tetric+n ceram+bulk+fill(2)

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Scientific Documentation


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Scientific Documentation TetricN-Ceram

Bulk Fill Page 2 of 20

Table of contents

1. Introduction ........................................................................................................................ 31.1 A short overview of the history of composi tes ....................................................................3

1.1.1 Basics ............................................................................................................................. 31.1.2 Filler technology .............................................................................................................. 3

2. Tetric N-Ceram Bulk Fill .................................................................................................... 42.1 Ini tiators ................................................................................................................................... 42.2 Light insensi tivi ty .................................................................................................................... 82.3 Filler technology ..................................................................................................................... 9

3.Addi tional mater ials investigations ............................................................................... 133.1 Polishability ...........................................................................................................................133.2 Wear in the Willytec chewing simulator wi th IPS Empress antagonis ts ........................17

4. Technical data .................................................................................................................. 185. Biocompatibi li ty ............................................................................................................... 19

5.1 Cytotoxicity ............................................................................................................................195.2 Mutagenicity ..........................................................................................................................195.3 Irri tation and sensit ization ...................................................................................................195.4 Conclusion .............................................................................................................................19

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


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1. Introduction

Composite materials became available to dentistry in the nineteen-sixties [1]. First, they weremainly 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 agrowing demand for invisible esthetic restorations not only in the anterior region but in-creasingly also in the posterior region. This has led to a consistent increase in the demandfor 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. It also reflects a continuous developmentof dental restorative materials, which led to clinically reliable enamel/dentin adhesives andcomposite materials that offer the required physical qualities, esthetic possibilities and han-dling 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 1962with the synthesis of the monomer Bis-GMA, which was filled with finely ground quartz [1]. Atthe time, only chemically curing two-component resin-based materials were available Withthe advent of photo-polymerization, UV-curing systems were initially offered [2] until in thelate nineteen-seventies, the first report on a dental filling material that cured with blue light inthe visible range was published [3].

1.1.2 Filler technology

The first composites contained only macrofillers. These macrofilled composites showed afavourable 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 besufficiently wear resistant while maintaining an acceptable surface quality during clinical ser-vice. However, these microfillers could not overcome two essential problems: First, inorganicmicrofillers do not reinforce a composite material as effectively as macrofillers, which resultsin low flexural strength and a low flexural modulus. Second, microfillers severely increase theviscosity 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 be largely over-

come by preparing an initial microfilled composite which is then ground to a fine powder thatcan be employed as filler in the final dental material. Such fillers are called "prepolymers".Ivoclar Vivadent used this filler technology as early as in the development of Heliomolar. Mi-crofilled composites typically demonstrate a higher wear resistance than other types of com-posite 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 optimallycombine 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 fillerload. The results of these improvements were high physical strength and reduced polymeri-zation shrinkage. Examples from the Ivoclar Vivadent range include Tetric and Tetric N-

Ceram.


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2. Tetric N-Ceram Bulk Fill

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

This new composite represents the consistent next step in the development of compositetechnologies. It can be applied in increments of up to 4 mm without any adverse effect on thematerial's polymerization behaviour or mechanical properties. This advantage is achieved bya well-balanced composite filler technology.

2.1 Initiators

Light-curing composites set by way of free radical polymerization. In the process, incomingphotons are absorbed by a molecule (photoinitiator). The energy absorbed excites the mole-cule. In its active state, the molecule enables the formation of radicals if one or several acti-vators are present. The resulting free radicals trigger the polymerization reaction. Such aninitiator molecule is able to absorb only the photons of a specific spectral range.

Camphorquinone is a typical example of an initiator molecule that is widely used in polymersynthesis.

Fig. 1: Absorption spectrum of camphorquinone

With a peak sensitivity at 470 nm, camphorquinone reacts to visible light in the blue lightrange. Since it exhibits an intense yellow tinge due to its absorption properties, other initia-tors were and are used in dentistry, for instance in composite bleaching shades and in col-ourless protective varnishes.

350 370 390 410 430 450 470 490 510 530

Wavelength [nm]

O

O


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Fig. 2: Absorption spectrum of phenylpropanedione (PPD)

PPD (phenylpropanedione): The absorption spectrum of PPD extends from the UV wave-length range to approx.490 nm.

Fig. 3: Absorption spectrum of Lucirin TPO

Lucirin TPO is an acyl phosphine oxide. This photoinitiator has become popular because itcompletely bleaches out after the light reaction has finished. Its sensitivity peak is located ina considerably lower wavelength range.

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 incrementsreliably 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 withenamel-like translucency quickly reach their limits when they are faced with the demand for aquick and reliable cure in increments that are thicker than the usual 2 mm.

This is another area where Ivoclar Vivadent makes a consistent effort to improve the qualityof dental materials and offer innovative solutions. Tetric N-Ceram Bulk Fill comprises Ivocerin- a newly designed, patented photoinitiator - in addition to the conventionally used initiator

350 370 390 410 430 450 470 490 510 530

Wavelength [nm]

C

O

C CH3

O

350 370 390 410 430 450 470 490 510 530

Wavelength [nm]

C P

O O


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systems to achieve a material that can be quickly and reliably cured in increments of up to 4mm.

Ivocerin is a germanium-based initiator and complements the current range of standard initia-tor systems.

Ivocerin

Fig. 4: Schematic representing the absorption peaks of various initiators. Material samples of the ini-tiators and their respective colours are shown below the schematic.


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Fig. 5: Absorption spectra of Lucirin TPO, camphorquinone and Ivocerin in comparison, measured inthe laboratory.

Ivocerin is a new initiator that features a high absorption coefficient and is therefore highlyeffective even if used in only small quantities.

Ivocerin allows for an increased quantumefficiency and is therefore far more effec-tive than camphorquinone or Lucirin.

This enables the material to polymerizefaster and, as an additional advantage,increases the depth of cure. Hence, Ivo-cerin acts as a polymerization boosterand is therefore far more effective thanconventional initiator systems.

As Ivocerin produces a highly reactivepolymerization, small amounts of it aresufficient. This also means that its prop-erties can be effectively used in tooth-coloured pastes with an enamel-liketranslucency.


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2.2 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 isemanated. As daylight and operating light comprise a certain amount of blue light, they actas a blue light source and may contribute to the (premature) polymerization of compositematerials. 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 completelyprotected from ambient light or they must be applied under special light-protection shieldsthat filter out the blue light spectrum. However, when applying and contouring restorativematerials, 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 treatments, light-sensitive composites involve a considerable disadvantage. Against such a background, ma-terials with a reduced light sensitivity offer an increased scope of flexibility.

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

One of the objectives in the development of Tetric N-Ceram Bulk Fill was to offer a materialthat is as insensitive to light as feasibly possible. To achieve this objective, Tetric N-CeramBulk Fill incorporates a light sensitivity inhibitor patented by Ivoclar Vivadent. This inhibitordelays the polymerization process if small amounts of blue light are present but does notimpair polymerization under the intensive blue light of a properly functioning curing light.

Fig. 6: Sensitivity to ambient light of various composite materials, determined according to ISO 4049

(R&D Ivoclar Vivadent AG, Schaan, 2012)


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2.3 Filler technology

The filler technology of Tetric N-Ceram Bulk Fill is based on the clinically proven Tetric N-Ceram:

Glass fillers result in low wear and favoura-ble polishing properties, or in low surfaceroughness and a high gloss. Tetric N-CeramBulk Fill incorporates two types of glassfillers with different mean particle sizes toachieve the desired properties.

Barium aluminium silicate glass filler of a mean

particle size of 0.4 m

Barium aluminium silicate glass filler of a meanparticle size of 0.7 m

Prepolymer fillers are instrumental in lower-ing the shrinkage and shrinkage stress.

Prepolymer filler mixture consisting of monomer,glass filler and ytterbium fluoride


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Ytterbium fluoride confers high radiopacityto dental materials and is capable of releas-ing fluoride.

Ytterbium fluoride of a mean particle size of 200nm

Spherical mixed oxide provides the basis for

reduced wear and a favourable consistency.The spherical shape of the particles is ideal-ly suited for minimizing the thickening effectas they provide the largest volume and, atthe same time, the smallest surface possi-ble. Primary particles, i.e. individual bodies,and secondary particles, or agglomerates,combine to form an ideal consistency.

Mixed oxide of a mean particle size of 160 nmFig. 7: Range of fillers used in Tetric N-Ceram Bulk Fill

The refractive index represents another advantage of mixed oxide. Since the refractive indexof 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 toothstructure. 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, the light canpass through the medium unhindered andthe structures are invisible, as shown in theglass on the right.If the refractive indices are different fromeach other, the light is refracted and thestructures become visible, as shown in theglass on the left.


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Low material shrinkage during polymerization means less strain on the adhesive bond andless deformation of the tooth structure. This, ultimately, translates into improved marginalintegrity.However, volumetric shrinkage is only one of the factors at play; the shrinkage force and therelated shrinkage stress constitute additional important factors that put a strain on the adhe-sive bond. Consequently, they all affect the marginal integrity of a composite restoration.

Minimizing the shrinkage stress is particularly important in a material that is applied in incre-ments of up to 4 mm. For this reason, Tetric N-Ceram Bulk Fill contains a shrinkage stressreliever - a special filler which is partially functionalized with silanes. Since the shrinkagestress reliever features a lower modulus of elasticity, it acts like a microscopic spring, attenu-ating the forces generated during shrinkage.

Fig. 8: Schematic representation of the mode of functioning of the shrinkage stress reliever

The polymerization shrinkage (% vol) of Tetric N-Ceram Bulk Fill after 1 hour was measuredwith a mercury dilatometer.

Fig. 9: Comparison of the polymerization shrinkage of various composites (Investigation: R&D IvoclarVivadent, Schaan, 2012)


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The volumetric shrinkage of Tetric N-Ceram Bulk Fill is lower (and in some cases significant-ly lower) than that of other composite materials.

Composites are fixed to the tooth structure by means of the adhesive and cannot shrinkfreely during the shrinkage process. The shrink force that builds up in the course of theshrinkage process puts a strain on the adhesive bond. The shrinkage force of various mate-rials was examined. The measurements were performed by means of a Bioman shrinkagestress measuring device (light exposure with Bluephase, HIP, for 10 seconds, shrinkageforce measurement over a period of 30 min).

Fig. 10: Shrinkage force of Tetric N-Ceram Bulk Fill in comparison with other composites (R&D IvoclarVivadent, Schaan, 2012)

The shrinkage stress is determined by means of the shrinkage force measured on the sur-face of the test specimens, i.e. the shrinkage stress is the shrinkage force per unit area (MPa= N/mm2).


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Fig. 11: Shrinkage stress of Tetric N-Ceram Bulk Fill in comparison with other composites (R&DIvoclar Vivadent, Schaan, 2012)

The results of the investigations have shown that the shrinkage force (Fig. 10) and theshrinkage stress (Fig. 11) of Tetric N-Ceram Bulk Fill are lower than those of other compo-sites.

3. Additional materials investigations

3.1 Polishability

Polishing represents a critical step in direct restorative treatment because it is the final stage

in the treatment procedure. A pleasing surface gloss is decisive for the clinical success andesthetic appearance of a composite restoration.

A restoration surface that is too matte in relation to the surrounding tooth structure producesan unsatisfactory esthetic result. In addition, a rough surface is conducive to staining andplaque accretion. Special attention was therefore given to achieving advantageous polishingproperties in the development of Tetric N-Ceram Bulk Fill.

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

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


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Fig. 12: Mean surface roughness of various composite materials compared to Tetric N-Ceram Bulk Fillafter polishing with OptraPol Next Generation in relation to the polishing time. The reference materialwas black glass = 92.6 (R&D Ivoclar Vivadent, Schaan, 2012)

Tetric N-Ceram Bulk Fill showed a significantly higher surface gloss than all the other materi-als investigated. The materials investigated produced the following surface gloss results after30 seconds (in descending order; according to ANOVA post hoc Tukey B with p Synergy D6 = Brilliant NG = Filtek Z250 > Spectrum TPH3 = Ce-ram.X mono+ > QuiXfil

The roughness was also determined after these intervals. The smaller the surface roughnessvalue is, the better is the polishability of the material. A mean surface roughness of


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The mix and size of the fillers are responsible for the excellent polishability and high gloss ofTetric N-Ceram Bulk Fill. Large fillers do not produce the same smooth and glossy surface asdo small fillers. Compared to other materials, Tetric N-Ceram Bulk Fill comprises fillers of acomparatively small size. The differences in filler size can be clearly seen in the scanningelectron microscope (SEM) as shown below in Fig. 14:

Fig. 13: Mean surface roughness (m) of various composite materials compared to Tetric N-CeramBulk Fill after polishing with OptraPol Next Generation in relation to the polishing time. (R&D Ivoclar

Vivadent, Schaan, 2012)


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Fig. 14: SEM images of various compositematerials (R&D Ivoclar Vivadent, Schaan,2012)

3.2 Wear in the Willytec chewing simulator with IPS Empress antagonists

Dental materials are subjected to in vitro simulations of mastication processes to estimatetheir 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 obtainresults 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 50N and a sliding movement of 0.7 mm. The vertical substance loss ismeasured by means of a 3D laser scanner. A vertical loss of less than 200 m is consideredlow, a loss ranging between 200 300 m is considered medium.

Fig. 15: Mean vertical wear of restorative materials and their antagonists (R&D Ivoclar Vivadent,Schaan, 2012)


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4. Technical data

Tetric N-Ceram Bulk Fill

Standard composition (in weight %)

Dimethacrylates 21.0

Prepolymer 17.0

Barium glass filler, Ytterbium trifluoride, Mixed oxide 61.0

Additive, Initiators, Stabilisers, Pigments < 1.0

Physical properties

In accordance with:

EN ISO 4049:2009 Dentistry Polymer-based restorative materials (ISO 4049:2009)

Specification Example value

Flexural strength MPa 80 120

Water sorption (7 days) g/mm 40 24.8

Water solubility (7 days) g/mm 7.5 < 1.0

Radiopacity % Al 100 260


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5. Biocompatibility

To minimize the risks related to biocompatibility as far as possible from the outset, care istaken to ensure that mainly raw materials that have been used in dental composite materialsfor many years and have been proven in vivo to be safe are used in the development of anew material. For this reason, we may draw on the experience gathered with proven dentalcomposite materials and their ingredients to evaluate the toxicological properties of Tetric N-Ceram Bulk Fill.

5.1 Cytotoxicity

Samples of Tetric N-Ceram Bulk Fill were extracted in RPMI 1640 medium according to ISO10993-12. Subsequently, L929 cells were brought into contact with this extract for 24 hours.The vitality of these cells was measured after 24 hours with the help of tetrazolium dye(XTT). Extracts of Tetric N-Ceram Bulk Fill did not show any relevant effects on the cell cul-tures. Tetric N-Ceram Bulk Fill was therefore found to be not cytotoxic.

5.2 Mutagenicity

Extracts of material samples were examined in a reverse mutation test (Ames test). None ofthese tests indicated any mutagenic activity.Ivocerin was also subjected to extensive testing. This material did not show any signs of mu-tagenic activity either.

5.3 Irritation and sensitization

Like virtually all light-curing dental materials, Tetric N-Ceram Bulk Fill contains methacrylatesand dimethyacrylates. Particularly if uncured, these materials may have an irritating effectand may cause sensitization, which may lead to allergic reactions, such as contact dermati-

tis. Allergic reactions are very rare in patients but may occur more frequently among mem-bers of the dental staff, who handle uncured composite materials routinely every day. Suchreactions can be avoided by choosing clean working conditions and avoiding skin contactwith uncured material. It should be noted that commercially available medical gloves do notprovide effective protection against the sensitizing effect of methacrylates.

Tetric N-Ceram Bulk Fill must not be used in patients who are known to be allergic to any ofits constituents.

5.4 Conclusion

On the basis of the data available, we can conclude that Tetric N-Ceram Bulk Fill does notpose 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.


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6. Literature

1. Bowen RL. Dental filling material comprising vinyl silane treated fused silica and abinder 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 ofultraviolet light. J Am Dent Assoc 1970;80:324-330.

3. Bassiouny MA, Grant AA. A visible light-cured composite restorative. Clinical openassessment. 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 fr Dentalzwecke. 1975; Patent No. DT 24 03 211A1.

6. Suzuki S, Leinfelder K, Kawai K, Tsuchitani Y. Effect of particle variation on wearrates 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 andfor external Ivoclar Vivadent partners. They are not intended to be used for any other purpose. Whilewe believe the information is current, we have not reviewed all of the information, and we cannot anddo not guarantee its accuracy, truthfulness, or reliability. We will not be liable for use of or reliance onany 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 orimplied, 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 associatedwith 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 toprocure substitute information) arising out of your or anothers use of or inability to use the informationeven if we or our agents know of the possibility of such damages.

Ivoclar Vivadent AGResearch & DevelopmentScientific ServiceBendererstrasse 2FL - 9494 SchaanLiechtenstein

Contents: Dr Marion WannerDate: September 2012

tetric+n ceram+bulk+fill(2)

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