Tips and tricks for creating long-lasting restorations

June 28, 2018

How to strike the right balance between function, esthetics and longevity.

When crafting restorations, dentists strive to strike a balance between function, esthetics and longevity. While it isn’t always possible to achieve all three, there are some measures that doctors can take to ensure that they get the best possible outcome.

Achieving those long-lasting restorations includes proper material selection, technique and experience.

Every case is different

Unfortunately, there’s no one-size-fits-all approach, especially when it comes to getting long-lasting restorations.

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“For each patient, we have to individualize our treatment plans and our selection of materials based on our patient and what we think is going to work best for them,” says Dr. Jeffrey Lineberry, DDS, a general dentist in Mooresville, North Carolina. “We also have to look at where we are working in the mouth. Are we working on a front tooth? And then we have to consider the different types of materials. Of course, when it comes to different materials, we have to consider some of the newer porcelains, like zirconia-based ones, that are stronger. Then we have lithium disilicate, or e.max, that has been around for a while.”

“It really is on a case-by-case basis,” adds Dr. Sarah Jebriel, DDS, a cosmetic dentist in Newport Beach, California. “I do like to put e.max restorations on posterior teeth, but then there are some patients who are bruxers and I know they’re not going to wear their mouthguard. Just due to their past history, I do disclose it might not be as natural looking, and we are going to try and make it blend as seamlessly as possible, but because of your history, we have to place that.

“With some patients, we try to be conservative, and we’ve done composite bonding and I’ve done the biggest, nicest bevel, and I’ve etched, and I’ve done everything to get this bond perfect, but it breaks,” she continues. “But the patient is a bruxer, and he’s not wearing a guard, and he travels all the time and doesn’t sleep well, and I know he’s grinding at nighttime, so I end up having to do a full set of veneers on the top for him.”

As a cosmetic dentist, Dr. Jebriel places extra emphasis on esthetics. But sometimes function has to trump looks. Happily, patients don’t look at their restorations with the same critical eye that she does.

“I might do e.max veneers,” she says. “I can layer them, but they’re not feldspathic. To me, they are a little more opaque than I would like, but to the patient, they’re beautiful. And I make sure that they have those nice, broad contacts, and we don’t have a lot of flat plane occlusion with broad contacts. For me, that’s not what my eye is drawn to, but for the patient, he loved it and it works for him. I don’t see him every week in the office because there’s a problem. It’s working.”

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Often, clinicians just try to fix the problem. And while that is, of course, what they need to do, it’s important to understand the patient and his or her unique situation before jumping right in.

“I am treating a patient now who has had multiple sets of veneers fail, and it’s because of her bite,” Dr. Jebriel says. “She’s got a really deep overbite and I said, ‘We can’t do this on you until we’ve get you in a better place.’ I was the first person who told her that. Sometimes you see a person who has an ugly, old restoration, and you instantly think, ‘I can make this better,’ but you’ve got to look at all the parameters before you dive into a situation.

“I think the biggest thing is getting a history on the patient,” she continues. “‘Have you had a lot of restorations break before?’ And evaluating their TMJ. ‘How do you feel in the morning?’ Ask a lot of questions, and really evaluate the bite because before you get involved with the patient, you’ve really got to see what their habits are and what their bite is like and then really educate them on improving their bite first. You can do everything perfect and it can still break because it’s not right.”

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Choosing materials

Materials are a huge contributor to the longevity of a restoration, and the material used will be dependent on a number of factors.

“The material of choice is going to be a composite, so you need to choose a product that has good physical or mechanical properties that are going to withstand the load of chewing, mastication or occlusion,” says Dr. Rolando Nunez, DDS, clinical affairs manager, BISCO Dental Products says. “But it also has to have the ability to withstand wear and to be easy to place. And those are very objective, but when you look at subjective features, it’s more about the handling, the stickiness, the ability of the product to be placed and spread out and packed in areas that are needed based on the preparation.”

Bonding agents have improved over the years, but with that evolution comes different requirements for a technique.

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“Understand your bonding agent and understand your bonding technique in order to use it properly” Dr. Nunez advises. “Understanding your bonding technique is related not only to your training as a dentist but also to the intrinsic properties of the product you are using, which leads to following the manufacturer’s instructions. It’s not good to generalize the use of a bonding agent. Different bonding agents are placed differently. One must understand that, and even though you’re using a specific technique, you should use the bonding agent accordingly in that technique.”

In terms of indirect restorations, while materials continue to improve and evolve, sometimes taking a step back is appropriate.

“There’s still gold,” Dr. Lineberry says. “Gold is still an excellent restoration. Sometimes, when patients are presented with gold, they decline it, but some of them, when they hear that it is a long-lasting, durable material, it’s surprising how many patients will choose gold still.”

Not surprisingly, patients may shy away from gold because of esthetics, but it can still be a great option.

“I think most people are concerned about people seeing their gold tooth, so to speak,” Dr. Lineberry observes. “But if the tooth is properly prepared, in other words, if you prepare it for a gold inlay or onlay and put the margins in an appropriate place, you can hide that very well, or in a very back second molar, especially an upper second molar, it’s very difficult to see that unless you have a really toothy grin.”

Using the correct technique

Technique matters, and there are several considerations when trying to get the longest lasting restoration.

“We have to begin with the end in mind,” Dr. Lineberry says. “We need to know our materials. In other words, we need to know that certain materials need certain reductions in the mouth and certain thicknesses of materials for them to be strong and durable. It’s up to the clinician to properly prepare the tooth to give the laboratory enough clearance to fabricate a restoration that is going to be durable and long-lasting.”

Proper preparation, Dr. Jebriel says, requires enough reduction.

“We all love to be conservative in a case when we have to do an inlay or an onlay or a crown,” she says. “We need that proper reduction because that’s the No. 1 reason why a lot of these restorations fail.”

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Good isolation around where you’re working is also necessary to achieve the best bond, especially when using hydrophobic bonding agents.

“Isolation plays a huge role,” Dr. Nunez says. “It’s not necessarily supported by the literature as a strong point, but I think thoroughly isolating with a rubber dam prior to doing your bonding procedure is always a good idea. I believe that every restorative dentist should be applying a rubber dam and isolating their field of work.”

“When it comes to a lot of the newer materials, bonding techniques are a lot more technique-sensitive than the yesteryear of just using zinc phosphate cement for indirect restorations,” Dr. Lineberry adds. “We are using more and more bonding systems, but they are more technique-sensitive, they are more moisture-sensitive, so we have to be much more in tune with proper isolation to do that.”

“Bonding technique is really important,” Dr. Jebriel says. “Although I used to hate using rubber dams, I do a lot of inlays and onlays, and I love using the Insti-Dam. It’s a single-tooth rubber dam, and you just pop it on. It’s so easy. You get nice isolation. If you’re cementing No. 31 for a crown, how else do you get isolation? It’s hard to do it with a rubber dam. When you still have the walls intact, you can put a nice rubber dam on, microetch and do whatever bonding technique you like to do.”

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Working with the lab

When it comes to indirect restorations, another member of the care team is added - the laboratory. As such, doctors must be able to give the labs exactly what they need to fabricate the best restoration.

“Make sure that the lab receives an adequate copy of the tooth that they are making,” Dr. Lineberry says. “When I say ‘copy,’ we used to talk about impressions and molds. Now, we have digital scanners, but it’s still important for the dental laboratory. Or, if you have a CAD/CAM machine that’s going to be fabricating, it has to have the information in order to fabricate an excellent restoration. Like the old saying goes: ‘Junk in, junk out.’”

Coupling quality indirect restorations with good technique helps deliver the best outcomes.

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Digital impressions, obviously, are the way to go, especially for milled units like e.max” Dr. Jebriel says. “You can drop them in from across the room and the fit is great. At the same time though, it goes back to great reduction. I, personally, like it when I check the box to do a reduction coping. I like that. I hate it when they ask to spot the opposing. Patients sometimes say, ‘Why are you adjusting my other teeth?’ It goes back to enough reduction and being clear with your lab.”

The trend in dentistry is to move toward digital impressions. However, there are times when it’s still best to do both analog and digital ones.

“I have talked to some of my technicians regarding indirect restorations,” Dr. Jebriel says. “I think for feldspathic, the non-milled powder/liquid restorations, they actually prefer the regular, conventional impression because it’s really hard to do the foil technique with the margins that come out with the digital impression, which is interesting. It’s food for thought. If you’re considering doing feldspathic or powder/liquid indirect restorations in the anterior, maybe do both just to ensure the longevity of the restoration.”

Discover a new material

Different clinicians have different work styles. Some doctors may prefer one material over another, and that matters, as they know they will get the best results.

“A lot of times it’s not just the bonding material but what works well on your hands,” Dr. Jebriel explains. “If you are used to using etch and bond, and that works well for you, I would continue using it. We get confused with all these different generations, but ultimately I think it’s what works best in your hands.”

Finding the best material is simply a matter of experience and occasionally stepping out of one’s comfort zone.

“You find out through time,” Dr. Nunez says. “It’s like whatever activity you’re doing. For instance, I’m a Mac user. My life does not run on Windows. I only like half a teaspoon of sugar in my coffee. It goes over time. You’re able to understand what you want from the product and how you like it to handle. Some people will like a thicker composite; some people will like a softer composite. Some people don’t like the product to have a certain viscosity. Some people like it more packable; some people like it more flowable. Some people like it more opaque; some people like it more translucent. Things vary with each clinician.

“There is a general consensus about how the product should handle, but at the end it is very subjective because everybody feels differently,” he adds. “Even if you give the same instrument to 10 different dentists, they are all going to have a different opinion.”

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With the constant influx of new materials, dentists may be overwhelmed by so many new options. Ultimately, it comes down to the practitioner and where he or she wants to be when it comes to new products.

“The dental market is very dynamic, and you have different types of people,” Dr. Nunez says. “You have a certain group of people that you might want to call the ‘early adopters.’ They’re always looking to try new things. And then you have the guys that are waiting for the early adopters to provide feedback on whatever new stuff is up, usually the early adopters are key opinion leaders. They try these products before most people, then they go out and lecture about it and provide their two cents on them. And then you have the guys that are just not willing to change. They have a comfort zone. They like what they have and it is very difficult for them to look sideways because their experience tells them that there is no need for a change.”

Trying something new can be a good thing, no matter if the doctor elects to switch products or not.

“When you try something new, it is a win-win situation,” Dr. Nunez says. “If it’s better than what you have, you win. You’ve got something newer and maybe better. Maybe, if what you try isn’t as good as what you had, then you win, too, because you can say, ‘I proved what I have is really good.’