Bioactive glass ionomer cement (GIC) fillings often eventually need to be replaced. A better understanding of how they form at the molecular level could lead to more durability, say scientists from Queen Mary University of London (QMUL) and Aberystwyth University.
Typical dental glass cement comprises glass powder, liquid polymer, and water. As defined by the United Nations and EU Commission, it’s the preferred nontoxic choice to mercury amalgam, which has been used to fill teeth for almost 200 years.
The researchers used nano-level dentistry to examine 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 to find that dental cement sets in fits and starts rather than hardening continuously. They also identified the moments when the cement starts to approach the toughness of dental tissue during the first 12 hours of setting.
“Our work opens up the possibility of tailoring the strength of nonmercury 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,” said Dr. Gregory Chass of QMUL’s school of biological an chemical sciences.
Understanding these “sweet points” could lead to better applications of GIC fillings and easier treatment options for patients. The findings also could have implications for other industries that use cement, such as construction, and for testing the toughness of other materials.
“The resulting insights are essential for optimization of GIC performance for intra-dental restorations, urgently required with the global withdrawal of mercury amalgam,” said David Watts, editor in chief of Dental Materials.
The study, “Atomic and Vibrational Origins of Mechanical Toughness in Bioactive Cement During Setting,” was published by Nature Communications.