Composite resins

Top PDF Composite resins:

Partnership for Polymer Intermediates & Composite Resins

Partnership for Polymer Intermediates & Composite Resins

• DSM will contribute its global caprolactam business (Europe, North America, its 60% stake in DNCC (China) and the caprolactam licensing business), DSM’s acrylonitrile business and DSM’s Composite Resins business including its 75% stake in JDR (China) • DSM’s 65% stake in the service organization Sitech Services held via its caprolactam

23 Read more

Effect of Tea on Color Change of Silorane and Methacrylate based Composite Resins

Effect of Tea on Color Change of Silorane and Methacrylate based Composite Resins

This in-vitro experimental study was conducted on P90 and Z250 composite resins. The characteristics and composition of these materials are presented in Table 1. Ten specimens measuring 10 mm in di- ameter and 2 mm in height were fabricated with A3 shade of the mentioned composites. The re- quired amount of the mentioned composites were placed into the molds and pressed by placement of one mm thick glass slabs beneath and above the metal mold. By doing so, air entrapment, voids and surface irregularities were eliminated. Samples were cured for 120 s from each side using the over- lapping technique and LED light-curing unit (Star Light Pro, Italy) with 600 mW/cm 2 intensity (in- tensity of the device was assessed with a radiome- ter after fabrication of each specimen). Specimen surfaces (upper, lower and lateral surfaces) were polished by the use of low-speed hand piece and Soflex polishing discs (3M ESPE) starting from
Show more

5 Read more

Effect of an Increase in Nano-Filler Content on the Mechanical Properties of High-Leucite Composite Resins Useable in Dentistry

Effect of an Increase in Nano-Filler Content on the Mechanical Properties of High-Leucite Composite Resins Useable in Dentistry

In this study, flexural strength values in the conventional composite resin group and the groups with composite resins reinforced with nanoparticles at 1%, 5%, 10% and 20% concentrations were 51.4 ± 59.08, 52.4 ± 85.08, 52.1 ± 11.77, 56.5 ± 90.75 and 58.5 ± 15.75 MPa, respectively. The most important consideration in relation to the material strength is the fact that the strength is not an inherent property of a material, i.e. the material strength depends on the material status and the technique used to determine its strength. In addition, the discrepancy between the results of studies might be attributed to various factors, including the preparation technique, the composite resin type and the amount and size of nanoparticles incorporated into the material. In fact, in the present study, as it was expected the ceramic fillers were more resistant to the tensions applied and overall they resulted in an increase in the flexural strength of composite resins Figure 1 and Table 1.
Show more

6 Read more

The effect of duration of finishing and polishing on the surface roughness of two composite resins

The effect of duration of finishing and polishing on the surface roughness of two composite resins

who emphasized that the composite resins with higher percentage of loading and better distributed particles in the resinous matrix have greater surface smoothness. Resin composites with harder and larger filler particles like Composan ceram hybrid composite are expected to have higher Ra value after polishing. Harder filler particles are left protruding from the surface during polishing as the softer resin matrix is preferentially removed. Also this study corroborated with Duygu et al 26 , who demonstrated that hybrid composite showed high roughness average value Ra, likely due to the size of the filler particles that were exposed after polishing or dislodge. Also in this study, it was found that there was no significant difference between the groups that finished and polished for 15 seconds and those for 30 seconds (for the same material). This result may contribute to the effectiveness of finishing kit used in this study with a relatively short polishing duration in remov- ing the scratches from the surfaces of composite resin and produced a smooth surface. Morgan 27 reported that the ability to produce a smooth surface with the use of the finishing kit depends on their cutting filler particles and matrix resin equally. This result came corroborate with those of Vera et al 20 , who stated that increasing the
Show more

6 Read more

Effect of Accelerated Artificial Aging on Translucency of Methacrylate and Silorane-Based Composite Resins

Effect of Accelerated Artificial Aging on Translucency of Methacrylate and Silorane-Based Composite Resins

shade of composite resins and was clinically acceptable in some and unacceptable in some others. The majority of studies on the service and survival of silorane-based composite resins have focused on their mechanical properties and only limited studies have investigated their optical characteristics. Furuse et al, [19] indicated that silorane-based composites had superior color stability and translucency compared to methacrylate-based composite resins. Perez et al, [9] reported that silorane-based composites had better polymerization-dependent chromatic stability but less translucency compared to six methacrylate-based composite resins. Kaizer et al, [20] showed that the translucency of silorane-based composites and the opacity of methacrylate-based composites increased by water storage. Considering the small number of studies comparing the translucency stability of methacrylate- and silorane-based composites and their controversial results, this study aimed to compare the translucency stability of three methacrylate-based (Filtek Z250, Filtek Z250XT and Filtek Z350XT) and one silorane-based (Filtek P90) composite after accelerated artificial aging (AAA). The null hypothesis was that AAA would have no effect on the translucency of methacrylate- and silorane-based composites.
Show more

9 Read more

A comparative evaluation of flexural strength of composite resins on glass fibre reinforcement

A comparative evaluation of flexural strength of composite resins on glass fibre reinforcement

Hybrid composites are formulated to provide better strength, wear resistance, polishability and coefficient of thermal expansion of hybrid composite, is close to that of tooth structure (Burgess, 2002). So that posterior teeth can also be restored with resin based composites (Burgess, 2002). Mechanical and physical properties of reinforced composite resins are comparable to the enamel and dentin which makes it materials of choice for restoring posterior cavities (Williems, 1993). In the present study, it was hypothesized that use of reinforcing fibres will improve the load bearing properties of hybrid and microfill composites. Fibre reinforcement is currently a popular approach in aesthetic dentistry, since the composite resin itself fails to maintain an adequate retention to supporting structures (Alfredo de Aquino Gaspar Junior, 2009; Takahito, 2006). For reinforcement, glass fibres are taken because of excellent transparency and can bond chemically to dental polymers such as methyl methacrylate, Bis-GMA, or UDMA by silanization. The strength of the fibre reinforced composite structure is dependent on the adhesion between the FRC framework and veneering composite (Lassila et al., 2005). In cases where composites are reinforced with glass fibre, position of the fibres may affect the initial and final failures of composite. So the reinforcing capacity of fibres is dependent on their adhesion to the resin, on the orientation of the fibres, and on preimpregnation with the resin (Freilich et al., 1998; Takahito, 2006; Bae et al., 2004). Glass reinforcement fibres are made of silicon oxide, aluminum and magnesium (Vistasp. 2007). So in this study, pre-impregnated unidirectional braided glass fibres were used as a reinforcement to improve the mechanical properties of hybrid and microfill composites. According to the methodology used, fracture load was applied vertical to the glass fibre layering.
Show more

6 Read more

Subjective Comparision of Optical Integration of Mono Shade Technique and Dual Shade Layering Technique of Composite Resins.

Subjective Comparision of Optical Integration of Mono Shade Technique and Dual Shade Layering Technique of Composite Resins.

Although ceramics of various kinds have been introduced in today’s market, which provide ideal characteristics, they may not be economically viable for every patient 48 . It is in this circumstance that we fall back on composite resins which has made its comeback into dentistry in a big way. This approach reflects a contemporary attitude towards restorative dentistry, which systematically favors the selection of the most conservative option, without compromising biological, functional and esthetic integrity. Composites are usually applied to replace decayed or missing tooth structure in a more conservative manner, which requires less tooth preparation. For these reasons, composite resins currently occupy a prime position among restorative materials as they typically offer excellent esthetic solution and acceptable longevity at a lower cost than equivalent ceramic restorations. They are totally inexpensive to the clinician as well as to the patient 15 .
Show more

90 Read more

Effect of Energy Drinks on Discoloration of Silorane- and Dimethacrylate-Based Composite Resins

Effect of Energy Drinks on Discoloration of Silorane- and Dimethacrylate-Based Composite Resins

who showed higher color change in Z250 than Filtek Z350XT immersed in different energy drinks. The staining susceptibility of a composite resin might be attributed to its filler type. Inorganic fillers might debond from the matrix, leaving a void, and thus increasing the surface roughness and making the surface susceptible to extrinsic discoloration. The nanofilled composite resin used in our study contained silica fillers with a particle size of 20nm and clusters of zirconia/silica particles with sizes ranging from 0.6 to 1.4μm. It seems that the smaller filler size of Filtek Z350XT nanofilled composite resin might have allowed a smoother surface after polishing, which was less susceptible to exterior staining. Another reason for higher staining of Filtek Z250 could be a high proportion of silane present in the structure of this composite resin. It has been suggested that silanization of filler particles plays an important role in discoloration due to the fact that silane has high water sorption [25,26]. In this study, immersion in artificial saliva induced the lowest discoloration in all tested composite resins, which is consistent with other investigations. Artificial saliva has no pigments; thus the color change might be due to water sorption of the matrix, which results in swelling and plasticizing of the polymer along with interfacial gaps created between the filler and resin matrix that allow stain penetration and discoloration [4,11]. Discoloration of materials also depends on duration of exposure to coloring agents in the oral cavity [27]. As observed in the present study, in all the study groups there was a significant increase in ∆E of composite resins with an increase in the immersion time. Increased interaction between the chemical agent and resin, in addition to enhanced penetration of staining substances into resin, might be possible reasons for this finding [2].
Show more

10 Read more

In vitro evaluation of the shear bond strength between fiber posts and methacrylate or silorane based composite resins

In vitro evaluation of the shear bond strength between fiber posts and methacrylate or silorane based composite resins

New CR materials have been developed to be used in thicker increments either as an intermediate layer in composite resin restorations or as the final restorative material. A photoactive group was added to these to control the kinetic of the polymerization and also a polymerization modulator in the center of the dimethacrylate urethane mono- mer, increasing the monomer size compared to regular restorative CR. This modification reduces the polymerization shrinkage compared to the flowable and packable meth- acrylate-based CR [20, 21]. This CR is used to simplify the incremental technique and reduce clinical hours, with up to 4 mm increment thickness [22, 23]. The depth polymer- ization capability and lower polymerization shrinkage of this group of composite resins could aid in obtaining the most root-wall-fit personalization of the fiber post within the customization post technique, guarantying the thinner cement layer possible (Table 1).
Show more

11 Read more

Effect of Bleaching on Shear Bond Strength of Composite Resins to Bovine Enamel Using Three Bonding Agents

Effect of Bleaching on Shear Bond Strength of Composite Resins to Bovine Enamel Using Three Bonding Agents

Discoloration of teeth, especially the anterior teeth, is a serious problem in cosmetic dentistry and re- quires an effective treatment [1]. Reduced caries prevalence accompanied with increased living standards and improved awareness about cosmetic dentistry has provided a chance for the patients to seek more extensively for their cosmetic needs [2]. In the past, severe internal discolorations of vital and non-vital teeth were treated with crowns and veneers. This was often followed by damage to the tooth structure and biological problems [3]. With advances in dental materials, more conservative methods were proposed to solve these problems including bleaching and micro-abrasion [4]. Bleaching is used in mild discolorations such as fluorosis and in severe cases such as tetracycline pigmentations, or as a pre-treatment adjunct to la- minate veneers [5]. Sometimes composite restora- tions are needed after bleaching and sometimes bleaching reveals defects in teeth that may require replacing previous restorations. Use of composite resins immediately after bleaching is still contro- versial [6]. Therefore, there are many reports on the reciprocal effects of bleaching materials and bond strength of composite resin materials to ena- mel. Many studies have reported a significant re- duction in bond strength of composite material in bleached enamel compared to unbleached enamel [2, 3, and 7]. Several studies have shown that bond strength of composite resins decreases after bleach- ing. The delay period required to restore the bond strength following bleaching is still a matter of debate, but a one-week delay returns the bond strength to the unbleached tooth level [8]. As such, this study aimed to compare the effects of bleach- ing materials on shear bond strength of composite resin to bovine enamel using three types of bond- ing agents.
Show more

8 Read more

In Vitro Efficacy of Listerine Whitening Mouthwash for Color Recovery of Two Discolored Composite Resins

In Vitro Efficacy of Listerine Whitening Mouthwash for Color Recovery of Two Discolored Composite Resins

Original Article Objectives: durability and clinical service. Considering the increasing use of composite resins Color stability of composite resins has a significant role in their and their gradual discoloration, this study aimed to assess the efficacy of Listerine whitening mouthwash for color recovery of two discolored composite resins. Materials and Methods: This in-vitro experimental study was performed on 20 samples fabricated of Filtek Z350XT (3M ESPE, St. Paul, MN, USA) and IPS Empress Direct (Ivoclar Vivadent, Schaan, Liechtenstein) composite resins. Primary colorimetry was performed using a spectrophotometer. The samples were immersed in a coffee drink for 7 days. They were then immersed in Listerine mouthwash for 4 minutes daily for 56 days. After this period, the color change of composite resins was reevaluated. Data were analyzed using repeated-measures analysis of variance (ANOVA) and t-test.
Show more

6 Read more

Effects of Wet and Dry Finishing and Polishing on Surface Roughness and Microhardness of Composite Resins

Effects of Wet and Dry Finishing and Polishing on Surface Roughness and Microhardness of Composite Resins

Composite resins are increasingly used for direct restoration of teeth due to their optimal esthetics, favorable physical and mechanical properties, availability of efficient bonding systems and public concerns regarding amalgam [1,2]. Composite resins are classified based on the type, distribution and size of their filler particles. Microhybrid and nanohybrid composites are extensively used in anterior and posterior teeth [3]. Smoothness of the surface of composite restorations affects their durability and esthetic appearance [4]. Rough surfaces are unesthetic and result in discoloration of restoration [5], plaque accumulation, development of secondary caries and gingival inflammation [6] and wear of the opposing teeth [7]. The composite surface in
Show more

7 Read more

Led light effect on knoop microhardness of conventional composite resins and bulk fill

Led light effect on knoop microhardness of conventional composite resins and bulk fill

In conventional composite resins, the depth of polymerization is limited due to light attenuation, which leads to light reflection from the surface of the material, dispersion by filler particles and absorption by photoinitiators. Faced with these limitations, bulk fill resins have emerged from the need to reduce the clinical working time for direct composite resin restorations and by accepting the application of 4mm thick layers while maintaining a satisfactory degree of conversion and reducing the polymerization shrinkage (Par et al., 2015). Bulk fill resins generally include small amounts of fillers material to reduce light scattering, as light penetration is closely related to theamount of particles present (Ilieet al., 2013). They have modifications in their translucency/opacity to allow adequate conversion of monomers to polymers, even with the insertion of 4mm increments and the addition of photoinitiators with greater light absorption (Junior et al., 2014). However, the polymerization depth as established by the ISO 4049 method seems to be overestimated for bulk fill composites. For this reason, it is recommended to use specific microhardness measures to determine the polymerization depth (Flury et al., 2012). In addition, microhardness data for a specific material provides information on its wear, polishability and abrasive effect on antagonist teeth (Marovic Table 1. Means and standard deviation of surface microhardness (Knoop) values of experimental groups for top and bottom surface
Show more

5 Read more

Color Stability of Three Composite Resins following Accelerated  Artificial Aging: An In-Vitro Study

Color Stability of Three Composite Resins following Accelerated Artificial Aging: An In-Vitro Study

AAA exaggerates thermal, humidity and UV radia- tion conditions causing irreversible endogenous changes in the materials. As reported by Santos et al, [13] these conditions are exaggerated and do not exactly correspond to oral conditions. Consi- dering the fact that AAA conditions are much more exaggerated than oral conditions, AAA protocol needs to be moderated to some extent to better si- mulate the oral environment. Moreover, as men- tioned earlier, many other factors such as the type of light-curing unit directly and indirectly affect the color stability of composites and color change is the result of a combination of all these factors. Thus, future studies are recommended to assess the effect of type of light-curing unit on the color sta- bility of composite resins.
Show more

6 Read more

The effect of two finishing and polishing systems on the surface roughness of two composite resins

The effect of two finishing and polishing systems on the surface roughness of two composite resins

40 samples were prepared by pouring a plastic tube 2.5cm in diameter and 2cm in height with cold cure acrylic resin. The cy- lindrical cavities of 6mm in diameter and 2mm in depth were cut at the center of cold cure acrylic resin blocks, by placing a metal mold on the acrylic resin at the dough stage of setting of acrylic resin. Two types of composite resins were used, 20 samples of each type of material were prepared. Specimens were randomly divided into two groups and each group then subdivided into two other groups of 10 samples each. Composite resin was inserted into the mold, a celluloid strip and a glass slab were placed over the composite resin under the load of 200 gm 10 to remove excess mate-
Show more

6 Read more

Surface Roughness of Different Composite Resins After Application of 15% Carbamide Peroxide and Brushing with Toothpaste: An In-Vitro Study

Surface Roughness of Different Composite Resins After Application of 15% Carbamide Peroxide and Brushing with Toothpaste: An In-Vitro Study

Furthermore, in the present study, NH and MH composite resins exhibited a greater increase in surface roughness compared to MF composite resin. This phenomenon was also observed by Voltarelli et al [30]. Generally, the surface roughness of each material is the cumulative effect of several factors, including the type, shape, size, hardness and the distribution of filler particles, the type of resin matrix, the ultimate limit of the material’s conversion rate after polymerization, the quality of bond between the filler and the resin matrix and the stability of the silane coupling agent [18,21,22]. The surface roughness increases with an increase in the size of filler particles and their irregular shape vs. their sphericity. Monomodal composite resins (containing small spherical filler particles) have the smoothest surface while multimodal composite resins (containing filler particles with irregular shapes and different sizes) exhibit the roughest surface. Fillers with small sizes can attach to the resin matrix and yield a smoother surface [21]. The presence of small particles between larger fillers results in a reduction in inter-particle distance and the amount of resin matrix, improving the general properties of hybrid
Show more

7 Read more

Translucency and Masking Ability of Various Composite Resins at Different Thicknesses

Translucency and Masking Ability of Various Composite Resins at Different Thicknesses

shade or poor-color match up since the translucent ma- terials are affected by the discolored tooth structures or even the darkness of the oral cavity [4-6]. To minimize the effect of background color, shade composite resins (dentin/opaque) have been used as a backing in a layer- ing technique [7-9].The proper knowledge of differ- ences in translucency and the required thickness to mask dark background of the applied resin seems to be essen- tial, though little information is available [4-5, 10-11].

6 Read more

Relationship between Color and Translucency of Multishaded Dental Composite Resins.

Relationship between Color and Translucency of Multishaded Dental Composite Resins.

Opaque dentine shades had the lowest total and diffused translucency values, and the translucent enamel shades had the highest translucency values in Esthet-X composite resin. A similar pattern was observed with Filtek Supreme resin. Dentine shades had the lowest total and diffused translucency values, and the enamel shades had the highest translucency values. These findings are consistent with the findings of Kamishima et al. [27] who reported that the opaque shades of the composite resins were less translucent than other shades. Similarly, Ikeda et al. [21] demonstrated that opaque shade was less translucent than body shades of several restorative composite materials. Translucency of these materials is influenced by the di ff erence in the refractive indices between resin matrix and filler. As mentioned above, di ff erent shade groups of the composite resins used in this study have di ff erent compositions in terms of filler contents and nanofiller particle sizes. Composite resins with lower filler size and content are more translucent.
Show more

5 Read more

The effects of different opacifiers on the translucency of experimental dental composite resins

The effects of different opacifiers on the translucency of experimental dental composite resins

The increasing demand for aesthetic procedures encourages the manufacturers to develop dental composites with shades that can highly mimic the natural tooth and also have the ability to hide tooth discolorations. These shades include dentine, enamel, opaque and bleach shades which contain various opacifiers and pigments. However little is known about their effect on the optical properties of the composite resins.

25 Read more

Quantification of monomer elution from four composite resins and its cytotoxic effect on human gingival
Fibroblasts: An In vitro study

Quantification of monomer elution from four composite resins and its cytotoxic effect on human gingival Fibroblasts: An In vitro study

Goldberg et al (2008) 16 reviewed the in vitro and in vivo studies which identified that some components of restorative composite resins, adhesives and resin-modified glass ionomer cements are toxic. The mechanisms of cytotoxicity are related firstly to the short-term release of free monomers occurring during the monomer–polymer conversion. Secondly, long-term release of leachable substances is generated by erosion and degradation over time. In addition, ion release and proliferation of bacteria located at the interface between the restorative material and dental tissues are also implicated in the tissue response. Molecular mechanisms involve glutathione depletion and reactive oxygen species (ROS) production as key factors leading to pulp or gingival cell apoptosis.
Show more

108 Read more

Show all 5827 documents...