Materials of the future

The quest for a direct dental restorative material that combines the ease-of-use and durability of amalgam with the biocompatibility and esthetics of composites has lead a team of scientists at Southwest Research Institute (SwRI) in San Antonio to develop a material concept on a nanometer (10-9 meters) scale.

According to Kent Coulter, Ph.D., SwRI Surface Engineering & Materials Chemistry Section Manager, the process involves evaporating zirconia then condensing it onto a roll of PET film substrate that has been nanoembossed with a checkerboard pattern that transfers to the condensed zirconia layer. Once the patterned substrate is dissolved, the zirconia layer breaks off into flake-like nanoplatelets that measure 200 nm by 200 nm and are only 40 nm thick.

“The key is the flat shape,” said Coulter. “It has a high aspect ratio with around 395 times more surface area than a sphere with the same mass.”

The zirconia nanoplatelets are then incorporated into a liquid crystal polymer matrix that causes the flakes to orient in a specific direction, which Coulter said allows the zirconia to self-heal in the event of any crack formation through aphase transformation. In addition, the liquid crystal polymer would act as a delivery medium for the zirconia material. “It would be delivered just like a standard dental composite,” said Coulter.

Not quite yet

A practical zirconia nanoplatelet restorative is not quite ready for chairside availability. “We’ve demonstrated the science behind it, now we are in the that product development phase,” said Coulter. Part of the problem now is that the material at its current stage of development needs to be thermally cured to achieve the desired hardness. Coulter added that research continues on developing the material into a form that can be photocatalyzed using a standard UV dental curing light.

While SwRI has applied to continue the National Institutes of Health-funded research program, the practical application of the material is starting to attract outside interests. “We’re in the process of working with a couple commercial clients to take it to the next step,” said Coulter. “That is where we’ll focus our efforts.”

About SwRI

Southwest Research Institute is an independent, nonprofit applied research and development organization. The staff of more than 3,200 specializes in the creation and transfer of technology in engineering and the physical sciences. SwRI occupies more than 1,200 acres in San Antonio, Texas, and provides nearly 2 million square feet of laboratories, test facilities, workshops and offices.