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 su perior to conventional glass ionomer cements (GICs) but with the command se t 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 t o highlight the improvements in hardness and creep resistance imparted to t he cement through the application of ultrasound. The instant set imparted b y the application of ultrasound provides improved surface hardness and cree p, 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 am ount. Rapid setting allows for shorter chair time and an improved clinical technique, making restorations more convenient for both the patient and cli nician. (C) 2001 Elsevier Science Ltd. All rights reserved.