryloxyethyl trimellitic anhydride, 4-META (5 wt % on monomer), increased the optimum flexural strength by about 20% (to 240 MPa). Evidence that 4-META increased the adhesion of filler particles to the polymeric matrix was obtained by examination of fracture surfaces.
Measurement of color parameters demonstrated that hydrophobic composites had less staining capacity and greater ease of stain removal when compared with conventional composite materials. Accelerated aging of samples is important in staining tests. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/67469/2/10.1177_00220345820610010901.pdf
The leakage of filler elements from four composites after storage in water was investigated. The results showed that all fillers leaked Si, and that the micro-filled composite and the Ba- and Sr-containing glass composites leaked more Si than did the quartz-containing material. The leakage from the different fillers was explained by hydroxy-ion and stress-corrosion attacks.
Hydrophilic diluents in composite formulations slightly increase water sorption of cured resin. This increased water uptake does not result in a significant improvement in the marginal adaptation, although other properties of the resulting composites are very satisfactory.
Composite materials were made by sedimention of ceramic powders in methyl methacrylate which was then polymerized by γ-irradiation. Inclusion of 4-methacryloxyethyl trimellitic anhydride (4-META) generally was found to result in an increase in Knoop hardness number, Young's modulus, and transverse strength. Most emphasis was placed on transverse strength which was found to be increased by ca. 30% by inclusion of 4-META (5 wt %) in composites made with silanated LiAlSiO4.
However an abrupt decrease in strength was found for composites with greater than ca. 83 wt % silanated LiAlSiO4. This was shown by fractography to be due to increased porosity and dewetting at the higher filler contents. Fractography also indicated that inclusion of 4-META results in a more coherent polymeric matrix. Further evidence for greater coherence was obtained by showing that 4-META confers resistance to disintegration by chloroform.
The Nature of the Crosslinking Matrix Found in Dental Composite Filling Materials and Sealants. In: Biomedical and Dental Applications of Polymers Physical Properties and Finished Sur-face Texture of Composite Restor-ative Resin
- G F Cowperthwaite
- J J Fay
- M A Malloy
COWPERTHWAITE, G.F.; FAY, J.J.; and MALLOY, M.A. (1981): The Nature of the Crosslinking Matrix Found in Dental Composite Filling Materials and Sealants. In: Biomedical and Dental Applications of Polymers, C.G. Ge-belein and F.K. Koblitz, Eds., New York: Plenum. DENNISON, J.B. and CRAIG, R.G. (1972): Physical Properties and Finished Sur-face Texture of Composite Restor-ative Resin, J Am Dent Assoc 85: 101-108.
The Effect of Water Immersion on the Surface To-pography of Composite Restoratives
- G J Pearson
- W C Keys
- R J Verrall
PEARSON, G.J.; KEYS, W.C.; and VERRALL, R.J. (1976): The Effect of Water Immersion on the Surface To-pography of Composite Restoratives, IADR Progr & Abst 55(D): D144, Abst. No. 154. SMITH, P.N. and FISHER, M.M. (1984):
New Dental Materials, Chemical Technology Review
- P G Stechler
STECHLER, P.G. (1980): New Dental Materials, Chemical Technology Review, No. 151, Composite Restor-ative Materials, Park Ridge, New Jersey: Noyes Data Corporation, pp. 28-114.
Dental Applica-tions for Composites: A Review. The 12th Annual Meeting of the Society for Biomaterials
- D T Turner
TURNER, D.T. (1986): Dental Applica-tions for Composites: A Review. The 12th Annual Meeting of the Society for Biomaterials. Minneapolis, St. Paul, Minnesota, USA. May 29-June 1. In: Trans Soc Biomater, St. Paul, MN: Society for Biomaterials, pp. 213-214. 288 KALACHANDRA/INFLUENCE OF FILLERS ON THE WATER SORPTION OF COMPOSITES
Improved Properties of Hydroxyapatite Composites
- Marshall
Properties of Sealants Containing Bis-GMA and Various Diluents
- Brauver
Adhesion of Bowen's Resin to Teeth by Photopolymerization
- Nagata
The Effect of Water Immersion on the Surface Topography of Composite Restoratives
- Pearson
Dental Applications for Composites: A Review.
- Turner