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.