title: Ultrasonic monitoring of the setting of glass-ionomer luting cements.
abstract: This study used ultrasonic measurements to monitor the setting behaviour, and changes in the elastic modulus, of glass-ionomer cements. The ultrasonic equipment comprised a pulser-receiver, transducers, and an oscilloscope. The two-way transit time through the mixing cement disk was divided by two, in order to account for the down-and-back travel path, and then multiplied by the sonic velocity within the material. The sonic velocities of the longitudinal and shear waves were used to determine the elastic modulus. In the earliest stages of the setting process, most of the ultrasound energy was absorbed by the cements and the second echoes were relatively weak. As the cements hardened, the sound velocities increased until they reached a plateau. The changes in sound velocities differed among the glass-ionomer cements tested. The mean elastic moduli of the specimens ranged from 2.6 to 6.2 GPa after 15 min, from 13.4 to 20.4 GPa after 24 h, and from 11.4 to 22.4 GPa after 1 month. The ultrasonic method used in this study has considerable potential for determining the setting processes of luting cements.
authors.affiliation: Department of Operative Dentistry, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Kentarou
authors.initials: K
authors.lastname: Mori
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Inage
authors.forename: Ryo
authors.initials: R
authors.lastname: Kawamoto
authors.forename: Motoka
authors.initials: M
authors.lastname: Tonegawa
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kurokawa
authors.forename: Keishi
authors.initials: K
authors.lastname: Tsubota
authors.forename: Toshiki
authors.initials: T
authors.lastname: Takamizawa
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
mesh_terms: D003764:Dental Materials / Q000737:chemistry*; D004548:Elasticity; D005899:Glass Ionomer Cements / Q000737:chemistry*; D013997:Time Factors; D014465:Ultrasonics
chemical_list: D003764:Dental Materials; D005899:Glass Ionomer Cements