Image of glass cement fillings,
copyright Semmelweis University Dental School
(November 9, 2015) Scientists led by Queen Mary University of London (QMUL) and Aberystwyth University have revealed ‘sweet points’ for dental fillings, where cement used to fill cracks regain elasticity before hardening indefinitely. This could have implications for creating more durable and longer-lasting fillings in the future.
Typical dental glass cement, a UK innovation, is made from glass powder, liquid polymer and water, and is the preferred non-toxic choice* to mercury amalgam, which has been used for filling teeth for almost 200 years.
Publishing in the journal Nature Communications, the team used nano-level dentistry to measure how cement sets in real-time.
They looked at the surface between the hard glass particles and surrounding polymer as the strength of the cement develops.
Guided by computer models, they used intense beams of neutrons from the Science and Technology Facilities Council’s (STFC) neutron and muon source, to find that dental cement sets in fits and starts rather than hardening continuously. The findings identify ‘sweet points’ in time: when the cement starts to approach the toughness of the tissue that our teeth are made of and occur in first 12 hours of setting.