Restorative Series - The Single Crown Part 2

In Part 2 of our Single Crown podcast series, hosts Dr Jill Fisher and special guest host Dr Liam White continue the discussion with Prosthodontic Specialist Dr Michael Mandikos, covering the finer details that can make all the difference in single crown success.

Topics include:
• Checking and adjusting crown margins
• How and when to use fit checkers effectively
• Conforming crowns to a patient’s existing occlusion
• Common mistakes and clinical tips for better crown fit
• The big question — should you adjust adjacent teeth?

This episode covers the practical clinical steps, decision-making, and specialist insights to help you deliver predictable single crown restorations that all of your patients deserve.

For more information about products Michael uses visit Brisbane Prosthodontics Dentist Information

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Transcript

Dr Jill Fisher 0:09

Welcome back to the Correct Dentistry Podcast. And this is part two of our first in our restorative series on the single crown. So if you didn't hear part one, please look it up in the feed because in part one we spoke at length about all of the specific checks Michael does when he's looking at a single crown as it comes back from the lab and then how he checks the contacts on the model and then in the tooth. Once again, I'm joined by Dr. Michael Mandikos and Dr. Liam White. Liam is a first-year postgrad pros student at the University of Queensland, and of course Michael is a specialist prosthodontist. So welcome back.

Dr Michael Mandikos 0:50

Thanks, Jill.

Dr Jill Fisher 0:51

So moving on from checking the contacts, what is your next intraoral check that you do?

Dr Michael Mandikos 0:59

Right. So if the contacts are good for a single crown, there's nothing impeding that crown from fully seeding on the preparation that you cut. At least there shouldn't be anything. So if you then go to seed it and you can't see the margins close, or you can probe an open margin, obviously something's holding it up. Well, it's not the contacts anymore. It's got to be something to do with internal fit. And the first thing that you would jump to if you've done some kind of crown course is to look for, you know, some spray like a occlude. Do you remember that? That coloured dust makes a big mess in the mouth. You know, or maybe you go and get the fit checker or something like that. But the reality is for most people, I mean, I know a lot of people do same-day dentistry, but for most people, that crown has had a, or that tooth, sorry, has had a provisional crown in place. So very often there's provisional cement somewhere. And I know that sounds so obvious, but people often miss it. Sometimes there's provisional cement, it's obvious. Sometimes the provisional crown was made. And when it was made, it was made over the prepared tooth. And on that day, the dentist also did a bit of a core buildup and composite. So now some of the provisional material stuck to the core, you know. So, and that could have happened, of course, after the PVS impression or polyether impression or scan. So now you've got a tooth which actually has a little bleb on it somewhere that's not on the die, and that's what's holding things up. So you may be able to see that. You might be able to see the temporary cement. If you can't see those things, that's when you default to your fit checking materials to see what the difference in fit is. Somewhere the crown is designed to fit over a die that's a different shape. Like what's happened?

Dr Jill Fisher 2:43

I've watched you use these fit checking materials, and you are actually the person who taught me to use them. I don't think I had any in any interaction with them as a dental student. And I tend to remember you had a coloured pencil in your kit when you're using the silicone. Can you talk us through how you use those fit checking materials?

Dr Michael Mandikos 3:03

Yeah, the coloured pencil, I thought you were going to ask about, because that one unfortunately is gone. It was from my grad program. It lasted about 12 or 15 years, kept sharpening it until it was a little nub. So yeah, basically it's just just a red pencil, but try and get like a hard red pencil. So a fit checking material is going to, if if you mix it up, so I guess there's two different ways that I'm aware of that are sort of frequently used. One is the sprays, the occlude spray. Anyway, long story short, I would I wouldn't use that because it's messy. And if the prep gets wet, um, you know, it interferes with your ability to read it. So what I use is the silicon material, which is made by GC called Fit Checker. Uh, there's a white-colored one, which you'd use most of the time for castings, for gold and for PFM restorations. But if you're working with all ceramics, they also make a dark blue one so that it contrasts against the crown. And so you mix this material up, you load the crown as if it's cement, you seat it on top of the tooth, you hold it until it sets, it's only going to take about 20 seconds to set. Take it out and you look inside the crown, and if it's, let's say it's the dark blue one, it's quite opaque. And where there's a little white spot, you're seeing the porcelain of the crown. So now that's telling you that that's the binding point. And so that's where the red pen comes out to mark it. If you're working inside a PFM restoration, then you're using the white version, you're looking for a dark spot in the white version, and you're doing the same thing and marking it. So the question really then is is if that's the point where it's you've tried to seed it and it's it's binding at that point, that's the positive. So what's the positive? Well, of course, look at the prep in that area first, and maybe you see some resin from the temporary. Maybe you see some um some residual temporary cement. You know, grooves, if you make little grooves for resistance form, they frequently fill with cement. You don't just quite get all of it out. So you're really looking for that. If if that's not there, then you say, well, I'm going to adjust the inside of the crown or I'm going to adjust the tooth. Now you have to make a judgment call. Um if you know that the crown, you know, has normal volume, you're only talking about, you know, 40, 50 microns of adjustment with a burr. So you're not really doing very much. So probably adjust the inside of a casting. If you're working with Emax, you might look at it, particularly if it's a little bit thinner and say, well, I wonder if in that area I should come back and just touch the prep instead of touching the Emacs and and you know, disturbing the surface of the Emax and maybe creating some microcracks. And I might be overthinking it there a little bit, but there'll be cases where your crown is maybe a bit thinner than you want it to be, and you just say, Well, I'm gonna adjust, I'm gonna adjust the prep rather than adjust the inside of the crown.

Dr Liam White 5:42

And just to clarify, when you're saying positive, you're talking about a positive defect. Could you just elaborate a bit what you mean exactly by a positive and a negative defect in a crown fit?

Dr Michael Mandikos 5:52

Yeah, if you could think of the if you looked at a cross section through your dye and it's a molar, where it's gonna have an axial wall at the mesial, it's going to sort of go up and down a couple of times on the occlusal, and it's going to go down an axial wall on the distal. And that's the shape of the molar. And you should have a crown, and it's got a little bit of taper, can't be perfectly parallel. So it's got a little bit of taper. And when your crown goes on, it just slides right over the top and it seats at the margin. So a positive error there would be the dye um is straight. No, the tooth is straight. Wait on which one is it? The dye is straight, but the tooth is a little bit over-contoured on the mesial axial wall. Or one of you, like your transition line from the um axial wall across the occlusal, one of those sharp areas. Something there on the tooth is a little bit fuller in contour. There's more of it there than there is on the dye. Um, and really the only way that that something like that should happen is during the the fabrication process, maybe the dye was chipped or or scraped a little bit, and so the crown was made closer to the tooth structure, now it comes to the mouth and doesn't fit. Or something changes on your actual tooth where you've got residual cement or residual temporary material stuck on it.

Dr Jill Fisher 7:13

So you mentioned when you recognize there's a fitment issue or something holding up your crown, you have the choice between um adjusting your crown or the tooth. And I know I'm going back a big step, but do you ever, when you're checking your contacts, ever make consideration to adjusting the adjacent tooth instead of adjusting your crown? Like do you ever disc the contact of the adjacent tooth? For the contact. For the contact.

Dr Michael Mandikos 7:38

For the contact, yeah. I do, I do sometimes adjust the adjacent contact. Now, in saying that, it comes down to looking at your crown and looking at its actual anatomical form. And occasionally you have a crown that, you know, maybe it looks like they've really built the mesial out a tremendous amount to reach the adjacent tooth. And you think to yourself, it'd be nice if the mesial wasn't built out as far, you know. Um, so then I might adjust the the crown and bring it in a little bit. Other times you've got this like, you know, perfectly axial wall contact point, your prep margin is almost touching the adjacent tooth, you know, it might be better for you to adjust the adjacent tooth because you're only talking tiny adjustments. And you can extend that kind of argument. I know it's very hard to describe, you know, in a podcast setting, it's a bit abstract, but sometimes there's a there's an angle on the insert because the teeth are all leaning, and and so you can get that situation. I don't do it often. Um, again, if you've got a big bodgy old composite in the other tooth, you know, it's better to adjust away a bit of composite than your porcelain, provided it doesn't play with those insertion angles or grossly change the the contours of the tooth. And the crown.

Dr Jill Fisher 8:50

What um bur do you use to do that?

Dr Michael Mandikos 8:53

To adjust to adjust an adjacent tooth, I still use the same marking film because it leaves a clear mark and gives you an idea of how small an area you have to adjust. So if it's a really small area, I might look at it and think I can use um it's a Kerr carbide burr, it's a jet carbide burr 7903. It's a little flame carbide burr, and you can sort of angle it pretty easily, just use a small portion of its cutting surface and you can adjust to a very small area. If the area gets a bit broader, then actually move to a disc. I'd use a soflex disc and I'd probably use a medium disc, not the coarse, so that it wouldn't cut too quickly. And again, you're spinning slowly, dry, and just touching the tooth slowly, and you've got to be prepared to do it a few times. You're not gonna get it in one.

Dr Liam White 9:37

And sorry to interrupt, but just quickly, when you're saying course, what colour are you using?

Dr Michael Mandikos 9:41

Oh, so coarse, so so the coarse is the dark orange, soflex plastic. Um, then you've got like a lighter colour orange uh for the medium, and then you've got well, at fine, you've got yellow. I guess between medium and fine, it's kind of somewhere a less, less orange, more yellow colour. I can't kind of remember it. But um, that's the plastic ones, and I only use the plastic ones for that. And with paper, you've got dark blue, sort of a mid blue, then then a kind of a light blue, and then a very light blue, having you for for fine. And if if that's all you had, you'd use those. But plastic's easier to use in this situation.

Dr Jill Fisher 10:16

So you've gone through using the silicone after the silicone's set and you've made your little mark on the crown, you peel out your silicone layer.

Dr Michael Mandikos 10:26

Yeah, the layer.

Dr Jill Fisher 10:27

You've made your adjustments, maybe you check it again in in a similar way. But if you place your crown then and your margins seem to close, how are you intricately checking that margin all the way around?

Dr Michael Mandikos 10:39

Um, so this, yeah, this means you've got a buckle and a lingual margin which you can see, and if you can't see, you can at least feel it. And then you've got into proximal margins. So buccal and lingual speak for themselves. I mean, you can you can either see it, you can blow air and see into the sulcus a little bit, and you can definitely press down hard on the crown with your finger and just feel for the margin. As you get to the proximal, this is where you have to trust your records. So if the crown looks good on the die, you look at the die and your margins don't look too bad. Like, you know, you're on a good day, you cut a good crisp line, and the crown closes on the die, it's going to close in the mouth. Like it's, you know, you you either just didn't impression it properly or so that part, you know, I'm very comfortable with. The idea of then taking an x-ray to see if it's closed interproximally is is a nonsense because the crown can't be open on the buckle and the palatal, or buccal and lingual, and be open interproximally. It can't. Unless it doesn't fit on the dye because crown made the the lab made your crown short. You know, you'd see it on the dye. So you don't need an x-ray to do it. So interproximally, basically, I I I trust the dyes after I've confirmed everything else that I can check, which is buccal and lingual.

Dr Liam White 11:52

So just to clarify, you don't routinely take a pre-op pre-cementation bitewing to check.

Dr Michael Mandikos 11:58

Never. Never. I cannot remember ever taking a pre-cementation bite wing. I've taken the odd post-cementation bite wing to look for cement. When when it's been a difficult cleanup and you think there's resin in there somewhere, we do we do that. Yeah. But but I mean, you know, we might do that twice a year.

Dr Liam White 12:14

Just hypothetically, say you took that, so it's not seating. You take you look at your fit checker and you see there's not a mark on there. What do you do then?

Dr Michael Mandikos 12:23

Yeah, that's the one I don't like. So occasionally the the fit checker is not really giving you a good reading. Um two things that I try. The first one is um I'll do it again in case you know I did something wrong. I dry the tooth well so that there isn't a moisture film uniformly holding things up. Um when I do it the second time, I'll place it down, I'll probe through the fit checker again, make sure just quickly, and you don't have long because fit checker sets pretty quickly. Probe through it, buccal and lingually, just make sure it feels down. And then I'll I'll actually try to rock it. And once it's set, I'll take it out and see if that demonstrated an area. So then it doesn't. And you say, right, I'm back to the same square one. I don't have something closing. I go back to the dies and I say, well, is it correct on the dies? And you look at the dies, you go, yeah, it is. On the model, it fits, but it's not fitting in the mouth. So you're really down to distortion. Something's distorted, is my impression distorted? And you think to yourself, well, it might have, but what else could I check before I just kind of give up because the impression's distorted? And the thing that I would look for is anything sharp, any sharp transition line. So we talked before about up an axial wall transitioning to the occlusion. If that uh line angle join is very crisp, you know, there can be some distortion there, or something didn't pour up exactly the way you wanted to, or heaven forbid the lab has somehow abraded it in the manufacture process. And now from the lab's perspective, your dye is perfect, but it's rounded. And in the mouth, it's crisp. And when you look at dentine in the mouth, it's so translucent that you can't often see that. So before I suspect impression distortion, because I don't think I see that very much at all, I take a burr and I go to everything that's sharp and I just dust it off. Like take that crisp line angle and just bullnose it ever so slightly, and then try it back in. And you'll be surprised how often that works. The second thing is that rocking action without the fit checker in there. Sometimes you can you just rock it and you say to yourself, I I know that's binding. And because of the way it's rocking, I can sort of sense the fulcrum is dead center, it's more to one side than the other. And you go looking at your margin and you look and you say, you know, perfect shoulder margin. And then I get to here and it's more of a feathery, chamfery margin. Then it's shoulder again. It's like, okay, so somewhere here, there's an error because of my crappy margin. It, you know, it's my fault. So I go inside the crown in that area and I start relieving the first half millimeter of the casting or the crown in that area.

Dr Liam White 15:01

And are you taking in internally or the crown? So you're not touching the margin.

Dr Michael Mandikos 15:06

Not not the bottom of the margin. As you come up into the intaglio surface, just that first half millimeter or so. I start trying to sort of almost um, what's the word, shave it away a little bit so that it might be more passive in that area. Because again, you'll be surprised when you can get that rock, you only have to do it once or twice. And then you you learn, you can feel it, you can actually tell where it's rocking. And when you say adjust it, and when I get it, I always, always turn to my assistant, because the patient's wondering what's going on. I always turn to my assistant and go, I got it.

Speaker 3 15:35

Yeah. So it was worth persisting. I got it, right? Because then it makes everybody feel better.

Dr Michael Mandikos 15:40

Including me.

Dr Liam White 15:41

Um, with that, what do you like what do you use specifically when you said, Oh, I just I just adjusted a bit. Like, what are you using? Are you using a red football bur? Are you using a yellow football bur?

Dr Michael Mandikos 15:50

So, yeah. So if I was adjusting gold there, I'm using looking for a fine diamond to adjust it. Oh, I mean, that's not true. Probably a medium diamond. And it's normally, to be honest, it's normally the burr I use for veneers because it's got a it's got a nice taper, which is the chamfer end. And that is one I remember. That is a um 102R from Shofu. Yeah. Um, but if it's ceramic, then I want to use um I've got a similar-shaped bur, which is um 102R, it's yellow band diamond. And it's also got that point, but it's a diamond this time, very specifically, very fine because it's ceramic, water spray, and you're just trying to very lightly touch that area. Or that gold diamond that um yeah, Dentovision bur, but for for the life of me, I can't remember its number. I use it all the time.

Dr Jill Fisher 16:35

Well, put it in the show notes.

Dr Michael Mandikos 16:36

Yeah, okay, we'll put it in the show notes. Because again, you're just trying to cut porcelain as smoothly as you can, but in a very defined area. I I couldn't rub a wheel inside the crown without taking the margin away.

Dr Liam White 16:46

Yeah, just to clarify, you said with Emax you use water. What what happens if you don't use water when you're trying to or sorry, porcelain as well, but what happens if you don't use water when you're trying to adjust it?

Dr Michael Mandikos 16:54

It's it's more that thing of you have to think of every time the the bur is spinning. Microscopically, that's a cylinder with all these particles of diamond on it, which are very hard. So everything they touch, they're gonna they're gonna cut. And microscopically they're they're big, you know, like it looks like the sort of thing that would you wouldn't want to touch with your fingers, it'll it'll cut you. So you've got to almost think of that diamond spinning round and round and round, hitting the inside of the crown as it's turning and chipping that surface and and initiating cracks. And so, you know, we know with an all-strand crown it fails from the inside out. It's crack propagation from a floor somewhere internally. So you don't want to be generating flaws unnecessarily. But the bottom line is there's practicality and there's theory, and that the the closer you get to the theory, great, but it's still got to be practical. So, you know, I go with a fine diamond, and if I can use water spray, I can. If I'm going dry, minimally my assistant's blowing lots of air just so it doesn't heat up.

Dr Jill Fisher 17:50

On that point, you mentioned before that you can't often see a sharp transition line in dentine, but of course, on the stone model it's really obvious and you feel terrible. Um, if your crown is not rocking, it's seeding beautifully, the margins are closing, but you've noticed on the die and you've you're placing an Emax or a ceramic crown, and you notice that you have left some sharp transitions, would you anyway clean them up and round them off, or do you leave them alone?

Dr Michael Mandikos 18:19

Well here I can't speak from evidence. Um but but I guess what I would sort of say is the likelihood is you'd look inside, because you're talking all ceramic now, you'd turn your crown over, you'd look inside, and you wouldn't see the crisp line reproduced in the crown. Meaning that if it's been made by software and a computer, they've they've just dye spaced it out. So that's comforting. Um but then there's the whole idea that because you're bonding that crown, not looting it to place, the stress transfer should be really uniform. So the crispness of that margin should have less of an impact than if it was looted to place. But I think in reality it's still likely to contribute. So if you're trying to be pure about it, and again, I'm please please understand I am speculating. Um if if someone like Pascal one day is watching this and his his knowledge of biomechanics is is greater than mine, uh, you know, he he might contradict me. But I guess you know there'd be some benefit in rounding it. But you know, in all ceramics as a general concept, you're always trying to round. With metals, different story, you know, and and if it was crisp and everything fits, you'd just leave it crisp. You've you've seen the beautiful preparations for Andy does and the the increase that it gives in retention by doing that. So you just leave it crisp.

Dr Jill Fisher 19:39

So we've checked the contacts, we've checked the margin, the internal fitting surface to close the margin.

Dr Michael Mandikos 19:48

So we're happy it seats. Well, now the last thing left to check is the occlusion. Um and so with any crown, obviously the the final check is the human articulator, that's your mouth. So you'd like to have been able to check on whatever your articulation system is first. And I always say that if if the crown looks borderline high on your articulator, you just accept it. You can make that adjustment. And after you've done it a few times, you get an idea, is that going to be so much adjustment that I grind everything away, in which case I'm sending this case back to the lab, or is it just a small adjustment? So if your articulator suggests a tiny bit higher, that's okay. If your articulator suggests it's pretty good, okay, I'll probably accept that too. If your articulator shows you're in infra occlusion, you should send that back. And that's why you get the case in in advance, right? You send it back and you say to them, add some more gold, add some more porcelain, whatever it is. And uh, because you don't want to be putting in crowns that are in infra occlusion deliberately. If it happens as a complete honest error and it's not too big, you know, I'll accept that. But you don't want to do it. You want to put them in proper occlusion. So now we're going to check proper occlusion because we think this crown's good. So put it in the mouth. Well, if it's a gold crown, house the patient closed, right? Um, if it's a PFM crown, I'll almost always do that too. And that's because no real harm can come to the restoration during the train. Now you move on to Emax. Well, of course, Emax can be layered or it can be monolithic. If it's monolithic, unless it's the thinnest, most fragile of Emacs restorations, not much harm can come to it if the patient decides to overclose. If it's zirconia, same thing. But if it was layered Emax and it was kind of thin, or if it was a PFM and you had a butt margin of porcelain, now you just got to be a little bit careful because when you say to some patients, close, you get the trapdoor patient, right? And it's like, I I didn't say snap shut. I didn't, you know, I didn't say be a crocodile. I said just, just, just gently close. But some people they can't help it because that's they just bite hard. And um, hopefully you picked up on that before you asked them to close. Other people will close and then they'll clench. And if your crown rocks, you you can chip some porcelain and And I've got a beautiful photo of a case that that happened to me on. The only upside of a bad clinical situation is I've got this great photo of it. But you know, once that happens to you, you'll never let it happen again. And so the only way around that is if you're going to get the patient to close on a crown that's got a potentially fragile margin, is you've got to stabilize that crown with your finger. You've got to press on the buckle because it's the only place you can get to. And you've got to maybe just keep your hand on their jaw to kind of guide the force or guide the speed with which they close, and then they can close. But if you've got protected margins, because they're 100% mills zirconia, they're pressed Emax, they're metal, you know, you don't have to worry about those sorts of things. So that's when we're checking occlusion. The only time I don't check occlusion is that super fragile crown or an onlay. Um, and when I say onlay, a ceramic onlay, because even if it's a even if it's a conia onlay, it can move and you still can't really tell. So you're trusting the articulator, cementing it, and then doing a post-cementation adjustment and polish.

Dr Liam White 23:01

I mean, to cut right to it too, when you're saying checking occlusion, like what exactly are you looking for? Are you looking for two dots? Are you looking for lines? What what are you looking are you taking a pre-byte record, you know, considering that you've got a conformative, so as in you're trying to match what's there before, are you taking like a byte articulated before? I'm sorry, I think like again, byte paper, getting the byte down, taking a photo. What do you do?

Dr Michael Mandikos 23:22

Yeah, it's a good question. I thought as a um pros student, you'd be asking if I'm looking for tripod contacts.

Dr Liam White 23:29

No way.

Dr Michael Mandikos 23:31

So let's just quickly dispel that right away. We do we don't look for contacts with tripodized occlusion. What do you mean, though? So um yeah, so um the first thing that you can do to help yourself is prescribe the crown to the lab with one occlusal point of contact, right? So you eliminate the tripod discussion. And so typically what I do is I say to the lab, you know, when you've articulated that, you'll see, well, let's imagine it's a lower six. So if it's a lower six, it's got an upper six which hangs out to the buckle. It overhangs on the buccal. So the upper six has a palatal cusp, which might form contact with the lower, or the lower six might have a buccal cusp, which forms a contact with the central uh developmental groove of the upper. So you say to the lab, which one of those is the best place for a good contact point based on what you can see on the lab, in the on the model, because they can turn the model around, they can look at it. What's going to be the best anatomy? And you ask them to make a high contact point there. So if it's in the developmental groove, you you ask them to bring down one of the triangular ridges and give it a really positive bit of porcelain or gold. If it's the buccal cusp, make that buccal cusp tip a little bit higher. That's the contact point. But before that, from their perspective, how they do it is they make the whole crown out of contact and they just build that point into contact. And then they put it into super occlusion. So it's a little bit too high. So now you bring it to the mouth and you know that crown has to be in high contact. And unless you're a boof head, by the time you adjust it, it's going to be in contact. It doesn't start out of occlusion. That's why I hate the lab cards that say, how do you want your interproximal contacts? Tight, correct, or open. Well, they don't say open, they say light or something, which means open.

Speaker 3 25:12

Yeah.

Dr Michael Mandikos 25:13

Well, like, of course, everyone wants to tick correct, but if you're smart, you tick tight. So you've got a bit to work with. Same with the occlusion. They they say, do you want it high, accurate, or low? Because they're they're dealing with someone who says, I just got to get this crown in in 10 minutes and I don't want to be adjusting occlusion. So build it out of occlusion. That doesn't help the patient. Other teeth start to move and drift, contact points open, food packs occur, like it's not good, not good dentistry. So if you start by having your crown deliberately high, but in one point, then you know when you put your articulating film in, there's only one point that should mark. Unless something went wrong with the articulation, it's always the one point. You keep rubbering that one point until it's even with everything else, which is the second part of your question. What do you do first? So before you put the crown in, put some articulating paper in on anterior to it and posterior to it and confirm which teeth touch when that crown's not in place. And as you're adjusting your crown, you get to the point where you think it's making a good contact, check those two adjacent teeth, they should still be in contact. And then that way you know you've got a good static contact.

Dr Liam White 26:18

And just interrupt, sorry, but when you're saying check, are you getting like a shims, like not shim stock, but you're getting them the bite down, you're trying to pull the articulated paper out. Yep.

Dr Michael Mandikos 26:26

Exactly. The same mylar film, same thickness, putting it between the adjacent teeth. Because the teeth contact, there's no gap. So the film won't come out. It'll tear if you pull hard enough, but it'll leave a mark where the contact is. So you do that on the tooth, mesial and distal, and the tooth that you're working on, you start doing it with a narrow strip that only fits on your crown, doesn't spread on the others, so you don't get confused. And you keep going until you can pull it and it grabs and it leaves a mark, but you can do the same mesally and you can do the same distally.

Dr Liam White 26:55

What about something like zirconia? Because it's a bit of like some people say you can adjust it, some people say you can't. What do you do in your practice when you do you get them to build up the zirconia crown high as well? And do you adjust it down? And if so, how do you go about it?

Dr Michael Mandikos 27:09

So in some respects, the zirconia crown is probably the one that I would want the lab to do that every time on. Yeah. Because it's so much harder to adjust the zirconia crown accurately because the material's harder to cut. So if I was adjusting Emax, it cuts, but it cuts faster than zirconia. If I was adjusting feldspathic porcelain, it cuts faster than Emax. So I don't want a zirconia crown with multiple contacts that are high and adjust and adjust and adjust takes forever, right? So that one's probably the exception. But if you use the same principle, you've only got one spot to adjust. And so you can still use the adjustment wheel, the coarse wheel I was talking about. But the moment you think there's a bit more adjustment because something's gone wrong and you've got to adjust a lot of zirconia, there's a there's a wheel loosely referred to by the lab as a heatless zirconia wheel. I don't really know how you can abrade away a material without generating heat, but maybe it's heat less, like less, not heat without, you know, touch less heat or something. And that definitely cuts the zirconia faster, but of course it leaves a more abraded surface, which you then have to polish. So if there was a really gross error, I would use that wheel first, then I'd move to the one that I would normally use, the normal, the normal course, and then from there um polish it up with medium and fine.

Dr Liam White 28:27

Yeah, okay. So you would just polish the zirconia after you make the gross adjustments, you'd polish it similar, the same way you would as an Emax right now. You just use that same set of rings. What about lateral? Lateral excursions.

Dr Michael Mandikos 28:38

So then that's the last part of occlusal adjustment. So you if you we're doing single crowns today, and so when you're working with a single crown, you're conforming to the patient's occlusion. You're doing one tooth, and if that patient's overclosed, you're building one crown to that overclosed dentition. If they've got a perfect dentition, you're building the crown to that dentition. So that patient already has some sort of guidance. So protrusive guidance and a left and right guidance. And because you're conforming, you have to accept that guidance. So it would be mostly not the right thing to do to create a new guidance with your crown, unless your crown happens to be the canine, maybe, and you're trying to build in canine guidance. So we check that static occlusion. And as soon as we've got that to where we think it's perfect, go back with the bigger piece of paper, get the patient to close, you say, now go left, now go right. And this is the easy part. Because you're conforming, assuming it's not a canine, let's say it's a premolar or a molar, you don't want it in contact. You don't want it to usurp the natural guidance that's already there. So this is the really easy adjustment. Any mark other than that centric contact, you you remove because it's an interference one way, shape, or form.

Dr Liam White 29:50

So pretty much to summarize, you get your crown, or you so you literally get the lab to make it high, intentionally make it high on those points, either the buckle cusp of the lower mandibular, your lower teeth, sorry, or you want the palatal to be, or or you want the palatal of the upper teeth to be pushing down. So that's like a mortar and pestle kind of kind of thing. Exactly. And then you check it, you say, okay, adjust it, just it adjust it, do, do, do it. Okay, now I'm pretty happy with it in centric. So, or sorry, when it when it stops, and you need them to grind in side to side, and you're saying, I don't want any lines there. I just want to see those two little dots. Do you use a different color paper or anything like that when you check the ?

Dr Michael Mandikos 30:26

That's the beauty of turning the paper over. Yeah, oh okay. So if you use one of the Milo films that I use, which is black on one side and red on the other, you can mark the centric point in black, and then when you go for guidance, flip it over so that any mark that turns up in red theoretically should be interferences in lateral protrusive.

Dr Jill Fisher 30:44

And do you ever um adjust the opposing tooth?

Dr Michael Mandikos 30:51

All right. Call it off. Call it off now. All right. So I'm gonna start by by quoting my dear late friend Harry Hughes. And um when when Harry would would speak at his lectures, he he was colourful. And if you gave him the champagne at lunch before he spoke in the afternoon, he was colourful and he'd he'd drop some bombs, right? Um, but he used to just say, you know, and if you've gone in there and there's some issue with the crown or whatever, you go and you remake that. The patient is not paying you to adjust the opposing tooth and blah, blah, blah. And he would go off his rocker. But it for whatever reason, it was just a real pet peeve of his. And so sometimes you hear those things and you think, well, you know, that that's a that's a um sideline post for me. You know, that that's that's setting the parameters for me. That's that's my compass. I've got to make sure I try and avoid those things. And the reality is that despite best efforts, you you get tricked sometimes, but it's always your fault. Like if there's not enough occlusal space and you've got to adjust an opposing tooth, it's always your fault. You either didn't prepare enough, and when you say you didn't prepare enough, it's because you had an interference. And, you know, it but the interference was there in CR and it guided the patient, and then you were you prepped the tooth and the interference disappeared and you the patient drifts back and you've lost some space. So you didn't check it and then you didn't prepare enough. Number two, you made a provisional that fell off, you know, and the teeth over-erupted. Number three, you made a provisional out of something soft and it abraded away, you know, and and space was lost. It's always your fault. I mean, the patient can't do it to you. It's it's your fault. So if you look at it from the point of view of it's your fault, then you can look at it the other way and say, well, do I get out of it by adjusting their tooth? Well, you've got to look at it and say, well, yeah, actually, as it turns out, I'm so lucky. The opposing tooth is a cusp cap in amalgam or composite. I can adjust it.

Speaker 3 32:38

Yeah.

Dr Michael Mandikos 32:39

The opposing tooth is um is a crown and it's um, you know, it's it's porcelain, I can tell it's veneered, there's plenty of room, I can adjust it. The opposing tooth is a virgin tooth with perfect enamel, and you look at it and go, well, do I want someone to do that to me? And so you you suck it up because you know it's your fault.

Speaker 3 33:00

Yeah.

Dr Michael Mandikos 33:00

So that doesn't mean that I haven't done it in some instances, but what I really want to convey is that um because I've done it in some instances, I'm I'm more acutely aware of not creating that problem. And I'd like to think that problem really doesn't occur now in my practice. And so now I can stand on my, you know, high, high position and throw stones at other people and say, Don't do it. But yeah, if it happens to you and you really have to do it and you can get away with it without really doing any major damage, by all means do it, make it a learning point and make sure it doesn't happen to you again.

Dr Liam White 33:35

Like just as a like, you know, I guess the impression of this. Nowadays, like I mean, especially when I was going through when I was young, like on Instagram or even my first job or so, it's a lot of pressure. Like the average time, you know. I I remember I'd book an hour and a half for a crown prep and then be like half an hour for a for a crown cementation. That that's it. That's it. Just give me like a rough idea. From start to finish, from the say you're getting the dye, or you're checking out of the mouth, you're checking it in the mouth, then you're checking it, the contacts, etc. Just very roughly. How like just how long would you say each stage would take?

Dr Michael Mandikos 34:08

Okay, so don't see so in my practice there's the initial consultation, even if it's a single crown. But and that's just because you've got to get to know the patient. In in a general practice, you know the patient, right? And it's part of another procedure. So let's put that one aside. So the day comes, you're gonna you're gonna do the crown preparation. So we used to book an hour and a half. Progressively over the last four or five years, we're probably sometimes it's an hour and a half, sometimes it's two hours. It's always two hours if I suspect some degree of core. So if there's an old amalgam there, I'm gonna remove it, I'm gonna bond in some core. Might only be a little bit, might be a lot. So if I suspect a core, it's two hours. If it's absolutely run of the mill, simple as it gets, maybe it's even a bit more online-like, then we're we're back at 90 minutes, one and a half hours. Um it goes to the lab. The assessment that I do is, you know, it comes back onto my bench, I said before, and it sits there between me and the computer. It's probably a three or four minute assessment, you know, that I'm looking at that and saying, we can progress this case, keep the patient's appointment, I don't have to send anything back. So in some respects, it's that's not very much. If it was a multiple unit case, it might be a 10-minute assessment, but it's still not not really a lot. So then the patient comes in and the insert appointment for a single crown is is an hour. So really I'm talking about what, three hours or two and a half hours plus five minutes. So it's not really that much. But I suppose the thing is to look at it and say, well, you know, it we do dentistry as a business. I mean, we want to help people, but you don't do it for free. So there is a business and you've got to say, well, what's my alley rate? And you know, I mean, I know long time ago when the concept of a practice manager, uh not a practice manager, a practice coach was new long time ago, the first thing they did was, oh, you've got to do more Crown and Bridge, you know, because it was just seen as as being a a moneymaker. But when you actually put the time in, it's really sort of the similar alley rate to anything else you do in dentistry.

Dr Jill Fisher 36:04

We Liam and I could ask you questions on that, but I think um it's clear we have to wind up. But I I've got a final question or statement, I suppose. I mean, I've worked with you a long, long time and I've fielded a lot of emails and questions from dentists trying to ask you about the way you work. And so often the question is, you know, which lab do you use because my lab's sending me rubbish or this job failed, my lab did the wrong thing. And what I've heard from you time and time again tonight is you say it's my fault, or you're looking at what I did wrong, what what can I check? Um, and I think that is so evident that you you're arguably one of Australia's best prosthdonists, and you're always thinking, well, what have I done wrong if this crown isn't fitting? So it's a real mindset shift. It's so easy to blame the lab when the when the unit doesn't go in. And at the university level, I know the the pros lab on fitment day. You know, if the if the crown doesn't fit, it's obviously the lab's job, you send it back. But can you just talk on that? Because you know, you you are very humble and self-depreciating, but it is just the ethical considerations you put into everything you do. You checking everything so methodically, not because you're looking for blame, but you know what these steps are that need to be checked. And the final, final thing would be, well, the lab's stuffed up.

Dr Michael Mandikos 37:28

Yeah. Um I've had a couple of you know, very obvious lab stuff ups over time. But they're easy to pick when you've got a system, when you're methodical. So if you're not methodical, you can't ever blame the lab. I mean, you you can think you're blaming the lab, but you can't be sure. And you know, there was there was a period, um, gosh, it's got to be more than 15 years ago, where we were using resin dye. So resin as a dye material is great because you it's hard to abrade it. Um so you know, the lab can you can just about dropkick it around the room, you know, and do whatever you want. It doesn't abrade away. It's quite quite indestructible. So if you've ever seen some lectures where someone's showing some cases and they've got blue dyes, if you've got those blue dyes, it's a resin. Anyway, um, all of a sudden it was like, and actually it was a contact point issue from memory. Um, these issues with contact points, that they were open. If you'd you'd try them on the dye and they actually looked okay, but you'd put them in the mouth and they were just faintly open, you know, three pieces of articulating paper. So I called the lab up and I said, you know, it's a few cases in a row now where this has been happening, maybe, you know, four out of five in a row. And, you know, Mark said, actually, a couple of people have sort of said the same thing to us. You know, we had trouble getting this uh blue star material and then it came and I'm actually starting to wonder if it was a batch-related issue. And at that time, you know, they made a decision they wanted to, because resin takes longer to pour up and everything, they went back to a good quality stone and the problem disappeared immediately. So how do you get to the point where you're sort of saying, there's a problem I'm seeing and it's not me, right? Because it's it's gonna be you, most likely. Well, the way you do it is by having systems and being methodical. And if you always do something the same way, or if you make a change, you make one change to your protocol before you implement another change. Then if you're always doing things the same way and you didn't make notes on the day, oh, that was the day that lady came in and she, you know, she got up halfway through the appointment, she vomited, you know, there was water everywhere, she wouldn't sit still. Like you might say, well, that was a day where things didn't go to plan. But if everything's just a normal appointment, you haven't made any special notes about something being different. You always make use the same impression material, you always do it in the same manner. Then if something goes wrong, there's only another factor in there, and it's the lab. And then you can start to think, well, what could have gone wrong at their end? And and of course, the beauty of doing a a PROS program is you you do your lab work, Liam, as you well know, and as you're about to find out, you can do a lot of lab work. And so you'll live and die by your lab work. You you will cut better crowns because you want to do an easier lab procedure. You know, everything you'll do will get better. And then you'll understand the lab work, and then one day, if something's going wrong, you know your side and their side and you can piece it together. But if you're not methodical, you can't pinpoint where the problem is. And it's always when something changes that something goes wrong. And the change can be really simple. You had a bad day, you prepped a bad crown. You know, you allowed an impression to go through that had a bubble in it. Or the lab tech was sick, you know, and someone else filled in. Uh, or he said, you know, yeah, you know, something terrible's been going on in my life and you know, I haven't been myself and I'm not focusing. You know, there's always something that changes. And if you're methodical, you can find it.

Dr Liam White 40:51

So just I guess I know we've sort of run a bit short on time, but to summarize for people who want to go home on a Monday and do what you're doing. And do it. Do it. So just to clarify the steps of procedure. So step one, you check it on a dye. You'll check the context first on your dye and you push down. You want to feel that almost like resistance to seating. Yes. Like it's almost not going to seat. Seat. And then you'll go around on that dye and you'll literally grab a sickle probe and you'll push it down hard and you'll go all around on the the individual dye.

Dr Michael Mandikos 41:18

On the individual, on the section dye. Yeah, not the stone dye with the with the contact process. Yes.

Dr Liam White 41:22

So you'll take it off the one with all the other teeth. Yeah. You put on that one with this, just the dye itself, you'll go around with the probe. Yep. And you'll pretty much repeat that in the mouth. The first thing you've got to sit down, you'll check the contacts, which you've asked most of the time, can you make it tight, please? Make it tight. You want it to be tight so you've got that excess. You check it, you'll get you with the articulating paper between, you'll sit it up down, you'll check it. And that I will when I've watched you, that actually takes a while. Because you have to be it'll be like, touch, touch. Touch, touch. Touch, touch. What do you reckon, Narelle?

Dr Michael Mandikos 41:53

Touch touch. It's true. Otherwise, you open it up too quickly, you get frustrated and you grind too much and you open the contact.

Dr Liam White 41:59

So I guess what I'm trying to say. It's a very slow process. Like it and and you can't take 20 goes sometimes.

Dr Michael Mandikos 42:04

Yes. Yes. Sometimes three or four, but sometimes twenty.

Dr Liam White 42:07

And you go down and you'll you'll check the margin. And you what you're trying to see is if you've noticed on the diet any little overhangs or positive overhangs, you're trying to see if you can reproduce on the mouth. If you can, then you know you can adjust it.

Dr Michael Mandikos 42:18

Yep.

Dr Liam White 42:18

And so that's going on. If there's anything problem, if it's not seating and the contacts are fine, you'll check it with an internal fitter. Yep. You'll either run you'll either round down sharp angles. Correct. Yes, if you can't see it on the obvious on the fit checker, but if there's anything on the fit checker, you'll use, so for an Emax, is it a it's a fine red, correct me if I'm wrong, it's it's the it's a red band bur.

Dr Michael Mandikos 42:39

Red band bur, yeah.

Dr Liam White 42:40

And you'll sorry, yeah, the bur, not the not the handpiece. You'll just adjust it until you see it fully seat on the margin like it did on the dye.

Dr Michael Mandikos 42:46

Yep.

Dr Liam White 42:46

Yeah. Following that, you'll then check the occlusion, which again you've asked specifically to be high. Yep.

Dr Michael Mandikos 42:52

And it's only in one point.

Dr Liam White 42:54

In one point. Yeah, not all. No, but one point. So it's either the really, again, if say, for example, it's molars that are contacting or premolars, it's the functional cusp from the lower. You'd ask that to be high, the buccal cusp high, or you've asked the palatal cusp to be high, or whatever works out better. But it's one, it's only one point of contact. Correct. There's two dots, or yeah, two dots on one fence. Anyways, and then after you've you've again, it's that same touch, touch down, touch, touch down, touch, touch down. And then after that, you you give them to bite down side to side, and you don't want any lines. Nothing in so all you're looking for is two little red dots, and then you get the articulating paper behind it and in front of it to check that you've still got a tug while the crown's in place. Correct. Is that pretty much how to for dummies?

Dr Michael Mandikos 43:41

You say for dummies, but the reality is like we just edit that little bit that you did there, and and that's it. Yes. That's that's the protocol. Cool. Yeah.

Dr Jill Fisher 43:49

Well, we've got a lot more to ask you because now we have to glue it in. And we're going to make that another program because obviously we can spend another hour on that. So any Questions, please send them through to info at codental.com.au. The burrs that Michael mentioned will be available in the show notes, and as Michael mentioned, he has them available also listed on his website, brisbaneprosthodonics.com.au. Liam, thank you for joining us. You're an excellent guest. Thank you, Michael, for sharing everything you do in such great detail and with such class. See you next time.

Dr Michael Mandikos 44:25

Till next time.