Simplifying Luting: The benefits of self-adhesive resins and other methods

January 14, 2020

Streamlining the luting process can improve patient outcomes and productivity, and increase profitability.

Simplifying luting of restorations can have many benefits for the practice. There are many ways to do it and a variety of materials that can streamline the method. Two general dentists speak out on what makes their luting process in their practice.

Resin cements

Resin cement has long been the preferred luting agent for many types of indirect restorations because of its strength of bond, durability, and lack of solubility in water. However, its use also requires multiple bonding steps, which can be time-consuming in today’s dental environment. 

Another luting option is the self-adhesive resin, which requires no etching, priming, or bonding agents to adhere to the tooth’s surface. Instead, the bonding agent has been added to the material. 

The most significant benefit of a self-adhesive resin is its simplicity, says Jeff Lineberry, DDS, FAGD, a general and cosmetic dentist with a private practice in Mooresville, N.C. While self-adhesive resins will not have the same bond strength as a single or dual-cure resin cement, bond strength is still improved over a glass ionomer material. 

“In other words, like a package for baking a cake, everything is already in there. You just put it together, and you get a reasonable outcome with the self-adhesive resins,” Dr. Lineberry says. 

In addition to a reasonable outcome for bond strength, some self-adhesive resin has low solubility in water, like resin cement, and some even releases fluoride, like a glass ionomer cement, Dr. Lineberry says. Self-adhesive resin is also a material that is less technique-sensitive because it reduces the number of steps needed compared to a traditional single or dual-cure resin cement.

Alex Kalmanovich, DDS, a private practice dentist in Laguna Beach, Calif., has used self-adhesive resins but found that he prefers the increased bond strength of dual-cure adhesives. He has since moved away from self-adhesive resins, but he sees situations where they could be useful, like cementing a metal crown.

Self-adhesive resin cements represent manufacturers trying to produce a genuinely universal cement, Dr. Lineberry says. However, he describes himself as “old-school” and says he likes to have a variety of materials available in his practice for luting.

“I like to have more than one hammer in my toolkit,” Dr. Lineberry says. 

How to simplify luting in your practice

With anything done in the practice, dentists should have a game plan designed ahead of time that assistants and staff can understand clearly. Furthermore, if a change is made, it should be introduced to the whole team.

For example, cementing a crown with adhesive cement is similar in sequence of steps to restoring with composites. With composites, the same steps are always followed. However,

Dr. Kalmanovich says dentists know the flow, which enhances efficiency and the patient experience. The same principle applies to resin cement.

“When you have that system set up, especially for your resin cement, it makes things run a lot smoother, and the patients are going to feel more comfortable,” Dr. Kalmanovich says. “Everyone knows where all the materials are, everything's prepared ahead of time, and everything runs like a well-oiled machine.”

Having a particular cement that’s used with the material of the restoration is one way to simplify luting, according to Dr. Lineberry. For example, he uses resin-modified glass ionomer while luting zirconia every time, he says. If it’s e.max, then he will use a self-adhesive. For an inlay or onlay, he uses regular resin cement. This way, the team knows how to prepare for the luting process based on the restoration type that’s being placed, which enhances efficiency.

Using the right materials for the type of restoration another way to simplify the process, per Dr. Lineberry. There are situations where the most durable bond with multiple-step resin cement may not be necessary.

“In other words, you don’t necessarily need an 18-wheeler just to move a mattress across the street,” Dr. Lineberry says.

Clinicians need to be aware of the materials themselves, Dr. Lineberry advices. Some materials cure harder and faster than others. Take the the resin-modified glass ionomer from GC America, which starts to set up in 90 seconds. The team knows they need to start cleaning by then, which is fine because he is aware of that characteristic.

In contrast, luting with past materials, Dr. Lineberry had three to five minutes before he needed to clean. But, if he were using the GC America material that sets up in 90 seconds, he would be in significant trouble if he were still using the old timeframe as his reference point, he says. 

“It’s important to read the products and know the times,” Dr. Lineberry says. 

Self-adhesives also allow for a more streamlined cleaning process. The crown can be seating with a self-adhesive cement, light cured for a few seconds, and then immediately cleaned, Dr. Lineberry says. This quicker cleanup is much more efficient than waiting several minutes for a single or dual-cure resin cement to cure.

“That can be a time-saver,” Dr. Lineberry says. 

Common pitfalls for luting-and how to avoid them

Over-curing cement before cleaning away the excess is still a common pitfall for dentists, both Drs. Lineberry and Kalmanovich say. Cement that is cured is more difficult to clean up than when it is still uncured, a lesson Dr. Kalmanovich says he learned from experience.

“I've had times where I had to get in there with scalers and had a difficult time getting all the cement out,” Dr. Kalmanovich says.  

Self-adhesive resins can also be challenging to clean up, Dr. Lineberry says. Many of the self-adhesive resins are dual-cure, which usually means there are three to five minutes of working time before it sets, Dr. Lineberry says. However, when exposed to too much curing light, the material prematurely sets, and the working time could be as little as two minutes. 

“Then, it takes a long time for you to try to dig out some of the product interproximally,” Dr. Lineberry says. “That can be a real pain.”

These clean up challenges can be avoided by diligent management of the light exposure according to the manufacturer’s instructions, Dr. Lineberry says. Dentists can try a tack cure for one or two seconds, then clean up the excess while the cement is still in gel form, Dr. Kalmanovich recommends.

Along those lines, another common pitfall is not following the manufacturer’s instructions. Resin cement requires many steps to prevent moisture contamination. If there isn’t adequate moisture control, it could lead to a poor bonded restoration, post-operative sensitivity, and staining around the margins. 

“Making sure your tooth is isolated is critical, especially with adhesive cement,” Dr. Kalmanovich says. 

When cementation on indirect restorations, is simplified, it benefits the practice in many ways, from patient care to productivity to profitability. Simplifying luting makes restorations flow well and finish predictably, according to Dr. Lineberry. Also, patients are less likely to have post-operative sensitivity from technique issues, which reflects well on your practice. Furthermore, putting a systematized approach in place based on restoration types is more efficient.

“As the saying goes,” Dr. Lineberry says, “time is money.”