Indian-American chemist Sumita Mitra named European Inventor Award 2021 finalist
New Delhi, India, 6 May 2021 – The
European Patent Office (EPO) announces that the Indian-American chemist Sumita
Mitra has been nominated as a finalist in the “Non-EPO countries” category of
the European Inventor Award 2021. Mitra was the first to apply nanotechnology to
the production of dental materials, leading to the creation of a new composite to
repair teeth which has many advantages over conventional materials.
Mitra’s material
overcomes many of the limitations of previous dental composites, which were
either too weak to be used on biting surfaces, or quickly lost their polish and
became physically unattractive. In addition, her invention is more
versatile than other composites, meaning it can be used in any area of the
mouth, and simplifies the filling procedure for dentists. Commercialised as Filtek™
Supreme Universal Restorative since 2002 by 3M, the US multinational for whom
Mitra worked for more than 30 years, the technology and the products developed from
it are today used by dentists around the globe.
“Mitra’s invention takes what was an emerging
technology at the time – nanotechnology – and applies it to a new sector to provide
a solution for dentists and relief for patients,” says EPO president António Campinos,
announcing the European Inventor Award 2021 finalists. “Patents have protected Mitra’s material
and helped ensure that her invention remains commercially successful nearly 20
years after its launch.”
The winners of the 2021 edition of
the EPO's annual innovation prize will be announced at a ceremony starting at
19:00 CEST on 17 June which has this year been reimagined as a digital event
for a global audience.
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European Inventor Award 2021 finalist Sumita Mitra |
Making a new nanomaterial
Until
the late 1990s, dentists wishing to perform natural-looking tooth repairs
relied on a combination of two materials: composite microfills, which were
aesthetically-pleasing but too weak to be used in teeth towards the back of the
mouth and biting surfaces; and stronger, but less attractive hybrid composites.
A key problem was the size of the filler particles which are suspended in the
resin to impart it with strength, colour, and opacity. Traditionally, these fillers
consisted of dense, large particles, such as quartz or glass, milled down into
finer particles – but as the resin gradually wore away, these particles begin
to protrude from the material or were plucked from its surface, resulting in
bumps and craters which scattered light. The result was a filling which quickly
lost its reflectivity and polish.
It
was while working in the oral care division of US multinational 3M that Sumita
Mitra became aware of the limitations of existing composite materials. At the same
time, nanotechnology was emerging as a field of research and Mitra decided to
explore how these new developments could be applied to dentistry. She began working
on nanotechnology-based solutions for a new dental material, driven by a desire
to use her expertise in polymer
chemistry and materials science to develop inventions that solve
real-life problems for people.
Mitra’s
idea was to replace composite fillers with nanoparticles – ultrafine particles
measuring between 1 and 100 nanometres in diameter – which are smaller than the
wavelength of visible light and do not therefore scatter it, resulting in a
material which retains its shine. At first, Mitra and her team at 3M
incorporated uniform nanoparticles measuring less than 20 nanometres in size (1
nm is a billionth of a metre) into resins, but although the materials they
created were strong and attractive-looking, they were difficult to mould,
making them unsuitable for dentistry.
She
and the team therefore developed a technique for creating linked clusters of
nanoparticles, which they called ‘nanoclusters’, combining these with single
nanoparticle of varying diameters, resulting in a strong, durable and shiny
material, with excellent handling properties. By adding tiny amounts of
pigment, and altering the chemical composition of the nanoparticles, the team
also created a range of different shades, which can be matched to individual
patients’ teeth, and layered to create a more natural finish. “The use of
nanotechnology gave me the opportunity of making a new material,” says Mitra.
“It restores peoples smiles and improves the quality of their lives”.
Following
the successful development process, Mitra worked closely with 3M’s patent
attorneys to construct the patents to protect her ground-breaking work. Besides
her contribution to the Filtek range, Mitra is named as inventor on 58 granted
European patents
for inventions that have resulted in various dental innovations including
resin-modified glass ionomers and new adhesives which can be found in other 3M products.
“The patent was essential for safeguarding the invention so that others could
not infringe on the technology,” she says.
Lasting
impact in dentistry innovation
The
material based on Mitra’s work, Filtek™ Supreme Universal Restorative, was
launched by 3M in 2002 and, although several new generations have been
developed since, the current line of products is still based on Mitra’s
European patents. 3M
regards the material as unique because it combines durability with aesthetic
qualities not reached by competitors’ products which rely on micro- or
nano-hybrid fillers instead.
Mitra’s invention has contributed to the company being
named as one of the top three manufacturers for the global composite
filing in the dental restoration market in 2019. The
material’s strength is its versatility according to her: “You have all the
desired properties of a tooth filling in one material. That is why this
technology has been used to make so many different types of tooth restorations
around the world.”
Although Mitra
retired from 3M in 2010, the enduring success of her invention continues with Filtek
products used in one billion tooth restorations worldwide by dentists to date. Today
she continues to contribute to research and development
through her own consulting company. She also volunteers in her community and
hopes to inspire young people to develop an interest in science.
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