Dental Advisor: Bonding Agents - 2008

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4^th-generation

• Multiple bottles
• Separate etching with phosphoric acid - called total-etch or etch and rinse
• Separate primer and adhesive
• Both light- and dual-cured formulations
• Either acetone or ethanol solvent

5^th-generation

• Single bottle or unit dose
• Separate etching with phosphoric acid - called total-etch or etch and rinse
• Combined primer and adhesive in one bottle
• Both light- and dual-cured formulations
• Either acetone or ethanol solvent

6^th-generation (Type I, Self-etching Primer + Adhesive)

• Two bottles, Liquid 1 - acidic primer, Liquid 2 - adhesive; acidic primer applied to tooth first, followed by adhesive
• No etching with phosphoric acid
• Light-cured formulation
• Water solvent
• Several products (Clearfil LINER BOND 2V, Nano-Bond, Prelude SE) have separate catalysts for dual curing
• Compatible with self-cured composites

6^th-generation (Type II, Self-etching Adhesive)

• Two bottles or unit dose containing acidic primer and adhesive; a drop of each liquid is mixed and applied to the tooth
• No etching with phosphoric acid
• Light-cured formulation
• Water solvent

7^th-generation

• Single bottle containing acidic primer and adhesive - no mixing
• No etching with phosphoric acid
• Light-cured formulation
• Water solvent
• Some products (Clearfil DC BOND, Futurabond DC, Xeno IV Dual Cure) have separate catalysts for dual curing

Table 1. Effect of Mode of Curing on Tensile Bond Strength of Xeno IV Dual Cure to Tooth Substrates.

Table 2. Ranges of Tensile Bond Strengths.

• Adhesive - resin used to bond the composite to the primed tooth surface.
• Dual-cured bonding agent - bonding agent that can be light-cured or self-cured.
• Etchant - typically phosphoric acid used to clean and demineralize the tooth surface, used primarily for 4^th- and 5^th-generation bonding agents.
• Inverted cone tensile test - test for measurement of tensile bond strength developed by Dr. John Powers at the University of Michigan in 1986.
• Light-cured bonding agent - use of a light-curing unit is required; bonding agents typically contain camphorquinone (CQ) as the polymerization photoinitiator.
• Modified smear layer - result of self-etching primers that modify and combine with the smear layer rather than removing it.
• Primer - hydrophilic monomer used to wet and penetrate the tooth surface.
• Self-cured bonding agent - bonding agent with catalyst that allows self curing without light activation.
• Self-etching (acidic) primer - primer with acid groups producing low pH that interact with tooth structure and resin adhesives.
• Smear layer - layer of tooth structure produced when enamel and dentin are ground with a diamond or carbide bur. This layer must be removed or modified for good bond strengths.
• Ultradent bond strength test - test for measurement of shear bond strength (SBS) developed by Ultradent Products.

Eugenol-containing Materials

• Eugenol-based materials can lower bond strength to dentin.
• If a eugenol-based material must be used, pumice the tooth before bonding.

Hemostatic Agents

• Residual chemicals from hemostatic agents (ferric sulfate, aluminum chloride or other chemicals) can lower bond strength to dentin.
• Rinse contaminated areas for at least 10 seconds with water, acid etch or scrub before bonding.

Saliva, Blood and Plasma

• Contamination with these fluids can lower bond strength.
• Rinse contaminated areas for at least 10 seconds with water before bonding.

Water

• Most bonding agents with water solvent bond well to dry or moist dentin.
• Avoid over-wet (pooled water) or over-dry (desiccated) dentin before application of the bonding agent.

Whitening Agents

• Residual oxygen from take-home or in-office whitening can lower bond strength.
• Wait several days to one week after whitening before a bonding procedure.

Etching with Phosphoric Acid

Most manufacturers of self-etching bonding agents recommend the use of phosphoric acid to etch uncut enamel before application of the self-etching primer or self-etching adhesive. Even so, the improvement in bond strength may not be large. If the phosphoric acid also etches dentin, the bond strength of the self-etching adhesive to dentin may be reduced. This reduction may occur if the self-etching adhesive fails to completely penetrate the additional demineralized dentin produced by the phosphoric acid etch.

Apply extra coat(s) of bonding agent as needed to obtain a shiny surface.

• Pumice technique – pumice can be used on uncut enamel before applying the bonding agent to improve bond strength.
• Pre-etch technique – apply phosphoric acid to enamel before preparing the tooth. This technique eliminates the need to etch uncut enamel while the dentin is exposed, avoiding possible contamination of dentin with phosphoric acid.

• High-leucite Feldspathic Ceramic
• IPS Empress, Ivoclar Vivadent; Cerpress, Leach & Dillon; Finesse All Ceramic, DENTSPLY Ceramco; OPC, Pentron Laboratory Technologies distributed by Zahn Dental
• Indicated for inlays, onlays, crowns, veneers (excluding 2nd molar crowns)
• Bond, then cement
• etch with phosphoric acid
• rinse
• apply bonding agent (4^th- or 5^th-generation)
• cement with light-cured or dual-cured cement

Note: Posterior restorations can be bonded with 6^th- or 7^th-generation bonding agents eliminating steps 1 and 2.

• Lithium Disilicate
• IPS e.max, Ivoclar Vivadent; 3G, Pentron Laboratory Technologies distributed by Zahn Dental
• Indicated for anterior and posterior crowns and 3-unit bridges up to 2nd bicuspid
• Bond, then cement
• etch with phosphoric acid
• rinse
• apply bonding agent (4 th- or 5th-generation)
• cement with light-cured or dual-cured cement or use a self-adhesive resin cement

Note: Posterior restorations can be bonded with 6^th- or 7^th-generation bonding agents eliminating steps 1 and 2.

• Alumina
• Procera, Nobel Biocare; In-Ceram, Vita
• Indicated for anterior and posterior crowns and 3-unit bridges
• Cement
• no etching or bonding
• use a self-adhesive resin cement or resin-modified glass ionomer cement
• Zirconia
• 3M ESPE Lava Crowns and Bridges, 3M ESPE; CERCON, DENTSPLY Ceramco
• Indicated for anterior and posterior crowns, 3- and 4-unit bridges (span length 44 mm), implants, Maryland bridges
• Cement
• no etching or bonding
• use a self-adhesive resin cement or resin-modified glass ionomer cement • or resin cement with ceramic primer and bonding agent

• Use a one-step, light-curing technique.
• Apply bonding agent to tooth and resin cement to veneer, place veneer and then light cure.

Veneers greater than 1.0-mm thick

• Use a two-step, light-curing technique.
• Apply bonding agent to tooth and light cure, apply resin cement to veneer, place veneer and then light cure.
• Be sure to thin the bonding agent with air before light curing.

Note: Instructions for some resin cements recommend additional application of the bonding agent to the veneer without separate light curing before cementation (3M ESPE RelyX Veneer Cement, 3M ESPE; Variolink Veneer, Ivoclar Vivadent; Variolink II, Ivoclar Vivadent).

• Carefully follow instructions on application time and use of air to thin the adhesive and evaporate the solvent. With less volatile solvents (water, ethanol), more air is needed for evaporation and should be used within three minutes of dispensing. Bonding agents with acetone should be used immediately after dispensing.

• Some bonding agents etch the surface of the metal matrix band, making it difficult to remove the band. Scratching the surface of the metal band with a spoon excavator after bonding but before placement of the composite is helpful.

• Generally compatible with self-cured composite cores or resin cements.
• Prime the tooth, apply the adhesive and light cure, and then place the composite core.

5^th-generation bonding agents

• Generally not compatible with self-cured composite cores or resin cements.
• The acidity of the bonding agent can interfere with the setting of the composite.

6^th-generation (Type I) bonding agents

• Generally compatible with self-cured composite cores or resin cements.
• Prime the tooth, apply the adhesive and light cure, and then place the composite core.

6^th-generation (Type II) bonding agents

• Generally not compatible with self-cured composite cores or resin cements.
• The acidity of the bonding agent can interfere with the setting of the composite.

7^th-generation bonding agents

• Generally not compatible with self-cured composite cores or resin cements.
• The acidity of the bonding agent can interfere with the setting of the composite.
• Dual-cured systems (Clearfil DC BOND, Futurabond DC, Xeno IV Dual Cure) are compatible.

Many of our clinical consultants responded to a survey on the usage of bonding agents. The results of the survey are shown below.

Editor's Note: The survey results were not used to rate products.

Summary: A majority of clinical consultants use 6^th- and 7^th-generation bonding agents.

Summary: Clinical consultants reported postoperative sensitivity more oftent with 4^th- and 5^th-generation bonding agents.

Summary: Clinical consultants preferred 5^th-generation bonding agents for the techniques indicated above.

Requests for reprints should be directed to The Dental Advisor.