Science that makes a material difference

In his cutting-edge laboratory at Dundee dental school, Professor Graham Chadwick pursues his groundbreaking research in a speciality that is making a big impression on students

30 May, 2016 / indepth
 Bruce Oxley    Mark K Jackson

When Professor Graham Chadwick joined Dundee Dental School 26 years ago, the world was a very different place. This was the year Nelson Mandela was released from prison and Margaret Thatcher resigned; it was also the year Tim Berners-Lee created the first web server to lay the foundations of the world wide web.

In terms of the dental world, things have certainly moved on radically since then as well, specifically in terms of the materials that are used and how they are tested.

The son of a Carlisle dentist, Graham followed in his father’s footsteps and studied dentistry at Newcastle, graduating in 1985. His interest in dental materials was inspired by his materials science lecturer John McCabe, now emeritus professor at Newcastle. Graham said that he was one of the few who took an interest in the subject as it was not seen as “stimulating” as other areas. He said: “I think this view is a bit of a shame because materials science is the pharmacology of dentistry. If you make wrong choices about materials and their application, you get in to trouble, so it’s actually very, very important.”

I think if you are just a lab-based person you get out of touch with what is going on, so clinical work is important

Professor Graham Chadwick

After graduation, Prof Chadwick moved into a full-time research role in dental materials at Newcastle, focusing on 3D measurement of new posterior composites. The techniques and collaborations applied in his PhD research would be used later to measure dental erosion. Full-time materials science research posts were rare in the late 1980s but Graham became the first recipient of the Tregarthen Research Studentship which helped fund his research activities.

During this time he also did a locum at his father’s Carlisle practice as well as some sessions in a practice in Newcastle, before undertaking hospital jobs in Newcastle for a couple of years after being awarded his PhD in 1988.

Graham explained that, while he saw a career in research and was keen to continue his interest in materials science, he says it was important to continue his clinical work as well. He said: “All that I do is influenced by my experiences as a practising dentist so I’m not just a lab-based person. I think if you’re just a lab-based person you get out of touch with what’s actually going on, so clinical work is important. Clinical work will occasionally flag up issues about materials, stimulating laboratory investigation that hopefully gives answers to improve the situation.”

It was at this point that Graham came up to Dundee, initially as a lecturer in conservative dentistry. He was promoted to senior lecturer in 1999 and in 2012 to the post of Professor of Operative Dentistry and Dental Material Science (personal chair).

He explained that Dundee has a significant historical pedigree in dental materials, firstly in the form of the late John Anderson who is believed to have penned the first key textbook on dental materials for dental students.

And Graham’s predecessor in the role was Dr Charles Lloyd, a world authority on fracture toughness in resin composites, who did a lot of work on the International Standards scene and introduced him to the area himself.

Graham currently participates on a number of committees looking at International Standards, including filling and orthodontic materials (CH101/1) and prosthodontic materials (CH106/2). He also represents the UK as principal expert at ISO for ceramics, cements with adhesive components, polymer-based restorative materials, impression materials and CD CAM.

The Dundee dental materials laboratory

The materials laboratory at Dundee Dental School is situated right at the top of the building at Park Place and was refurbished three years ago to Graham’s precise specifications. The lab focuses upon the aetiology and prevention of dental erosion and the performance of the materials used to treat this condition. The lab supports undergraduate materials teaching, the Dundee-taught masters course in prosthodontics as well as those undertaking research for higher degrees.

Filled with an array of machines, both mechanical and digital, the laboratory is able to test the hardness, toughness and durability of a range of materials and substances. Alongside the computer screens there are a number of pieces of equipment that Graham explained are not in regular use anymore but serve a very important function, such as the valve- driven Instron machine from the 1950s. He explained that the older pieces of equipment actually give students a better idea of what is going on in some cases.

He said: “These older machines provide a more visual means of teaching people how testing equipment works because you can actually feel and see how it works. Whereas when we get on to our more modern pieces of equipment, that in some cases have superseded the ones that we’ve retained, it’s just an electronic box of tricks and it’s difficult to see what’s actually going on.”

And one of the areas that Graham explained he is most proud of is the development of three robots – Romulus, Remus and Hadrian – that measure in vivo tooth wear. Bizarrely, their creation involved a collaboration with an oceanographic surveyor from Australia and engineers in medical physics. Graham met the surveyor, Dr Harvey Mitchell, during his time at Newcastle when Mitchell was across from the University of Newcastle in New South Wales. He contacted him again in the late-1990s when he was continuing his research into tooth wear.

He said: “Through Dr Mitchell we devised a system for measuring the wear of these new composite materials. At that time we were placing them on denture teeth in order to make replicas readily and they were photographed down a microscope in stereo. He taught me to use an old-fashioned Second World War stereo comparator – big plates and wheels in a dark room where we could data log and fly something called a floating mark about on the surface, so that was in essence 3D measuring. Although rather crude.”

The development of these robots was state of the art in the late 90s and produced an early form of “DIY CAD/CAM”. Graham continued: “I think the development of Romulus, Remus and Hadrian has to be one of the proudest moments in my time at Dundee. Their findings challenged the assertion that erosion was cause and effect and indicated that individual susceptibility played a major role.”

More recently, erosion research has led to the development of an artificial mouth model called Saltus which, following the Roman theme, is named after the Roman garrison town near where PhD student Abubaker Qutieshat is from originally. Earlier this year the model won the European Federation of Conservative Dentistry Merit Award for its ability to mimic the interaction of saliva and the dental substrate during the process of consuming an erosive beverage.

And, due to the difficulties in sourcing human teeth for use in the laboratory, Graham and Abubaker have managed to find quite an unusual tooth substitute, namely ostrich eggshell. He explained: “Our initial results, because we’re still in the early days yet, indicate that it is quite good. It is also very thick, so from a little square that we might cut out of it we have a lot of mileage for the erosion research.”

Graham explained that, unlike human teeth where the red tape needed to source is prohibitive, the ostrich eggs can be easily bought quite cheaply on Amazon. He said: “When we started the work on the artificial mouth we envisaged we’d get through a lot and we actually haven’t even got through one because they’re so big!

“We would envisage this substrate as a preliminary screener reserving scarce tooth tissue to more detailed testing of promising drink formulations.”

The next generation

Dental students at Dundee get their first taste of the materials lab in first year and Graham believes these practical lessons are important to supporting their undergraduate tuition.

“First-year students, who haven’t met patients yet, will do practicals on impression materials and they’ll come in to use some of the testing equipment in here to find out about the properties of those materials that they’ve been taught about in lectures,” he said.

“I think the students appreciate this because, certainly in the early years of the undergraduate programme, they can feel that there’s a lot of science and they’re looking to translate that to the chair side.”

And, in their final year, Graham explained another initiative in the dental materials course, the Dental Materials Den, which has really brought the subject alive for students. The final years are separated into small discussion groups and are tasked with developing a new (theoretical) material. They take an existing material and they have to give it a novel tweak before presenting their idea to their peers and a sceptical panel of judges including a sales rep and scientific rep from a dental company.

He said: “It brings materials alive and that’s the point really. The students actually do get genuinely excited about materials which is a good thing.

“They participate in arguing and questioning their peers with sensible scientific questions, which is good because it all feeds back into the learning process.”

Graham explained that while one might expect there to be a lot of funded research going on in the dental materials field, the number of pure dental funded research projects is very small. Most of it is done at company level but he believes the clinical academic and the GDP still have roles to play.

He said: “Even today products will come onto the market but, although they might comply with a standard, there may well be issues. A clinical academic or a GDP can sometimes spot something and it has been known for products on the market to suddenly come off the market because someone with a box of materials has found something new and surprising, and tested it in a different way.”

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