From THE DENTAL ADVISOR: Self-adhesive resin cements and esthetic resin cements
Self-adhesive resin cements eliminate the need for separate etchants and primers for bonding ceramic and metal restorations to tooth structure. These cements are available in tooth-colored, translucent, and opaque shades, and are dual-cured. Esthetic resin cements require a bonding agent for adhesion to tooth structure and separate primers for bonding all-ceramic restorations. These cements are available in a variety of VITA™ and translucent shades, and most are dual-cured. Special light-cured esthetic resin cements are available for bonding all-ceramic veneers.
This issue of THE DENTAL ADVISOR discusses and recommends self-adhesive and esthetic resin cements and gives clinical tips for using these cements.
Dentistry is rapidly moving from the cementation of PFM and gold restorations with traditional cements (glass ionomer, resin-modified glass ionomer, zinc phosphate, zinc polycarboxylate), to bonding of all-ceramic restorations with resin-based cements. Self-adhesive resin cements eliminate the need for separate etchants and primers for bonding to tooth, alloy, or ceramic substrates.
Characteristics
- Packaging includes capsules, auto-dispensed, and auto-mixed paste/paste syringes
- May require refrigeration – bring to room temperature before using
- Self-etching – no phosphoric acid or special primer needed
- Dual-cured – can be light- or self-cured
- Fluoride-releasing
- Usually available in universal, translucent, and opaque shades
Recommended uses
- Cast alloy crowns, bridges
- Ceramo-metal crowns, bridges
- High-strength ceramic (alumina, zirconia) crowns, bridges, inlays, onlays
- Posts (cast metal, ceramic, fiber-reinforced resin)
Composition and reaction
Self-adhesive resin cements are composed of diacrylate resins with acidic and adhesive groups and glass filler. They are usually dual-cured resins that can be light-activated and can self-cure. During setting, self-adhesive resin cements typically undergo a change in pH from acidic (pH 2) to less acidic (pH 5-6). The early acidity of the cement allows it to be self-etching.
Properties
Self-adhesive resin cements bond to tooth structure and other materials with low (5-8 MPa) to medium (8-15 MPa) bond strengths. The separate use of a bonding agent is not recommended. Although bonding agents may be compatible with self-adhesive resin cements, their use makes the manipulation more complicated and does not dramatically improve bond strength to tooth structure. Flexural strength and modulus measured when these cements are light-activated are generally higher than when they are self-cured. Higher bond strengths can be obtained with esthetic and adhesive resin cements that are bonded with separate bonding agents or primers. Self-adhesive resin cements are reported to have values of linear expansion of 0.5% to 1.5% over two months. Use of these cements with all-ceramic restorations is not a concern.
Clinical observations
Self-adhesive resin cements have a lower incidence of sensitivity than adhesive or traditional crown and bridge cements. Marginal staining of self-adhesive resin cements has been reported to be lower than with traditional cements. A recent survey of clinical consultants of THE DENTAL ADVISOR indicated that self-adhesive resin cements were most commonly selected for cementation of high-strength (zirconia) all-ceramic restorations.
Clinical tips
- Don’t over-dry the tooth — moisten with water if needed.
- To minimize staining at the enamel-ceramic margin, etch the enamel with phosphoric acid for 10 seconds before cementation.
- Some cements (Embrace Wetbond Resin Cement, Pulpdent; MonoCem, Shofu) require a gel barrier for complete setting.
- Use light-activation whenever possible — dual-cured cements typically have increased flexural strength and bond strength when activated with a light.
- Translucent shades may be sensitive to ambient light.
- Excess cement is easy to remove after several seconds of exposure to a curing light, but hard to clean up if too much time elapses.
- Contraindicated where there is not enough retention — use adhesive resin or esthetic resin cements.
- This should not be applied directly on exposed pulp or dentin that is close to the pulp.
- Some products provide extension tips for the capsules for post cementation.
- Do not use a lentullo spiral to spin cement into a canal space for post cementation. Place the cement on a post before placing in the canal.
- Use a silane primer with silica-based all-ceramic restorations (3G All Ceramic System, Pentron Ceramics; Cerpress SL, Leach and Dillon; Creation CP, Jensen Dental; IPS e.max CAD, Ivoclar Vivadent; IPS e.max Press, Ivoclar Vivadent; IPS Empress CAD, Ivoclar Vivadent).
To read more, including information on esthetic resin cement and more clinical tips, visit www.dentaladvisor.com.
