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Light-cured lining materials: a laboratory study
1School of Dental Science, University of Melbourne, Australia.
Objectives:
The purpose of this study was to compare seven light-cured lining materials (four glass ionomer and three non-glass ionomer), with a chemical-cured glass ionomer lining material.
Methods:
Specimens were prepared and tested according to the methods prescribed in Australian/International Standards for compressive strength, diametral tensile strength, depth of cure, radiopacity, and acid erosion. Other tests were adhesion to dentin and adhesion to resin composite.
Results:
Compressive strengths ranged from 48.6 MPa to 307.1 MPa, and diametral tensile strengths from 5.8 MPa to 34.8 MPa. Most of the light-cured materials were stronger than the chemical-cured glass ionomer. Depth of cure increased with increased irradiation times, with values of 0.63 mm to 6.43 mm for 60 s irradiation. Radiopacity was in the range of 0.91 mm Al to 1.07 mm Al. All materials were unaffected or only slightly affected by acid erosion. Adhesion to dentin was effectively zero for the non-glass-ionomer products. Adhesion to composite was from 6.23 MPa to 25.1 MPa, and thermocycling affected only three light-cured and the one chemical-cured glass ionomer.
Significance:
All products complied with the requirements of standards, where available. Incremental placement and curing is necessary for some products. Adhesion to dentin is better with glass ionomers, whereas their adhesion to composite may be unreliable.