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Smile, and the world smiles with you, so the old saying goes. Many people stop smiling, or hide their smile as the years go by, because they are embarrassed by the state of their teeth. A major focus of 21st Century dentistry is restoring the power and beauty of a smile through an innovative combination of engineering, art, science and technology that is improving oral health, and change lives dramatically along the way. In the first of a two-part series, Johannesburg dentist Dr Sam Thandar spoke about his revolutionary use of laser technology to take the fear and pain out of visiting the dentist. In the second part, he explains how he uses computer aided design and milling (CAD/CAM) technology to restore decaying and broken-down mouths, and helping people to smile widely with confidence again. Here’s what he has to say. – Marika Sboros
I’m Marika Sboros from Biznews Health. This is the second of a two part series on dentistry in the 21st Century. I’m talking to Dr Sam Thandar. He is principal dentist and medical director of Thandar Inc, a revolutionary dental practice in Rosebank, Johannesburg. Sam, in the first series, we spoke about very innovative use of laser equipment and today I’d like to speak to you about CAD/CAM. First of all, what does it stand for?
CAD/CAM is actually an acronym for Computer Aided Design/Computer Aided Milling. It is something that has revolutionised our dental practice and our patient experience. It has made dentistry exciting for our practice because we now have full control, in terms of everything that we do.
For most people out there, at some point in their lives, they’ve probably had a crown done or an implant crown, a filling or a veneer, or something along those lines.
Or all of those things?
Absolutely, or all of those things together. Generally, you go to the dentist, you have your first anaesthetic, they do the preparation on your teeth, take all sorts of moulds and impressions of the remaining tooth structure, then send it off to a dental laboratory. You leave the practice with a temporary cap on. You come back a week or two weeks later to have the work fitted on. It’s a second appointment, a second anaesthetic, the fitting and off you go. That’s the conventional way of doing these sorts of procedures.
And it’s the long way?
And it’s the long way, and in today’s day and age, people don’t have time to come up and down. Time is really a scarce resource.
With our CAD/CAM unit, if you come to into the practice and for a ceramic filling, we would go in there, prepare the tooth structure, remove the decay, and remove the existing filling, or whatever may be. Instead of doing an impression, a conventional impression, we then take a digital 3D impression of the remaining tooth structure.
Is that all with the CAD/CAM?
Yes, that’s with the CAD component of the CAD/CAM, and all it is is pretty much taking a high-resolution photograph, for lack of a better description. We then take multiple images of this, so if I’m working just on one tooth I would take images of four, to five, to six teeth on the same arch, on the opposing teeth, on the bite and the unit then takes all these images that I’ve expose, and stitches them together to create a virtual 3D model of your mouth.
It then looks at genetic biting patterns at how your teeth come together, and anatomical variations on the tooth surface, and then creates a proposal, for what your filling or new cap needs to look like. Once we are happy with this design, we then send that information wirelessly, through to our milling unit, which is also onsite, and a ceramic block that’s placed in there, and the mill actually machine cuts the exact specification, out of that ceramic block.
The entire turnaround time, from start to finish for a crown at our practice is, on average, about an hour.
How does that compare with the old way?
Compared with the conventional way, you would come in for about an hour, the first time around, or an hour-and-a-half, and then probably another 45 minutes – two weeks down the line for a single crown. We can now do something like that in 45 minutes to an hour, from start to finish.
The important thing is firstly, you leave with the end result. There are no temporaries, and temporaries introduce a lot of bacteria into the mouth because they are very porous materials. It’s pretty much bacteria-static.
What does bacteria-static mean?
It doesn’t allow bacteria to adhere to the surface on that, and that way we find that the gum and the tissue responds a lot more favourably than having a temporary in there over a prolonged period.
The second advantage is that these ceramic restorations are very much enamel like, so it’s almost like putting on a layer of synthetic enamel (if I’m doing a cap) or putting on a synthetic enamel-like veneer onto the tooth structure.They are highly biocompatible materials.
The third big advantage is that these ceramics are fully bonded onto the remaining tooth structure, whereas conventional crowns tend to be cemented on and that cement interface tends to undergo some breakdown over a period of time. It’s susceptible to moisture absorption, and with that you do get some bacteria building up underneath.
With the bonded restoration – bonded restoration seems to be the gold standard, in terms of dentistry moving forward, purely from the fact that we get a high quality seal, we get a seal that is impervious to moisture, (in most cases). At the same time, when you bite down on a tooth you instantly have a nerve response going to your TMJ (to your joint) saying how much pressure you’re creating on the tooth. That’s where the tooth is. That’s how hard the material actually is, and for example, you bit onto a peppercorn and instantly you would get the jaw reflex saying: “That’s too hard – release.”
With these ceramic restorations that are fully bonded onto the remaining tooth structure, we’re still maintaining a great degree of that nerve response coming back from the joint. It’s not dulling that nerve response.
For me one of the biggest advantages with CAD/CAM dentistry is that the preparation on the remaining tooth structure is minimal – to the point that we can make our ceramic caps at 500 microns thick. You can imagine: we’ve got to file away or remove a lot less tooth structure underneath to create space for 300 or 500 microns of ceramic.
From a conservative perspective, I absolutely love this technique of dentistry, even more so when we are doing our cosmetic cases. Generally, in most cases, the cosmetic work we do is on teeth that are really damaged, that need some form of reconstruction.
I’ve noticed a growing trend with younger patients coming in for cosmetic work, which I’m very reluctant to do anything extensive on them. I tend to be as conservative as possible – look at an option like doing some ceramic veneers or minimal preparation veneers. In that case, there is very little damage or very little preparation or removal, of underlying tooth structure that we need to create, to accommodate these ceramics bonding on.
Right, so it’s also not just about cutting down on time, but you are getting a much better result that also lasts longer.
Absolutely. It’s a much better, more conservative result, and it’s highly accurate. A lot of studies have shown that taking a digital impression is far more accurate than taking a conventional impression, because when you take a conventional impression, there is some distortion of the impression material. There always has to be. That’s why our preparation style can be super non-invasive purely because we don’t have to create extensive areas to work in. We need to remove what’s necessary, replace what we’ve removed, and that’s what it allows us to do.
When it comes to CAD/CAM, it’s very important knowing exactly how to use the unit, and understand what it can do – understanding the limitations and almost starting to think the way the computer thinks, you know. I think there’s about eight or nine algorithms running in the background, just to create what the surface of that tooth is going to look like, and that’s building information from all the remaining teeth that are there.
There’s a specific way you need to scan with it and prepare the tooth, to enable and maximise the benefits that you get out of it.
From that perspective, it really is an exciting unit, and it can do a lot for our patients. One of the things I like most is the aesthetic value and the cosmetic side of how great these restorations look, once we’re done.
They look almost identical to natural teeth, in terms of thickness and shape, and colour translucency and light translucency, so from that perspective we are very pleased with it.
How many restorations have you done with the unit?
We’ve done over 10,000 restorations with our CAD/CAM unit, to date, and there are specific parameters that can play around with on the CAD unit, in terms of setting the minimal of thickness and how you design that restoration, and there’s very much a human element that it requires. It’s a little bit like art.
Two of us at the practice can do exactly the same patients, but from a cosmetic and a profiling perspective, get a different result. So you can rely on the unit to do its standard thing, or you can get in there and get really creative and maximise the benefits – get the lines in a specific angle, and get the ceramics to reflect light in a specific way.
That’s the part of dentistry that excites me the most, because it requires a great degree of engineering and understanding what’s going on the background.
It requires a great degree of skill, in terms of how you prepare the tooth and the finesse you use, and still getting the exact dimensions you want but still being very conservative about it. Then taking all that information and actually getting really creative, with the artistic side of it, and designing that ceramic to make it look like a real, live tooth.
To know exactly on, for example, a central incisor there’s a millimetre-and-a-half translucency that we want at the tip. We want the edges to curve up at three degrees on the one side, and five degrees on the other. We want some corrugation and texture on the surface of that ceramic, and we want to create mamelons and papillas, and these are natural little things, and perikymata (ridges), and all these funny little weird things which you’d find on a natural tooth.
We want to create that, but in a way that it looks like it always belonged there. Like when we do our cosmetic cases, we take teeth that are, generally, pretty damaged and worn down. They are aesthetically, unpleasing, and we transform them.
If you look at the way the Americans do it – I think it looks ridiculous because you look at those teeth, and you know straight away they are completely synthetic, artificial.
The Hollywood smile, yes.
There’s absolutely no life, no character, no gradient, no embrasures, no line angles – it is just a perfect set of piano keys, for lack of a better description.
We take our patients coming in for cosmetic work and I often look at their photographs from 15 to 20 or 30 years ago, or whatever it is, to build some information, but there’s a lot of other factors that we’ll look at. I look at the distance between the outer canthus of your eyes and look at the width of your nose. I look at the shape of your forehead.
It never occurred to me you would need to look at people’s facial structure, eyes, and nose, when designing teeth?
Absolutely, also the shape and taper of the jaw, distance from the bottom of your nose to the bottom of your chin. We take all that information into account. There’s a piece of clever software that they’ve designed that’s called Smile Design, so I can actually take physical measurements of those parameters, input it onto the unit, so the scan, the preparation and let the unit create a proposal.
In most cases, I like treating it as a completely blank slate, so I design it completely out of what I would think would look great in that patient’s mouth.
I always think of dentistry as a combination of engineering, science and art – all pretty much put together. Over and above all of that, is a psychologist or psychiatrist sitting at the top, knowing how to deal with and interact with people, to build that rapport.
I see my patients coming in for the first time or for their first consultations and they are very reserved. They tend to hide their smiles, to smile in a way that they don’t want to show their teeth. And then I see them a few weeks late after the procedure, and it’s the same person, but a completely different personality and a completely different zest for life, and a completely different energy.
It’s amazing what a smile can do, so that’s why we do what we do, so yes, I think we’ve got a very interesting future in dentistry lying ahead.
I’d say so. Thank you for talking to me, and to my listeners out there, thank you for listening.