CE 2James R. Dunn, DDSProfessor Loma Linda University School of Dentistry Loma Linda, California

iBond : The SeventhGeneration, One-Bottle Dental Bonding AgentTM

Abstract: Dental adhesive systems used for bonding dental resins to enameland dentin have evolved through several generations, with changes in chemistries, mechanism, number of bottles, application technique, and clinical effectiveness. The trend in the latest generation of dental bonding systems is to reduce the number of components and clinical placement steps. The introduction of iBondTM, a single-bottle dental adhesive system, is the latest of the new generation materials, and combines etchant, adhesive, and desensitizer in one component. This article will show that laboratory test results comparing the bond strength and margin-gap sealing of iBond TM with other latest-generation dental adhesive systems have shown similar results.

A

dhesion of dental resins to enamel and dentin has progressed dramatically in the 40 years since Buonocore1 introduced the technique of etching enamel with phosphoric acid to improve the adhesion of resin fillings to enamel. The first dental adhesives bonded resins to enamel only, with little or no dentin adhesion or sealing of dentin margins. Subsequent generations of dental adhesives have dramatically improved the bond strength to dentin and the sealing of dentin margins while retaining a strong bond to enamel. The use of dental resins as cements as well as direct and indirect restorations will continue to increase as the use of metals in dentistry decreases, and patients demand more esthetic procedures. Because almost all of the current restorative treatments either require or are enhanced with the use of dental adhesives, it is important that reliable and easy-to-use adhesives are available. This article discusses iBondTM,a, the first of a new generation of dental adhesives in which all the components for dental adhesion are contained in a single bottle and applied using a one-step technique that requires no mixing.

Chronology of Dental AdhesivesThe development of dental bonding systems has continued to evolve over the past 40 years, with variations in chemistries, mechanisms, numbers of bottles, application techniques, and effectiveness. In an attempt to simplify the confusion, one common method is to classify dental adhesives into a series of generations.2 Although this method is an oversimplification of the complexity of dental adhesives, it allows us to quickly understand the general characteristics of each group of adhesives and choose an appropriate material for our practices. The first- and second-generation bonding agents used during the late 1960s and 1970s did not recommend etching the dentin and relied on adhesion to the attached smear layer. The weak bond (2 MPa to 6 MPa) to the smear layer still allowed dentin leakage with clinical margin stain.2 The third-generation systems of the 1980s introduced acid-etching of dentin and a separate primer designed to penetrate into the dentin tubules as a method to increase bond strength. Systems such as ScotchbondTM 2b increased the bond strength to dentin to approximately 12 MPa to 15 MPa and decreased dentin margin failure. However, with time, margin staining caused clinical failure.2a b

Learning ObjectivesAfter reading this article, the reader should be able to: discuss the different generations of dental adhesive systems. compare the laboratory testing results of iBondTM with other new-generation adhesive systems. describe the chemical components, mechanism, and clinical steps of iBond dental adhesive. 14

Heraeus Kulzer, Inc, Armonk, NY 10504; 800-431-1785 3M ESPE, St. Paul, MN 55144; 800-634-2249

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Table 1Comparison of the Classification and Components of Dental Adhesive SystemsStep Etching of enamel and dentin 4th Generation 5th Generation 6th Generation Self-etching primer Self-etching primer Resin/ sealer Shear Bond Strength (MPa) Self-Etching Adhesives 6th Generation 7th Generation (mixing required) (no mixing required) Self-etching, selfpriming resin/sealer Self-etching, selfpriming resin/sealer Self-etching, selfpriming resin/sealer Self-etching, self-priming resin/sealer desensitizer disinfectant Self-etching, self-priming resin/sealer desensitizer disinfectant Self-etching, self-priming resin/sealer desensitizer disinfectant

Etchant

Etchant Self-priming resin/sealer Self-priming resin/sealer

Priming of dentin Sealing of enamel and dentin

Primer Resin/ sealer

The fourth-generation adhesive systems of the early 1990s used chemistry that penetrated both the etched and decalcified dentin tubules and dentin substrate, forming a hybrid layer of collagen and resin. Fusayama3 and Nakabayashi4 described the penetration of resin into dentin to give high bond strengths and a dentin seal, and Kanca5 introduced the idea of wet bonding with these systems. The fourthgeneration adhesive systems exhibited dentin

35 30 25 20 15 10 5 02 12 5 25 25 20 25

1st

2nd

3rd

4th

5th

6th

7th

D

ental adhesives have dramatically improved the bond strength to dentin and the sealing of dentin margins while retaining a strong bond to enamel.

GenerationFigure 1Comparison of shear bond strength to dentin of the different generations of dental adhesive systems.

bond strengths in the low to mid 20-MPa range, and significantly reduced margin leakage compared with earlier-generation systems.2 These earlier systems required a very exacting technique of controlled etching with acid on both enamel and dentin, the correct amount of water on the surface of the dentin, and the placement of two or more components on both enamel and dentin. Because of the clinical complexity with multiple bottles and multiple application steps, dentists began asking for a simplified adhesive system. The fifth-generation systems introduced during the mid 1990s combined the primer and adhesive while maintaining high bond strengths.2 Controlled etching, surface wetness, and resin placement continued to be a clinical challenge. The sixth-generation dental adhesive systems introduced in the late 1990s and early 2000s eliminated the separate acid-etching step by incorporating an acidic primer that was placed on the enamel and dentin after tooth preparaVol. 24, No. 2 (Suppl)

tion and isolation from saliva. The primer remained on the tooth and an adhesive was placed over the primer. Later modifications to the sixth-generation systems required mixing the acidic primer and adhesive before place-

B

ecause almost all of the current restorative treatments either require or are enhanced with the use of dental adhesives, it is important that reliable and easy-touse adhesives are available.

ment on the dentin and enamel. These systems also were reported to reduce the incidence of posttreatment sensitivity found in previous systems.6 The bond strength to dentin and enamel is lower than the fourth- and fifthgeneration systems.2 Seventh-generation systems were introduced in

Figure 2iBondTM single-dose unit and bottle.

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Table 2Comparison of the Number of System Components and Clinical Placement Steps of Dental Adhesive SystemsGeneration 1st 2nd 3rd 4th 5th 6th 7th # Steps 2 2 3 3 2 1 1 Description Etch enamel, apply adhesive Etch enamel, apply adhesive Etch enamel, apply primer Total etch, apply primer Total etch, apply adhesive Apply selfetch adhesive Apply selfetch adhesive # Components 2 2 23 35 2 2 1

late 2002 and combined etchant, primer, and adhesive in a single bottle, eliminating an additional mixing and/or placement step over the sixth-generation systems. Laboratory studies show that bond strengths and margin sealing to be equal to the sixth-generation systems.2 Table 1 compares the classification and components of the fourth-, fifth-, sixth-, and seventh-generation dental adhesive systems. Figure 1 compares the dentin bond strength of the different generations of dental adhesive systems. Table 2 compares the number of system components and clinical placement steps of the different generations of dental adhesive systems. arlier systems required a very exacting technique of controlled etching with acid on both enamel and dentin, the correct amount of water on the surface of the dentin, and the placement of two or more components on both enamel and dentin.

E

40 35 30 25 20 15 10 5 0

Shear Bond Strength (MPa)

Enamel Dentin

iBondTM Dental Adhesive SystemiBondTM is a seventh-generation, single-component, no-mix, one-step application dental adhesive with an etchant, adhesive, desensitizer, and photoinitiator (Figure 2, Table 3). Table 4 shows the function of each ingredient.

24.2 27.2 12.5 15.1

30.1 29.0

24.5 26.5

27.4 25.9

5 minutes

24 hours

7 days

Thermocycle

30 days

Scientific TestingA strong bond to enamel and dentin and a secure dentin margin seal are two clinical concerns dentists have when using dental adhesives. Adhesive bond in the laboratory is measured using either shear or tensile force testing. iBondTM showed comparable bond strengths with fifth- and sixth-generation bonding agents. Figures 3 through 5 show bond strength studies from several testing laboratories.

Testing PeriodsFigure 3Shear bond strength of iBondTM to enamel and dentin at different times after light activation. Courtesy of Dr. C. Munoz, University of Loma Linda, Loma Linda, California; 2001.

Tensile Bond Strength (MPa)

30 25 20 15 10 5 0

24.0 22.0

iBondTM Prompt19.9 20.2 16.0 15.0

15.0 15.0 8.0 4.6 8.2 7.7 b g

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ecause of the clinical complexity with multiple bottles and multiple application steps, dentists began asking for a simplified adhesive system.

d

d

a

c

a

c

b

Enamel Enamel Superficial Moist

Super- Deep Deep ficial Dentin Dentin Dry

Figure 4Tensile bond strength of two self-etching products (iBondTM and Prompt,b) to enamel and dentin with moist and dry surface conditions (composite = Charisma). The letters a, b, c, and g are statistical references from test results, with the same letter having no difference. Courtesy of Dr. J. Powers, University of Texas, Houston; 2002.

Margin sealing can be shown with scanning electron micrography or dye penetration between the composite and dentin. Figures 6 and 7 show marginal gaps and marginal resistance to dye leakage.

Clinical UseSelf-etching dental adhesive systems requireVol. 24, No. 2 (Suppl)

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Table 3iBondTM Dental Adhesive System Matrix Components UDMA 4-Meta (pH = 2.2) Solvents Acetone Water Photoinitiators Camphorquinone Disinfectant/Desensitizer Glutaraldehyde Stabilizers Fillers none

Table 4Function of Each IngredientIngredient 4-Meta Effect/Property Etching and conditioning of enamel and dentin Wetting of the surface Promotion of infiltration Bonding to collagen via hydrogen bonding Bonding to Ca2+ ions of the apatite via chelation complexes Film-forming properties Cross-linking

CE 2

UDMA

Glutaraldehyde Disinfection/desensitizing agent Cross-linking of collagen fibrils Acetone Water Facilitates solvent evaporation Solvent for monomers Hydrolysis of 4-Meta to 4-Met (= acid) Provides water for etching process Solvent for monomers

fewer clinical steps than previous generation adhesive systems. However, all dental adhesives, including self-etching systems, require a careful placement technique to ensure maximum adhesion and margin seal. The following placement steps are recommended for maximum effectiveness when using the iBondTM adhesive system: 1. Isolate the tooth from saliva contamination during the adhesive procedure. 2. Complete the preparation with abrasive instruments. 3. Clean the preparation, removing all debris with water. Remove excess water. 4. Saturate the microbrush with iBondTM liquid from either the bottle or singledose vial. 5. Apply 3 consecutive coats of iBondTM to both the enamel and dentin followed by gentle rubbing for 30 seconds. 6. Use gentle air pressure or vacuum to remove the acetone and water solvent. 7. Cure for 20 seconds with a dental curing light of at least 500 mW/C2. 8. Place composite.

Shear Bond Strength (MPa)

20

10

0

iBondTM (exp) Control

Gluma,a Etching + Gluma Desensitizer Desensitizer + iBondTM (exp) + iBondTM (exp)

Figure 5Shear bond strength of iBondTM to dentin and enamel in combination with Gluma Desensitizer with and without separate etching after 24 hours storage in water at 37C (exp = experimental iBondTM without glutaraldehyde). Data on file, Heraeus Kulzer, Inc, Armonk, New York.

Before thermocycling After thermocycling

Percentage of Perfect Margins

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ll dental adhesives, including self-etching systems, require a careful placement technique to ensure maximum adhesion and margin seal.

100% 80% 60%99.6 95.5

ConclusioniBondTM is the first single-component dental adhesive that contains all of the components for dental adhesionetchant, adhesive, and desensitizerin a single bottle, and is applied using a one-step technique. Laboratory testing confirms that iBondTM has physical characterVol. 24, No. 2 (Suppl)

40% 20% 0% iBondTM

Figure 6Percentage of perfect margins with Charisma,a as the restorative material, showing margin gaps before and after thermocycling. Courtesy of Dr. U. Blunk, University of Berlin, Germany; 2002. Compendium / February 2003

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CE 2Microleakage Score

Dye penetration in class V cavities after thermocycling 2,000 cycles (5C to 55C)

2.5 2.0 1.5 1.0 0.5 0 iBondTM Prompt Touch & BondTM,c Single BondbMeans are not significantly different at P < .05

Means are not significantly different at P < .05

iBondTM Prompt Touch & BondTM,c

Single Bondb

Enamelc

Dentin

Parkell Dental, Farmingdale, NY 11735; 800-243-7446

Figure 7iBondTM shows testing results similar to other dental self-etching adhesives. Data on file, courtesy of Dr. C. Munoz, University of Loma Linda, Loma Linda, California; 2002.

istics similar to other self-etching adhesives and may be used in all clinical situations where dental adhesives are required.

References1. Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res. 1955;34:849-853. 2. Van Meerbeek B, Inoue S, Perdigao J, et al. In: Fundamentals of Operative Dentistry. 2nd ed. Carol Stream, Ill: Quintessence Publishing Co, Inc; 2001;194-214. 3. Fusayama T, et al. Non-pressure adhesion of a new adhesive restorative system. J Dent Res. 1979;58:1364. 4. Nakabayashi N. Resin reinforced dentin due to infiltration of monomers into the dentin at the adhesive interface. J Jpn Dent Mat Devices. 1982;1:78-81. 5. Kanca J III. Resin bonding to wet substrate. I. Bonding to dentin. Quintessence Int. 1992;23:39-41. 6. Miller MB. Self-etching adhesives: solving the sensitivity conundrum. Pract Proced Aesthet Dent. 2002;14:406.

AcknowledgmentThe author would like to thank Dr. Mark Pitel, Heraeus Kulzer, for the tables used in this article.

DisclosureThe Center for Dental Research at Loma Linda University received a research grant from Heraeus Kulzer for laboratory studies of iBond TM.

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