This computational model of glass polymer cement shows the glass particle in the center, surrounded by polymer and water molecules. Image: Queen Mary University of London.Scientists at the Queen Mary University of London (QMUL) and Aberystwyth University in the UK have uncovered 'sweet points' for dental fillings, where the cement used to fill cracks regains elasticity before hardening indefinitely. This could have implications for creating more durable and longer-lasting fillings in the future.
Typical dental glass cement is made from glass powder, liquid polymer and water, and is the preferred non-toxic choice to mercury amalgam, which has been used to fill teeth for almost 200 years. As reported in Nature Communications, the team used nano-level dentistry to measure how the cement sets in real-time.
They looked at the interface between the hard glass particles and surrounding polymer to investigate how the strength of the cement grows as it hardens. Guided by computer models, they used intense beams of neutrons from the Science and Technology Facilities Council's (STFC) neutron and muon source to reveal that dental cement sets in fits and starts rather than hardening continuously. This allowed them to identify 'sweet points' in time, when the cement starts to approach the toughness of the tissue that our teeth are made of, which occur in first 12 hours of setting.
"Most of us have fillings in our teeth and know that a crack means a trip to the dentist for a replacement," explains co-author Gregory Chass from QMUL's School of Biological and Chemical Sciences. "Our works opens up the possibility of tailoring the strength of non-mercury cements by homing in on the special setting points, which we call 'sweet points', to make environmentally-friendly dental fillings that not only last longer but could prevent further tooth decay."
Understanding 'sweet points' of dental cement could lead to better fillings and easier treatment options for patients. "Dental fillings are really complex materials," said co-author Neville Greaves from the Department of Physics at Aberystwyth University. "Using neutrons we have discovered how mechanical toughness develops, element by element. This is fundamental physics in action for the general good."
The findings could also have implications for other industries that use cement, such as construction, and for testing toughness in other materials.
"It is always gratifying to see outcomes such as this coming from science at STFC's facilities and, in this case, our neutron and muon source," said Andrew Taylor, executive director of STFC's National Laboratories. "Neutrons have such a broad range of applications and are used by scientists looking at everything from stresses and strains in plane wings to progressing methods to producing more effective antibiotics. We can see here how a fundamental technique is applied to an everyday issue that we can all identify with."
This story is adapted from material from the Queen Mary University of London, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.