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UBC Theses and Dissertations

Effects of aging on dentin bonding and mechanical properties of restorative glass ionomer cements. Chander, Kunal


Objectives: To examine changes in shear bond strength to dentin (SBS), flexural strength (FS) and diametral tensile strength (DTS) of four restorative glass ionomer cements: Fuji II LC (GC/America), Equia (GC/America), Ketac Nano (3M/ESPE), and Ketac Molar (3M/ESPE) after aging in artificial saliva. Materials and Methods: For SBS testing, sound extracted human permanent molars were ground to flat occlusal dentin surfaces and fixed in circular molds with auto-cured acrylic resin.. Teeth were randomly divided into four groups: Fuji II LC, Equia, Ketac Nano, Ketac Molar. For each dentin surface, two glass ionomer cylinders were bonded. Specimens were stored in artificial saliva (37°C) and tested at 24-hour and 6-month time points (Shear Testing Machine, Bisco). For each material, FS bars (25mm x 2mm x 2mm) and DS discs (4mm x 2mm) were fabricated, stored in artificial saliva (37°C), and tested at 24-hour and 6-month time points. (Shimadzu). An additional FS study was conducted with glass ionomer specimens, stored either in distilled water or artificial saliva (37°C), and tested at 24-hour and 2-month time points. (Shimadzu). Data analysis included two-way ANOVA (p<0.05) with post-hoc Tukey’s tests to compare interactions. Results: There were no significant differences in SBS after 6 months storage, except for Ketac Nano, which showed a significant decrease in bond strength after aging. There were no differences in SBS among the four glass ionomers, at 24 hours or 6 months saliva storage. The diametral tensile strength values did not change significantly after aging except for Fuji II LC. All materials had a significant increase in flexural strength after aging regardless of the storage media (water or saliva). Fuji II LC had significantly higher DS and FS compared to other materials, at both 24 hours and 6 months storage. Conclusions: Aging did not affect SBS of materials except Ketac Nano. Flexural strength of all glass ionomer cements increased over time. Storage media did not affect flexural strength properties. Diametral tensile strength remained unchanged over time for all materials. Overall, Fuji II LC had superior mechanical properties compared to other materials.

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