It consists of a self-etching primer, which is an aqueous solution of acidic hydrophilic monomers, and an adhesive resin, which is a hydrophobic resin that is light-cured.
Bonding to enamel can be enhanced via acid etching.
An adherend is the material to which adhesive is applied, bonded to another material, such as enamel, dentin, alloy, or ceramic.
It is mechanical interlocking associated with bonding of an adhesive to a roughened adherend surface.
The smear layer is a poorly adherent layer of ground dentin produced by cutting the dentin surface, which needs to be removed before applying adhesive.
Provides resistance to separation of an adherend substrate from a restorative or cementing material, distributes stress along bonded interfaces, and seals the interface via adhesive bonding.
1) Etch & rinse (three-step and two-step), 2) Self-etch (two-step and one-step), 3) Multi-mode/Universal (etch & rinse and self-etch).
Excessive etching can lead to hypersensitivity and tissue damage.
Removing the smear layer is important because it can carry bacteria and affects the bonding process.
Hybridization involves collagen degradation and the formation of a hybrid layer where resin infiltrates the dentin, creating a bond.
Wettability refers to the relative affinity of a liquid for the surface of a solid, indicating how well a liquid can maintain contact with a solid surface.
The hybrid layer is an intermediate layer of resin, collagen, and dentin produced by acid etching of dentin and infiltration of resin into conditioned dentin.
It achieves both micromechanical interlocking and chemical bonding.
Adhesive failure is the failure at the interface, which can be increased by a bilateral interface.
1) Adhesive, 2) Hybrid layer, 3) Resin tags, 4) Dentin.
Phosphoric acid removes the peripheral mineral and smear layer from the surface, creating microporosities and increasing the wettability of the tooth surface.
Surface tension should be greater than surface energy for efficient bonding.
The contact angle is the angle of intersection between a liquid and a solid surface, measured from the solid surface through the liquid to the liquid-vapor tangent line.
Resin cannot coat collagen in the same way that mineral does, which will eventually lead to failure.
It may reduce sensitivity by preventing over-etching and desiccation, but it also has insufficient enamel etching ability compared to phosphoric acid.
Self-etching primers etch and prime the tooth simultaneously, incorporating the dissolved smear layer and demineralized products into the hybrid layer instead of removing them.
Primers are needed to maintain the expanded collagen network while etching and to allow infiltration of hydrophobic adhesive monomer. They contain hydrophilic monomers dissolved in solvents like acetone, ethanol, or water.
The size of dentinal tubules affects interaction with materials, with deeper tubules leading to worse bonding due to the buffering effect of dentinal fluid.
The adhesive layer allows resin adhesives to infiltrate between collagen fibrils.
Factors include cleanliness of the surface, presence of impurities, fluidity of the adhesive, and the contact angle.
The hybrid layer forms between the adhesive and tooth surface, resulting from the impregnation of dentinal tubules and interfibrillar spaces with hydrophobic resin monomers.
The smear layer forms due to cavity preparation and may contain sealed tubules and microorganisms; it can be removed by acid etching or self-etch adhesives.
Adhesives fill the interfibrillar space of the collagen network and create a hybrid layer, preventing fluid leakage at the margin. They are mainly composed of hydrophobic dimethacrylates and a small amount of hydrophilic monomer (HEMA).
Higher surface energy enhances wettability, allowing adhesives to spread and penetrate better, leading to improved bonding.
Resin tags are extensions of resin that have penetrated into etched enamel or conditioned dentin.
Enamel is mainly composed of 88% inorganic calcium hydroxyapatite.
Moisture control is crucial to prevent collagen fibril collapse and to ensure proper resin infiltration into the dentin.
Wetting allows the adhesive to form micromechanical interlocks and chemical bonds by spreading over and penetrating the surface.
Factors influencing adhesion include surface energy & wetting, formation of hybrid zone, micromechanical interlocking, and chemical bonding.
Tooth composition is not homogenous, and adhesives that bond to enamel may not adhere to dentin.
It is recommended for direct composite resin restorations and provides superior and more predictable bond strength to dentin.
1) Adequate removal or dissolution of smear layer from enamel/dentin 2) Maintenance or reconstitution of dentin collagen matrix 3) Good wetting 4) Efficient monomer diffusion & penetration 5) Polymerisation within tooth structure 6) Co-polymerisation with resin composite matrix.
Dentin bonding agents create a thin layer of resin between conditioned dentin and the resin matrix of a composite material.
The hybrid layer allows for entanglement of resin adhesive with the collagen network, enhancing bond strength.
Cohesive failure is the failure within the adhesive, which may occur if the bonding agent is applied too thickly or due to incomplete curing.
A viscous cement-like material that fills gaps between bonded materials.
Surface energy is the excess energy of molecules at the surfaces of materials above that of molecules found in the interior, quantifying the work needed to disrupt intermolecular bonds.
Microleakage refers to the flow of oral fluid and bacteria into the microscopic gap between a prepared tooth surface and restorative material.
Phosphoric acid gel removes the smear layer, removes mineral, leaves the collagen matrix, and creates microporosity for micromechanical bonding.
Etchants are used to remove smear layers and dissolve the mineral phase, allowing for micromechanical interlocking. A common etchant is 37% phosphoric acid applied as an aqueous gel.
Ionic bonds.
Luting material can penetrate into irregularities on the intaglio of the casting, providing anchorage for mechanical retention.
Discoloration at margins can occur due to bond failure.
A smaller contact angle indicates that the adhesive forces at the interface are stronger than the cohesive forces holding the adhesive molecules together, allowing the liquid adhesive to spread more broadly.
The three-step technique is technique-sensitive and time-consuming, which may prevent the formation of an adequate hybrid layer in dentin and risk excessive drying of etched surfaces, collapsing the collagen network.
The three types of dentin bonding systems are Etch & rinse, Self-etch, and Multi-mode.
Cohesion is the force of molecular attraction between molecules or atoms of the same species.
They arise from dipoles induced by uneven sharing of electrons and are weaker than primary bonds.
Dentin conditioner is a substance used to prepare dentin surfaces for bonding by enhancing their adhesive qualities.
The components include an etchant (37% phosphoric acid), a primer (hydrophilic functional monomers like HEMA in organic solvent), and a bonding resin (solvent-free hydrophobic adhesive resin).
It is recommended to selectively etch enamel before application to achieve stronger bonding.
Yes, it can bond to various substrates including metals, silica, and zirconia.
Sound tooth structure must be conserved, optimal retention achieved, and microleakage prevented.
Primary bonds are chemical bonds that depend on atomic structures and the ability to form stable configurations.
They are specific dipole attractions in polar compounds, such as in the sorption of water by synthetic dental resins.
It eliminates the separate etch and rinse steps, allowing for a one-step application process.
The three-step technique involves etch, primer, and bonding agent applications, while the two-step technique combines etch and self-priming resin into one step.
Surface energy and wetting, interpenetration (formation of hybrid zone), micromechanical interlocking, and chemical bonding.
The types of adhesion include chemical adhesion, mechanical adhesions (structural interlocking), and a combination of both.
It occludes dentinal tubules.
Dental adhesives must compete with water, either displacing it or incorporating it.
Dentin conditioner is a 10% Polyacrylic/Polyalkenoic acid applied to dentin that dissolves the inorganic structure, leaving a collagen mesh. It allows infiltration of an adhesive resin into collagen fibrils and forms a hybrid layer, creating strong resin bonds between polymer and dentinal collagen.
STEP 1: Apply self-etching primer; STEP 2: Apply adhesive resin.
A dentin conditioner is an acidic agent that dissolves the inorganic structure in dentin, resulting in a collagen mesh.
If too much water is left, resin infiltration cannot fully replace the water in the collagen network, potentially causing leakage.
Outer shell valence electrons can be removed from metallic atoms to form positive ions, resulting in free valence electrons that give metal characteristics.
Acid etching uses 37% phosphoric acid applied to enamel to remove mineral (HA & enamel rods), exposing the collagen matrix, while dentin conditioner dissolves the inorganic structure in dentin. Acid etching creates microporosities, increases surface energy, and favours resin infiltration.
Adhesion is the force of attraction when molecules of one substance adhere to or are attracted to molecules of another substance.
Adherents include resin composite, ceramic, and acrylic.
Resin tags are formed during polymerization and micromechanically interlock with hard tissue, enhancing the bond strength.
It does not always require molecular attraction; strong attachment can be achieved by mechanical means.
Self-etching primers can be classified as mild, intermediate, or strong, with strong primers providing better bonding to enamel and mild primers offering better bonding to dentin.
An adhesive is the material used to cause bonding and promote adhesion of one substance to another, such as adhesive resin, silane primer, or tin plating.
Valence electrons are shared by adjacent atoms, forming stable and electrically neutral molecules.
Debris can promote air entrapment at the interface, affecting adhesion.
Secondary bonds arise from charge variations among atomic groups that induce dipole forces attracting adjacent molecules.
Steps include cleaning the adherend (e.g., etching), ensuring good wetting, achieving intimate adaptation, and proper curing.
