The history of dental materials

There are many applications of materials in dentistry, and there are many stories attached to the application of materials in dentistry. And what I always like to do with my students is to put the use of materials in context as to where these materials came from so that the students realise that they don’t just pop out of thin air. And one of those stories is the story associated with the manufacture of dentures. You probably know somebody who wears a denture. And we currently have plastic dentures. But way back, it wasn’t like that. And we have to go right back to the beginning of the 18th century with the introduction of porcelain as a manufacturing base within Europe.

Until the beginning of the 18th century, porcelain was actually only imported from China. We didn’t know in Europe how to make porcelain. And it wasn’t until a French Jesuit priest called Father d’Entrecolles actually came back from a missionary visit to China to tell everybody in Europe how to make porcelain. He discovered by going to a place called Jingdezhen how the Chinese made their porcelain. And it wasn’t that difficult in the sense that it only involved using three ingredients. Kaolin, which we know is clay, silica, which we often know as quartz, and a glassy material called feldspar. And if you mix those the right way, then you get something called porcelain.

And it’s from that point onwards that the Europeans started making porcelain. So companies like Meissen evolved at that time, Sevres in France evolved at that time, producing high quality porcelain. So by the middle the 18th century, porcelain started being used by French dentists to make dentures because porcelain lends itself well to reproducing the colours of the teeth and the colours of the soft tissues. And so you can produce very nice looking dentures. They weren’t particularly functional at the time because dentists didn’t really understand what would make a good or bad denture. But they were purely for aesthetic purposes, in other words.

And in actual fact, if anybody had a denture like that, when they wanted to eat, they had to remove the denture and eat without it, which made it look often that people lived on air, because any lady would not be seen taking a denture out at a dinner table. And so they would not eat their food. And everybody was wondering why their plate was still full at the end the dinner. But they would have made sure they had dinner before they had dinner, if you see what I mean. And so they were not particularly functional, but they looked good.

At the same time, they started making dentures out of ivory, carving them from ivory because ivory is a beautiful material to shape. And they would then make the base out of ivory. And then the teeth were either collected from cadavers, or they would have been made out of porcelain to fit into the ivory. And so, again, not a particularly functional denture, essentially only really just there for aesthetic purposes. The most well-known denture in that category is actually the dentures worn by George Washington. He had a number of dentures made. One of his dentures was claimed to weigh something in the region of about two pounds because the base of the denture was lined with lead.

And to allow the upper denture to stay in place, there were springs attached to push it up against the upper part of the mouth, what we call the palate. And so that was the state of play for quite some time and very, very exclusive use of dentures. So people would either have them made out of porcelain or carved out of ivory. This situation then changed in the middle of the 19th century with the introduction of vulcanite. Vulcanite was a method of taking rubber and curing it to make it into a very hard rubber by a process called vulcanization. This was invented by Charles Goodyear in the middle of the 19th century.

And at that point then, one could make dentures out of vulcanite. It was a much cheaper material to use, and much easier to process. And consequently, the demand also would rise, and more people could afford to have dentures at that stage. The one thing that was holding it all back was the fact that to have a denture made, you have to have all your teeth out because at that stage, they weren’t really particularly good at making partial dentures. And so having your teeth out at that time was a very traumatic experience because you have to think what that might feel like when you don’t have any anaesthetic to have all your remaining teeth removed.

And so there wasn’t a great demand for the dentures because people still had problems having all their teeth removed. That situation also changed in the middle of the 19th century because of the discovery of anaesthetics. And most people don’t realise this, but anaesthetics were actually discovered by a man called Horace Wells, who was a dentist in America. And the way he discovered it is quite an interesting little story. He went to a musical with a friend of his. And at that time in the music hall, they discovered the interesting features of laughing gas or nitrous oxide, as we should call it, really.

And so what they did was they actually got people from the audience to come up onto the stage and exposed them to nitrous oxide and then see how they reacted to it. And obviously, everybody had a really good time to see all these people behaving silly on the stage. Now, the problem with nitrous oxide is sometimes people just laugh and get very funny, and other people can get quite aggressive under the influence of nitrous oxide. And Horace’s friend actually got very violent under the influence of the nitrous oxide, and had to be subdued by a number of people on the stage. In the fight that took place, as they tried to subdue him, he actually cut his leg quite badly.

And when he came out from the influence of the nitrous oxide and he was guided back to his seat, he sat down next to Horace Wells. And Horace looked at him and said, here, you’ve cut your leg. And he said, well, I didn’t feel it. I didn’t feel a thing. And Horace put two and two together, and thought, well, maybe this is because of the exposure to the laughing gas. So the story goes that the next day he actually went and got himself some laughing gas, exposed himself to laughing gas and then actually extracted one of his own teeth to see if it would hurt or not. And of course, it worked.

And he then told the world about this discovery, which was very nice of him because he could have patented the discovery and made a lot of money for himself. He didn’t, so we all got the benefit from it. Unfortunately, he didn’t see much benefit from it, because he actually died at a very young age. He was only 33 when he eventually died. But it did mean that new things could happen, like the introduction and the invention, I suppose, of the dental drill. Because until then, the dental drill wouldn’t have a place. And that also meant once you had the dental drill, you could see filling materials beginning to appear.

So by the end of the 19th century, we would have filling materials as well and so on. Of course, going back to the dentures, now we have lots of people looking for dentures because they can all have their remaining teeth extracted relatively painlessly. So the demand for dentures would rise phenomenally. This was all great news for Charles Goodyear because he actually charged dentists $1 a denture to use his patented process. So he was actually making money out of dentistry, so to have lots of patients needing dentures was very profitable for him. And then the situation really changed again in the 1930s and 1940s. In the early 1930s, they discovered how to make acrylic resins.

It was part of the plastics revolution that was taking place at the time. And the acrylic resins were one example. And people might recognise it as Perspex or Plexiglas, the kind of product names that one would come across. And they started making acrylic dentures in the 1940s and early 1950s, and refining that process. And somewhere else in this programme, you will actually learn how a denture is made. And we still to this day make dentures out of acrylic resins and are still looking for novel ways of making dentures with new materials. But again, that’s another story. Thank you.