Restoring smiles with nanomaterials
Winner of the European Inventor Award 2021
Until the late 1990s, dentists struggled to find an optimal material to secure fillings in place to repair decayed or broken teeth. Commonly used options (composite microfills and hybrid composites) were either too weak for biting surfaces or became dull and unattractive over time.
While working in the Oral Care Division of the American multinational 3M, Sumita Mitra became determined to find an alternative. The root of the problem lay in particle size: hybrid composites were milled from quartz, glass or ceramics. Through daily use, the resin would wear away and the particles begin to protrude. The microfills comprised loosely packed particles that resulted in a weak filler. Initially, Mitra and her team incorporated uniform nanoparticles approximately 20 nanometres in size into resins. While these had better mechanical and optical properties, they remained unsuitable in dentistry. They then tried a new approach and developed a technique for creating loosely bound clusters of nanoparticles of varied sizes. They combined these nanoclusters with precisely engineered individual nanoparticles of varying diameters, resulting in a robust, durable and lustrous material with excellent handling properties. By adding tiny amounts of pigment and altering the nanoparticles' chemical composition, the team also created a range of shades to match individual patients' teeth.
Legacy in dentistry
Mitra's ground-breaking filler FiltekTM Supreme universal restorative was commercialised by 3M and launched in 2002. The product line continues to build on her patented material, with newer generations of Filtek introduced in 2005, 2012 and 2019. The technology and the products developed from Mitra's work are today used by dentists worldwide, benefitting countless patients.
Having retired from 3M in 2010 after 32 years of service Mitra 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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