Best practices for temporary cements

Provisional restorations are a key step in the restorative process, and their success is just as important as that of the definitive restoration.

While temporary cements are designed to be just that-temporary-it doesn’t mean they can be substandard. However temporary your provisional restoration may be, it’ll need to last successfully until the permanent restoration can be placed. Temporary cement should provide the adequate strength to hold the restoration for as long as necessitated, but retention should also be low enough to allow the provisional restoration to be removed-without damaging the tooth-when the time comes to place the definitive restoration.¹  

So, what makes an ideal temporary cement? According to experts, the ideal cement should allow for easy cleanup and removal of excess cement (both when the provisional is placed and removed), good retention (but easy removal), compatibility with the final restoration and a good marginal seal to help reduce post-operative sensitivity.² It’s also important  to take into consideration the cement’s ease of use, degree of adhesion to enamel and dentin, sensitivity to moisture, biocompatibility with other restorative materials, it’s working and setting time, as well as the shelf life.³

While it seems like a lot to consider, temporary cement selection can essentially be boiled down to four critical areas:

1.     How long will the provisional need to remain in place? 

2.     How retentive is the preparation? 

3.     Do esthetics need to be taken into account?

4.     What type of adhesive technique will be used for the definitive restoration? 

“It’s a balancing act,” Dr. Jason Goodchild, director of clinical affairs at Premier Dental Products Co., says. “The idea is-and wouldn’t this be perfect-that you would have a cement that would provide a really strong bond, but when you took it off, it was easy to remove and none of it would remain on the tooth. Ideally, it would all come off on the temporary. But I’m not sure that perfect cement exists, so there’s always a bit of a tradeoff to consider.”

Temporary Cement Selection
There’s no one-size-fits-all solution when selecting a temporary cement, since each clinical scenario has its own unique challenges. However, there are some that can check off a lot of requirements.

“I think cements are personal preference,” Goodchild says. “Most dentists have a go-to, something they use almost all the time. I’ve always had a standard one for most preps, and then I have things that I know will stick a little better or be more retentive.

“There are some clinical situations where you’ll deviate from your go-to choice-like if you have a really short tooth where need extra retention because you know there’s not a lot of retention in the prep,” he continues. “Or, perhaps you have an esthetic case and you need to have something that has some color or is clear, so that it doesn’t impact the color of your provisionals. I always have a clear provisional cement that won’t shine through the provisional material so it doesn’t change the color. So, you probably have at least two types of cements in the office as a result.”   

There are numerous options for each of these clinical situations, and with so many available products, navigating the market can be intimidating. Goodchild says the first step is figuring out which type of temporary cement you want to use. 

“You can really put temporary cements in three different buckets,” he explains. “Zinc-oxide based, resin based and then polycarboxylate.” Each type comes with its own pros and cons, so you should revisit the four critical areas of consideration before making a determination.

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Polycarboxylate Temporary Cements
Polycarboxylate temporary cements have been the go-to for dentists for years, as they provide good retention, easy cleanup and have low instances of post-operative sensitivity. These cements are ideal for longer-term temporaries, or temporaries that demand greater retention.

“We have used polycarboxylate cement in dentistry for a long period of time as sort of an intermediary–it’s pretty darn strong but it allows you to get the temporary back off again,” Goodchild says. “One example is Durelon (3M Oral Care), and that’s a strong cement. Polycarboxylates like this actually help prevent sensitivity and they are generally good cements-but the major downside is that when you take the provisional off, all of the cement is on the tooth. None of it is on the temporary, and you have to sort of chisel it off the tooth, which can be annoying and painful for the patient.”

Available in powder/liquid form, or as a paste automix syringe, polycarboxylates have short working time, so they must be mixed quickly and accurately. They are also a poor choice for esthetic provisionals since the opaque color of these cements may show through the temporary.

Zinc-Oxide Temporary Cements
Zinc-oxide temporary cements are a mainstay of dentistry, first used in the 1930s. The zinc-oxide cements can be broken into two subcategories: those with eugenol (ZOE cements), and those without (ZONE cements).

“Zinc oxides are pretty common,” Goodchild says. “These are popular cements, with or without eugenol.”

The eugenol in ZOE cements diffuses throughout a tooth’s dentin, resulting in a therapeutic, sedative effect on teeth, which can lead to reduced post-operative sensitivity. They also have a strong antibacterial effect. However, eugenol can be tricky, because it can permeate the tooth structure and prevent good bonds from forming between the dental adhesive and cement.  

“There are reasons to use or not use eugenol,” Goodchild says. “The eugenol may interact with resin bonding. But, the positives of eugenol are that it is antibacterial, and it soothes and calms the tooth. It’s pretty easy to remove, and generally speaking it’s easy to get these cements off of the tooth if any remains; a lot of it stays inside the temporary.”

Instead of eugenol, ZONE temporary cements contain a mixture of carboxylic acids that won’t interfere with definitive bonding. This makes them compatible with resin cements, and they are reported to have stronger retentive than their eugenol-containing counterparts. However, they don’t have the sedative, soothing effect that ZOE cements possess, so they can lead to more post-operative sensitivity.

Resin-Based Temporary Cements
Resin temporary cements are growing in popularity, thanks to their high bond strength, quality esthetics and great retention. 

“I believe their retention is a little better than zinc-oxide cements, but it does make it a little harder to take it off, and sometimes you have more excess to clean off,” Goodchild says.  “So, I think it’s really a balance.”

Some resins also contain desensitizing agents (such as potassium nitrate) which can lead to reduced post-operative sensitivity. They are also compatible with most permanent cements and bonding materials, as well as resin core buildup materials, and are ideal for implant provisional cases, as the temporary can be removed without damaging the implant. However, with the pros come some cons: Resin temporary cements are prone to microleakage and discoloration, and are reported to absorb odors.

Tips for Success
First things first, Goodchild explains, you have to make sure you know how to use the cement you’ve selected. 

“I’m a back to basics kind of guy, so my first step is always to read the directions,” he says. “Not everybody does, but even temporary cements, there are differences between them. For example, when you are using Temp-Bond temporary cement (Kerr Dental) the tooth has to be really dry, versus materials like Integrity TempGrip (Dentsply Sirona), it doesn’t have to be dry. So, getting the best results may be really dependent on following the instructions.”

Technique is critical for success as well. Even if you follow directions, not taking the time to properly execute the basics can be a big mistake.

“When you follow the directions you really get the best possible outcome,” Goodchild says. “But other basic stuff is, don’t overfill the provisional. Sometimes people just line the inside rather than filling it up-and less is more in some cases. Or, especially over a freshly based core buildup, you should place Vaseline so that you don’t get bonding to the resin. So, there are a few little things to note, but for me it’s all about really reading the directions to get the best possible outcome.”

Selecting the correct cement-and using it properly-can both affect a provisional’s outcome. But Goodchild says that it is important to remember two other key factors: creating a quality temporary and achieving good occlusion. 

“I really believe that retention of a provisional restoration is only partly due to the cement,” says Goodchild. “The rest of it’s due to making a good temporary and also adjusting occlusion. I like to think, ‘hey did I make a great-fitting restoration, and did I adjust occlusion?’ Because I believe that one of the biggest reasons why provisionals become dislodged prematurely is because they are biting on them too hard and the force of biting on it over and over again dislodges it.”

In the end, it’s all about balance and assessing and approaching each case as a unique situation.

“The take-home message is, no two clinical situations are identical and you really have to take each one individually to get the best possible outcome,” Goodchild concludes. “With provisionals, you balance everything out. Do I need strength? If I have strength, it might end up sticking to the tooth. If I don’t have strength, it’s going to be easy to get off, but it could fall off easily–and it won’t be on the tooth when I take it off. There’s a balance you have to have, and taking each case individually helps me make the choice.”

References

1.     Ramp MH, Dixon DL, Ramp LC, et al. Tensile bond strengths of provisional luting agents used with an implant system. J Prosthet Dent. 1999;81:510-514.

2.     Farah JW, Powers JM. Temporary cements. The Dental Advisor. 2005;22(6):2-4.

3.     ADA Professional Product Review. Temporary Cements. 2011;6(1):13-16.