IADR Abstract Archives
Acid Resistance of Lithium Disilicate Glass Ceramics
Objectives: Recently, Lithium Disilicate Glass Ceramics (LDS) have been widely used, especially for esthetics restorations. Esthetics are more important for ceramic restorations in anterior teeth and acid resistance is also an important factor for long-term esthetics. Bleach shades of glass ceramics are often used in esthetic areas. Bleach shade for Initial LiSi Block was recently developed to fulfill the esthetic needs from the clinicians. The purpose of this study was to evaluate the acid resistance for bleach shade LDS blocks in comparison with, uncolored zirconia (3Y-TZP), and another shade of LDS block.
Methods: Three test groups were prepared, 1) Bleach shade of Initial LiSi Block (GC, LS), 2) Bleach shade of e.max CAD (Ivoclar Vivadent, EM), and 3) Initial Zirconia Disc HT (GC, ZR). In addition, A2HT shade of Initial LiSi Block (GC, LS-A2HT) was used as a control. Flat specimens of LDS 15 x 13 x 2mm were sliced from the blocks, and EM were heat-treated for crystallization according to the manufacturer’s instruction. Afterword, these samples were polished by P1000 Diamond paper. Specimens of ZR were milled, fired following instruction, and finally polished by P1000 diamond paper in the same size as LDS specimens. Acid resistance was evaluated using the test method based on ISO6872. Specimens were immersed in 4vol% acetic acid solution at 80°C for 16h. Dissolved amount was calculated from the difference in specimen weight before and after immersion (n=3). Data were statistically analyzed by one-way ANOVA and Tukey-test (p<0.01).
Results: Table indicated that LS had significantly less amount of acid dissolution than EM. In addition, dissolved amount of LS was at the same level as ZR and LS-A2HT.
Conclusions: The acid resistance of bleach shade of Initial LiSi Block was comparable to zirconia and already released Initial LiSi Block. This indicated that it can be useful in esthetic areas.
Methods: Three test groups were prepared, 1) Bleach shade of Initial LiSi Block (GC, LS), 2) Bleach shade of e.max CAD (Ivoclar Vivadent, EM), and 3) Initial Zirconia Disc HT (GC, ZR). In addition, A2HT shade of Initial LiSi Block (GC, LS-A2HT) was used as a control. Flat specimens of LDS 15 x 13 x 2mm were sliced from the blocks, and EM were heat-treated for crystallization according to the manufacturer’s instruction. Afterword, these samples were polished by P1000 Diamond paper. Specimens of ZR were milled, fired following instruction, and finally polished by P1000 diamond paper in the same size as LDS specimens. Acid resistance was evaluated using the test method based on ISO6872. Specimens were immersed in 4vol% acetic acid solution at 80°C for 16h. Dissolved amount was calculated from the difference in specimen weight before and after immersion (n=3). Data were statistically analyzed by one-way ANOVA and Tukey-test (p<0.01).
Results: Table indicated that LS had significantly less amount of acid dissolution than EM. In addition, dissolved amount of LS was at the same level as ZR and LS-A2HT.
Conclusions: The acid resistance of bleach shade of Initial LiSi Block was comparable to zirconia and already released Initial LiSi Block. This indicated that it can be useful in esthetic areas.