A preliminary comparison of the mechanical properties of chemically cured and ultrasonically cured glass ionomer cements, using nano-indentation techniques

There is a requirement for a dental cement with properties comparable or superior to conventional glass ionomer cements (GICs) but with the command set properties of the resin-modified GICs. The objective of this work was to show that the application of ultrasound to conventional Fuji IX commercial glass ionomer cement imparts a command set, whilst improving the short-term surface mechanical properties. Nano-indentation techniques were employed to highlight the improvements in hardness and creep resistance imparted to the cement through the application of ultrasound. The instant set imparted by the application of ultrasound provides improved surface hardness and creep, particularly within the first 24h after setting. The surface hardness of the chemically cured Fuji IX (176 MPa) increased by an order of magnitude when set ultrasonically (2620 MPa), whilst creep reduced to a negligible amount. Rapid setting allows for shorter chair time and an improved clinical technique, making restorations more convenient for both the patient and clinician. (C) 2001 Elsevier Science Ltd. All rights reserved.