Mechanical properties and bond strength of glass-ionomer cements.
OBJECTIVE
The objective of this study was to evaluate the mechanical properties and bond strength of glass-ionomer cements (GICs) and resin-modified GICs (RM-GICs) that are indicated as restorative materials for the Atraumatic Restorative Treatment (ART) technique.


METHODS
Fifteen disk specimens for the diametral tensile strength (DTS) test and fifteen cylindrical specimens for the compressive strength (CS) test were made of each GIC: Ketac-Fil, Ketac-Molar (ESPE), Fuji IX and Fuji PLUS (GC). Forty human molars were sectioned and embedded in resin with either buccal or lingual surfaces exposed for the tensile bond strength (TBS) test. The surface was ground until a flattened area of enamel or dentin was obtained. After conditioning, inverted truncated cones of GICs were prepared on the flat tooth surfaces. The powder:liquid ratio of Fuji PLUS was adjusted for restorative purposes. Prior to testing, specimens were stored for 24 h (TBS test) and for 1 h, 24 h, and 7 days (CS and DTS tests) in deionized water at 37 degrees C. They were then loaded at a crosshead speed of 1.0 mm/min for CS and 0.5 mm/min for DTS and TBS tests until failure occurred. The data were submitted to two-way ANOVA at 0.05 level of significance, followed by a Tukey-Kramer test for multiple comparisons.


RESULTS
The mean CS values ranged from 90.27 to 170.73 MPa and DTS means from 6.21 to 22.32, with test periods from 1 h to 7 days. The means for TBS ranged from 4.90 to 11.36 MPa and from 2.52 to 5.55 MPa in enamel and dentin, respectively. No differences were found between materials with the CS test except at 1 hour. The resin-modified GIC (RM-GIC) had the highest DTS, with no changes between the test periods, and the highest TBS for both enamel and dentin.


CONCLUSIONS
Among the GICs tested, RM-GIC showed higher values of DTS and TBS.
Pereira
Lúcia Coelho
LC
Anápolis Dental School, Goiás, Brazil.
Nunes
Margareth Calvo Pessutti
MC
Dibb
Regina Guenka Palma
RG
Powers
John M
JM
Roulet
Jean-François
JF
Navarro
Maria Fidela de Lima
MF
D000704:Analysis of Variance; D019245:Compressive Strength; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000379:methods; D003743:Dental Enamel / Q000648:ultrastructure; D003793:Dental Restoration, Permanent / Q000379:methods; D003804:Dentin / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008298:Maleates / Q000737:chemistry; D008963:Molar; D019279:Resin Cements / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
D005899:Glass Ionomer Cements; D008298:Maleates; D019279:Resin Cements; C110713:fuji IX; C110712:ketac-molar; D014867:Water; C040964:Ketac-Fil