Which Generation Bonding Agent is the Best? 2024 Adhesive Systems – PDP192

Protrusive Dental Podcast

What is the best bonding agent to use?

Does it actually matter? Spoiler: it does!

How do you get the best bond to dentine and enamel with the adhesive system you are using?

Dr Sam Sherif joins us in this episode, where he discusses bond strength in detail as well as sharing his top tips in achieving long lasting adhesion for our daily adhesive Dentistry. There’s a lot to learn in this one so get ready those onions ready!

https://youtu.be/FICDBVljsGw

Watch PDP192 on Youtube

​Protrusive Dental Pearl: Always read the directions for use – ESPECIALLY for your adhesive systems!

Need to Read it? Check out the Full Episode Transcript below!

Did you know? Paid members on Protrusive Guidance can access the PDF summary notes as part of the Protrusive Vault. Oh and be sure to answer the quiz for 1 CE credit!

If you liked this episode, you will also like Immediate Dentine Sealing Part 2

Click below for full episode transcript:

Jaz's Introduction: Did you know that the strength in which enamel binds to dentine at the DEJ is approximately 50 megapascals? So when we're looking at the literature for which adhesive system or which bonding agent we should be using. Do we actually need more than 50 megapascals?

Jaz’s Introduction:
A lot of adhesive systems will easily give you 20 megapascals. Is that good enough? It probably is. We know that adhesive density in the right environment, done skillfully, can work, and sometimes all you’re achieving is 10 to 20 megapascals. However, if there are a few things that you could do in your practice, in your protocols, to reach the higher ends, 50 and even beyond, then perhaps we should consider and learn these techniques.

For me, it depends on how complicated it makes your procedure. Like if it becomes really technique sensitive, so that only 10 percent of the time you’re getting 70 megapascals and then 80 percent of the time you’re getting like 10 megapascals, that’s not predictable. That’s not a predictable way of doing it. So how can we make our bonding protocols more predictable so we get a higher bond strengths more consistently.

That’s what today’s episode is about because I asked Dr. Sam Sharif, which is the best adhesive system, which is the best bonding agent, and to tell us which generation or generations on bonding agents should we be buying.

Hello Protruserati, I’m Jaz Gulati and welcome back to your favorite dental podcast. Today’s a very geeky one we go into science behind the bonding and I love how Sam will break down the different generations which we’ve all come across a different generations of bonding systems and we fell asleep in that lecture and there’s just far too many generations. But actually we make it clinically relevant and I love that he actually gives you sound advice on which generations to avoid and which generations to go for, and which bonding agents he believes in and what the literature is saying.

If you’re a new listener, welcome to Protrusive. It’s great to have you here. If you’re a returning listener or watcher on YouTube or on the Protrusive Guidance app, it is so great to have you back. You’ve picked a good one to re engage back into. Very clinical relevant in our daily dentistry. And towards the end of the episode, we’ll actually cover little nuances and how we can actually get the higher bond strength. This episode is eligible for CPD. There will also be premium notes which get released in the Protrusive Vault of Protrusive Guidance app. We should totally download an iOS or Android.

Dental Pearl
The Protrusive Dental Pearl I have for you is to read the instructions for whichever adhesive system you’re using. Now, I’ve said this before, but some cool things that I learned here is that in some adhesive systems and some bonding agents, if you air abrade the dentine in something I do routinely, you are actually hindering your bond strength.

Whereas with other systems, you really enhance the bond strength by using air particle abrasion. So if, like me, you’re just blanketly air abrading everything, then we need to reconsider. It kind of depends. Is that compatible with your adhesive system? So I would just pause, even if you’ve done this before, but it’s been a few years.

I would just pick up the literature again, find the literature, ideally independent if you can. And Sam does reference a really cool paper, this group that releases a paper every 10 years looking at how to optimize bond strength, so I will add that paper to the protrusive vault. But the main lesson is to really use whichever adhesive system you’re using in the way that the manufacturer intended.

And only really deviating from that or enhancing that if some evidence base suggests that actually by tweaking this protocol you could get a better result. But essentially, don’t make it up as you go along. Please don’t just etch for a random number of time, and just using it in a way that the material was not designed to. Hope you enjoy this very geeky episode, and I’ll catch you in the outro.

Main Episode:
Dr. Sam Sherif, someone who every time I see the word adhesive dentistry, biomimetic dentistry, you come to mind. My friend Niall always raves on about you and your knowledge and wisdom, and I’ve been following your stuff online for a while now. Welcome to the show. How are you?

[Sam]
Thank you very much, Jaz. I’m glad to be here. I’ve been excited to get on your show. Something I listen to going to work each week. So, so thank you for having me on.

[Jaz]
Amazing. Well, I think the kind of stuff we’re covering tonight is absolutely, I think, fundamental because we’re there at dental school learning about these adhesive systems, bonding agents, and the generation and stuff for an exam.

But I think what I’m really excited to pick from you is actually the real world application of it, as well as actually answering these niggling questions that which generation actually is the best and how long will this continue for? Will it go into like generation 50 and 60 and that kind of stuff.

And it’d be interesting to see how close you think we are to the pinnacle of bonding and the little nuances. So it’s gonna be a very geeky episode, I feel. And I think that’s going to be a fun one for all the Protruserati to listen to. For those people who haven’t heard of you, haven’t seen your stuff, please tell us about yourself, where you work, what kind of stuff you’re into.

[Sam]
Yeah, I’m a prosthodontist and I work in Harley Street. I came back from America about 12 years ago after I finished up with Guys. I went over there, I did pros and I did a PhD at Harvard med school. And then it was choice of either staying in Boston as faculty or going to LA. And I got a very nice offer in Beverly Hills.

So I went over there. And stayed out there for a few years. I ended up buying that chap’s practice. But I think in the end, the lure of Europe for Europeans is too much with the easy travel. So came back.

[Jaz]
I mean, what a location history, right? That’s very impressive. In Beverly Hills, did you ever come across Lane Ochi?

[Sam]
Yeah, another great prosthodontist. Yeah, came across Lane.

[Jaz]
He’s such a great guy. I’m a huge, huge, huge fan of Lane. So great. I didn’t know you practiced in Beverly Hills. Amazing. And then now you’re in the heart of London. Man, that is quite a career trajectory. How much do you think, this is completely like random, not like in my list of questions, but your PhD, I didn’t know you did a PhD, so you’re a proper doctor. When you were doing your PhD, how, was it like super academic or was it clinical?

[Sam]
My PhD was on the academic side. So to graduate, you have to do your residency. So you choose your specialty and you have to pick a three year master’s or a five year doctorate. The doctorate I did it in was a lot to do with implants and the bacteria around implants. You’d order the bacteria, you’d grow the bacteria, you’d run the DNA, DNA hybridizations. So that was fun. But overall, the program, you know, would be very clinical, but also very research because we do eight till six in the clinic, and then you’d have research time or classes at night. And then you do your lab work, like all good pros residents.

[Jaz]
Do you have a life? Like when you’re doing, when you’re like, that sounds so intense. Do you have a life? I mean, people who do masters and MClinDent and that kind of stuff. They always tell me that you literally have no life, but did you experience that as well?

[Sam]
So we were all jealous of the endo residents, because the endo residents would Wednesday afternoon, go off, moonlight, do some work. Some of the days they would do that. The pros residents would be doing their lab work, casting, designing. And then we’d have classes, and I think you take it for granted, but I spoke to a lot of people here, perio residents, and we’d have famous perio residents, Monday, Tuesday, night, from Ferrier faculty just come and give us tutorials to three pros residents, three perio residents in the first year.

So, I would say those were the best years in my life, even though there weren’t much of a life that you were locked in there and you tend to get about a two minute walk from the dental school because that is going to be your life for five years.

[Jaz]
Amazing. How did you get into, in terms of you could go but you do everything. You’re a prosthodontist, your research and PhD and implant focus and the bacteria around that, but your true, I mean, what you teach on and what you put out there is a lot of the biomimetic adhesive dentistry. And they make sense now why I know some of the courses run and go very deep into literature as well. So it’s starting to all make sense to me now. How did you get attracted to that particular part of dentistry?

[Sam]
It was 2005 and Harvard had an exchange with Switzerland and Urs Belser, who was Magne’s mentor, came over for a sabbatical for six months. And the book had just come out two years before, so he signed it for all of us.

And it was kind of a mind switch that we started preparing onlays under rubber dams. And you can imagine in pros, when you’re doing 26 teeth, 28 teeth, There aren’t usually a lot of rubber dams. We’d be bonding everything under rubber dams. And it was from Belser that it started, that we had Belser in the clinic.

And Belser is a tutorial for six months. And then, they sent some of their people, I guess, to Minnesota, which was Magne. They sent some of their people to Harvard. And so we got faculty from them and it just developed and I like the accuracy and the intricacy and it’s a cookbook approach. You have to follow 1, 2, 3 and do it accurately. I think all of us in dentistry, maybe you’re nerds with a little more personality or engineers with a tiny bit more to us, but we like that geekiness of knowing what we’re doing is the right thing for patients.

[Jaz]
Okay. I didn’t know that. I see all these things I’m learning about you as well. So, yeah. What an influence from Urs Belser that kind of, again, you can’t connect the dots looking forward. You can connect them looking back. And I always like to inquire about my guests, how did they, why did they go into that particular niche and stuff? So that’s great. So you’re in a great position then to answer about the different bonding agents that sort of adhesive system.

So they go from the first generation, second generation, how do you feel about for the students who are listening and maybe revising for exams and actually the real world wet fingered dentists out there on their commutes thinking, do I really need to know about the different generations?

Well, whether you do or don’t, it’d be nice to have a little overview. So Sam, could you just enlighten us about the different generations? What are the different nuances between them?

[Sam]
Sure. If we go over the first three very quickly, because no one really uses them, but first generations came around in the early fifties. These had a problem of high shrinkage and very low bond strengths, 2 to 3 megapascals. Now, for reference for everyone, enamel bonds to dentine are just over 50 megapascals, so 2 to 3 is nothing, okay? The second gen came around in the late 60s. They couldn’t get a strong bond to the calcium that was in the smear layer, and these had about 5 to 6 megapascals.

Again, not great, similar to glass ionomer to dentine, okay? Third generation, took another 15, 20 years, came around in the mid 80s. This was the first time they tried to deal with the smear layer with very weak acids, and they were worried about pulpal inflammation. So what happened was that the bonding to dentine was very weak.

So we really start to get into the game with the fourth generations. These came around in the mid 1990s, and this is the three step total etch technique. So if we divide it for the listeners, you’re either etching to condition the surface, or you’re air abrading. Or you’re doing nothing. So for fourth and fifth generation, you’re acid etching.

For the sixth generation onwards, there’s no acid. So there’s no rinsing. It’s just going with a primer, and there was a different primer. So, fourth generation, it would really be a three step. So, we’d have an acid etch, okay? And by this time, became phosphoric acid. And the founder of this was Professor Fusayama.

He’s a famous guy, he found caries detecting dye as well. So, a lot of things happened over at Tokyo Medical and Dental University. This was in ’79, around the same time he found caries detector. And what he found was that if he uses phosphoric acid, and the percentage now is agreed upon as 37. 5%, but it was going between 30 and 50.

And if you go up to 50, you get too many of the salts coming out of the tooth. You’ll see it comes very chalky. So we’ve got the 37. 5. And then he had a two bottle system. And in the two bottle system, he had hydrophilic monomers, which are dissolved in organic solvents. Now, these solvents, they are super volatile and because they’re volatile they displace the water from the tubules and that’s what we want to do, we want to push it out.

So the acid etch in step one exposes the collagen network, exposes the intertubular dentine and then we get resin tags formed. And then another chap from over there Nakabayashi in H4 termed this the hybrid layer which we all know about. So you can see how it starts to fit together. Now, if we talk about nuances, we said we want to have wet bonding, okay? We don’t want to over dry the tooth.

[Jaz]
This was for fourth generation that they were advocating wet bonding, right?

[Sam]
Exactly. So if we over dry it, the water is removed, okay? And the collagen fibrils collapse. I want people to think about it in their mind like the carpet or a rug at home when you hoover it. And then when you walk on it, you can see the footprints. If you imagine, if you over dry the collagen fibres now that they’re etched, they just collapse, like a rug or a carpet when it’s warped upon. Now, the water formed the function of a plasticizer. Plasticizer means it just holds something up.

Obviously not a direct analogy, but when water plumps up chickens, things like that. So it plumps up the collagen. When it plumps it up, it’s more available for the primer and then the bond to infiltrate. Okay. We don’t want it too wet because our bond is hydrophobic. So what we need is some hydrophilic monomers.

To go in there, to chase out the water, but still plasticize or leave these collagen fibrils upstanding, okay? And what they found is that a great one to do that would be alcohol. And that is the agent that’s in OptiBond FL, which is the main fourth generation that everybody knows about. So then what happens is that these plasticizers allow deeper penetration.

Kanca in ’92 was the one who coined the term wet bonding. So if you over dry, I want them to think of it as Swiss cheese, what the collagen looks like. You really shrink everything, all the dentine. It shrinks the volume available for penetration by about 65%. So if you re wet it, the area that the primer can get into becomes a lot more available.

So it’s not a carpet that’s criss crossed anymore. It’s not Swiss cheese where the holes are very small. Everything’s a lot bigger. We can get a lot more penetration. The other thing that we have to be careful of, though, in fourth generation is, because we’re etching, we’re actually removing what’s called the whitlockite crystals that are in the tubules.

Whitlockite is calcium and phosphate. If you imagine when tooth gets decay, MMPs jump into action and they act to try and defend the pulp. So what they do is they cause the dissolution of the hydroxyapatite around the tubule. And they form a little plug in the tubule. So now no more bacteria or caries front can move towards the pulp.

Now this is calcium rich, so it’s great to bond to. It also has another option. It doesn’t allow fluid to the pulp, or bacteria to the pulp. It doesn’t allow fluid to come up to the developing hybrid layer from the pulp. So in teeth that are vital, that have a pulp, we have to be careful because if we’re going to remove this plug, we’re going to risk getting water underneath the hybrid layer, which isn’t a good thing. Okay, so that’s fourth generation. We’ll run over the others quickly. Fifth generation was late 90s.

[Jaz]
I just want to ask you about that. So you’re teaching about the deep details, which is great. And maybe that’s starting to make sense to me now where I heard, probably from someone who’s gone to your course, I think Sheideh went to your course once and we were talking and she was teaching me some stuff and she said that whilst dentine bonding is, well, in certain schools of thought, it may not be as predictable as enamel bonding. Actually, you can achieve a higher bond strength to dentine than you can to enamel. Is that correct?

[Sam]
That is spot on correct. Because you’ve got to think of dentine as like rope. It’s very tensile, means you can pull on it. If you think of enamel, when we do a class one, and we over etch the enamel, and we’ve got a really good bond on there, and then what do we go and do?

We go and cure everything. We see these little white cracks in the edge of the enamel, because enamel is brittle. And so enamel, you’re going to top out in the low 30 megapascals. Remember we said enamel joins to dentine at about 50. With dentine, depending on what you do, and we’ll talk on the nuances of treatment with Optibondophil, etc.

You can get between 59 and 74 megapascals with however you treatment plan. So dentine is a lot stronger, so, we all got asked in school what’s stronger, everyone thought enamel, but it’s really dentine.

[Jaz]
And is it because, is it something to do with this calcium rich plug that’s formed in the tubules? Is that partly responsible, we think, or not really?

[Sam]
That’s one of the things, if you’re using a sixth generation, or a self etch, maintains the calcium. But even with OptiBond FL, what’s happening is, a dentine bond develops a lot slower than an enamel bond. An enamel bond, within a minute, is mostly developed, so by the time you’ve cured it, and that’s when the clock starts ticking, and start packing your composite in, the enamel bond is almost there.

The dentine bond takes time, okay? So we know that at about half an hour, it’s 95 percent formed. But it will take five days to be 100 percent formed. Obviously, we’re not going to wait half an hour, we’re not going to wait five days. But it’s a case of doing small layers, letting it develop. The analogy I’d give you is, at home or in your office, when you want to hang a clothes hookup, you clean the wall, you put it on the wall, and then you don’t go and hang your coat straight away. It says leave it for half an hour, etc. That bond is developing in the adhesive against your wall, the same way the bond is developing at the hybrid layer.

[Jaz]
Okay. Brilliant. Well, I think, is that same thing as decoupling with time? Right?

[Sam]
That is decoupling with time. Yep.

[Jaz]
Okay. Perfect. It’s all coming back to me now. So a hat tip to Sheideh, our mutual friend for teaching me some things from osmosis. So please tell me you’re on a fifth generation.

[Sam]
Generations. These came around in the late nineties and this was a simplified approach to the fourth generation. This fourth generation suffered some issues that was very technique sensitive. So what they said is, we’re going to have acid etch still, because acid etch gets rid of all the smear layer, gets rid of all the contaminants, gives us a surface to have micro mechanical bonding. But let’s make it easy, let’s put everything in one bottle. Now, you can imagine when you put chemistry that’s hydrophilic primer and a hydrophobic bond in one bottle, they don’t like each other.

They want to fight. So, what happens is you don’t get as much penetration with the primer and then you have to air thin it, and whenever you air thin, you introduce oxygen, so you get an oxygen inhibited layer. So you may, not blowing it with the three in one, you may introduce oxygen at the dentine adhesive interface. So then you’ve got no bond there, and you’ll get an adhesive failure. You may introduce oxygen between the layers of the adhesive, so you’ll have a cohesive failure in the bond. So we don’t want oxygen. We don’t want this oxygen inhibited layer there.

[Jaz]
I never even considered that as a molecular possibility, but obviously it makes sense. But I never even considered the air thinning would introduce oxygen. It makes sense now, but yeah, I definitely hadn’t considered that.

[Sam]
And then when you look at the instructions, some of the instructions will tell you to do that. But when you think it out, and you read papers, you don’t want to oxygen. You don’t want to air thin this. What you want to do-

[Jaz]
So is it better to use a high volume suction?

[Sam]
Use the high volume suction. And if you’ve got excess, you can wick it away with a clean micro brush. So these have lower bond strengths and they suffered similar problems because they weren’t correctly use of sensitivity. And you can tell this as well because whether the nurse puts it in the dapkins dish or she puts it on the back of your glove, fifth generation, the seventh generation, the ones that are going to run down to your watch because they’re not filled.

They’re a lot thinner, and this has other problems that we can chat about when it comes to the nuances of the gold standard bonding agents. So then if we move to the sixth generation, so fourth and sixth are where you want to be restructured in your bonding agent. Sixth generation example would be SE bond two.

These are self etching, by their name, primers, and it’s a two bottle system again. So we have the hydrophilic chemistry in the primer, we’ve got weak acids, hydrogen ions, in the primer, and we’ve got a hydrophobic bond. And the idea here is we’re going to attach those calcium ions. So we don’t have micromechanical bonding.

What we have here is ionic bonding, which is very strong, okay? There’s not a lot of difference between this and OptiBond FL. Now, the big plus is that it’s not as technique sensitive as fourth generation. Because we don’t have the drying issue. The other advantage of it, perhaps, is that we treat the surface with air abrasion.

So if you treat the surface of dentine with air abrasion, and this is a paper by Van Meerbeek, his group in Belgium put a paper out every 10 years on all the bonding systems. Your bond on dentine will go from 37 megapascals with SE BOND 2 to 54 megapascals by air abrading. Because when you’re air abrading, what you’re doing is compacting the smear layer.

If we think about what acid etch does, acid etch gets rid of the smear layer problem because it just dissolves it strong enough. Okay? The weak acids, which are hydrogen ions in the self etching systems, are not strong enough. So, if we don’t compact that smear layer with a form of treatment and the best way of doing it is with air abrasion, we’re going to get a much weaker bond. Okay. So really-

[Jaz]
And with the air abrasion, I mean, are there some adhesive systems that perhaps you’d hinder their bond strengths by air abrading?

[Sam]
Indeed. This is a very good point. If you go back to OptiBond FL and Van Meerbeek’s shown this, if you air abrade with OptiBond FL, you’re going to drop your bond strength 10%. So he drops the bond strength to 54 from 59, just by air abrading. Because that’s relying on having no smear layer there. So, it’s system specific. Now, let’s say somebody in their practice doesn’t have an air abrasion system, whether it’s a fancy AquaCare or a 200 pound Danville machine. What they can do with the surface treatment of six generations is use a very fine diamond and use it like it’s in a slow speed.

It’s going to be obviously in the high speed, but you’re just polishing. You’re not trying to cut. And what this will do is compact that layer as much as possible. You won’t get up to the 54 megapascals, but you’re still going to be better than any other system other than 4th generation.

[Jaz]
Okay. That’s a top tip right there for those. Cause it’s a common question I get from Protruserati. I don’t have an air abrasion unit. What can I do? Well, there’s your answer guys. Use a fine bur for a six gen and run over it. So that that’s going to help us to get better bond strengths.

[Sam]
And so then if, if we start to finish up the generation, so six generation also was something important when SE bond came out, which was MDP. So MDP is great because it helps us bond more reliably to dentine and MDP is used to bond to zirconias. If we follow the Markus Blatz articles from 2013 onwards. So, what you see when that patent ran out in 2012, 2013 was a slew of other companies that were now able to incorporate MDP. If we go to the seventh generation, these came out between 2002 and early 2005.

These were a single step self etch. So they had the weak hydrogen ions. They had the hydrophilic primer and the hydrophobic bond all in one bottle. So, we can imagine the bond strength was going to be very low in these adhesives. 8th generation came out in 2010 and this was Voco Futurabond. Okay.

This was better than the 7th generation because it had nanofiller in it. These nanofillers are about 12 microns in size, and what they could do is they could penetrate into the tubules better, okay? When they penetrate better, we get stronger bonds, and they also had a longer shelf life than the seventh generations, okay?

So when we’re looking at what to use, gold standard would be fourth and six, okay? Because these ones have got the research on them, they’re a lot thicker, we can go through that. I wouldn’t recommend a single bottle system, but if someone said I really need it in my clinic, What can I use? You have to play around with it and there’s nuances of making two layers to the IDS, but I’d probably go with an 8th generation. Over a seventh generation or fifth generation, if I was limited to one bottle. But I think, we’re not in that much of a rush that we need to skip out, maybe 20 seconds of priming and 20 seconds drying.

[Jaz]
Can you give us some examples of which other brands of eighth generations are there?

[Sam]
Eighth generations, what you’ll have is you’ll have the 3M Scotch bond. Okay. If that’s a good one to talk about. If we look at the chemistry that’s in that one bottle, we’ve got weak hydrogen ions, which approximately around pH 2. 8. So they’re not strong enough to etch enamel, okay? So whenever you don’t etch enamel, what’s going to happen is that you’re going to get staining down the line.

So that may not be an issue for you, on an occlusal on an upper 7, but probably if you’re doing a lower 4 on a shorter patient, and they’re gonna see that staining, it’s gonna be a problem. You’ve got the hydrophilic primer, the hydrophobic bond, but this is where the big problem comes in, because they started putting silanes in there, and an MDP.

Now silane needs to exist at pH 5. 5. So we’ve just said that the hydrogen ions are at 2. 8. So what’s happening, we have an ineffective hydrogen ion that’s not etching the way it should, and we’ve got a denatured silane component, which is also a problem. Whenever you have silane that’s on its own and it’s not a two bottle system, silane’s going to have a much shorter shelf life as well. So you’ve really got to be on top of what’s in your bottle. For you, use it for different applications.

[Jaz]
So checking the expiry date, basically to make sure, so the shorter expiry dates.

[Sam]
Exactly.

[Jaz]
And a G premium bond?

[Sam]
This one’s promising. It’s got some good research out there with the G premium bond. So this is one I’m actually excited to look at what, what comes out of it. They say you never want to be the first by which something’s tried, but the last by which it’s set aside. So, I’ll give it a little time, but that’s one.

[Jaz]
Being honest, the reason we’re using is cause that’s what my principles and we all decided that, okay, this is a good system for us. And so I’ve been using it for a few years, but it’s difficult to say. And my data and my colleague’s data work in a practice. What we need is to look at the actual data from clinical trials. But having said that, how many of these adhesive systems actually have clinical trials, because there are these benchtop studies, which we get some information from is better than just producing a bond without any data, obviously, about how they’re bonding to extractive teeth and stuff.

But in research, it’s very difficult to actually apply that because there’s so many other different factors. Their occlusion could be different, their muscles could be different, their quality of enamel and dentine, the caries removal could be different. And that’s why it’s difficult to get that kind of data. Is there anything you can add to this sort of conversation about getting data for what’s actually clinically going to be good rather than what’s going to be good in the labs?

[Sam]
What I would say is you’ve hit the nail on the head that it’s very hard to get it. An example would be the depth of dentine that you’re in. If there was sclerotic dentine, which is more mineralized, that will give a higher bond strength, so it would be an unfair test. What they’ve done in some of these tests is they’ve done the restoration, and then they’ve extracted them from Vivo, and then done the bench tests. I would go with the concept of the more bond strength you’ve got on a bench top, the more it’s going to be better for life.

Because when you chew on it, you lose 10 percent of bond strength immediately. Okay, so if you have a non gold standard adhesive, so a non gold standard would be one that’s not Opti bond FL, not SE bond 2, you’re already probably in the 20 megapascals. And that’s if you’re in the superficial dentine.

As soon as you get down into deep dentine, depending on your protocols, if you do everything with the protocol, as it says, you probably lose 25 percent of the strength the research shows. If you don’t do it with the protocols and you start layering too quickly, you lose 50%. So we’re already at the low teens.

And then we know that you’re going to lose 10 percent of it as soon as the patient bites on it. So there’s aging of the bond. So I would prefer to go with a bond that has these bond strengths in the 40s, 50s, 60s. rather than the ones that are in the 20s on a benchtop.

[Jaz]
Brilliant. I think that’s a nice overview of the different adhesive systems. When will it stop? It will never stop, right? Innovation will always continue. I mean, we’re on generation nine now, is that right?

[Sam]
Yeah, we’re out there now. I think obviously commercial aspects come into play and it’s quite natural for someone to think, the iPhone 15 is better than the iPhone 10. Okay, and the same if you think generations that generation nine is going to be better than generation four. If we’re looking is OptiBond FL still the gold standard? Is it still predictable? I go back to the research if anyone wants to look at the Van Meerbeek papers that come out of the Catholic University of Leuven In Belgium, he puts them out every ten years.

He looks at everything. He’s independent. So it’s not paid for by a certain company, what he shows is that you’ve got two big ones, which is SE Bond 2 your sixth generation. You’ve got your OptiBond FL. A close third would be AllBond (Bisco), but the main two are those, and there’s reasons for it. If you look at OptiBond FL, it’s filled.

That’s what the F stands for. It’s light cured. Okay, so it’s 48 percent filled, it’s radiopaque, and it’s very viscous. So if you put it on your glove, it doesn’t run. And that tells us something. One we’re going to get a more uniform layer than with a very thin one that feels like water, like a fifth generation.

[Jaz]
I think G premium is like a four micron thickness, I think, something like that. It’s very, very thin.

[Sam]
They’re thin. The OptiBond FL is 80 microns, and that’s on a flat surface. So you’ve got to be careful because the OptiBond FL is really, it’s 48 percent flowable composite in there. So one of the things to do is really shake that bottle as soon as you pick it up.

Other things with it are that it mimics the modulus of elasticity of deep dentine, OptiBond FL. with this 80 micron layer, but here’s one of the reasons I like it, and I’m not stuck to one system. The oxygen inhibited layer that we spoke about is about 30 microns. Okay, so that means the top 30 microns of your composite doesn’t cure.

Not a problem with composite because you’ll put glycerin or you’ll polish it away, but imagine that you have an adhesive that’s 20 microns thick. Or four microns thick. That’s not curing. So OptiBond FL is 80 microns, okay? So we’ve got 50 microns below it, minimum, okay? The other thing to look at is when you come back two weeks later at the IDS to reactivate it, how do we reactivate it?

We use air abrasion. Air abrasion research says can remove about 15 microns of adhesive. So again, let’s say we even had a thicker one, a quality one. Let’s say we had SE Bond 2, which I like. It’s 40 microns. So if we’ve lost 30 and we haven’t taken precautions, which we can discuss, we’re down to 10. When we come to reactivate, we’re on dentine.

So when you look at some of the studies out there, they say IDS doesn’t work. People get post op sensitivity. It’s because they’ve got exposed dentine or the hybrid layer has been cured. So that’s the other advantage of having a thick iDS layer, if you’re doing it for that, or if you’re just using it for your composite, it’s the advantage of having a material that mimics that deep dentine, how it flexes, so the tooth gradually gets stiffer as it gets to the cusps.

[Jaz]
What do you use? And do you change what you use depending on if it’s an aesthetic case versus a posterior case?

[Sam]
Yeah, I’ll give a very general rule. If it’s direct dentistry by that, I mean, class ones, class twos, class fives, a deep cavity, I’ll use SE Bond 2. The reason for that is SE Bond 2 is not as technique sensitive. The chance of post op sensitivity is not there, because we’ve got these whitlockite crystals blocking the tubules. There’s no transport to and from the pulp. We also won’t get these water trees that come up underneath the hybrid layer with water moving from the pulp. And that start to disturb the hybrid layer. So that’s my direct dentistry.

Now let’s say I have a root canal treated tooth and it’s come back from the endodontist. That’s probably going to have had Miltons all over the place. And Miltons, if we think about it, is a bleach. And how do we denature dentine? We pour bleach on it. If we want to denature enamel, we put acid on it.

So we’ve already denatured the dentine. So we’re not going to bond well to denatured dentine. So I want to clear all that off. So I’ll refresh in all of the dentine with a rough diamond bur. And then what I want to do is acid etch it to get that damaged collagen away. So I’m not going to get any sensitivity by definition.

The tooth is dead. I’m not going to get any water movement from the pulp. So the pulp is left in the endodontist’s office. If I’m doing veneers, I’ll have to use OptiBond to use OptiBond FL. Because if we’re removing 0. 7 millimeters, depending what we need, we don’t have room to put a resin coating on of clear flowable.

So our protection for our hybrid layer, for our oxygen inhibited layer, not to have an effect on the bond. It’s the 80 microns of OptiBond FL. And what I’d probably do is I’d put two layers of OptiBond FL on a veneer prep. If I’m doing-

[Jaz]
This is like IDSP or veneer prep basically, right?

[Sam]
Yes, for the veneer prep. If I’m doing, I don’t do ortho, but if someone’s bonding brackets or bonding attachments, whether it be Invisalign or any of the other competitors. The bond strength that you’re going to get with SE Bond 2, it’s going to be 22 megapascal with its self etch system. If you air abrade, you’ll get 26.

And this is, again, is research from 2003, Van Meerbeek. If you use OptiBond FL and you acid etch, you’re up to to low 30s already. So that’s a sizable difference. So if you’re finding that your attachments are breaking off, maybe you can use the acid etch and the OptiBond FL and increase that bond strength substantially on enamel. But dentine, dentine that there isn’t really a statistically significant difference between the 54 micro tensile bond strength megapascals we get with SE bond 2 and the 59 we get with OptiBond FL.

[Jaz]
Well, it’s a nice guideline of direct. You’re doing SE Bond 2, Indirect, OptiBond FL, for the reasons mentioned. I was at Marco Gresnigt’s lecture, probably said his name wrong, and just fascinating data about the benefits of IDS for the veneer preps, and how stable that is, and how much better it is. better your bond strengths are. So that’s very promising and I’m glad that you’ve echoed that as well. So discuss the different bonding generations.

You’ve made a nice clear recommendation that fourth and six is kind of where you want to be, but watch out for the future. OptiBond FL is probably still up there as the gold standard along with SE Bond 2 as an alternative. And I know what your approved list is. So now I’ve got two things to explore with you.

So top tips and actually maximizing the bond strength. You’ve already mentioned a few like shaking that bottle. Right. You’ve already mentioned about air abrasion, but the interesting thing, which I didn’t appreciate is actually air abrade, according to the adhesive system that you’re using. And that was interesting to know that, okay, certain systems you may be hindering by using air abrasion.

What other tips could you share for those dentists listening out there who are driving into work that they’re going to use today to just get those a few extra megapascals and just do serve their patients better.

[Sam]
Perfect. So if, if we go from the start, let’s compare the OptiBond FL 2. So if you’ve got the OptiBond FL, what you want to do as soon as you’ve finished taking the caries, you don’t want to finish taking the caries with your steel bur or whatever, because that’s going to be more of a polished surface.

You want to roughen that surface so it’s very wavy and it’s replicating almost a DEJ. So I’ll get a coarse bur out. The bur I like to use is the round bur, 014 burs. So it’s a round bur you’re never going to perforate. Easy to go high speed get carries out, but it’s also rough. So that’s tip one. Okay, so think of it, you’ve got to treat the surface of that dentine before you move ahead and start putting etch on. Then what I’ll do is-

[Jaz]
Can I ask actually again, I’m going to interject and just ask here, so there was this concept of etching and bonding that for adhesive dentistry, you want a nice smooth surface. Is that referring to enamel? You want nice, smooth enamel to etch, but dentine, you want rough dentine to work with. Is that a good way to think about it?

[Sam]
Again, it’s system dependent. If you’re using something with an acid etch, which is going to clear that smear layer away, you want the surface to be rough and wavy because we’re going to rely on micro mechanical. If we’re going to have a self etching primer. We want as smooth as we can get.

So again, it’s horses for courses and I think we’ve all been guilty of it at dental school. Whatever the nurse passes us, we treat it in the same way. And we’re not-

[Jaz]
I’m sure this episode already has been revelatory for dentists like, Oh, hang on a minute. I didn’t know I wasn’t supposed to be air abrading for this. I’m sure there’s been lots of aha moments already. So that’s very, very fascinating.

[Sam]
Yeah. So if we look at OptiBond FL, we’re going to etch the enamel for 30 seconds and that’s the recommendations of Brecci, of Magne, of Van Meerbeek. And we’re going to etch the regular dentine for no more than 15 seconds.

If we’ve got sclerotic dentine. As we said earlier, it’s more mineralized and the tubules may be closed, so we want to go 20 to 25 seconds on the sclerotic dentine. So it’s kind of nice. We’re becoming more like scientists when we’re in there instead of just, which we’ve all done, painting the stuff all over the place and it doesn’t become as much of an investigation.

Then what we’re going to do, we’re going to rinse it for at least 15 seconds. And what I say is 15 seconds plus another five seconds after you see the last bit of the color of the acid etch disappear up the high volume suction because it can still linger and have an effect. Step four would be don’t over dry it.

You want to leave the dentine looking shiny. That’s the best way I can describe it. And a good way to do that is I go in at 90 degrees. So let’s say we’re doing a lower left six. I’ll go in from the lingual side. And with my three in one. And I’ll get the nurse to use the saliva ejector at 90 degrees as well.

And we’re just going to dry that off because I don’t want to over dry the dentine. Okay. Then we come to the primer. Again, if we use an OptiBond FL, we want to shake the primer well. If you look at some of the research Magne came out in the JPD with the Brazilian group, he talked about having unidose.

[Jaz]
I was there at the lecture at the BACD, he was talking about that actually.

[Sam]
Ah, so he published it in the end, there’d been a lot of talk about it and it was unpublished data for a few years. In the unpublished data he said he was getting up to 74 megapascals of bond strength versus 59. I think in the paper it came to about 71 or 72.

So, what he does is, if you think that when you’ve got a bottle, that bottle, probably the day you open it, before there’s been evaporation, because there’s alcohol in there, is a lot better if you’re that patient than the patient that’s getting it six months later, or depending on how much dentistry you do, and the shelf life a year later.

Okay? So, with these unidose, they’re almost like rockets, okay? If you kind of remember what the in school, the OptiBond Solo Rockets would come in where you’d twist it and it was all in one. So, in the study, they heated for 15 minutes the primer to 68 degrees, okay? And what they found is this caused more activation, more penetration, and higher bond strengths.

Now, the trick is, Magne will use the term massage the dentine as you prime it. My tip to people listening was you can’t, or is, you can’t over prime dentine. It doesn’t matter how many layers you put, but I’d put at least two. Okay. So what’s happening is it has to be an active process. You have to be gently moving that primer into the dentine.

Now, if you’ve etched the enamel, you don’t want to be scrubbing vigorously because if you nick the edge of the enamel, that enamel, it’s weaker because it’s had an acid etch on it and you may be breaking off prisms. Okay, so you’ve got to be careful with the edge of the microbrush. Once I’ve got the primer where I want it to be with however many layers, again I’ll go at 90 degrees and do the negative suction, or negative drying, instead of putting force on that exposed collagen, I’ll use the saliva ejector and my 3 in 1, and it’s just a gentle flow over the tooth. If you think like in an operating theater, a laminar flow, the air’s just going one way. Then what we’ll have as the sixth point would be to place the adhesive now, okay? And I tend to switch to a smaller microbrush for the adhesive.

The adhesive is very thick. As I said, I don’t want it to pool in corners, okay, which also means I don’t want it to be on the edges or if you think the inclines, I’m a class two, if you think of the gingival box where it goes up, I don’t want it to be thin where it goes over a corner. So I’ll manipulate it with the micro brush.

Now the good thing with OptiBond FL is it’s radiopaque. So if it’s thick, nobody will think you left caries. We’ll come to a nuance of SE bond 2, because that’s a radiolucent. So you have to write in the notes so that three years down the line, nobody thinks you left a blanket of decay there, and then we’ll cure this.

What I may do with the curing, depending how close I am to the pulp, a nuance with this, I may do three seconds of cure, back off for a little bit with the light, come back, because if you hold the light cure to your skin, you won’t be able to hold it that long, nevermind to a pulp.

So I’ll probably take the light curing in stages. We’ll cure it, and then we will be ready if we’re going to place the next layer of composite, we’re ready. If we’re going to do the IDS, I’ll tell you this is the nuance. With polyethers, you get adherences. So, the OptiBond FL will stick to the polyethane, you’ll see this on the impression where you get tears or you get a little bit of purple left on the prep, okay?

So, different ways to get around this, I wouldn’t advise using alcohol because that removes the unreacted monomers. So you won’t be able to reactivate them for the IDS procedure. And you can prophy them or you can cure it under glycerin one of these two. If we look at the steps in SE bond 2 to try and maximize your bond strength.

With SE bond 2, we’re gonna air abrade for 10 seconds. From 10 millimeters away off angle. So I’ll normally say at 45 degrees, ’cause again, we don’t wanna be angling right down the the tubules. And for this you want to be using something around the range of 27 to 30 microns, and it’s aluminum oxide that we would use this, or you can use the new ones, which like the silica and these ones.

[Jaz]
Yeah, they’re very promising, but how do you feel about CoJet?

[Sam]
Again, I try and keep it straightforward what’s on research. So I’ll use the aluminum oxide and having spoken with AquaCare, they’ve given me the silk. To try, but I use aluminum oxides, I think theirs is 29 microns, that’s what I’ll be using with, but no more than, than 10 seconds for this.

After this, I will rinse it. We don’t have to worry how we dry it, as opposed to the fourth generation, which again, that’s the first step where it’s not technique sensitive. Then, this is a difference when you use the primer. The primer has water as its carrier versus alcohol in OptiBond FL, so you’re going to have to gently massage them in for 20 seconds still, but you’re going to have to dry the SE Bond 2 for 20 seconds because it’s water, whereas it’s only 10 seconds for the alcohol based OptiBond FL, so we’ve got to dry it.

Again, if it’s not an active process of placing the primer, if it’s just putting it on and waiting, that’s not activating the monomers. So another tip would be, it does have to be gentle agitation for the full 20 seconds. We’ll dry it in the same way with negative drying, negative suction. And then what we’re going to do is place our adhesive, we’re going to find the adhesive is a lot thinner, but I’m still only going to place one layer.

I’m not going to be tempted to place two because the adhesive in thicker layers can be weaker and also it’s going to show on the radiograph as a larger black line because it’s not filled. Okay, which is the problem. Now, this is going to need to be reinforced because it’s not thick enough to deal with the oxygen inhibited layer.

You can have 0.5 millimeters of a flowable, and that flowable should have a low shrinkage. So some of the flowables that work would be a majesty flow or VOCO flow because these ones shrink about 1.9%, which is low. A lot of flowables will shrink around 3%. If you imagine you’ve got this hybrid layer developing and then you put something on it, which is 0.5 millimeters, which is huge in comparison to 40 microns, and it shrinks at quite a rate.

It’s gonna rip off the hybrid layer. The next tip would be, as we said, you want to wait before you get thicker than one and a half millimeters. So what I will tend to do is I will take about five or 10 minutes to place my first millimeter of composite. Maybe place the matrix band, light cure it, just so that first layer, like the hook on the wall, has had time to develop.

And then we’ll go from there. Now the nuance with these is that PBS material, it doesn’t adhere, but it’s inhibited by the free monomers in these. So, again, if this is our final layer, what we have to do is cure it under glycerin. We have to pumice it to get an accurate impression. If I can add something, actually, then when it comes to SE Bond 2, as we said, the acids will etch enamel, but you will get staining down the line.

Okay. So this wouldn’t be good for an aesthetic case. So the way that I would deal with that is that once I’ve sealed the dentine with that 0. 5 millimetres of resin on top of my adhesive layer. I’ll refresh the enamel in case any adhesive went onto it. And then what I will do is I’ll etch it once more.

And there’s no harm to etching again if it’s in an accurate defined zone. And again, that’s research from Brecci. And I’ll place adhesive just there. Now the reason for this is with the 6th generation, we’re relying on calcium. If we get acid past the DEJ, which even under a microscope is gonna happen, as accurate as we are and as stiff as that acid etches. We’re going to lose 25 percent of our bond strength. If we get any acid, that’s the DEJ. So if I have everything sealed, I know I’m not going to get sensitivity and I’m going to maintain my bond strength. It just means I have to spend a couple more minutes refreshing the enamel, placing the adhesive again. And that’s how I would do it with SE Bond 2, if you want to be aesthetic and maintain all the tips to get as high a bond strength as you can.

[Jaz]
I think the great point you made there, which is a reminder is I’ve read before where if you are going to etch your dentine, then you will significantly reduce the bond strength using certain systems. But some people think that, oh, you should never etch dentine, but it really depends on which system you’re using. So for certain systems, it is a good thing to etch dentine. In other systems, it is going to have a, like an SE bond 2, you’re going to have a negative effect on the bond strength by using it. So really got to go deep into literature on how to use the system that you have, right?

[Sam]
Yep, definitely. And I think that makes us again, it makes dentistry more interesting. It turns something mundane, like a class two, which you probably fret most about getting the contact point, something interesting.

Cause you’re going to go through every step from caries removal, crack removal, the adhesive that you’re using, how you’re treating the surface, how you’re layering it. And then you can have the fun with your anatomy. But I think sometimes we put. the horse before the cart, we’re bothered about the anatomy and we don’t know what’s going on below it.

And then we get these failures. So I would say if we have a restoration fail under five years, we can’t really blame the patient for not flossing or he got recurrent decay. That’s us and our bonding protocol that’s failed.

[Jaz]
And certainly whenever I’m doing even just the humble class 2, I like just visualizing what each component is doing in my mind. I’m seeing all these tubules, resin tags and stuff. So like I said, instead of just looking at time thinking, okay, what time is lunch time, I think you’re involved in the artistic, you’re in the nuances, you’re in the magnification. I just think it brings a bit more joy to our day to try and get try and do the best adhesives protocol that you can do every time where possible.

So I think it actually enhances our work. Speaking of work, I’m a big fan of your work, Sammy. Please tell us about how we can learn more from you. I know you do teaching in London, probably around the world as well. Where is the best place to learn more about all the things that you teach and I think is rubber dam that you do, adhesive dentistry in general. Tell us about the full flavor of what you offer.

[Sam]
So, our course is called Get Bonded, Stay Bonded, and you can find that either in the Facebook group, you can come and post your questions, you can just peruse and watch, or you can actually get involved, or you can go on the website, getbondedstaybonded. com. Now, the courses that we run, run from what we do every day, which is basically diagnosing what a tooth needs, removing the caries, the cracks, learning about these adhesives that we’ve talked about, and that’s the level one. So we do three of those a year, and they’re always somewhere nice. So we do the Dorchester Hotel Park Lane, we do the Intercontinental Park Lane, or we do somewhere fun.

We’ve done Anfield up in Liverpool, we’ve done St. James’s Park in Newcastle, we’ve done Villa Park. So we’ll attempt to take it up north once a year, and then the rest will be in London. And then we have done some in other countries. Level 2 takes us into, it’s probably 90 percent hands on. This is how to do the three types of onlay preps, with the five types of interproximal margins.

How to do semi direct composites. How to do beautiful posterior composites and how to use the ribbond in the wall, the Del Piero technique. So this is on type of dances, all small group settings. So we’ve got a lot of one to one together. Okay. And that’s a two day course. Level one is a one day course.

And that’s on the Saturday, Level 1. Level 2 is on a Friday and Saturday. And then we do once a year the Level 3. Now the Level 3 is fun because me as a prosthodontist, I do a lot of bigger cases. But this kind of dentistry, when you feel the dentistry and feel what you’re doing more, it’s more fun.

Okay. But the Level 3 is all about treatment planning and occlusion. So, I like to give dentists a cookbook approach so we know what to do in steps. So we will learn how to treat and plan the Class 2 Div 1 patient on models, the Class 2 Div 2, the Class 3 patient, how to treat them, and this will all be in ceramic, not composites, and the anterior open bite patient.

So we’ll talk about how to cross mount models, how to diagnose, how to come up with sequencing. And this is a three day course. This is in December. We do this each year. And I don’t know if you know Dr. Ash from America, Dr. Ash Lifts. She’s big out there.

[Jaz]
Of course.

[Sam]
Yeah.

[Jaz]
Oh, brilliant.

[Sam]
So I get her to come over. She’s involved in that. And Dr. Germán Dorgan who, these are the ones, some have had rubberdam. We’ve had photography before, but we’d be happy to see anyone to help them just enjoy the dentistry more, get it more predictable. And I think when you do the small things like we’re talking, choosing adhesives, you become more confident with the bigger things.

Like that I can do a tabletop only and it won’t come off. I know I can do a veneer and it’ll stay bonded. So it just makes us work and life a little bit more interesting when they have that confidence in what they’re doing.

[Jaz]
Definitely. When you have that clinical backing and the knowledge that you should get on courses, then you get to apply it, lifts your confidence, lifts the level of treatment you can offer and how you can serve our patients, what it’s ultimately about.

And I think I’ve heard great things about your courses, both from Sheideh, who works to work with at Richmond and also. Niall, one of the Protruserati you always raise on about your courses. And I’ve already had German and Ash on the show as well. So completing the three with you. So Sam, thanks for discussing all these adhesive systems and giving you a little nuances and top tips.

I’ve had a lot of like moments like, wow, okay, I didn’t know that, or I didn’t know this. And I’m going to read up more about this. So it’s always about inspiring people to do the due diligence and look up, how can we get 1 percent better each day, and you’ve definitely helped us be several percentage points better today. So thanks so much for your time. And I’ll put the links to your courses and the show notes. Everyone can check out all this wonderful stuff you’re doing. Appreciate you coming on.

[Sam]
Thank you very much, Jaz.

Jaz’s Outro:
Well, there we have it guys. Thank you so much for listening all the way to the end. Hope you enjoyed that very geeky episode. I know how geeky you guys are and lots of you will now be going on to the quiz and answering the questions. How do you access this quiz? Okay. So for those of you who are new to Protrusive, you can do this on the laptop. You can go to protrusive. app, the website, and then sign up, and then you can then download the Android iOS app and use your new login to access the app.

And on one of our paid plans, you can get access to the CPD or CE quiz. With the ultimate education plan, you get access to a whole load more premium content and courses. One of the questions in our quiz today is which generation of adhesive systems does SE bond 2 belong to? That’s which generation of adhesive systems does SE bond 2 belong to?

Do you remember? If you do, it’s an easy way to get CPD because let’s face it, if you reach this part of the episode, you probably usually listen to the end anyway, so you might as well rack up those CPD points throughout the year as you’re listening to Protrusive. Our CPD Queen Mari will send you the weekly certificates and every quarterly, which no other education provider does, will send you quarterly certificates and an annual summary of all the education you’ve done with us.

So I want to thank Mari. I also want to thank my producer Erika, as well as the wider team in Krissel, Nav, Emma, and Gian. And one more thing before you go about your daily life. Could you just, wherever you’re watching or listening from, hit that subscribe button. If you’re watching on Protrusive Guidance, then please share this with someone.

Tell someone about Protrusive Guidance. I’d love to get the best collection of the geekiest and nicest dentists together in the world. Thanks so much. And I’ll catch you same time, same place next week. Bye for now.