tetric evoceram bulk fill

Scientific Documentation

Scientific Documentation Tetric EvoCeram® Bulk Fill of 20

Table of contents

1. Introduction ........................................................................................................................ 3

1.1 A short overview of the history of composites .................................................................... 3

1.1.1 Basics ............................................................................................................................. 3

1.1.2 Filler technology .............................................................................................................. 3

1.2 A new level of efficiency in posterior restorations ............................................................. 4

1.2.1 Filler technology .............................................................................................................. 4

1.2.2 Polymerization booster ................................................................................................... 6

1.2.3 New shades .................................................................................................................... 7

2. Technical data .................................................................................................................... 8

3. Laboratory investigations ................................................................................................. 9

3.1 Depth of cure ........................................................................................................................... 9

3.2 Light insensitivity ..................................................................................................................11

3.3 Polishability ...........................................................................................................................12

3.4 Wear in the Willytec chewing simulator with Empress antagonists ...............................15

3.5 Polymerization shrinkage – mercury dilatometer ..............................................................16

3.6 Polymerization shrinkage – buoyancy measurement .......................................................16

3.7 Shrinkage force .....................................................................................................................17

5. Biocompatibility ............................................................................................................... 19

5.1 Cytotoxicity ............................................................................................................................19

5.2 Mutagenicity ..........................................................................................................................19

5.3 Irritation and sensitization ...................................................................................................19

5.4 Conclusion .............................................................................................................................19

6. Literature .......................................................................................................................... 20


1. Introduction Composite materials became available to dentistry in the nineteen-sixties [1]. First, they were mainly used in the anterior region, where the colour of amalgam was not desired. Since ef-fective bonding agents became available at the beginning of the nineteen-nineties, compo-sites have found increasingly broad use as universal restorative materials. There has been a growing demand for invisible esthetic restorations not only in the anterior region but increas-ingly also in the posterior region. This has led to a consistent increase in the demand for composite materials.

It goes without saying that not only the desire of the patient for invisible restorations has con-tributed to the success story of dental composites. This development also reflects a continu-ous development of dental restorative materials, which led to clinically reliable enamel/dentin adhesives and composite materials that offer the required physical qualities, esthetic possi-bilities and handling properties.

1.1 A short overview of the history of composites

1.1.1 Basics

The first step in the development of composite materials was achieved by Bowen in 1962 with the synthesis of the monomer Bis-GMA, which was filled with finely ground quartz [1]. At the time, only chemically curing two-component resin-based materials were available. With the advent of photo-polymerization, UV-curing systems were initially offered [2] until in the late nineteen-seventies, the first report on a dental filling material that cured with blue light in the visible range was published [3].

1.1.2 Filler technology

The first composites contained only macrofillers. These macrofilled composites showed a favourable shrinkage behaviour and flexural modulus, but their surface properties were inad-equate and their wear properties poor. They therefore were clinically not successful [4].

In 1974 a patent was granted to Ivoclar Vivadent on a composite employing microfillers [5]. Microfilled composites brought a breakthrough because they were the first material to be sufficiently wear resistant and maintained an acceptable surface quality during clinical ser-vice. However, these microfillers could not overcome two essential problems: First, inorganic microfillers do not reinforce a composite material as effectively as macrofillers, which results in low flexural strength and a low flexural modulus. Second, microfillers severely increase the viscosity of a composite due to their high specific surface, which does not allow for high inor-ganic filler contents. Therefore, microfilled composites exhibit a high polymerization shrink-age. These disadvantages, in particular the polymerization shrinkage, can largely be over-come by preparing an initial microfilled composite which is then ground to a fine powder that can be employed as filler in the final dental material. Such fillers are called “prepolymers”. This filler technology was successfully used as early as with the development of Heliomolar. Microfilled composites demonstrate a typically higher wear resistance than other types of composite materials because of the smaller size of the particles [6].

Hybrid composites represented the next logical step in the development of composite tech-nology. As the term ‘hybrid’ suggests, a variety of different fillers are employed to optimally combine the properties of all types of fillers to achieve a further improvement in the mechani-cal properties of the final material. Additionally, this technology allows for a very high filler loading. The results of these improvements were high physical strength and reduced polymerization shrinkage. Examples from the Ivoclar Vivadent range are Tetric and Tetric EvoCeram.


1.2 A new level of efficiency in posterior restorations

The clinically reliable, successful universal composite Tetric EvoCeram for anterior and pos-terior applications is now being followed by the next development: Tetric EvoCeram Bulk Fill. This material has been especially designed for posterior teeth.

This new composite represents the consistent next step in the development of composite technologies. It can be applied in increments of up to 4mm without any adverse effects on the material’s polymerization behaviour or mechanical properties. This advantage is achieved by a well-balanced composite filler technology.

1.2.1 Filler technology

The filler technology of the new Tetric EvoCeram Bulk fill is based on the clinically proven Tetric EvoCeram:

Glass fillers result in low wear and favourable polishing properties, or in low surface rough-ness and a high gloss. Tetric EvoCeram Bulk incorporates two types of glass fillers with different mean particle sizes.

Barium aluminium silicate glass filler of a mean particle size of 0.4 µm

Barium aluminium silicate glass filler of a mean particle size of 0.7 µm


Prepolymer fillers are instrumental in lowering the shrinkage and shrinkage stress. Prepolymer filler mixture consisting of monomer, glass filler and ytterbium fluoride

Ytterbium fluoride confers high radiopacity to dental materials and is capable of releasing fluoride. Ytterbium fluoride of a mean particle size of 200 nm

Spherical mixed oxide provides the basis for reduced wear and a favourable consistency. The spherical shape of the particles is ideally suited for minimizing the thickening effect as they provide the largest volume and, at the same time, the smallest surface possible. Primary particles, i.e. individual bodies, and secondary particles, or agglomerates, com-bine to form an ideal consistency

Mixed oxide of a mean particle size of 160 nm

The refractive index represents another advantage of mixed oxide. Since the refractive index of the mixed oxide is matched to that of the polymer, the degree of translucency is not dimin-ished and, as a result, the restoration is virtually indiscernible from the surrounding tooth structure. The example below shows how virtually invisible restorations are achieved by co-ordinating the refractive indices of the fillers and matrix.


If the refractive index of the fillers corre-sponds to that of the matrix, light can pass through the medium unhindered and the structures are invisible, as shown in the glass on the right. If the refractive indices are different from each other, the light is refracted and the structures become visible, as shown in the glass on the left.

1.2.2 Polymerization booster

The darker and/or the more opaque a material is, the more shallow is the depth of cure be-cause less light reaches the initiators. It is often not possible to polymerize thick increments reliably unless the material is highly translucent or contains only a limited amount of light-refracting fillers. The conventional initiator systems employed in tooth-coloured materials with enamel-like translucency quickly come up against their limits when they are faced with the demand for a quick and reliable cure in increments that are thicker than the usual 2 mm. This is another area where Ivoclar Vi-vadent makes a consistent effort to improve the quality of dental materials and offer innovative solutions. Tetric EvoCeram Bulk Fill comprises a newly designed, patented photoinitiator (polymerization booster) in addition to the conventionally used initiator sys-tems to achieve a material that can be quickly and reliable cured in increments of up to 4 mm.

The new initiator allows for an in-creased quantum efficiency, which en-ables the material to polymerize faster and, as an additional advantage, in-creases the depth of cure. Hence, this new initiator acts as a polymerization booster and is far more effective than conventional initiator systems. As it produces a highly reactive polymeriza-tion, small amounts of it are sufficient. This also means that its properties can be effectively used in tooth-coloured pastes with an enamel-like translucen-cy.


1.2.3 New shades

IVA - between A2 and A3 - for teeth with a slightly reddish tinge IVB - between B1 and B2 - for slightly yellowish teeth IVW - white - for light-coloured and deciduous teeth


2. Technical data

Tetric EvoCeram Bulk Fill

Standard composition in weight %

Dimethacrylate 19.7

Barium glass filler, ytterbium trifluoride, mixed oxide 62.5

Prepolymers 17.0

Additives, catalysts, stabilizers, pigments <1.0

Physical properties indicative value*

Flexural strength (MPa) 120

Flexural modulus (MPa) 10,000

Vickers hardness HV 0.5/30 (MPa) 620

Water absorption (µg·mm-3) 24.8

Water solubility (µg·mm-3) < 1.0

Radiopacity (% Al) 260

Maximum layer thickness (mm) 4

Translucency (%), depending on shade 14 – 16

*The values listed are purely indicative; they do not represent specifications.


3. Laboratory investigations

3.1 Depth of cure

Vickers hardness profile

The curing depth can be determined by measuring the Vickers hardness on the top and bot-tom surface of 4-mm thick test samples. It is generally accepted that a material meets the required hardness standards if the Vickers hardness measured at a depth of 4 mm is at least 80% of the maximum hardness measured on top of the test sample.

Establishing a Vickers hardness profile is a far more laborious approach but it produces re-sults that are clinically more relevant. To determine the hardness profile, a completely cured specimen (approx. 6 mm thick) is cut lengthwise and the Vickers hardness is measured from top to bottom at intervals of 0.5 mm.

The chart below shows the hardness values of the shades IVA, IVB and IVW at a depth of 4 mm as determined in the Vickers hardness profile of the individual materials. The values measured on top of the specimens were set at 100% and the values measured at the depth of 4 mm were expressed in relation to the top surface value. Various light intensities were used and the curing times were adjusted accordingly (Figs 1-3).

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500 mW/cm220 s

1200 mW/cm2bluephase

10 s

2000 mW/cm2bluephase 20i

5s

Surface 100 100 100

4mm depth 83.5 83.9 87.1

Fig. 1: Shade IVA, top surface hardness and 4-mm hardness as a percentage of the top hardness, measured in conjunction with different light intensities (R&D Ivoclar Vivadent, Schaan, 2011)

[%]


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10 s


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Surface 100 100 100

4mm depth 84.4 85.9 81.2

Fig. 2: Shade IVB, top surface hardness and 4-mm hardness as percentage of the top surface hard-ness, measured in conjunction with different light intensities (R&D Ivoclar Vivadent, Schaan, 2011)

0102030405060708090100

500 mW/cm220 s


10 s


5s

Surface 100 100 100

4mm depth 84.7 83.4 85.7

Fig. 3: Shade IVW, top surface hardness and 4-mm hardness as a percentage of the top surface hardness, measured in conjunction with different light intensities (R&D Ivoclar Vivadent, Schaan, 2011)

[%]

[%]


The results show that all the shades reliably meet the required 4-mm hardness values in con-junction with all of the above curing settings.

3.2 Light insensitivity

The time available to apply and contour a composite material before it commences to poly-merize plays an important role in determining the material’s user friendliness.

Composite materials normally contain photoinitiator systems that react to the blue light por-tion of the visible light spectrum. It does not matter from which light source the blue light is emanated. As daylight and operating light comprise a certain amount of blue light, they act as a blue light source and may contribute to the (premature) polymerization of composite materials. The higher the intensity of the ambient light is, the shorter is the working time be-fore the material begins to polymerize. To prevent composites from polymerizing prematurely, they either need to be completely protected from ambient light or they must be applied under special light-protection shields that filter out the blue light spectrum. However, when applying and contouring restorative materials, these options are often not feasible. Since surgical loupes with headlights are be-coming more popular and are also used more often in direct restorative dental treatments, light-sensitive composites involve a considerable disadvantage. Against such a background, materials with reduced light sensitivity offer an increased scope of flexibility.

A material’s sensitivity to ambient light is usually determined using the conditions defined in ISO 4049. The longer the period of time before the material polymerizes, the less sensitive to light it is.

One of the objectives in the development of Tetric EvoCeram Bulk Fill was to offer a material that is as insensitive to light as feasibly possible. To achieve this objective, Tetric EvoCeram Bulk Fill incorporates a light sensitivity inhibitor patented by Ivoclar Vivadent. This inhibitor delays the polymerization process if small amounts of blue light are present but does not impair polymerization under the intensive blue light of a properly functioning curing light.

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Tetric EvoCeramBulk Fill

QuiXfil x‐tra fil SonicFill Venus Bulk Fill SDR

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Fig. 4: Sensitivity to ambient light of various composite materials, determined according to ISO 4049 (R&D Ivoclar Vivadent AG, Schaan, 2011)


3.3 Polishability

Polishing represents a critical step in direct restorative treatments because it is the final stage in the treatment procedure. A pleasing surface gloss is decisive for the clinical success and esthetic appearance of a composite restoration.

A restoration surface that is too matte in relation to the surrounding tooth structure produces an unsatisfactory esthetic result. In addition, a rough surface is conducive to staining and plaque accretion. Special attention was therefore given to achieving advantageous polishing properties in the development of Tetric EvoCeram Bulk Fill.

For the experiment below, eight specimens were prepared for each material according to the manufacturer’s directions. The specimens were roughened with sanding paper (320 grit) to achieve a defined initial surface roughness. After the specimens were stored in a dry-storage area at 37 °C for 24 hours, their gloss was measured with a novo-curve glossmeter and the surface roughness was determined with a FRT MicroProf measuring device.

Next, the specimens were polished using a single-step OptraPol Next Generation polisher at a pressure of 2N at 10,000 rpm under water cooling. The specimens were polished for 30 seconds in total, while the surface roughness was measured at intervals of 10 seconds.

Fig. 5: Mean surface roughness of various composite materials compared to Tetric EvoCeram Bulk Fill after polishing with OptraPol Next Generation in relation to the polishing time. The reference material was black glass = 92.6 (R&D Ivoclar Vivadent, Schaan, 2011)

The test samples made of Tetric EvoCeram Bulk Fill showed a statistically significant, higher surface gloss than the other materials investigated at all stages of the 30-second polishing time when they were polished with the OptraPol Next Generation polishing system (ANOVA, p<0.05).

The roughness was determined after 30 seconds. Below are shown the mean values and standard deviations. The smaller the surface roughness value is, the better is the polishability of the material. A mean surface roughness of <0.1 µm indicates excellent polishability, <0.2 µm suggests a good polishability, a value between 0.2 -0.4 µm corresponds to a medium polishability and >0.4 µm means poor polishability. Tetric EvoCeram Bulk Fill was found to show excellent polishability in the above test.


The mix and size of the fillers are responsible for the excellent polishability and high gloss of Tetric EvoCeram Bulk Fill. Large fillers do not produce the same smooth and glossy surface as do small fillers. Compared to other materials, Tetric EvoCeram Bulk Fill comprises fillers of a comparatively small size. The differences in filler size can be clearly seen in the scan-ning electron microscope (SEM) images shown below in Fig. 7:

Fig. 6: Mean surface roughness of various composite materials compared to Tetric EvoCeram Bulk Fill after polishing with OptraPol Next Generation for a polishing time of 30 seconds. (R&D Ivoclar Vivadent, Schaan, 2011)


Fig. 7: SEM images of various composite materials (R&D Ivoclar Vivadent, Schaan, 2011)

Except for Venus Bulk Fill, all the other materials contain comparatively large fillers, which correlates with the polishing results described above.


3.4 Wear in the Willytec chewing simulator with Empress antagonists

Dental materials are subjected to in vitro simulations of mastication processes to estimate their clinical behaviour in the patient.

Ivoclar Vivadent uses a Willytec chewing simulator to measure the wear resistance of restor-ative materials. The aim is to use a procedure that is as standardized as possible to obtain results that can be compared with each other. To achieve this, standardized ceramic antago-nists are employed and plane test samples are subjected to 120,000 masticatory cycles, ap-plying a force of 50 N and a sliding movement of 0.7 mm. The vertical substance loss is measured by means of a 3D laser scanner. A vertical loss of 200 μm is considered low, a loss ranging between 200 – 300 μm is considered medium.

Fig. 8: Mean vertical wear of restorative materials and their antagonists (R&D Ivoclar Vivadent, Schaan, 2011)

The significantly highest wear was found in test samples made of QuixFil. Comparable wear results were found SDR, Venus Bulk Fill and Tetric EvoCeram Bulk Fill; SonicFill showed a significantly higher wear. With regard to antagonist wear, the significantly highest wear was recorded in the SonicFill and X-tra Fil test samples.


3.5 Polymerization shrinkage – mercury dilatometer

Low shrinkage results in less stress on the adhesive bond and lower deformation of the tooth structure during polymerization. This results in better marginal quality. Therefore, polymeriza-tion shrinkage (% vol) after 1 hour was measured with a mercury dilatometer.

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Tetric EvoCeram Bulk Fill SonicFill x‐tra fil

Shrinkage [%]

Fig. 9: Comparison of polymerization shrinkage of various composites (Investigation: R&D Ivoclar Vivadent, Schaan, 2011)

The volumetric shrinkage of Tetric EvoCeram Bulk Fill is similar to that of other bulk fill com-posite materials.

3.6 Polymerization shrinkage – buoyancy measurement

The polymerization shrinkage was also measured with the buoyancy technique using free floating test samples in silicone oil. For this purpose, the materials were tested in a defined quantity and shape. Five measurements were carried out for each material and each meas-urement was carried out over a period of 60 minutes.

Fig. 10: Course of volumetric change over a period of 60 minutes in various composites (Investigator: Dr Ing. C. Koplin, Fraunhofer Institut für Werkstoffmechanik IWM, Freiburg, Germany, 2011)


At the beginning of the polymerization process, an expansion in volume can be observed. This expansion is caused by the rise in temperature at the onset of the exothermic polymeri-zation reaction as well as by the exposure to light during photoactivation. The exponential decrease in volume almost completely stops after 10 minutes and after 60 minutes the final shrinkage value can be determined.

As expected, the two medium-viscosity composite materials Tetric EvoCeram Bulk Fill and Sonic Fill showed a lower shrinkage than the two flowable materials Venus Bulk Fill and SDR. The shrinkage values of both medium-viscosity and flowable materials were within the standard order of magnitude associated with these types of products.

3.7 Shrinkage force

The shrinkage stress values of a range of materials were measured in various layer thick-nesses. The measurements were carried out by means of a Bioman Shrinkage Stress meas-uring device (light exposure with bluephase, HIP, for 10 seconds; shrinkage force measure-ments over a period of 30 min). The results show that Tetric EvoCeram Bulk Fill produces less shrinkage stress in both 2-mm and 4-mm layers than the universal composite materials of other manufacturers when they are applied in comparable thicknesses. In addition, the test also revealed that the shrinkage stresses measured in the 4-mm layers were not substantially higher than those of the 2-mm layers.

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SonicFill

x-tra fil

Fig. 11: Shrinkage stresses of various materials measured in two layer thicknesses (R&D Ivoclar Viva-dent, Schaan, 2011)

Furthermore, the tests showed that the shrinkage forces measured for Tetric EvoCeram Bulk Fill in two different layer thicknesses were lower than those of the other composites tested. This is true for the layer thicknesses of 2 mm and 4 mm.


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Tetric EvoCeramBulk Fill

Filtek Supreme XTE Filtek Z250 Herculite XRV Ultra Estelite Sigma Quick

Shrinkage force [N]

2 mm 4 mm

Fig. 12: Shrinkage stresses of Tetric EvoCeram Bulk Fill in a layer thickness of 2 mm and 4 mm compared to the shrinkage stresses of other composites in a layer thickness of 2 mm (R&D Ivoclar Vivadent, Schaan, 2011)


5. Biocompatibility To minimize the risks related to biocompatibility as far as possible from the outset, care is taken to ensure that mainly raw materials that have been used in dental composite materials for many years and have been proven in vivo to be safe are used in the development of a new material. For this reason, we may draw on the experiences gathered with proven dental composite materials and their ingredients to evaluate the toxicological properties of Tetric EvoCeram Bulk Fill.

5.1 Cytotoxicity

Samples of Tetric EvoCeram Bulk Fill were extracted in RPMI 1640 medium according to ISO 10993-12. Subsequently, L929 cells were brought into contact with this extract for 24 hours. The vitality of these cells was measured after 24 h with the help of tetrazolium dye (XTT). Extracts of Tetric EvoCeram Bulk Fill did not show any relevant effects on the cell cultures. Tetric EvoCeram Bulk Fill was therefore found to be not cytotoxic.

5.2 Mutagenicity

Extracts of samples of a previous product with the same monomer composition were exam-ined in a reverse mutation test (Ames test). None of these tests indicated any mutagenic activity. The material’s polymerization booster was also thoroughly tested. No mutagenic activity was found for this raw material either.

5.3 Irritation and sensitization

Like virtually all light-curing dental materials, Tetric EvoCeram Bulk Fill contains methacry-lates and dimethyacrylates. Particularly if uncured, these materials may have an irritating effect and may cause sensitization, which may lead to allergic reactions, such as contact dermatitis. Allergic reactions are very rare in patients but may occur more frequently among members of the dental staff, who handle uncured composite materials routinely every day. Such reactions can be avoided by choosing clean working conditions and avoiding skin con-tact with uncured material. It should be noted that commercially available medical gloves do not provide effective protection against the sensitizing effect of methacrylates.

Tetric EvoCeram Bulk Fill must not be used in patients who are known to be allergic to any of its constituents.

5.4 Conclusion

On the basis of the date available, we can conclude that Tetric EvoCeram Bulk Fill does not pose any health hazard if it is used correctly. To ensure correct use of the material, the notes and directions in the Instructions for Use have to be observed and followed.


6. Literature

1. Bowen RL. Dental filling material comprising vinyl silane treated fused silica and a binder consisting of the reaction product of Bis phenol and glycidyl acrylate. 1962; Patent No. 3,066,112.

2. Buonocore M. Adhesive sealing of pits and fissures for caries prevention, with use of ultraviolet light. J Am Dent Assoc 1970;80:324-330.

3. Bassiouny MA, Grant AA. A visible light-cured composite restorative. Clinical open assessment. Br Dent J 1978;145:327-330.

4. Lutz F, Phillips RW, Roulet JF, Imfeld T. Composites - Klassifikation und Wertung. Schweiz Mschr Zahnheilk 1983;93:914-929.

5. Michl R, Wollwage P. Werkstoff für Dentalzwecke. 1975; Patent No. DT 24 03 211 A1.

6. Suzuki S, Leinfelder K, Kawai K, Tsuchitani Y. Effect of particle variation on wear rates of posterior composites. Am J Dent 1995;8:173-178.

This documentation contains a survey of internal and external scientific data (“Information”). The doc-umentation and Information have been prepared exclusively for use in-house by Ivoclar Vivadent and for external Ivoclar Vivadent partners. They are not intended to be used for any other purpose. While we believe the Information is current, we have not reviewed all of the Information, and we cannot and do not guarantee its accuracy, truthfulness, or reliability. We will not be liable for use of or reliance on any of the Information, even if we have been advised to the contrary. In particular, use of the infor-mation is at your sole risk. It is provided "as-is", "as available" and without any warranty express or implied, including (without limitation) of merchantability or fitness for a particular purpose. The Information has been provided without cost to you and in no event will we or anyone associated with us be liable to you or any other person for any incidental, direct, indirect, consequential, special, or punitive damages (including, but not limited to, damages for lost data, loss of use, or any cost to procure substitute information) arising out of your or another’s use of or inability to use the Information even if we or our agents know of the possibility of such damages. Ivoclar Vivadent AG Research & Development Scientific Service Bendererstrasse 2 FL - 9494 Schaan Liechtenstein Contents: Dr Marion Wanner Issued: October 2011

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