MAY 2003

Scientific Profile

Seasons®

DIRECT ESTHETIC COMPOSITE SYSTEM

4 Seasons®

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Table of contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31.1 Structure of teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31.2 Shade systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41.3 Optical properties of teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51.4 The 4 Seasons® system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

2. Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

3. In vitro investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83.1 Color, opacity and translucency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83.2 Filler composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113.3 Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

4. Clinical investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134.1 Dr. Joseph Dennison, University of Michigan, USA . . . . . . . . . . . . . . . . . . . . . . . . . .134.2 Dr. Gerard Kugel, Tufts University, Boston, USA . . . . . . . . . . . . . . . . . . . . . . . . . . . .134.3 Dr. Pier Nicola Mason, University of Padua, Italy . . . . . . . . . . . . . . . . . . . . . . . . . . .144.4 Dr. Knut Merte, Universitätsklinikum Leipzig, Germany . . . . . . . . . . . . . . . . . . . . . .144.5 Dr. Arnd Peschke, Internal Clinic, R&D Ivoclar Vivadent, Schaan, Liechtenstein . . . .14

5. Toxicology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

6. Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

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1. IntroductionThe increasing demand for tooth-colored restorations and the dentist’s artistic understanding and skill have led to a resurgencein direct composite restorative systems in the past few years. Dental manufacturers have developed modern composite andceramic-based materials, which are indistinguishable from natural dentition. These possibilities have not only caused patients to increase their dental IQ and esthetic expectations, but they have also spurred the ambitions of esthetically-aware dentists.Consequently, dentists specializing in esthetic dentistry are requiring materials which offer convenience as well as esthetic possibilities more than ever before.

Natural teeth are composed of dentin and enamel, embedded in pink soft tissue. Light passes through them, entering themfrom the front. Some light is reflected from the surface of the tooth, the remainder penetrates the surface and is either reflected,refracted or absorbed by the inner layers of the tooth or passes through the entire tooth into the dark oral cavity. The typicalcolor and light effects, which are created in the process, constitute the hallmark of the natural appearance of teeth. It goes with-out saying that restorations which mimic only the shade and shape of natural teeth are easily recognized as foreign even by theuntrained human eye. They must also mimic their treatment of light.

Bearing the structure of teeth in mind, we realize that truly indiscernible, lifelike restorations can only be fabricated if an adequate range of dentin, enamel and characterization materials are available – materials that allow not only the reconstructionof the external shade and shape but also the reproduction of the inner tooth structure and the resultant optical effects.

The following section will explore the natural structure and optical properties of teeth and provide an introduction to the 4 Seasons® restorative system.

1.1 Structure of teeth

The outermost layer of the exposed tooth consists of enamel, the hardest component of the tooth. The inner bulk of the tooth isdentin, which is softer and has less minerals than the enamel. In the center is the pulp, a living tissue (Fig. 1a). Most restorationsinvolve the replacement of lost tooth structure with a suitable restorative material. The aim of esthetic dental restorations is toreplace lost tooth structure in as lifelike a manner as possible.

Enamel

Enamel is extremely hard, consisting of 96% (wt) hydroxyapatite and 4% (wt) organic material and water (Eisenmann, 1998).Enamel is made up of rod-like prisms of approximately 5 µm in diameter (Fig. 1b). The hydroxyapatite crystals are packed togetherin the prisms in parallel order to the longitudinal side of the rods. The enamel rods are aligned roughly at right angles to theamelo-dentinal junction, whereas angles ranging from 55 to 100° are measured between the prisms and the outer tooth surface.The only areas where the enamel rods are arranged vertically to the tooth surface are the cusp tips and proximal edges (Fernandezand Chevitarese, 1991). The enamel prisms do not run a straight course from the amelo-dentinal junction to the outer surface.Groups of prisms make a series of bends along the course. This gives rise to what is know as the Hunter-Schreger bands(Fig. 1c). Thus, the enamel is characterized by a subtle, intricate substructure. This well-ordered structure is alsoresponsible for the typical etching pattern, which forms in the course of etching the enamel with acid (Fig. 1b, 1c).

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Dentin

The bulk of the human tooth is dentin. Dentin consists of 45% (vol) mineral and up to 30% (vol) organic material byvolume. Water makes up approximately 25% (vol) of the dentin (Schroeder, 1991). The inorganic components aremainly hydroxyapatite and the organic material is predominantly collagen (Torneck, 1998).

A characteristic feature of dentin is the dense arrangement of dentin tubules that traverse its entire thickness. A densi-ty of 59,000 to 76,000 tubules per mm2 can be observed in the vicinity of the pulp (Torneck, 1998). The diameter ofdentin tubules is approximately 2.5 µm near the pulp and 0.9 µm at the amelo-dentinal junction (Garberoglio andBrännström, 1976).

1.2 Shade systems

Dental materials are predominantly described in terms of their shade and transparency. Shade guides are used to helpdental professionals select the appropriate shade or inform the laboratory about the shades selected. The Chromascop(Ivoclar Viadent) and A-D (Vita) shade guides are examples of such shade systems.

Shade guides have become the standard for selecting shades by their visual qualities as seen by the human eye.However, shade guides are hardly suitable for industrial or scientific purposes, such as assuring uniform color propertiesamong different lots of materials or the research-centered shade measuring of teeth. Consequently, electronic shadematching devices, which perform reproducible quantitative shade measurements, are gaining in popularity. To date,these devices predominantly use the CIELAB L*, a*, b* color co-ordinates (Fig. 2).

The L*, a*, b* sets of coordinates has proved to be a valuable system to describe colors. However, this system is notcapable of identifying parameters such as opacity or transparency. Yet, these parameters affect the measurement ofcolor and should therefore not be neglected.

Fig. 2:CIELAB L*, a*, b* color co-ordinates. L* describes the lightness component of a color: L*=0 means ‘absolutelyblack’ and L*=100 means ‘completely white’. The a* co-ordinate plots the color on a red - green axis and the b* co-ordinate indicates the color on a yellow - blue axis.

Fig. 1a: Schematic structure of a molar.S, enamel; D, dentin; SD, amelo-denti-nal junction; P, pulp; Z, gingiva; L, peri-odontal membrane; K, bone.

Fig. 1b: Scanning electron micro-graphshowing etched enamel. The enamelrods are cut in an oblique manner.

Fig. 1c: Scanning electron micro-graphshowing etched enamel The enamelrods are cut longitudinally.

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1.3 Optical properties of teeth

Teeth are characterized by exceptional optical properties, which by far transcend the qualities associated with justcolor. For instance, teeth have fluorescent properties. In addition, dentin is far more opaque and intensely saturatedin color than enamel, whereas enamel features additional opalescent qualities. While the components of color canbe measured and described, properties such as translucency, opacity and opalescence are much more difficult todetermine objectively. Color measuring in the oral cavity appears to be rather difficult because the surrounding components and the reflections on the tooth surface affect the optical appearance of a tooth quite considerably.Furthermore, extracted teeth, which are no longer in contact with saliva, look different from what they used to doin the oral cavity. It is no surprise that publications measuring the optical properties of teeth are limited. A few ofthem are briefly discussed below.

A Japanese team of researchers measured the color of anterior teeth with a colorimeter in randomly selectedJapanese people (Hasegawa et al., 2000). By and large, the study reflects the evaluation of teeth as seen by thehuman eye. From the incisal to the cervical region of teeth, the red and yellow components gradually increase. The translucency is much higher along incisal edges, which are predominantly composed of enamel, than at the cervical sites. The pronounced shift towards red at the cervical margin may be attributed to the adjacent gingival or the more saturated dentin closer to the surface.

Another study measured the color of extracted upper incisors. The following color co-coordinates were measuredalong the central part of the teeth: L*, 70 ± 4: a*, -0.22 ± 1.4; b*, 18 ± 3 (ten Bosch and Coops, 1995). After removing the enamel, the color of the remaining dentin was measured again. A high level of correlation wasobserved between the color measurements of the entire tooth and the dentin core. From these measurements theauthors concluded that tooth color is mainly determined by the color of dentin. This fact, consistent with the visualdetermination during cross-sectioning of a natural tooth, is the foundation of the anatomical build-up and ValueShade system included in the 4 Season System.

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1.4 The 4 Seasons system

An esthetic restorative material should enable the dental professional to imitate the optical properties of naturalteeth accurately. Consequently, manufacturers are required to supply dentin, enamel and characterization materialswhose shades and levels of translucency are coordinated with each other and with natural dentition. On their part,dentists have to use the best possible layering techniques to reproduce the shade, shape and translucency of teeth insuch a way that they regain their original appearance. A system that is capable of satisfying all these requirementsis, therefore, best developed in close cooperation between the manufacturer, leading clinicians and input fromceramists on achieving lifelike restorations through layering.

In the course of developing 4 Seasons, the consistency and color coordination of the individual components were checked repeatedly by selected external dentists and color experts and subsequently adjusted to customer requirements. The result is a system that embraces forty shades. The table below provides an overview of all the shades and degrees of transparency available.

* Translucency measurements are approximate.

Table 1:4 Seasons system of materials

Being able to rely on an appropriate range of materials represents the first step towards farbricating an estheticallyimpeccable restoration. A technique guide has been prepared together with experienced dentists to support dentalprofessionals in their efforts to satisfy the requirements of their patients. Using case presentations as a basis, thisguide shows practitioners a route to attain results that meet exacting esthetic demands.

Shade Category Shade Designation Translucency* Color Code(Cavifil Cap or Syringe Plunger)

Dentin Shades (12 total)

Dentin (D) A1, A2, A3, A3.5, A4, A5, A6 Similar to Dark Blue B1, B2 natural dentin.C3D2 (7-8%)Bleach XL

Enamel Shades (28 total)Enamel Shaded (ES) A1, A2, A3, A3.5, A4 Similar to Medium Blue

B1, B2, B3, B4 natural enamel.C1, C2, C3, C4D2, D3, D4 (13-15%)Bleach XXL, XL, L, M (8-20%)

Enamel Translucent (ET) Amber, Clear, Super Clear (26%, 30%, 56%) Light BlueEnamel Value (EV) Low, Med, Hi (17-23%) WhiteEnamel Effects (EE) White, Blue (6%, 21%) Black

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2. Technical dataStandard composition (in weight by %)

4 Seasons is classified as a fine particle microhybrid restorative material. During the extensive development phase, optimized formulations of filler/resin combination, known to be clinically successful, were formulated specifically for the dentin, enamel and characterizing materials with the intent of altering only their optical properties while maintaining handling, physical and clinical performance requirements consistent throughout the entire system.

Physical properties according to EN ISO 4049

The physical properties of 4 Seasons materials are consistent with those of successful microhybrid materials providingideal strength in combination with functional resistance and ease of esthetic luster and polishability. What is uniquewith 4 Seasons is the exacting formulation of each category of shades – providing identical physical properties regardless of the optical possibilities. For example, 4 Seasons Super Clear – with a translucency of over 50% achievesthe same functional resistance and high physical properties as does the more opaque underlying dentin shades. Thisprovides the clinician and patient consistent handling and match of material properties regardless of the layering technique used or the individual shades preferred.

Dentin Enamel Super ClearAmber

RESINDimethacrylates 22.7 23.2 24.2

FILLERSBarium glass filler, silanized Ytterbium trifluorideMixed oxide, silanized 76.0 75.4 75.0Ba-Al-fluorosilicate glass, silanized Highly dispersed silicone dioxide

OTHERAdditivesStabilizers and catalysts 1.3 1.4 0.8Pigments

Dentin Enamel Super ClearFlexural strength (MPa) 135 135 135Flexural modulus (MPa) 9000 9000 9000Compressive strength (MPa) 260 260 260Absorption of water (µg/mm3) 19.8 19.6 19.6Solubility in water (µg/mm3) 1.0 1.0 1.0Radiopacity (% Al) 350 200 200Curing depth (mm) > 3.0 > 4.0 > 4.0Vickers hardness (MPa) 570 570 570Transparency (%) 7 - 8 13 - 15 56Density (g/cm3) 2.25 2.05 2.05

3. In vitro investigations

3.1 Color, opacity and translucency

The table below lists the CIELAB color co-ordinates as well as the degrees of opacity and transparency of the individual 4 Seasons materials.

Table 2:CIELAB color co-ordinates, levels of opacity (CR) and translucency (T) of the individual 4 Seasons components

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ShadeL* a* b* CR (%) T ( % )

Value Green to Red Blue to Yellow Opacity Translucency

Dentin A1 82 1.0 16.7 78 7.4Dentin A2 77 4.5 21.8 79 7.9Dentin A3 75 5.1 21.3 84 7.8Dentin A3.5 72 5.8 23.8 83 7.5Dentin A4 69 7.6 24.9 81 7.6Dentin A5 66 8.2 24.3 82 7.5Dentin A6 62 9.1 23.8 83 7.5Dentin B1 80 0.9 15.4 81 7.8Dentin B2 77 1.9 20.8 83 7.5Dentin C3 70 5.1 20.7 81 7.5Dentin D2 74 3.3 18.2 84 7.5Dentin Bleach XL 82 -1.4 9.4 70 9.1Enamel A1 76 1.0 13.3 57 14.2Enamel A2 74 1.8 16.4 63 13.7Enamel A3 74 2.7 20.4 61 13.7Enamel A3.5 72 3.5 22.9 60 13.5Enamel A4 68 6.2 25.7 61 13.8Enamel B1 77 0.3 11.6 57 13.7Enamel B2 76 1.5 22.3 62 13.2Enamel B3 72 4.4 26.5 64 13.9Enamel B4 71 5.5 27.0 61 13.8Enamel C1 74 0.8 16.4 64 13.1Enamel C2 72 1.7 18.7 66 13.9Enamel C3 69 3.5 19.6 65 13.2Enamel C4 66 5.6 22.6 65 13.5Enamel D2 72 2.3 16.9 60 14.2Enamel D3 70 4.8 22.2 65 13.9Enamel D4 67 5.8 23.3 64 13.7Enamel Value – LOW 64 -0.6 5.8 47 23.2Enamel Value – MED 73 -1.6 5.5 52 17.3Enamel Value – HI 77 -1.9 7.3 45 20.0Enamel Bleach XXL 85 -1.1 7.5 77 8.0Enamel Bleach XL 82 -1.7 7.5 66 10.0Enamel Bleach L 79 -1.8 7.7 53 15.0Enamel Bleach M 77 -2.1 9.8 47 20.0Enamel Effect White 88 -0.7 6.5 88 6.0Enamel Effect Blue 66 -1.8 -5.3 53 21.1Enamel Trans Amber 67 1.6 21.6 39 26.0Enamel Trans Clear 74 -1.7 7.8 36 30.0Enamel Trans Super Clear 72 -1.4 10.4 15 56.6

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Calibrated True Colors

When the a* b* values of each shade is graphed, the 4 Seasons Enamel and Dentin shades show a very consistent rise in a* andb* values within each shade grouping demonstrating True Color availability across the entire shade range. Similar depiction ofcompetitive materials demonstrate variable results across the entire shade range.

Filtek™ Supreme Body Shades

4 Seasons® Enamel Shades

4 Seasons® Dentin Shades

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Consistent Translucency

During the development of the 4 Seasons material rigorous efforts were made to insure consistency in translucency amongst the dentin and enamel subcategories. Meaning, regardless of the shade selected within each group, the individual shade would have a translucency similar to others in its category. Other competitive materials vary not only the shade but also thetranslucency in their individual groupings. This requires the clinical operator to factor in another variable in the restorativelayering process – the translucency. With 4 Seasons, there is tight tolerances in the translucency across the enamel and dentingroupings. Dentin shades of 4 Seasons have a range of 7.4-7.9% translucency whereas the enamel shades have a consistenttight range of 13.2-14.2% translucency. The ranges of competitive materials in translucency across their body, enamel and special shades often blur the differences between enamel and dentin shades.

} 6.3%

± 1.1%

± 4.0%

± 3.7%

± 0.5%± 0.6% ± 1.2%

4 Seasons offers a good variance in opacity/translucency between dentin & enamel categories, mimicking natural tooth structure.

4 Seasons offers a tight tolerance intranslucency within the enamel category.

4 Seasons offers a tight tolerance intranslucency within the dentin category.

4 Seasons®

Enamel

4 Seasons® Esthet•X™ Filtek™ Supreme

4 Seasons® Esthet•X™ Filtek™ Supreme

4 Seasons®

DentinEsthet•X™

EnamelEsthet•X™

DentinFiltek™ SupremeEnamels/Bodies

Filtek™ SupremeDentins

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Range of Translucencies in Special Shades

4 Seasons offers a full compliment and varying levels of translucency to select from based upon the clinical situation at hand.Translucency levels range from 6% (most opaque) to over 56% (most translucent) within the 4 Seasons system showing sequential steps of translucency throughout the range of special shades.

3.2 Filler composition

The filler composition plays an even more important role in highly esthetic restorative materials than it does in universal composites. Not only does a highly esthetic material have to fulfill particular requirements related to volume shrinkage, surface hardness, fracture resistance, flexural strength, flexural modulus, polishability, wear resistance and radiopacity, but the optical properties of its fillers and polymer matrix also need to be accurately coordinated with each other. A high level of coordination is vital to attain the shades and degrees of translucency required to achieve true-to-nature restorations.

As a consequence, particular attention was paid to the composition of the fillers in the course of developing 4 Seasons. The scanning electron micrographs below show the surface of 4 Seasons Enamel and 4 Seasons Dentin after polishing.

Fig. 4: Scanning electron micrograph of 4 Seasons enamel and dentin surfaces after they have been polished to a high gloss. The following fillers can be identified: white, ytterbium trifluoride; light grey, barium glass. The grey background represents the matrix.

Investigation: R&D Ivoclar Vivadent AG, Schaan, Liechtenstein

In addition to traditional A-D shades, 4 Seasons offers extra-light and extra-darkshades to meet the esthetic needs of allpatients. In addition, highly translucent enamelshades are available for surface characteriza-tion, while blue and white enamel effect shadesare available for internal characterization.

4 Seasons® Esthet-X™ Filtek™ Supreme Vitalescence®

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3.3 Wear

The wear behavior of restorative and prosthetic materials constitutes a vital parameter in the prospects of a restoration orprosthetic reconstruction. Wear processes affect the esthetic appearance and masticatory function of dental restorations. Varioustypes of wear mechanisms come into play in the oral environment; they often occur simultaneously: attrition (two-body wear),abrasion (three-body wear with the food bolus or tooth paste acting as the abrasive agent), erosion (chemical degradation) andfatigue/abfraction (chipping off due to crack formation).

Measuring the wear of dental materials in vivo involves lengthy, inaccurate procedures. Even if high-precision impressionmaterials are utilized, the restorations need to be worn for at least 12 to 24 months until the actual wear exceeds the meanvariation of measurements by a large enough margin to allow the rate of wear to be evaluated. For these reasons, dentalmaterials are subjected to in vitro simulations of mastication processes to estimate their stability under clinical conditions.

Ivoclar Vivadent uses a Willytec chewing simulator to measure the wear resistance of restorative materials. Standardizedantagonists made of Empress material are used to keep the data variance at a minimum. Plane test samples are subjected to120,000 masticatory cycles, applying a force of 50N and a sliding movement of 0.7 mm. An abrasive medium is not used in thistwo-body wear testing method. The vertical substance loss and volume loss are measured by means of a 3D laser scanner.

Fig 5:Volume loss and vertical substance loss of composite materials. The results are ranked according to volume loss, starting with the lowest measurement.

A vertical loss of less than 200 µm is regarded asbeing low. A loss between 200 – 300 µm representsa moderate rate of wear. In the above test, thewear behavior of both 4 Seasons Dentin and 4 Seasons Enamel closely resembled that of natural enamel.

Investigation: R&D Ivoclar Vivadent AG, Schaan,Liechtenstein

Fig 6:Tiles of materials were placed in the Proto-TechOral Wear Simulator. The device mimicsmasticatory dynamics, specifically employing ahuman enamel stylus, physiologic load levels, and a foodlike slurry for a third body. Tiles weresubjected to 100.000 cycles to mimic approx. 1.5years of clinical wear in the oral cavity.

Technique as described in:

Condon JR, Ferracane JL Dent Mater 1996Jul;12(4):218-26 Investigation: Ivoclar Vivadent, Inc., Amherst, NY

Volu

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Loss

(mm

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Verti

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ubst

ance

Los

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4. Clinical investigationsSeveral clinical studies on 4 Seasons have been initiated.

4.1 Dr. Joseph Dennison, University of Michigan, USA

Experimental: 53 Class II 4 Seasons restorations were placed in 30 patients with AdheSE, of which 5 were in premolar and 48 in molar teeth.

Current status: After 6 months, 48 restorations were evaluated. (Pending one year recall results; 93% Patient recall)

Results:

Conclusions: During the first 6 months, one restoration was replaced due to endodontic treatment and one due to fracture. All remaining restorations were in clinically acceptable condition.

4.2 Dr. Gerard Kugel, Tufts University, Boston, USA

Experimental: 50 Class V restorations were placed with an experimental variant of 4 Seasons using aself-etching adhesive AdheSE®.

Current status: After 6 months, all restorations were evaluated. (1.5 year recall results due July 2003.)

Results: At baseline, all restorations were in clinically acceptable conditions with respect to theparameters retention, color match, marginal integrity, anatomic form, secondary caries and gingivitis.

Conclusions: After 6 months, one restoration lost retention. Marginal discoloration of differing degrees was observed in 5 restorations. In all other mentioned criteria, restorations were in clinically acceptable condition.

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4 Seasons/AdheSE Baseline 6 MonthsMarginal adaptation 91%A, 9%B 59%A, 37%B, 2%C

Marginal discoloration 100%A 100%AAnatomic form 98%A, 2%B 88%A, 12%B

Restoration fracture 100%A 96%A, 2%B, 2%DSurface texture 100%A 96%A, 2%B, 2%C

Postoperative Sensitivity 91%A, 9%B 92%A, 4%B, 2,%C,2%DProximal contacts 92%A, 8%B 95%A, 3%B, 2%ASecondary caries 100%A 100%A

Survival 100%A 96%A, 4%D

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4.3 Dr. Pier Nicola Mason, University of Padua, Italy

Experimental: A total of 60 Class III and IV cavities were restored with 4 Seasons (Artemis®). Excite®

total-etch adhesive was used in 30 restorations, and AdheSE® self-etch adhesive was used in the other 30 restorations. The aim of this study was to confirm the surprisingly favorable results that AdheSE® produced in the enamel when examined in Class I and IIstudies as well as in laboratory investigations. It should be possible to obtain similar results in the anterior region.

Current status: The study was initiated in December 2002. Six-month results will be available in September 2003.

4.4 Dr. Knut Merte, Universitätsklinikum Leipzig, Germany

Experimental: Thirty patients who required at least two Class I or II restorations were treated with 4 Seasons. According to the split mouth design, one restoration was placed using theExcite total etch adhesive and the other was placed using the AdheSE® self-etch adhesive. 4 Seasons Dentin (Artemis®) and 4 Seasons Enamel (Artemis®) were placed in increments of max. 2 mm and light-cured.

Current status: All restorations were placed between December 2002 and February 2003.

4.5 Dr. Arnd Peschke, Internal Clinic, R&D Ivoclar Vivadent, Schaan, Liechtenstein

Experimental: The purpose of this investigation is to evaluate the clinical performance of 4 Seasons inconjunction with the tried-and-tested Syntac adhesive system and the newly developedAdheSE self-etch adhesive system in cavities of Classes I to V. All restorations are placedafter isolation with a rubber dam and all teeth treated are vital.

Current status: To date, 42 restorations have been placed using 4 Seasons (Artemis).

Results: In view of the experience gathered thus far, the clinical performance of the material canbe rated impeccable. 4 Seasons is easy to shape and exhibits high stability. The estheticintegration of the material in terms of transparency and shade is excellent; marginal discoloration, chipping of material or fractures have not been observed five months intothe investigation. Postoperative sensitivity did not occur in any of the patients treated.

Cavity class Syntac classic AdheSEI 2 1II 12 5III 8 6IV 4 0V 2 2

Total 28 14

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5. Toxicology5.1 Introduction

Dentists tend to place very high requirements on esthetic composite materials. When 4 Seasons was developed, particular attention was paid to using types of raw material that have been tried-and-tested in dental materials in vivo for many years. Consequently, we can fall back on the experience gathered withproven dental composites and their ingredients to assess the toxicological properties of 4 Seasons. 4 Seasonscontains the following fillers: barium glass, barium aluminium fluorosilicate glass, silicone dioxide and ytterbium trifluoride. Like Tetric® and Tetric® Ceram™, the monomer matrix of 4 Seasons is composed of Bis-GMA, urethane dimethacrylate and triethylene glycol dimethacrylate.

5.2 Toxicity of 4 Seasons

Fillers composed of glass and silicone dioxide are chemically inert. In addition, the fillers are embedded in aresin matrix in the course of polymerization. Consequently, they do not represent a toxicological risk. Thetoxicity of the ytterbium trifluoride filler, which endows the Ivoclar Vivadent composites with their excellentradiopaque properties, was tested on rats. None of the rats died when exposed to the highest tested dose of5000 mg/kg and pathological mutations of organs did not occur [1]. Furthermore, ytterbium trifluoride wastested for any radioactivity that may be present in addition to the naturally occurring radioactivity [2].

Tests showed that the LD5 level of both Bis-GMA and urethane dimethacrylate is higher than 5000 mg/kg [3].The LD50 level of triethylene glycol dimethacrylate is 10,837 mg/kg. As 4 Seasons comprises the samemonomers as Tetric and Tetric Ceram, the toxicology data of these materials may be used to evaluate thetoxicological risk of 4 Seasons. The cytotoxic properties of polymerized Tetric were evaluated in an Agar-overlay test using L929 mice cells. In this test, Tetric did not demonstrate a cytotoxic potential [4]. In view ofthe present data, it is safe to assume that 4 Seasons as well as Tetric and Tetric Ceram do not involve anyrelevant toxicological risk.

5.3 Mutagenicity of 4 Seasons

As 4 Seasons contains the same monomers as Tetric and Tetric Ceram, the results obtained on the mutagenicproperties of these two materials also apply to 4 Seasons. Polymerized Tetric specimens were extracted at 37 °C in water or DMSO for 30 days. The extracts were examined using a Salmonella typhimurium reversemutation assay (Ames Test). This test showed that Tetric is not mutagenic [5]. An umu-test on Tetric Ceramconfirmed these results. This test was also conducted with Salmonella typhimurium [6] and the extracts ofTetric Ceram were also negative in the Salmonella typhimurium reverse mutation assay [7]. In view of theseresults, we can conclude that 4 Seasons does not have any mutagenic potential.

5.4 Irritation and sensitization

Like all light-curing dental materials, 4 Seasons contains methacrylates. If uncured, methacrylates may have a slightly irritating effect. In addition, methacrylates may lead to sensitization and allergic reactions, such ascontact dermatitis, in predisposed individuals. The risk of allergies can be minimized by choosing a workingtechnique that forestalls any direct or indirect skin contact.

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5.5 Conclusion

Studies on the toxicology of dental materials that contain similar ingredients as 4 Seasons show that,

according to the current level of knowledge, 4 Seasons does not pose a health risk to users or patients,

with the exception of possible allergic reactions in predisposed individuals.

5.6 Literature on toxicology

[1] Acute Oral Toxicity (LD50) Study with Ytterbium-trifluoride, anhydrous in Rats. RCC Project 048881. July 1985.

[2] Certificate – Determination of radioactivity. RCC Project 045224. February 1985.

[3] Schmalz G (1998) The biocompatibility of non-amalgam dental filling materials. Eur. J. Oral. Sci. 106:696-706.

[4] Cytotoxicity test in vitro: Agar overlay assay. RCC Project 319926. March 1992.

[5] Salmonella typhimurium reverse mutation assay. CCR Project 314908, December 1992.

[6] Mutagenitätstest: Prüfung von Tetric®Ceram im umu-Test nach DIN 38 415-3. G. Leyhausen, MedizinischeUniversität Hannover, Interner Bericht. Dezember 1996.

[7] Salmonella Typhimurium Reverse Mutation Assay. CCR Project 563300. August 1996.

6. Literature

Eisenmann DR (1998). Enamel structure. In: Oral Histology. Development, Structure and Function. AR Ten Cate editor. St. Louis: Mosby, pp. 218-235.

Fernandez CP, Chevitarese O (1991). The orientation and direction of rods in dental enamel. J. Prosthet. Dent. 65:793-800.

Garberoglio R, Brännström M (1976). Scanning electron microscopic investigation of human dentinal tubules.Arch Oral Biol 21:355-362.

Hasegawa A, Ikeda I, Kawaguchi S (2000). Color and translucency of in vivo natural central incisors. The Journal of Prosthetic Dentistry 83:418-423.

Krejci I, Stavridakis M (2001). Marginal adaptation of class IV composites before and after loading. JDR 80:590.Schroeder HE (1991). Oral Structural Biology New York: Thieme.

ten Bosch JJ, Coops JC (1995). Tooth color and reflectance as related to light scattering and enamel hardness.JDR 74:374-380.

Torneck CD (1998). Dentin pulp complex. In: Oral Histology. Development, Structure and Function. AR Ten Cate editor. St. Louis: Mosby, pp. 150-196.

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Content: Dr. Urs LendenmannEdition: May 2003

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