Mastering Zirconia Crown Cementation — Transcript
[00:00:02] Welcome
Host: …for joining us tonight. We here at Sprig are super excited for this special webinar by Dr. Ross Levine. Please join us in welcoming Dr. Ross Levine.
Hi everybody.
[00:00:26] Family, training and outreach
Am I getting going? I guess. All righty. We’re starting this. We were just talking in my basement. I’m used to talking in front of a bunch of people, so I’m just talking to myself down here.
I want to welcome everybody. Tonight we’re going to cover mastering zirconia crown cementation: avoiding pitfalls for long-term success.
Disclaimer: I am not an employee of Sprig. I’m a board-certified pediatric dentist and practice in Bucks County, Pennsylvania. Here’s my family. I have a 7-year-old, Noah, my beautiful wife Abby, and twins, Lily and Logan, who are five years old. At our office — he’s not technically a therapy dog, but he’s our therapy dog — there’s Archie. He’s nine. He’s been coming to the office pretty much since he was a puppy. In my free time I enjoy coaching baseball. I coach both my boys, and coach soccer as well. And I left this in here for us pathetic Mets fans. Anything just feels sad for my family at this point. It’s been a rough season, so I left that in there. But we’re avid Mets fans. We’ve been to opening day with my boys the last three, four years. It’s a family tradition. So, a little about myself there.
I graduated from the University of Maryland in 2008, and went to Temple University in 2013, where I also did my residency program and graduated in ’15. I was chief resident from ’14 to ’15 as well. Then I got my board certification in ’17, so my 10-year re-up is this year or coming up next year. Not looking forward to that too much.
I come from a family of dentists. My dad is Dr. Robert Levine, a newly retired periodontist. My sister is Dr. Bari Levine. She’s right here. And then my mother and my mentor, Dr. Sheryl Radin. So, a family of dentists. My motto growing up was “Floss the teeth you want to keep,” and “Hurry up and graduate” were my mom’s favorite words growing up.
I leave this in here: my sister started the Growing Smiles Foundation. We last went down to Peru, I believe it was 2019. I bring this up for any younger residents, or anyone that has the time and doesn’t have children yet: I really encourage you to do any type of outreach. It opens your eyes to poverty in the world, and to the ability that you have to do dentistry anywhere. We did $160,000 worth of free comprehensive dental care. This is outside of Peru. We saw 250 children in five days. You can see this was before COVID; we’re not wearing masks.
I was joking in a lecture that if you can do dentistry in an Infinity chair, in plastic chairs, and in little mini chairs inside a kindergarten, you can do dentistry anywhere. The skills that we all have as dentists are translatable across the world, and as long as we have the tools to do it, you can do dentistry anywhere. So I highly recommend, if you have the time and ability, going on an outreach to help the world. It opens your eyes. You don’t know poor until you’ve seen places with no running water and wild dogs throughout the streets. It’s an eye-opening experience. So I throw that in there.
[00:03:36] The practice, patient reviews and why Sprig
This is our office. This is Growing Smiles in Floral Vale. We’re located in Bucks County, Pennsylvania, about 45 minutes outside of the city. This is our homepage. When I lecture, I always talk about Google reviews. I hate bringing it up, but it’s the way the world works at this point. Dental offices are no different than coming to a restaurant. In my lectures across the country, I’m very proud of the reviews that we have here. It’s what separates us from everybody else. It really is like working in the restaurant business. We are a service industry, unfortunately, is the way it’s looked at. So this is the way the world is now, and something to be aware of as you’re practicing.
That’s one of the reasons I enjoy working with Sprig and lecturing for them. It sets a standard for quality dental care. It’s very easy to do stainless steel crowns and Hall crowns and place SDF on teeth, but to actually go out there and do high-quality dentistry is what we strive for, and how I was brought up. So that’s why I enjoy working with Sprig.
Here’s our team. We’ve got 13 staff members: three hygienists, two EFDAs, two assistants and currently two receptionists up front. We have an open bay system, and two quiet rooms and two operatory rooms in the back. Here’s a little intro to our office. Everything’s kid-friendly, with a lot of figurines at eye level when you walk in. Here’s our open bay system. It was designed by a wonderful architect who was able to guide us through this, because my mom and I are not creative people. We’re wonderful dentists, but creativity isn’t our strong suit. So we’re lucky to have such a great architect.
[00:05:27] Starting with zirconia, and sedation in the office
My zirconia journey started in 2015 with my mom. She’d been a general dentist for — I’m going to get this wrong — like 15 years prior. There wasn’t really a great option for white posterior teeth at that point. With her background it was pulpotomy and a core buildup, pretty much. Parents in our area — we’re an upper- to middle-class area in Bucks County — don’t want silver teeth. So she was working around it by doing pulpotomies and buildups, and they would hold up pretty well. But we wanted a better alternative. So my mom and I flew up to Toronto in November of ’15 and got a certification. We were doing the first hands-on posterior crowns, and that’s where we started.
My sister told me to throw this in here, because all the cases I’ll show that are mine are done in my office. I’m openly a dinosaur. We trained with oral sedation at Temple, and I use it every day in the office. We still do a triple cocktail: chloral hydrate, Demerol, Vistaril. On certain occasions I’ll use midazolam and Vistaril, depending on the weight. And we use nitrous oxide on most operative cases.
All the cases I’m showing are done within the office. Nothing’s done under IV sedation or in OR settings. Not that I have anything against it; the way I was trained, I can do everything in-house. On very rare occasions we have to refer out to Penn or to a surgery center, maybe once a year. But everything I’m going to show you today was done with oral sedation or just nitrous oxide.
[00:07:03] Objectives, and why the prep comes first
The training objectives for today: we’re going to compare the common cements that are out there, a deep dive into cements. I’ll show you what’s out there, what we recommend as a practice and what’s been working for us. We’re looking at the strengths and weaknesses, backed by the scientific evidence. Then the advantages of Sprig crowns, which goes along with the question: are try-in crowns necessary? How to avoid the common pitfalls prior to cementing these crowns, and the best way to control hemostasis.
Here’s one of my cases. You can see how beautiful these crowns are, how pink the gingiva is around them, and how beautiful these crowns can turn out.
Cementing is the last step in this whole process of doing a zirconia crown. The steps before matter, and I’ll touch on some of them. As for crown preps, if your prep’s not right, the cementing really won’t make a difference, because you need a very solid foundation.
The Sprig U courses are coming back next year. Actually, I believe there’s one next week. They start back up in March in Las Vegas. If anyone hasn’t been to them, these are wonderful courses. Believe me, I’m not employed by Sprig to say this, but these are really the best hands-on courses to refine your skills in placing these crowns. I highly recommend reaching out to Sprig and signing up for one. They’re really the best hands-on course that’s out there.
At the very least, if you haven’t done a crown in a while or you’re starting to do it, the techniques are right there on the website. Even after taking the course, I would still watch these videos when I first started, because it is a very technique-sensitive approach to doing these crowns. The step-by-step mentality that we train is very important, and it makes for a much easier transition if you’re going from stainless steel crowns to doing these. The techniques are right there on the website for you.
[00:09:06] Retention depends on the prep: don’t taper
Talking about retention: zirconia crowns need to be passive-fitting. They rely entirely on the luting cement for their retention, and with these zirconia crowns, the Sprig ones especially, there’s no chemical bond to the tooth structure itself. So, as I mentioned earlier, prep design is the most important aspect, and one of the biggest issues is: do not taper the bur. These are completely opposite of doing stainless steel crowns.
I always make the analogy of skiing on the East Coast versus the West Coast. You tend to lean forward on the East Coast and lean back a little when you’re skiing powder. It’s the same thing when you’re prepping these crowns. You really want your bur tipped more towards the root, creating an undercut rather than tapering. Stay away from leaving any type of ledge, really try to keep that bur perpendicular, and remember not to taper.
[00:09:56] The ideal cement, and resins, RMGIs and BioCem
When we’re looking at the ideal cement, we’re looking for moisture-tolerant, easily handled, low film thickness, and fluoride release, depending on what part of the country you’re in. I’m not trying to get into a debate over that, but do you want it or not? Biocompatibility is a huge issue. As you can see with these crowns we placed, the tissue is beautiful around them. When you’re doing a quick exam, it’s easy to pass over these and forget that you’re actually looking at crowns. Reasonable setting times are really important, and obviously cost. Everything’s costing more now, so you’re looking for a solution that’s more cost-effective.
So where to start? There are different types of cements: glass ionomers, like Ketac Cem; resin-modified glass ionomers, like Fuji II and RelyX; a bioactive cement on the market, BioCem; and resins, the self-adhesive cements. I’m sure you know RelyX U200 and Panavia, the common brands. These are the ones I looked at, to give everybody an idea of what’s on the market.
The resins. The advantages are they’re really easy to use. For some of them, especially RelyX Universal, there’s no additional bonding agent or primer. Panavia, the next one over, you need to use a primer on. But the dispensing for these is so simple, and it creates a strong bond. RelyX Unicem doesn’t release fluoride, where the Panavia one does. Any resin cement needs to be dual-cure, which both of these are, because you can’t cure through the zirconia. You need to be able to tack cure, then cure on the outside when they’re cemented.
The disadvantages: they’re very technique-sensitive. Moisture sensitivity during placement can be an issue, because these cements are hydrophobic. Some of the teeth I save, as I’ll show you, have not much tooth structure left for retention, and you’re really into the sulcus, so there’s a lot of fluid in there. So you’d like more of a hydrophilic cement, but every case is a little different. If they’re not moisture-tolerant, it can compromise the bonding. And excess cement at the tooth–restoration interface can create bacterial adhesion and biofilm formation, due to the surface irregularities around these crowns. That can result in plaque accumulation, leading to soft tissue inflammation and demineralization, with some resin cements if you leave too much around the margins.
Resin-modified glass ionomers: the advantages are strong adhesion, a high fluoride release, low film thickness, and auto-mixing dispensing systems, very simple, as we saw with the resins. It’s easy cleanup, and these are also dual-cure. The disadvantage is limited working time for some; they can set up very quickly if you’re not paying attention. Some studies have shown an increase in microleakage around these crowns, and they can be moisture-sensitive as well. Working time is around two minutes and 15 seconds, with intraoral setting time around four minutes and 30 seconds. That’s pretty much average for the working time of a lot of the cements we’ll look at.
And then BioCem, from NuSmile. The advantage of this one, according to the manufacturer, is hydroxyapatite formation. There’s ion release: phosphate, calcium and fluoride ions. There’s less microleakage than conventional Ketac Cem, in one of their studies. There’s no primer or etching required, which can be an issue with some of the other resins. It’s easy handling, as you can see in the dispenser here, and it’s radiopaque, so it shows up on X-ray. Disadvantages: limited long-term clinical data, and cost. I’ll show you in a chart at the very end of the lecture; it’s a little more expensive than most of the other ones. And it self-cures. This isn’t a disadvantage, but the cure time is about two to three minutes, and you can accelerate the process by tack curing as well.
[00:14:11] Zinc phosphate and conventional glass ionomer
I threw this one in here, zinc phosphate. We still use it for stainless steel crowns. Durelon has been around forever; we still use it day to day. My mom was using this when she was a general dentist. It’s got a very long clinical track record, good compressive strength and good adhesion to the tooth. It’s fluoride-releasing and cost-effective. But there’s no chemical adhesion to zirconia. There’s definitely a lower tensile strength, and a higher solubility compared to some of the other cements out there.
And my favorite, my biggest disadvantage with Durelon: it’s very difficult to clean up. It makes a mess everywhere. These crowns do not come off, especially the stainless steel ones we cement with this stuff. But it’s a pain to clean; it gets everywhere. It holds these crowns on, and the working time is about the same as everyone else, about two minutes and 30 seconds, with total setting time about 10 minutes from the start of the mix. So some leeway there.
Lastly, the glass ionomers. The advantage is a chemical adhesion to the tooth. These are water-based cements with hydrophilic properties. They release fluoride. Biocompatibility is great with these cements. They’re self-cure as well, so you don’t have to tack cure them, and they’re definitely more cost-effective. Cons: some studies have shown some microleakage and some solubility over time. Working and cure time is about three to three and a half minutes. It also depends, especially with these liquid–powder ones, on how you’re mixing and how thick the mixture is. Total setting time can be upward of seven minutes if it’s a little thinner, and as little as five if it’s thicker.
[00:15:48] What the literature says: few studies, mostly in vitro
What’s in the literature? There’s not much out there. There are 13 studies published on retention of zirconia crowns in primary teeth. There really is a scarcity of comprehensive clinical studies assessing the influence of luting cements on clinical success in pediatric patients. The majority of existing studies are in vitro, so there’s not much that’s within the mouth. And even the clinical ones only vary between about one week and 36 months after crown placement. That’s not much, considering we’re placing crowns on two-, three-year-olds that need to last anywhere between three and six, seven years for some of these kids.
A recent randomized clinical trial showed that zirconia crowns have a statistically significant higher retention rate when using packable glass ionomer. Then the most recent study suggested that self-adhesive resin cement can be a viable option for cementing zirconia crowns, demonstrating satisfactory clinical performance. But the take-home was that they further highlighted the need for future studies comparing the various types of cement, because there really isn’t one that’s better than the other across the board. It’s really case-dependent, and what you feel comfortable using.
I pulled some studies from 2018 on. The first one we’ll look at is microleakage of cements with prefabricated zirconia crowns. This is an in vitro study comparing BioCem and Ketac Cem with NuSmile and EZ-Pedo crowns. They looked at 40 extracted permanent teeth prepared for zirconia crowns. There were four groups: NuSmile with BioCem, NuSmile with Ketac Cem, EZ-Pedo with BioCem, and EZ-Pedo with Ketac Cem. These were all thermocycled. As I said, it’s an in vitro study, so not as great as in the mouth, obviously. They cemented them and looked for microleakage afterwards.
The results: all groups showed some microleakage. According to their results, BioCem significantly reduced microleakage compared to Ketac Cem. NuSmile with BioCem had the least microleakage of all the groups, and EZ-Pedo with Ketac Cem had the most. The conclusions were that BioCem showed significantly less microleakage than Ketac Cem with both NuSmile and EZ-Pedo crowns, that NuSmile with BioCem was the most effective combination, and that BioCem is the preferable cement for zirconia crowns. But obviously there’s a catch: this study was supported and funded by NuSmile. This was back in 2018, when it first came onto the market. So take it for what it’s worth, but it’s hard sometimes to trust studies completely funded by the people putting the product out.
The next study, also 2018, is the effect of crown preparation on retention of prefabricated primary posterior zirconia crowns. They evaluated how different preparation heights affect retention. This wasn’t looking at the cement itself, but as I mentioned earlier, crown preparation is just as important, so I threw this one in. They used extracted teeth with prep heights of 1, 2, 3 and 4 millimeters. Crowns were cemented with a glass ionomer, Ketac Cem. A control group was not thermocycled, and all the others were thermocycled to simulate five years of oral conditions.
There was no real difference between the 2, 3 and 4 millimeter groups, but there was a significant difference between the 1 millimeter group and all the others. So you have to be over one millimeter for these crowns to stay. Most failures were adhesive failures between the tooth and cement. With any failure you see with these crowns, you’re going to find a lot of the cement still within the crown itself. You’re never going to find these crowns washed out of cement. It’s always the interface between the prep and the cement, rather than the cement and the crown. The conclusion was that at least two millimeters of occlusal–cervical height is critical for reliable retention of these prefab crowns on primary molars, that retention doesn’t improve much beyond two millimeters, and that failures were primarily at the tooth–cement interface, not crown–cement. So that’s important.
[00:20:09] Clinical trials and reviews, 2019 to this year
Next, a study in 2019 looked at the influence of luting cements on the clinical outcomes of zirconia pediatric crowns. This was a three-year split-mouth randomized controlled trial, one of the better studies out there. They looked at the clinical performance of NuSmile’s bioactive cement and packable glass ionomer over three years. There were 25 children, so a smaller sample size. They received 50 crowns, 25 per cement group, on mandibular first molars. They looked at crown retention, fracture and gingival condition, with follow-up to 36 months.
The results: glass ionomer showed significantly better retention than bioactive cement from three to 36 months. Survival with the glass ionomer was 88%, versus 40% for the bioactive cement. Mean survival time was over a thousand days for glass ionomer and under 500 for the bioactive cement. No fractures were reported. I wouldn’t expect fractures from the cements. Any fracture you see in a zirconia crown has to do with your prep: there’s a ledge there. If you’re seeing fractures with these crowns, it has nothing to do with your cementing process; it has to do with leaving a ledge. And a trick: wherever you see that fracture, that’s where your ledge is, especially in posterior crowns. On gingival health, luting cement type didn’t affect gingival condition. The conclusion was that packable glass ionomer is more reliable and retentive than bioactive cement for zirconia pediatric crowns, both cements provide strong fracture resistance in zirconia crowns, and the choice of luting cement did not influence gingival health.
In 2021, zirconia crowns for primary teeth: a systematic review and meta-analysis. The purpose was to evaluate retention and clinical outcomes of prefabricated crowns cemented with either self-adhesive resin cement or a glass ionomer. This is a retrospective study, so not as strong as a randomized controlled trial. They looked at 162 zirconia crowns placed on anterior teeth, so this was an anterior study. Follow-up was at 12 and 24 months, comparing RelyX Unicem and a glass ionomer, like Fuji II. The results were 95% retention at 12 and 24 months with the resin, where glass ionomer fell off a little: 91% at 12 months and 84% at 24.
The discussion suggested self-adhesive resin is superior for longer-term stability compared to the glass ionomer, with more debonding with the glass ionomer, in line with earlier studies showing high success rates for resin-based cements. The limitations were convenience sampling, the focus on anterior teeth, and potential operator and technique variability, because they knew what they were working with. They touched on the need for broader studies, including other cements and larger sample sizes, which is a common thread throughout the literature currently. The conclusion was that self-adhesive resin cement can be more reliable than glass ionomer cement for zirconia crowns on primary teeth. It showed better retention from 12 to 24 months, and they said it should be considered the preferred cement for pediatric crowns. I’ll disagree a little there. I think there’s definitely room for both in the field; it depends on the situation, which we’ll talk about. But they need more long-term studies. That was back in ’21.
Sorry, these slides got moved over. This was a comparison of luting cements with prefabricated crowns in primary teeth. I’ve got to scoot back a little here. The discussion with this one was that self-adhesive resin cements tended to perform better, though the findings weren’t statistically significant. That’s in line with previous studies showing resin cements often produce lower microleakage compared to resin-modified glass ionomers. A possible reason is that resin-modified glass ionomers contain a hydrophilic component, which may increase water absorption and microleakage under thermal stress. The limitations were sample size and potential differences from clinical conditions. But it showed lower microleakage with the self-adhesive resin cements than the resin-modified glass ionomer, and they can be a promising alternative in the future.
Going back to this one: they compared three luting cements over a 36-month randomized controlled trial. This is 2023, another of the better studies. They looked at long-term retention, plaque buildup and gingival health with prefabricated zirconia crowns in children, cemented with three types of material: glass ionomer, resin-modified glass ionomer, and an adhesive resin. This is one of the only studies that looked at all three, versus one on one. The methods: 90 children, randomly assigned to three cement groups, followed over 36 months with regular checkups. They evaluated crown retention, plaque index and gingival health. Crown survival at three years was 76% for glass ionomer, 50% for BioCem, and about 70% for the adhesive resin cement. Glass ionomer had the highest mean survival, and BioCem had the most crown debonding. Plaque accumulation was also lowest in the glass ionomer group, and gingival health was favorable and similar across all groups.
The conclusions were that traditional glass ionomer was the most reliable cement for prefabricated zirconia crowns in kids, showing the best retention and the lowest plaque buildup, and that zirconia crowns were durable and safe regardless of cement type, with no crown fractures. As I mentioned, I don’t think crown fractures have anything to do with the cementing process; it has to do with your prep. All cements supported good gingival health, but the glass ionomer offered an added benefit in practicality for everyday pediatric use.
Another study, in 2024, compared the clinical success of pediatric zirconia crowns with different luting cements. They looked at 53 children, 60 primary molars restored with NuSmile crowns, comparing BioCem; G-CEM LinkForce, which is a dual-cured adhesive resin; Fuji I glass ionomer; and Fuji II. This is a shorter study, with follow-up at 1, 3, 6 and 12 months. They looked at retention, plaque index, probing depth and periradicular pathology. Crown retention had no significant difference among the groups. Pulpal survival was about 86%, Fuji II had the best pulpal outcomes, and periradicular pathology was about 8%. Periodontal health improved over 12 months with all of them, but not significantly. I think that has to do with the crown itself: periodontal health gets better with these crowns. On plaque control, crowns had a significantly lower plaque index than the patient’s overall oral hygiene at 12 months.
The conclusion was that no luting cement was superior within one year. Fuji II showed the best pulpal survival, but not significantly, and these zirconia crowns consistently reduced plaque compared to overall oral hygiene. As you see in some of these other slides, plaque retention around these crowns doesn’t really exist compared to a normal tooth surface. And as I’ve been touching on, the choice of cement should be individualized, based on patient cooperation, tooth condition and operator preference. That’s a big take-home from a lot of the literature at this time, and obviously longer-term studies are needed.
I believe this is one of the last ones: an in vitro evaluation of microleakage of different cements with prefabricated zirconia crowns, from this year. Microleakage is a major cause of failure in full-coronal restorations, and different luting cements may influence microleakage, but evidence is limited in children. They looked at 36 extracted primary maxillary incisors, with Ketac Cem; two resin-modified glass ionomers, Fuji II and FujiCEM Plus; and the self-adhesive. This is the slide that got put out of order, but I’ll go back to it. The crowns were cemented and thermocycled, then microleakage was examined under a stereomicroscope and scored. RelyX, the self-adhesive cement, had the lowest leakage, but there was no significant difference among the groups.
[00:28:42] Why Sprig crowns: occlusal profile, internal space and a systematic prep
Touching on some of the advantages of Sprig crowns. I’ve worked with different types of crowns in my residency program, and I’ve been taking these courses and working with Sprig crowns for over 10 years now. Working on primary teeth has unique characteristics: thinner enamel and larger pulp horns, less surface area, and less retentive preparations. The best part about these crowns is the flattened occlusal profile. You can see with the competitors’ crowns, when they’re sectioned, how much more reduction you need on the occlusal table. With these you stay farther away from the pulp. They’re broader mesiodistally — or buccolingually, excuse me — to allow more room internally and more cement to stay within the crown.
And it’s a systematic approach. The best part about working with these crowns and with Sprig is that each bur has a specific use. The difference between prepping stainless steel crowns and zirconia crowns for me at this point is just the time it takes to change the bur out. It improves speed and efficiency, saves chair time and money, and decreases stress, knowing there’s a very systematic approach to these crowns.
I always throw this in when I’m lecturing at Sprig U: the biggest thing is, do not taper these burs. Make sure, as I mentioned earlier, that we keep it very parallel. Tapering leaves that ledge and can prevent these crowns from seating. So really try to keep the bur perpendicular, in anterior teeth especially. And as I was saying earlier, make sure you’re creating that undercut. When I’m using the flame, I’m pulling towards the root of these teeth to create a subgingival prep. The biggest error we typically see is improper subgingival preparation, and tapering, which leads to ledges that prevent seating.
So, as I’ve mentioned multiple times already, keep the bur perpendicular to the long axis on anterior teeth, and perpendicular to the occlusal surface on posterior teeth. Then focus on undercut pressure with the tip of the bur during the circumferential reduction. Really aim where the tip of the flame is, to create that undercut and decrease any potential for a ledge.
[00:31:01] Size down, and why no try-ins are needed
A common error we see is that the crown size is too big. Too much room compromises retention. Always use the smallest size possible. If you’re in between sizes, I always recommend sizing down. It leaves less area for things to leak in, and microleakage. It’s critical for back-to-back cases to get as much space as you can, so the smaller crowns the better. And Sprig having the space loss crowns can be case-saving. Sometimes you get so much space loss, especially with the E’s leaning into the D’s or the D’s leaning into the E’s. Having a smaller crown is critical for those back-to-back cases.
As I mentioned earlier, there’s no need for try-in crowns with EZ-Pedo, and that’s why you can use pretty much any cement you’d like with these. The best part is the Zir-Lock patented feature: there’s no need for try-ins and no extra step of autoclaving. Other brands use the interface of the inside of the crown; they’re all primed with something. These crowns work completely with mechanical retention. You can see the grooves within these crowns allow greater surface area for cement to sit in. So there’s no chemical bond required, and you don’t need to be as isolated. The other ones are prone to more failure, and you need more expensive cements, with priming agents and resin cements, which is an additional cost.
As I just mentioned, there’s twice the internal surface area with these crowns. That maximizes the cement surface bond, and the marginal lock prevents cement from leaking out and washing out. You can use any type of cement you want: glass ionomer, resin-modified glass ionomer or dual-cured resin. The take-home: these crowns really work with anything. It’s really personal preference what you want to work with.
[00:32:56] Tissue management: controlling hemostasis
Tissue management is the biggest step when it comes to making sure these crowns stay on, so you don’t end up with the issues we see on some of these message boards. This is one of my cases. You can see I had some leakage within here, and that’s when these teeth end up turning gray. Not controlling hemostasis well will compromise retention and cause microleakage. With this one, I found the cement was probably too thin, and I was probably playing around with it a little too much, which allowed saliva and blood to seep in, which turned it gray.
The biggest reasons we find for loss of retention and crown loss are movement during the initial set and lack of hemostasis. I really find that lack of hemostasis is the biggest issue for losing crowns. If you can get that area as clean as possible, you will have success there. Promise. In the beginning, when I first started doing these, I thought it was no different than a stainless steel crown, just prepped a little differently: I’ll pop the cement on there and it’ll work great. That’s not how it works. It really needs a cleaner, isolated crown prep in order to get these crowns to seat.
There are different ways to control hemostasis. Local pressure, like gauze and cotton rolls, is probably my biggest go-to, on top of the topical hemostatic agent I’ll touch on. If you have a laser over your shoulder, you can try electrosurgery or laser, which I don’t really recommend, but it can be used for hemostasis. Injection with a local anesthetic with vasoconstrictor: you just have to be careful monitoring the amount of epinephrine, especially in younger patients. There’s subgingival retraction cord; in some cases, placing retraction cord with or without hemostatic properties can be helpful. And timing. The biggest thing, especially if you’re doing anterior and posterior, is to prep the anterior teeth first. You can try on the crowns and let that tissue sit. The bleeding will stop purely on its own, and it allows a cleaner area to cement these crowns on, because the cleaner the prep is, the better your retention’s going to be.
First and foremost are these HemeRX pellets. They’re fast-acting pellets that deliver the hemostatic agent and retraction right where you need it. They come as little dry green pellets that you wet and pull apart, which I’ll show in a video in a second. I use these on every zirconia crown case. They minimize the risk of contamination. The biggest things are they’re tasteless and non-staining. They’re formulated without ferric sulfate and aluminum chloride, for patient comfort. It’s a superior hemostatic agent compared to what’s out there. It really increases the efficacy of these crown restorations and pulp therapy.
This isn’t one of my cases, but it’s one of the better views you’ll see of cementing these crowns. First, once you get your sizes right, you pull these hemostatic pellets apart, wet them, and plug them into the sulcus just like retraction cord. Pretty much use one per tooth and really wrap around, especially on the facial, to get the heme to stop, because you’ll see how red this looks in a minute. While your assistant is cleaning out the crowns — and I’ll give you another method for cleaning out these crowns — you take wet gauze, or sometimes they spray a little epi onto the gauze or cotton rolls, and I apply pressure. I’m squeezing the sulcus of these teeth to get the heme to stop.
You’ll see the tissue blanch, and once you remove these pellets, the bleeding stops pretty well within a minute or two. If you’re still getting bleeding, hold the cotton roll on that tooth and keep pressure until you can get your crown filled, and then cement it that way. You can see how all the heme stopped around the margins of these crowns. The biggest issue, especially with the crowns you saw that were gray, was heme seeping back into that crown.
[00:36:57] Which cement in non-ideal conditions, and what it costs
The final process is cleaning up. As we talked about earlier, everyone asks what cement they should be using. As I said, it’s all case-dependent. But these are a lot of the cases I see, especially in the anterior, by the time these patients find me. They’re almost well past restorability for a lot of places, but my mom and I pride ourselves on doing heroic dentistry. When these teeth are prepped, there’s not much tooth structure left, and you can see that. You can see the HemeRX pellets stuffed into the sulcus here, and you get that bleeding to stop. But this is not an ideal situation to be bonding.
What cement would you use in non-ideal situations? What has the longest successful track record in a variable, moist and possibly contaminated environment of blood, saliva and other debris? The answer across the board is glass ionomer and resin-modified glass ionomer. They’ve been around forever, and they work great. They’re definitely more cost-effective. It really matters what works in your office and in your hands. What we use is glass ionomer, Ketac Cem, which is what we’ve been using as long as I’ve been using these crowns.
This is a one-year follow-up. I think it was actually in the email for the Sprig website. We left a little bit of an open bite here, because there’s not much tooth structure left. He was just back in; I just didn’t get a picture of it again. Honestly, the hardest thing we do is trying to take before and after pictures on these moving targets. But the crown margins are great, the teeth are beautiful, and they stay on.
The rationale for glass ionomer cement: all clinical data shows it demonstrates success with zirconia crowns. It’s been used for decades in pedo for stainless steel crowns, and over a decade for zirconia crowns. It’s better suited for clinical situations with unpredictable isolation, like the case I just showed. All the Sprig U faculty, collectively placing over 50,000 crowns — pretty much everyone is using a glass ionomer. And it’s far less expensive than the other ones.
You can go through some of these. There’s the Maxicap one, a self-capsule that you can refrigerate, and that’s over $15 a unit. NuSmile’s BioCem is over $8, and you saw the retention wasn’t great on that one. The resin-modified glass ionomer is around $8 as well. RelyX is about $6.25. RelyX Unicem, the resin-based one, isn’t on this sheet, but it comes out to about $8.57, I’ve calculated, so it would be up here. There’s a very expensive cost of cement per unit to run a crown on, versus Ketac Cem, which is $2.38 based on the amount you’re using per crown. When you’re doing a lot of these, you’re doing that cost-benefit analysis of what’s going to retain your crown the most and what’s going to be most cost-effective. Ketac Cem is definitely top of the board there.
[00:39:56] Loading, seating and cleanup
Some other techniques: when you’re doing any type of pulp treatment, you want to place SmartMTA over the pulp horns or the chamber. You want to fill the crown with cement, and then fill the chamber with cement. You get that sandwich technique, as much cement in there as you possibly can, and you place the crown. You’re going to find a technique that works.
This is Dr. Andi’s case, and I can’t get the cement as thick as this. She always jokes around that it’s like a surfboard, or like toothpaste, how thick it is. And the room that we practice in — my mom was talking this morning about how hot it was — is so humid we could grow tomatoes in that room. It’s so hot and humid that I just can’t get the cement as thick as that. The thicker the better, typically. Obviously the setting time is a little quicker when it’s thicker. But being able to displace — you can see all this fluid being displaced out of these crowns — is important.
So always load the crown full of cement, and begin cleanup during that gel stage. Don’t wait for the final cure to move on. Once these are seated, they are not coming off. We do not mess around with these. You can move them side to side a little, rotating them, but never lift up and put back. Once you pull up these crowns, you get a rush of saliva and fluid into the interface between the cement and the tooth structure, and that’s where you get problems and where these teeth fail.
Cement cleanup can be a big pain, and there are many effective techniques. Obviously, wet first, then the gel stage. I always try to do it more toward the gel stage. I’m holding these crowns in there for at least a minute to allow them to adhere. Cement below the contact is always a challenge. You can see in this case these are always left subgingival, but the gingival tissue in children is so resilient that you’re not going to get bone loss around here, especially with glass ionomer. You can leave chunks of this in here and not see any issues. But you can explore and floss to get it out.
And the biggest take-home — I still remember Dr. Hanson giving a lecture back in 2015 — was: do not turbo-wash these. It’s so fun to go in there and blast air and water everywhere, but you’re going to disturb the cement setting. You can blow a little air if you need to see where there’s excess cement, but don’t go in and blast air and water together. You’ll blow out a lot of cement and end up with issues.
When you’re placing these, you can push apically, but don’t pull incisally, because the second you pull on these, if you’re not sure it’s set, that’s where all that fluid will seep into the crown. I’m holding these down with my thumb for at least a minute. The slide says 45 seconds; I’ll go 60 to 90 seconds total, to make sure these things are set. Here’s a one-year follow-up: you can see a little cement left behind on these back-to-back crowns I did. You can floss it out at this point, blow some air, or have my hygienist scrape it out with a scaler if I needed to.
It doesn’t happen in the primary dentition, but my father made it one of the banes of his existence: resin cements around implants. It led to peri-implantitis for thousands of patients who had these resin cements, which would lead to bone loss. The best part about primary teeth is you don’t have that; it doesn’t exist in primary teeth. As I showed earlier, resin cement can lead to a little more gingival inflammation. You’re not going to see this in primary cases, but keep it in the back of your mind that the resins do lead to more plaque accumulation. So that’s the heads-up. I always throw this in; these studies do exist.
On cementation technique: stainless steel crowns have that snap fit. That’s what we’re looking for when we place a stainless steel crown: that snap, it’s on there, we’re good to go. That’s not the case with zirconia crowns. They have to be passive, and you must create an undisturbed environment for at least 60 seconds when placing those crowns.
[00:43:58] Clinical pearls: overfill, hide the margin, clean the crown
My clinical pearls: always overfill. You can see how much excess cement I have here, flowing down the buccal, to get all the heme and saliva flowing away from the margin of that crown, so it’s not seeping right back up and decreasing that bond. So always overfill your crowns. If you’re doing pulp therapy, the more the better: smush some into the prep itself, into that open chamber, and add some into the crown. Make sure the crowns are overfilled. I’d much rather you have it overfilled than underfilled.
The biggest issue I see, on some of the message boards too, is seeing the margins of these crowns. When you’re placing these crowns, especially in the anterior, always slide the facial into the sulcus. Make sure these are seated subgingivally by sliding right into that sulcus, and you’ll hide that margin really well. I find it so funny: parents come in with kids that need anterior crowns, these teeth are blown out, and then they’re concerned about the little margin they can see at the gingival tissue, where it’s just fine. So asinine. But it’s things that come up in the patient populations we treat. So, a heads-up: make sure you slide the facial aspect of the crown into the sulcus.
Extra retention: when you’re doing pulp therapy, like anterior pulpectomies, leave some extra space. When I’m placing ZOE, I’ll scoop some out to make sure there’s extra space. Especially on posteriors, when I’m placing MTA, I make sure I have enough space for extra cement. It really acts like a post and core.
Contamination: you can rinse these crowns out with water, and my assistant uses a Q-tip to clean out the inside surface of these crowns. But I do have a MicroEtcher that sits on my table there, and I love it. It cleans up everything. There have been some studies showing it can increase bond strength and surface roughness on the inside of the crowns. I give it a couple of blasts of the MicroEtcher, then air-water, and we’re good to go. You don’t have to sterilize these crowns if you’re using them on the same patient. Once they’re cleaned out, you can cement them.
[00:46:10] Anterior and posterior tips, and when teeth fail
Other tips for the anterior, as I mentioned earlier: prep first and cement last. When you’re cementing the anteriors, stand over the patient. As I just showed, make sure the margins are subgingival. I’ve seen it on multiple Sprig boards and pedo boards: the parents are upset, what do we do? Unfortunately, the only thing you can do if you see that margin and the parents are really upset is take the crown off. The way to prevent that is making sure those are seated subgingivally. And if you’re doing cases where some teeth are shorter than others, especially E and F shorter than D and G, you can shorten the adjacent teeth to make the edges completely smooth across, rather than a child with teeth completely flared up or down.
The order when I’m cementing anteriors: I’m right-handed, so I cement E first, then F, together, then D, then G. That way I work right to left rather than left to right, so I’m not going across the teeth and bumping into them. Always cement E and F together, because those are the most important. If they’re off, everything else is going to look a little funny. When I cement these, I’m standing up, over top of the patient, rather than in the operator position, because your whole view and perspective is different. When you look at these kids, you’re looking at them face-on rather than from behind. So stand over them and cement E and F together.
Tips for posteriors: if you’re placing a Sprig crown next to a stainless steel crown, seat the zirconia crown first, then the SSC. You get a lot more leeway with stainless steel crowns; you can crimp them a little. Once the stainless steel crown is on and the cement is all over the place, you can push the zirconia crown a little, and if it’s not exactly where it was, the cement can be an issue. So if you’re placing a zirconia crown next to a stainless steel crown, always cement the zirconia crown first. In tight spaces when placing a first primary molar, you can disc the distal of the canine if you need to, to get more space for a path of draw.
And failures happen. We’re doing dentistry on teeth that are meant to exfoliate. It’s very easy to get down on yourself if you see some failures, but these teeth are meant to fail. First primary molars are the worst teeth in the universe; they have a mind of their own. But I’m always confident in the MTA we’re placing, and you can always go back and extract. I don’t like extracting too many, but we’re in the business of saving teeth. That’s what I’m here to do, and that’s what I try to do with these families. I’ve never had a family upset that we had to go back and extract the tooth later; you just give them a heads-up that some of these teeth are very guarded. I try to save teeth. That’s what we do. I know some places are a little more proactive about extracting, but especially in a child under six, with a D, and E’s especially, I’m always trying to save them.
[00:48:48] More than a thousand crowns in ten years: what made the difference
For the lecture I’m giving, I looked up how many crowns I’ve placed, using the zirconia crown code, D2929, if anyone’s interested. I’ve done over a thousand in 10 years. Then I looked up the recement code, D2920. So out of over a thousand crowns, I’ve only had to recement about 16. That’s about 1.47%, a very small percentage of the crowns. I’ve had to recement 1 in 24 or 25.
It really comes down to — I remember when I took that lecture, and when I started lecturing for Sprig — getting that hemostatic agent to work, and taking that extra second to get pressure on these crowns, to get the bleeding to stop and all that fluid out of there, and making sure the prep is clean. That’s what’s going to lead to success, not so much the cement itself. I do think glass ionomer and resin-modified glass ionomer are the way to go. There’s still definitely room for improvement with the resins. With glass ionomer you don’t have to worry about primer, or as many issues in non-ideal situations as with the resins. These glass ionomers work great, they’re more cost-effective, and that’s what we’ve been using for 10 years. So that’s it.
[00:50:08] Q&A
Host: Dr. Ross, we do have a few questions I wanted to put out there for you. The first one is from Laura Rosetto. She’s asking: do the HemeRX pellets have epi in them that we have to be mindful of with young patients?
I forget the actual amount of epi that’s in there. It’s a trace amount. It is a good question. One per tooth is really the standard we use. It’s such a trace amount that I’ve never had an issue with it, as long as it’s one per tooth. I’d have to look up the actual amount, but it’s a very, very small trace amount.
Host: Perfect, thank you for answering that. The second question is from Pamela Butler. She’d like to know what guide you use when prepping subgingival to prevent the collar from showing.
It’s got to be at least two millimeters subgingival. When you’re placing the shoulder, you’re right to the margin when you’re doing these crown preps. Then when you’re taking the flame, it has to be at least two millimeters subgingival.
I looked it up: it’s 0.5 milligrams of epi in those pellets. So it’s a very small amount.
Host: Great. If anybody else has some questions, we can spare a few minutes with Dr. Ross and get those answered. Otherwise we’ll finish up and allow people to have the rest of their evening to themselves and their families. I have a question from Robert Matthews. He’s asking: are you using the triple cocktail for your two-year-olds?
Yes. In the residency program it’s weight-dependent; it went up to 25 pounds, but there’s no literature to back that. As long as you’re over 20 to 25 pounds. It doesn’t matter the age; it’s really just weight. But yes, two-year-olds, two-, three-year-olds. Yes.
Host: Okay, I think that is it for our questions for the evening. Oh, we have one more just coming in, I’m so sorry. We’ll give everyone another minute if you want to type any questions into the question area. The next question is from Gregory Allen: have you tried the 3M astringent paste for gingival bleeding? Do you notice staining?
I haven’t used that one personally yet. I actually just ordered it after taking a Bioclear lecture. According to him — it was Dr. Solomon — he hasn’t really seen any staining issues with it. I just don’t know exactly what’s in that one. There’s a clear one, and then there’s one that’s got ferric sulfate in it. With the ferric sulfate one, I think you will see some staining, but as long as it’s the clear one, I don’t think you really should. But those HemeRX pellets are great. They’re very cost-effective. You wet it, pull it out a little bit and stuff it in the sulcus. Those things work wonderfully.
Host: We’ve got one more question here from Patrick Macaroni: when you’re cementing, are you filling the crown three-quarters full or more to achieve retention?
No, the whole crown’s got to be filled. When your assistant is filling it, make sure it’s filled to the very top of that crown. If you have extra space, if you’re doing any type of pulp therapy, you can fill the actual chamber with cement as well, and then fill on top of that. But the whole crown has to be filled. If you leave any space in there, you potentially won’t displace all that fluid, which can eventually seep right back up into that crown and cause a disturbance. So really overfill these crowns.
Host: All right, we’ve got another one coming in from Laura Rosetto: with zirconia crowns where you don’t have to complete a pulpotomy, do you see a higher failure rate due to the more aggressive preparation, compared to SSCs?
No. As I said, if you have a good passive fit when you’re prepping these teeth, and you get all of that heme out of the way and the bleeding stopped, there are no issues with these, really. I still do a fair amount, mostly still with pulp therapy, so I do get a little extra space in there. But even so, it’s been over two years since I’ve had a crown come off. It really comes down to getting the bleeding around these crowns to stop, and making sure you have a nice passive fit with the smallest crown possible. It’s a good question, but no, not really a difference.
Host: We’ve got a follow-up there, a clarification: failure from abscess, for example, not fracture.
Failure from that. You’re going to get failures. I don’t see any difference between stainless steel crown failures and zirconia crown failures. I think it’s all prep technique, honestly, and the vitality of the tooth. It’s case-dependent. But no, I don’t really see much of a difference in failures between the two of them. And that pretty much goes across the board for anyone who’s been placing a lot of these crowns.
Host: Perfect. We’ve got just a couple more here, Dr. Ross. What is your order of cementation for anterior C through H?
C through H. I would do E and F first. Centrals are always the most important, so I always do E and F first. Then I’d think of the laterals, so it’s E and F, then D and G, then C and H. That’s how I would do it. It depends if you’re right-handed too. I know my mom — if you’re left-handed — goes left to right, but I go right to left. So it would be E, F, then D and G, then C and H. That’s how I’d do it.
Host: Okay, we’ve got two more here. Daniel Charlin would like to know: any tips to avoid voids or air bubbles in the cement while loading the crown?
Make it a little thicker. It’s really making sure you have a good assistant mixing these for you, to a nice, almost toothpaste consistency. You really shouldn’t have many issues with air bubbles. It’s more with the injectable stuff that you can get air bubbles, but with Ketac Cem I’ve never seen an air bubble.
Host: And then Gabrielle Dawson would like to know: do you use the hand-mix Ketac Cem or the auto-mix?
The hand-mix. We’ve always used that one. I think it’s a little more cost-effective too. I know a couple of colleagues that use the auto-mix, but I like the hand-mix because you can dictate how thick you make the mix. Ideally, the thicker the better. I have two assistants, and one makes it a little thicker than the other, and I always prefer the one that’s thicker, to allow more displacement of that fluid around these crowns.
Host: All right, I think that concludes the questions in our chat. I did want to remind everybody again: thank you so much for joining us, and thank you, Dr. Ross Levine. Great information tonight; you did an excellent job. We’ll be sending out a survey along with your CE certificate tomorrow, so please look out for an email from education@sprigusa.com coming out tomorrow. Dr. Levine has also provided his contact info there on the screen. If you have any questions, you’re more than welcome to reach out to him. All right, thanks everybody. Any last message, Dr. Ross?
No. Good luck, everybody. If you have any questions, please feel free to reach out. That’s my personal email. I’m around, so happy to help. Have a good night, everybody.
Host: Thank you very much. Have a lovely evening, everybody.
