Heraeus Kulzer Adhesives Adhesive Guide
Contents Principles of adhesion Enamel Preparation and conditioning Dentin Conditioning Wettability and surface tension Classification of adhesive systems Classification according to generation Classification according to steps Etch & Rinse systems Etchant Primer Bonder 3-step systems 2-step systems Self-Etch systems 2-step systems All-in-One systems Tips References Product outline 2 4 5 7 8 9 10 11 13 14 15 16 18 20 21 22 23 24 25
Principles of adhesion Adhesives are substances used to retain or bond composites to dental enamel or dentin. They are very important for any restoration that does not have macromechanical retention. Adhesives and the relevant adhesive techniques should, therefore, guarantee reliable bonding, withstand separation of the individual layers and adequately distribute the forces that occur in clinical situations. As the interfaces between the composite, enamel and dentin have different chemicophysical properties, the adhesive system should always be precisely tailored to meet their specific requirements. Composites Modern composites comprise an organic content (resin), in which inorganic microparticle and nanoparticle fillers are dispersed. The adhesive reacts with the composite by copolymerizing with the resin content while it is being cured Enamel Enamel is the hardest substance in the human body. It comprises 96 % inorganic material. Water makes up 4 % of its total volume. Due to its high degree of mineralization enamel is very stable and inert. Its biomechanical properties are completely different to those of the substances below its surface. Dentin Dentin is formed from the mesoderm and comprises 70 % inorganic and 30 % organic material (percentages may fluctuate). 22 % of the total volume is water (inorganic). Dentin is neither inert nor homogeneous and is classified as follows: Primary dentin original, initially formed dentin. The outer and inner primary dentin differs in the number and diameter of the dentinal tubules. Secondary dentin original, initially formed dentin. The outer and inner primary dentin differs in the number and diameter of the dentinal tubules. Tertiary dentin or reactionary dentin outer layer, is formed as a reaction to chemical or mechanical effects. Generally a distinction is made between prismatic and aprismatic enamel (outer section of enamel in erupting teeth). 2
Principles of adhesion Schematic build-up of a tooth Enamel Primary and secondary dentin Tertiary dentin 3
Enamel Preparation and conditioning In 1955 Buonocore had already demonstrated that the enamel surface must be etched to attain optimal adhesion between the enamel and resin. Etching achieves the following: Non-homogeneous dissolution of the organic content and removal of the interprismatic structure of the enamel. Formation of an irregular, microporous surface. Greater wettability due to a reduction in surface tension and increase in free surface energy. Great care should be taken when using this technique, as prolonged contact between enamel and acid can result in overetching. This completely dissolves the interprismatic components and the tooth structure becomes extremely brittle. Optimal adhesion is not, however, produced solely by chemical conditioning of the enamel. A maximum number of prisms at the correct angle should also be present to withstand the contraction forces of the composite during polymerization. Depending on the area to be conditioned, the margins of the filling should therefore be prepared with a slight deep chamfer, bevel of 45 or a shoulder. 4
Dentin Conditioning It is difficult to differentiate precisely between the dentin and pulp. The correct description is therefore pulp-dentin unit. The number and diameter of the dentinal tubules vary greatly in this region of the tooth with fluctuations between 15000/mm 2 with an average diameter of 0.5 µm in the peripheral zones and 45000/mm 2 with a diameter of 8 µm in the deep regions of the dentin. Schematic build-up of the dentin structure with dentinal tubules A correct definition also has to be found for the smear layer. Eick defined it as an amorphous layer of organic and inorganic residue that is produced when grinding the tooth structure with manual or mechanical rotary instruments. Modern dentin-enamel adhesives are designed to produce a bond to the dentin by fully surrounding the collagen fibres and simultaneously filling the exposed cavities between the fibres with resin matrix. A layer of methacrylate groups, which react with the resin component of the composite, is also applied. Depending on the system used, the smear layer is removed or modified so that it is easier for the resin to penetrate inside the dentinal tubules. 5
Dentin Conditioning Dentin smear layer Source: Heraeus Kulzer, Wehrheim, Germany 6
Wettability and surface tension If two materials are to be permanently bonded together, the ratio between their free surface energy and wettability should be taken into account. Water drop on a surface with a) low surface energy and b) high surface energy. To ensure that an adhesive can be applied to a material, its surface tension should be lower than the free surface energy of the base. Dental enamel has high free surface energy due to its high proportion of inorganic substances in the form of hydroxylapatite. In contrast, dentin has low free surface energy. The surface of the dentin has to be chemically conditioned to increase its free surface energy in order to apply the adhesive. Enamel-dentin adhesive systems use different methods for conditioning the surface. Fig. a Each system incorporates: chemical solution for conditioning the tooth structure with acid: etchant bonding agent: primer the actual adhesive: bonder These 3 procedures do not relate to the number of treatment steps required, the number of system components or the type of conditioning used. Fig. b 7
Classification of adhesive systems Enamel-dentin adhesives are classified as Etch&Rinse systems and Self-Etch systems. In Etch&Rinse systems separate etchants (usually 35 % orthophosphoric acid) are used; these are applied to the enamel and dentin and then rinsed off. The bonding agent and adhesive are then applied to both the enamel and the demineralized dentin, which has already had the smear layer removed. It must again be emphasized that the number of components is not related to the number of clinical treatment steps. More bottles may be used with 1-step systems than with 2-step systems. For example, there are 1-step systems that require several components to be mixed together before use. In Self-Etch systems a solution comprising etchant/primer and adhesive is applied to the enamel as well as the dentin, which is covered with the smear layer. In 1-step systems the adhesive can be applied along with the etchant/primer in one step. In 2-step systems the adhesive is applied separately after air drying the etchant/primer solution. In Self-Etch systems demineralization of the enamel and penetration by the resin occur simultaneously regardless of the number of working steps. 8
Classification of adhesive systems Classification according to generation Generation Characteristics Tensile strength of the dentine Number of components I Very weak dentin bond approx. 2 MPa 1 II Weak bond and adhesive preparation required approx. 2-8 MPa 2 III IV V VI VII 2-component primer and adhesive system; selective etching; bonds to metal; low postoperative sensitivity Multi-component system; hybridization; etch&rinse; low postoperative sensitivity One-component system; etch&rinse; wet bonding; hybridization; no mixing required; low postoperative sensitivity Self-etching, multicomponent system, 1- or 2-phase, hybridization, low postoperative sensitivity Self-etching, one-component system; no mixing; non-sensitive to moisture; hybridization; low postoperative sensitivity approx. 8-15 MPa 2 to 3 approx. 17-25 MPa 2 to 5 approx. 20-24 MPa 1 approx. 18-23 MPa 2 to 3 approx. 18-25 MPa 1 9
Classification of adhesive systems Classification according to steps Etch&Rinse Systems Self-Etch Systems 3-step Etch/Primer/Bonding 2-step Etch/Primer & Bonding 2-step Etch & Primer/Bonding 1-step Etch & Primer & Bonding Single Dose Single Dose 10
Etch & Rinse systems In Etch & Rinse systems the dentin smear layer is removed with an etchant. This has to be rinsed off prior to application of the adhesive regardless of the number of steps involved in the system. Etch & Rinse systems always contain three components: Etchant This is also referred to as conditioner, as it conditions the tooth surface. It usually comprises 35 % orthophosphoric acid and removes the smear layer as well as the smear plugs in the dentinal tubules. The etchant demineralizes the dentin and intertubular dentin, exposes the collagen fibres and creates a funnel-shaped fibrous structure at the opening of the dentinal tubules. Primer The primer is a resin-based liquid with highly hydrophilic properties, which makes it very effective on dentin. The application of a primer increases the surface energy of the dentin. It infiltrates the exposed collagen weave, surrounds the fibres and displaces the water content. Bonder The bonder is the actual adhesive. It can infiltrate intratubular and intertubular dentin. As the bonder is transported by the primer, it forms a chemical bond instead of a microretentive bond. The micromechanical retention that is created on the dentin is a hybrid layer, i.e. a type of barrier between the filling and the inner tooth areas. There is therefore no interface, as there is cohesion rather than adhesion between the hybrid layer and dentin, which greatly reduces the risk of fracture. Unlike Self-Etch systems, Etch&Rinse systems can also be used with dual-curing luting cements without additional chemical activators. 11
Etch & Rinse systems Dentin after etching with 35 % phosphoric acid Source: Heraeus Kulzer, Wehrheim, Germany 12
Etch & Rinse systems Etchant Etchant is applied to the enamel first and then to the dentin after approx. 10 s. It is rinsed off after another 20 s. The total etch time for the enamel, which has a higher proportion of inorganic content, is therefore 30 s. This technique is referred to as selective etching. Care should be taken not to overetch the enamel to avoid the tooth structure becoming too brittle. Acids in current use demineralize the dentin to a depth of 1 10 µm and therefore do not affect or directly damage the pulp. The main effect of the etchant is on the surface due to the mineral content in the dentinal tubules, which acts as a buffer against the hydrogen ions. The etch gel must be rinsed off very carefully; this should take twice as long as application (approx. 1 min. in total). The etch gel should be rinsed off first with water before using a water-air spray to prevent splashes. Removal of excess water is another critical stage. If the residual dentin is overdried, the collagen fibres collapse and prevent adhesion; on the other hand, if the dentin is too moist, the hydrophobic resin cannot adequately infiltrate the tubules. Cf. also: The main topic of discussion based on current findings is the problem of the optimal moisture content required to attain an adequate bond strength (Inokoshi, 1997). The dentin should have a moist appearance prior to application of the primer. To achieve this, excess water should always be removed by suction and not by using a jet of air pointing directly onto the cavity. It is advisable to protect the adjacent teeth of the tooth to be treated before applying the etch gel. A Teflon strip can be used to protect the healthy tooth structure. 13
Etch & Rinse systems Primer The special properties of the primer or bonding agent allow it to infiltrate deep inside the dentinal tubules and bond with the collagen fibres. The moistness of the dentin prevents infiltration of the hydrophobic adhesive after conditioning. This is why hydrophobic conditioning of the dentin is required beforehand with a primer that contains amphiphilic monomers, e. g. HEMA, PENTA, or 4-META, in organic solvents. By using solvents such as ethanol or acetones/h 2 O, the monomers are able to infiltrate inside the organic structure. This displaces the water content inside the dentine tubules and replaces it with the monomers. As aqueous solvents evaporate more slowly than organic solvents, it is important to know the solvent content of the primer and take this into account during application. Great care should be taken during clinical application of the primer, which should be allowed to react for a minimum of 30 s. At the end of the reaction time the volatile components (solvents) are evaporated with an indirect jet of air (pointed towards the dental mirror). A thin monomer film remains after the solvent has been completely evaporated. The primer in the dentine renders it hydrophobic and compatible with the adhesive. 14
Etch & Rinse systems Bonder The adhesive, which is applied after the enamel-dentin structure has been conditioned, is resin-based and consists mainly of hydrophobic monomers, e. g. Bis-GMA or UDMA. It is also important during this stage to apply the adhesive very uniformly over the entire cavity. A different brush should always be used from the one used for applying the primer; a microbrush is recommended. The adhesive is polymerized after application. During polymerization the shape and depth of the cavity should be taken into account: the greater the distance between the light-emission window of the lamp and the surface to be polymerized, the longer the exposure time. Depending on the adhesive used, the adhesive layer should be polymerized for 20 40 s. Following polymerization the conditioned surface should have a shiny appearance. Otherwise the last step of adhesive conditioning should be repeated and the surface checked again. 15
Etch & Rinse systems 3-step systems In 3-step systems the etchant, primer and bonder have to be applied separately. 3-Step System: Etchant/Primer/Bonder Advantages Highly effective both on enamel and dentin Long-term clinical results Highly effective on porcelain and metal Can be used with dual-curing composites Disadvantages Technique-sensitive, success depends greatly on the skill of the operator Risk of overetching Risk of dry leakage Requires multilayer application 16
Etch & Rinse systems 17
Etch & Rinse systems 2-step systems 2-step systems consist of only a single solution containing primer and bonder. This is user-friendly, as fewer clinical steps are required; these steps must, however, be very strictly adhered to. Generally 2-step systems are based on a solvent containing acetone or ethanol, which evaporates very rapidly. 2-Step System: Etchant/Primer & Bonder Advantages Optimum effect both on enamel and dentin Long-term clinical tests Option of filling the adhesive with filler materials Application in only one step after etching Disadvantages Technique-sensitive, success depends greatly on the skill of the operator Risk of overetching Risk of dry leakage Requires incremental application Single Dose 18
Etch & Rinse systems 19
Self-Etch systems Self-etch systems differ from Etch&Rinse systems because they have a different effect on the smear layer: with Self-Etch systems the smear layer is not removed, but modified. Rinsing with water is also unnecessary. The homogeneous adhesive layer formed by an All-in-One Self-Etch system in an SEM image with 500 x magnification The etching effect of the Self-Etch systems is based on acidic monomers, which release protons on contact with water initiating the etching process. During etching the ph as well as the calcium and phosphate concentration gradually increases, which limits etching both in terms of time and depth. Generally phosphoric acids that are esterified with HEMA or 4-META and capable of releasing protons are used. The methacrylate groups also contained in the system are used for bonding the adhesive. Adhesive-Layer It should be noted that these systems do not have an optimum effect on unprepared enamel. Source: Heraeus Kulzer, Wehrheim, Germany 20
Self-Etch systems 2-step systems In Self-Etch, 2-step systems the first step is application of an etchant/primer component that modifies the hybrid layer and acts as a bonding agent. The component is applied to the entire cavity and an adequate reaction time has to be allowed before the adhesive is applied. 2-Step System: Etchant & Primer/Bonder Advantages Optimum effect on dentin Fewer clinical steps Disadvantages No optimum effect on unprepared enamel Multilayering technique Chemical bond with dentin 21
Self-Etch systems All-in-One systems All-in-One, Self-Etch systems are one-step systems, which reduce operator-related variables and consequently reduce sources of errors to a minimum. These one-component systems are usually applied to the enamel and dentin and then polymerized after the required reaction time (normally 20-30 s.); this forms a hybrid layer without the need for any further working stages. 1-Step System: Etchant & Primer & Bonder Advantages User-friendly Excellent results on dentin Chemical bond with dentin Available as Single Dose Disadvantages No optimum effect on unprepared enamel Cannot be used with dual-curing composites Multilayer application may be required Only effective on prepared enamel Single Dose 22
Tips Follow the manufacturer s instructions. Use different coloured brushes with multi-step systems to eliminate any possibility of a mix-up. The adjacent teeth are protected with Teflon strips against inadvertent etching. Remove excess adhesive with cotton pellets and not with the air jet (risk of irregular distribution). Ensure that bottles containing volatile solvents (e. g. acetone, ethanol) are always properly sealed. Excess adhesive can cause staining at the margins. Only etch the areas of the teeth required for adhesion and protect the adjacent tooth structure. Position the light source as close as possible to the cavity. Clinical photograph: Prof. A. Cerutti, University of Brescia, Italy Remove any excess adhesive from the light-emission window of the lamp. Check regularly if the adhesive has been fully polymerized. 23
References Michael G. Buonocore: A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res. 1955; 34: 849 853. Carvalho Rm., Fernandes Ca., Villanueva R., Wang L., Pashley Dh. (2001). Tensile strength of human dentin as a function of tubule orientation and density. J Adhes Dent 3 (4): 309 314. De Munck J., Van Landuyt K., Peumans M., Poitevin A., Lambrechts P., Braem M., Van Meerbeek B. A critical review of the durability of adhesion to tooth tissue: methods and results. J Dent Res. 2005 Feb; 84 (2): 118 132. Review. Harnirattisai C., Inokoshi S., Shimada Y. Hosoda H. Interfacial morphology of an adhesive composite resin and etched cariesaffected dentine. Oper Dent 1992; 17: 222 228. Pioch T., Stotz S., Buff E., Duschner H., Staehle Hj. (1998). Influence of different etching times on hybrid layer formation and tensile bond strength. Am J Dent 11 (5): 202 206. Van Meerbeek B., Van Landuyt K., De Munck J., Hashimoto M., Peumans M., Lambrechts P., Yoshida Y., Inoue S., Suzuki K. Technique-sensitivity of contemporary adhesives. Dent Mater J. 2005 Mar; 24 (1): 1 13. Review. J. D. Eick, A. J. Gwinnett, D. H. Pashley, S. J. Robinson. Current concepts on adhesion to dentin, Crit. Rev. Oral Biol. Med. 8 (1997) 306 335. 24
Product outline roduct Order No. roduct Order No. ibond All-in-One Self-Etch adhesive system Bottle Assortment (1 x 4 ml bottle, accessories) 66008943 Single Dose Assortment (40 x Single Dose, accessories) 66008944 Bottle Assortment Value Pack (3 x 4 ml bottle, accessories) 66019847 Single Dose Assortment (80 x Single Dose, accessories) 66009302 GLUMA Comfort Bond + Desensitizer 2-step Etch& Rinse adhesive system Bottle Assortment (1 x 4 ml bottle, accessories) 66001710 Single Dose Assortment (40 x Single Dose, accessories) 66005664 Bottle Value Pack (3 x 4 ml bottle, accessories) 66018222 GLUMA Comfort Bond 2-step Etch& Rinse adhesive system Bottle (1 x 4 ml bottle, accessories) 66001657 Bottle Assortment (1 x 4 ml bottle, 2 x 2.5 ml syringe Gluma Etch 20 gel, accessories) 66001658 GLUMA Solid Bond 3-step Etch& Rinse adhesive system Bottle Assortment (1 x 4 ml bottle each of primer and sealer, 2 x 2.5 ml syringe Gluma Etch 20 gel, accessories) 66000132 Primer (1 x 4 ml bottle) 66000133 Sealer (1 x 4 ml bottle) 66000134 GLUMA Etch Etchant GLUMA Etch 20 Gel (2 x 2.5 ml syringe, 25 application tips) 66000131 GLUMA Etch 35 Fluid (1 x 15 ml bottle) 66000129 GLUMA Etch 35 Gel (2 x 2.5 ml syringe, 25 application tips) 66000130 GLUMA Desensitizer Relieves sensitive cervical areas and postoperative hypersensitivity Bottle Assortment (1 x 5 ml bottle) 65872654 Bottle Value Pack (3 x 5 ml bottle, accessories) 66018221 Single Dose Assortment (40 x Single Dose, accessories) 66001854 25
Notices
Notices
Notices
Conception:: Heraeus Kulzer GmbH Thanks to: Prof. Antonio Cerutti Nicola Barabanti Stefano Sicura University Brescia, Italy Art.Nr.: 66035833 05/07 Heraeus Kulzer srl Heraeus Kulzer GmbH Grüner Weg 11 63450 Hanau Phone +49 (0) 6181 355 444 Fax +49 (0) 6181 353 461 info.dent@heraeus.com www.heraeus-kulzer.de Heraeus Kulzer Ltd. Heraeus House, Albert Road Northbrook Street, Newbury Berkshire, RG14 1DL Phone +44 (0) 1635 30500 Fax +44 (0) 1635 30606 Mail: sales@kulzer.uk www.heraeus-kulzer.com Heraeus Kulzer Australia Pty. Ltd. Locked Bag 750 Roseville NSW 2069 Phone +61 29 417 8411 Fax +61 29 417 5093 Mail: sales@kulzer.com.au www.kulzer.com.au