May 2010, Volume 6, Issue 5
Published by AEGIS Communications
Ceramic Adhesives: Cementing vs Bonding
Once the ceramic material for the restoration has been selected, the requirements for cementing or bonding can be specified.
Ceramic restorations are an esthetic, biocompatible, and costeffective alternative to ceramic-metal restorations.1,2 Zirconia-based and lithium-disilicate ceramics are rapidly growing segments within the ceramic category. Perhaps the most confusing decision for clinicians is bonding versus cementing of ceramic restorations. This article provides guidelines for cementing and bonding of ceramic restorations with an emphasis on ceramic adhesives.
Ceramic restorations can be classified as feldspathic porcelain, leucite-reinforced ceramic and lithium disilicate ceramic (which are silica-based ceramics), and zirconia (zirconium oxide). Whether these ceramics are prepared by the dental laboratory or by in-office CAD/CAM systems, the restorations are typically etched with HF gel and silanated before bonding. Alumina and zirconia ceramics are non-silica-based ceramics that cannot be etched or silanated; they require special ceramic primers for bonding.3 Once the ceramic material for the restoration has been selected, the requirements for cementing or bonding can be specified.
Silica-Based Ceramic Restoration
Low-strength silica-based ceramics, such as feldspathic porcelain and leucite-reinforced ceramic (flexural strength less than 140 MPa), should be bonded with resin cement, enamel/dentin bonding agent4 and ceramic primer.5 Examples of esthetic resin cements and their bonding agents are: Bifix QM/Futurabond DC (VOCO America, www.vocoamerica); CLEARFIL™ DC BOND (Kuraray America, http://www.kuraraydental.com); and DUO-LINK/ALL-BOND SE® (BISCO, http://www.bisco.com). Examples of adhesive resin cements and their bonding agents are: Multilink Automix Easy/Primer A & B (Ivoclar Vivadent. http://www.ivoclarvivadent.us), and ResiCem™/Primer A & B (Shofu Dental Corporation, http://www.shofu.com). Examples of ceramic primers for silica and non-silica-based ceramics are listed in Table 1.
Lithium-disilicate ceramics (flexural strength, 375 MPa) can be bonded with resin cement or cemented with self-adhesive resin cement.4 Examples of self-adhesive resin cements are: RelyX™ Unicem Self-Adhesive Universal Resin Cement (3M ESPE, http://www.3mespe.com); BisCem® (BISCO); CLEARFIL™ SA (Kuraray America); G-CEM Automix (GC America, http://www.gcamerica.com); Maxcem Elite™ (Kerr Corporation, http://www.kerrdental.com); SmartCem™2 (DENTSPLY Caulk, http://www.caulk.com); seT (SDI,http://www.sdi.com); and SpeedCEM (Ivoclar Vivadent).
Results of a 6-year clinical study of self-adhesive resin cement (3M ESPE RelyX Unicem Self- Adhesive Universal Resin Cement) have been reported.6 More than 5,600 restorations were cemented over the past 6.5 years and 1,739 restorations were available for evaluation. These restorations include ceramic inlays, onlays, crowns, and bridges; PFM crowns and bridges; posts; and CAD/CAM restorations. A low debonding rate of 2.6% was documented over the 6-year evaluation period. Among the evaluated restorations, 46 required re-cementation, including 24 ceramic onlays, 10 ceramic crowns, and 12 PFM crowns. Of the 24 ceramic onlays that debonded, 12 had little direct retention. In five of these debonding cases, a portion of the tooth fractured.
Zirconia Restoration (Good Retention)
Zirconia restorations with good retention can be cemented traditionally with glass ionomer, resin-modified glass ionomer and carboxylate cements, or with self-adhesive resin cements.3,7 The use of a ceramic primer in conjunction with self-adhesive resin cement may improve bond strength to the zirconia substrate.
Zirconia Restoration (Less than Ideal Retention)
Zirconia restorations with less than ideal retention should be bonded with adhesive resin cement, enamel/dentin bonding agent, and zirconia primer (Table 1).7 While ceramic primers will bond to as-sintered zirconia, bond strength can be improved by sandblasting the surface (Table 2).8,9 Guidelines for cementing versus bonding of zirconia restorations are listed in Table 3.7
Clinical tips for the use of resin cements and ceramic primers are listed below.
- Refrigeration of resin cements may be required; bring to room temperature before use.
- Do not over-dry the tooth before bonding; moisten with water until shiny if needed.
- Use total-etch or self-etch bonding agents for bonding to tooth structure.
- Use silane primer for silica-based ceramics.
- Use light-cured esthetic resin cement for veneers for better color stability.
- Translucent shades of resin cement may be sensitive to ambient light.
- For restorations with good retention, self-adhesive and adhesive resin cements containing acidic monomers usually do not require ceramic primers.
- To prepare zirconia for cementing or bonding, lightly blast zirconia intaglio surface with 50 µm alumina at 1.5 bar (20 psi), then clean in distilled water in an ultrasonic bath for 10 minutes.
By knowing the ceramic material being used and the quality of the retention, the requirements for cementing or bonding can be specified with expected success. Low-strength silica-based ceramics, such as feldspathic porcelain and leucite-reinforced ceramic, should be bonded with resin cement, enamel/dentin bonding agent and ceramic primer. Lithium-disilicate ceramics can be bonded with resin cement or cemented with self-adhesive resin cement. Zirconia restorations with good retention can be cemented traditionally with glass ionomer, resin-modified glass ionomer, and carboxylate cements, or with self-adhesive resin cements. Zirconia restorations with less than ideal retention should be bonded with adhesive resin cement, enamel/dentin bonding agent, and zirconia primer.
The authors have a financial interest in Dental Consultants, Inc (publisher of The Dental Advisor) and have a ownership stake in DCI and Apex Dental Milling (Authorized Lava Milling Center and Dental Mill-Crystal). Research was supported in part by 3M ESPE, GC America, and Kuraray America.
1. Powers JM, Sakaguchi RL, eds. Craig’s Restorative Dental Materials. 12th ed, St. Louis, Mo: Mosby Elsevier, 2008;373.
2. Farah JW, Powers JM. CAD/CAM dentistry. The Dental Advisor. 2008;25(9):6.
3. Farah JW, Powers JM. Zirconia-based ceramics. The Dental Advisor. 2007;24(10):2-4.
4. Farah JW, Powers JM. Self-adhesive resin cements and esthetic resin cements. The Dental Advisor. 2009;26(2):2-5.
5. Farah JW, Powers JM. The Dental Advisor Product Comparison Tables. Available at: http://www.dentaladvisor.com/clinical-evaluations/product-table-detail.shtml?t=125.
6. Farah JW, Powers JM. 3M ESPE RelyX Self-Adhesive Universal Resin Cement 6-year clinical performance report. (In: Esthetic fiber posts. The Dental Advisor. 2009;26(5):6-7.)
7. Powers JM, O’Keefe KL. Guide to Zirconia Bonding Essentials. New York, NY: Kuraray America, Inc; 2009:1-13.
8. Yapp R, Powers JM. Bond strength of resin cement to treated zirconia. The Dental Advisor Research Report. 2008;19:1.
9. Yapp R, Powers JM. Bond strength of Clearfil Esthetic Cement and Clearfil Ceramic Primer to treated and untreated ceramics. The Dental Advisor Research Report. 2008;18:1.
About the Authors
John M. Powers, PhD
The Dental Advisor
Ann Arbor, Michigan
John W. Farah, DDS, PhD
The Dental Advisor
Ann Arbor, Michigan