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Historically, resin cements have been around for quite some time, and they can generally be divided into three categories. Pure resin cements require treatment of the tooth surface with 36% phosphoric acid, followed by application of a bonding agent to the dentin, prior to introducing the resin cement, which can be either light-cured or dual-cured. Variolink II by Ivoclar Vivadent and Insure by Cosmedent are good examples of traditional resin cements.

Resin-modified glass ionomer cements have the following clinical benefits: very thin film thickness, moisture tolerance, and fluoride-releasing features. Aside from these benefits, they also have some drawbacks. One drawback to resin-modified glass ionomer cements is their tendency to expand after setting from water sorption and to fracture in nonmetallic restorations.1 GC FujiCem by GC America and RelyX Luting Plus by 3M ESPE Dental are examples of resin-modified glass ionomer cements.

The newest generation of resin cements are the self-adhesive or self-etch resin cements, which self-etch the dentin and therefore do not require pretreatment of the tooth, making them much easier to use in clinical settings.2 RelyX Unicem II from 3M ESPE Dental is a good example of a self-adhesive resin cement.

The vast majority of the dental restorations we place today are either ceramic (glass and oxides) or metallic, and this is where resin cements shine above the rest in terms of the qualities described in the list above. There was a time when multiple cementation steps were required for predictable, long-term success and low postoperative tooth sensitivity. Fortunately, it appears that we may be very close to realizing those goals with the self-adhesive resin cement systems that are currently available. The bond strength of self-adhesive resin cements is derived from phosphoric-acid-altered methacrylate monomers that allow the cement to attach to the tooth surface. When the monomers attach, they form a cross-linked matrix during polymerization, which results in superior bond strength.

While these cements are acidic in nature when applied to allow the cement to etch the dentin, they later transition to a pH-neutral state, once the cement is fully set.3 RelyX Unicem II, for example, has a pH of 2.0 after mixing, which gives it the ability to self-etch as well as its hydrophilic affinity for the moist collagen fibers in the dentin. However, once the cement sets, its pH becomes neutral (7.0), and it becomes hydrophobic to prevent water absorption or water tree development, both of which can adversely degrade the long-term stability of the hybrid layer.4 Although these cements offer high bond strength, it is still critical to be respectful of the tooth preparation resistance and retention-form principles, along with the limitations of any luting agent.

Many types of restorative materials are compatible with self-etching resin cements, including milled or pressed ceramic crowns, inlays, onlays; full gold crowns, inlays, onlays; and even porcelain-fused-to-metal (PFM) crowns. Self-etch resin cement’s ability to be the luting agent to a myriad of the most common restorative materials boosts efficiency and is clinically beneficial. Pressed or feldspathic porcelain veneers are probably the only ceramic materials that still require a traditional acid-etch, bond, and cement approach.

A primary concern for most dentists is the postoperative sensitivity that occurs with traditional resin cements, which require etching the dentin with 36% phosphoric acid and multistep bonding protocols.5 When an etch-and-rinse technique is used, special considerations include the etching time, the length of the rinsing time, and drying the tooth without overdrying prior to bonding. With a self-etch approach using resin cements, the process involves fewer technique-sensitive steps and affords a more forgiving environment that can translate to almost no postoperative sensitivity.

The majority of restorations-including full crowns, partial crowns, bridges, and inlays/onlays-can be cemented in one step with self-adhesive resin cements, regardless of whether they are predominately glass ceramics (including IPS e.max, CAD/CAM, and pressed), oxide ceramics (including zirconia and alumina), or metal-based restorations (including PFM).

Delivering services efficiently plays a critical role in the day-to-day function and profitability of the typical dental office. The advanced delivery systems of self-adhesive resin cements have made them easy to use. Automix syringes allow cements to be dispensed with more accurate ratios, compared to traditional hand-mixing, and they even come with mixing tips of varying diameters for different clinical situations (figure 1).6 Unit-dose capsules that can be activated by a triturator (avoiding costly waste) are another dispensation option for smaller jobs.

Since the majority of self-adhesive resins are dual-cure, cleaning up excess cement is easy and quick; gently wipe the cement, in a gel state, off at the margins after a brief exposure to a curing light.

Dentists are always cognizant of the need for the products used on their patients to be predictable and reliable over the long term. In the case of self-adhesive resin cements, there is no shortage of peer-reviewed documentation attesting to clinical success over time. The long-term performance of self-adhesive resin cements has been excellent; one study reported bond failure in less than 1% of patients and sporadic temperature sensitivity in less than 2% of patients.7-8

Self-adhesive resin cements are easy to use and suitable for the cementation of almost all dental restorations, with the exception of bonded porcelain veneers. Such a versatile material should not have a problem filling a very nice niche in every operatory.

References

  1. Kim YG, Hirano S. Setting shrinkage and hygroscopic expansion of resin-modified glass-ionomer in experimental cylindrical cavities. Dent Mater J. 1999;18(1):63-75.
  2. Christensen GJ. Why use resin cements? J Am Dent Assoc. 2010;141(2):204-206.
  3. Chaiyabutr Y, Kois JC. Determination of how shear bond strength is affected by time between initial application and light curing of self-adhesive resin cements. Kois Center Research. 2014.
  4. Tay FR, Pashley DH. Water treeing-a potential mechanism for degradation of dentin adhesives. Am J Dent. 2003;16(1):6-12.
  5. Christensen GJ. Resin cements and postoperative sensitivity. J Am Dent Assoc. 2000;131(8):1197-1199.
  6. Burgess JO, Ghuman T, Cakir D. Self-adhesive resin cements. J Esthet Restor Dent. 2010;22:412-419.
  7. 3M ESPE RelyX Unicem Self-Adhesive Universal Resin Cement 5-Year Clinical Performance. The Dental Advisor. 2008;6.
  8. Uluddag B, Yucedag E, Sahin V. J Adhes Dent. 2014;16(6):523-529.

David K. Chan, DMD, AAACD, graduated from Oregon Health Sciences University in 1989. He maintains a full-time practice focused on cosmetic and comprehensive dentistry, is an accredited member of the American Academy of Cosmetic Dentistry (AACD), and serves as president of an AACD-affiliated study club. A fan of continuing education, he serves as a mentor to dentists at Seattle’s Kois Center. He has published widely about advanced cosmetic dentistry, including several articles in the Journal of Cosmetic Dentistry.

For Further Information
More on the dental materials market in the US can be found in the report published by iData entitled US Market for Dental Materials which covers segments for dental cements, dental impression materials, direct restorative materials, dental bonding agents, dental core build-up materials, dental anesthetics, and dental material procedures.

The iData series on the market for dental materials also covers 15 countries in Europe. Full reports provide a comprehensive analysis including units sold, procedure numbers, market value, forecasts, as well as detailed competitive market shares and analysis of major players’ success strategies in each market and segment. Register online or email us at [email protected] for a US Market for Dental Materials report brochure and synopsis.

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