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Are you treating or mistreating your all-ceramic restorations?

Feb. 23, 2016
Pretreating all-ceramic restorations is critical to their long-term success. In this article, Maryanne Salcetti, DDS, explains how you should be pretreating restorations you've milled in your office and lab-fabricated restorations, and she identifies a solution for simplifying the etching and silanating process. A video demonstration is included.

Pretreating all-ceramic restorations is critical to their long-term success. In this article, Maryanne Salcetti, DDS, explains how you should be pretreating restorations you've milled in your office and lab-fabricated restorations, and she identifies a solution for simplifying the etching and silanating process. Be sure to check out the video demonstration at the end!

All-ceramic restorations have become a routine part of fixed-restorative dentistry. The long-term success of these restorations is dependent on multiple factors, including preparation design, the type of ceramic for the clinical scenario, occlusion, and how the surface of the ceramic is treated prior to bonding. Although many of us focus on proper diagnosis, treatment planning, and restorative design, proper conditioning of the bonding surface is a crucial part of the adhesive luting process.

In-office milled restorations

Many dentists who mill restorations in their offices conventionally etch the restorations with a hydrofluoric acid etchant and then apply a silane coupling agent prior to bonding (figure 1). One such silanating agent is Monobond Plus (Ivoclar Vivadent) (figure 2). Although Ivoclar Vivadent manufactures this silanating agent, most companies that make bonding resins have a silanating agent as part of their bonding kits. It is essential that the etching-silanating process occurs after the restoration has been tried in for the fit to be verified intraorally and before the bonding process.

Figures 1 and 2:
Hydrofluoric acid and silane in separate steps; Monobond Plus (Ivoclar Vivadent), a silanating agent

Lab-fabricated all-ceramic restorations

When a commercial laboratory fabricates the restoration, the lab (if instructed) will send it to the office pre-etched (figures 3 and 4). It is essential to understand whether a lab-fabricated crown has been sent to the office pre-etched. Over-etching can reduce the overall strength of the restoration.

Figures 3 and 4:
IPS Ceramic Etching Gel (Ivoclar Vivadent) is a 5% hydrofluoric acid-etching gel that can be used to treat the intaglio surface of an all-ceramic crown to enhance the bonding process. The gel is applied to the intaglio surface of an e.max crown for 20 seconds. This process can be done as a pretreatment by the laboratory technician or chairside after try-in.

After the fit and shade have been verified intraorally, the restoration needs to be cleaned before the silane and bonding resin are added. Cleaning the restoration is imperative because residual saliva, try-in paste, and/or blood will adversely affect the bonding strength.

Saliva, which contains alkaline phosphatase and other phospholipids, will react with the etched surface of the crown and render it inert to the silane. Acid etching (with 37% phosphoric acid or 5% hydrofluoric acid) will clean it, but the key to the success in this step is notto re-etch it if it was pre-etched.

If the restoration was pre-etched, you should only use Ivoclean (Ivoclar Vivadent) (figure 5). If you repeat the etching process, you will remove more filler particles, and the restoration will lose strength. Ivoclean is a universal cleaning paste that consists of an alkaline suspension of zirconium-oxide particles in water. You have to shake the bottle to make sure there is a uniform suspension of these particles prior to use. It is highly alkaline—and thus corrosive—so wearing gloves and eye protection is important. Ivoclean attracts the phosphate contaminates and leaves behind a clean oxide surface.

Figure 5:
Ivoclean (Ivoclar Vivadent) removes contaminants from saliva and blood, creating a surface conducive to bonding. Simply apply Ivoclean to the bonding surface of a crown, allow it to sit for 20 seconds, rinse with water, and dry with oil-free air.

Etching your own restorations

If you are etching your own milled restorations, pay special attention to the material, the concentration of the hydrofluoric acid, and the time spent etching (table 1). Not all restorations are created equal!

Table 1:
This table is a resource for treating various all-ceramic restorations with acid-etching. Note: Do not acid-etch zirconia restorations!

Etching and silanating simplified

There is a product that simplifies the etching and silanating process. Monobond Etch and Prime (Ivoclar Vivadent) is a one-step, self-etch glass-ceramic primer liquid (figure 6). Its advantage is that it shortens the pretreatment time of these restorations and eliminates the current need for two products. It’s easier to use, it reduces the risk of error, and it generates a strong and durable bond.

Figure 6:
Monobond Etch and Prime (Ivoclar Vivadent) simplifies the etching and silanating process. Apply it to the bonding surface of the crown for 20 seconds, allow it to rest on the surface for 40 seconds, rinse with water, and dry with a steady stream of air for 10 seconds.

To improve the bond strength and longevity of all-ceramic restorations, it is essential to properly manage not only the tooth but also the restoration. If you are working with a lab-fabricated restoration, communicate with the laboratory technician to determine whether the restoration was treated with hydrofluoric acid prior to being sent to your office. Pre-etched restorations should be cleaned with a cleaning paste, and restorations that are etched must be etched with the correct acid at the correct concentration and for the appropriate amount of time. To simplify this process, a new self-etching glass-ceramic primer liquid is now available.

Here is a video demonstration of Monobond Etch and Prime from Digital Enamel:

Editor's Note: This article first appeared in Pearls for Your Practice: The Product Navigator.Click here to subscribe. Click here to submit a products article for consideration.

Maryanne Salcetti, DDS, is a member of the Spear Visiting Faculty and a Spear Study Club leader. After receiving her DDS from Georgetown University, she taught removable prosthodontics at Georgetown University. She also completed a three-year specialty program in maxillofacial prosthodontics at Memorial Sloan Kettering Cancer Research Center and has more than 30 years of clinical restorative experience. She has served on the executive board of the Dutchess County Dental Society and was president of the society from 1994–1995. She is also an active member of the New York State Dental Society and served as a past dental chairperson for the United Way.