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Mechanical properties of dentin restored with glass ionomer cements
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d e n t a l m a t e r i a l s 3 1 S ( 2 0 1 5 ) e1–e66
22 Flexural strength of experimental highly viscous conventional glass ionomers
ural strength of experimental glass ionomer was comparable to those of commercially available glass ionomer cements. This study was supported by Grants-in-Aid for Scientific Research (C) No. 26462954.
Y. Hibino ∗ , Y. Nagasawa, H. Shigeta, J. Omatsu, H. Nakajima
http://dx.doi.org/10.1016/j.dental.2015.08.023 23
Meikai University School of Dentistry, Sakado, Japan Purpose: The objective of this study was to examine the flexural strength of experimental highly viscous conventional glass ionomers for restorative filling under various storage conditions. Methods and materials: A commercially available highly viscous conventional glass ionomer (Fuji IX GP EXTRA, GC, A) and an experimental highly viscous conventional glass ionomer (SI-R21402, Shofu, B) were tested. Rectangular specimens (2 mm wide, 2 mm thick and 25 mm long) were prepared according to each manufacturer’s recommended ratio (Cement A: P/L = 3.4/1.0, Cement B: P/L = 2.8/1.0, respectively). One hour after the start of mixing for both cements, specimens were stored in deionized water at 37 ± 2 ◦ C up to 1 week, or were subjected to thermal cycling between 5 ◦ C and 55 ◦ C water up to 3000 cycles for 60 s each using thermal cycling equipment (K178-15, Tokyo-Giken). The flexural strengths of each glass ionomer were determined at 1 h, 24 h or 1 week after the start of mixing using a universal testing machine (3366, Instron) at a cross-head speed of 1.0 mm/min using a three-point bending test at 23 ± 2 ◦ C in air. Five specimens were fabricated and tested for each experimental condition. The results were analyzed using ANOVA/Scheffe’s test (a = 0.05). Results: Table 1 shows the measured flexural strength (MPa, mean ± sd, n = 5) for the cements. The flexural strength for Cement A increased significantly with time elapsed after cement mixing (p < 0.05). The flexural strength for Cement B increased significantly at 1 week compared to that at 1 h (p < 0.05). The flexural strengths of both cements after 3000 thermal cycles were greater than those at 1 h (p < 0.05). The strength of Cement A at 24 h after the start of mixing was lower than after 3000 thermal cycles (p < 0.05); however, Cement B showed no significant differences in flexural strengths between 24 h immersion in deionized water and 3000 thermal cycles (p > 0.05). Statistically no significant differences in flexural strengths of both Cements A and B were observed between thermal cycling and 1 week (p > 0.05). Conclusion: Under the present experimental conditions, the flexural strength of highly viscous conventional glass ionomer for restorative filling increased with time. The flex-
Table 1 Storage condition
Cement A
1h 24 h 1 week 3000 thermal cycles
8.8 13.4 21.3 22.4
± ± ± ±
0.9 1.4 2.3 1.7
Cement B 7.2 13.5 23.5 17.9
± ± ± ±
1.1 2.1 4.5 2.4
Mechanical properties of dentin restored with glass ionomer cements P.H. Dos Santos 1,∗ , A.P. Guedes 1 , M.D. Moda 1 , T.Y. Suzuki 1 , A.G. Godas 1 , S. Pavan 2 , R.H. Sundfeld 1 , A.L. Briso 1 1 2
São Paulo State University, UNESP, Brazil FAI University, Brazil
Purpose: To evaluate the effect of erosive pH cycling using solutions on the mechanical properties of dentin restored with glass-ionomer materials. Methods and materials: Eighteen bovine dentine slabs (6.0 mm × 6.0 mm) were restored with Riva Self Cure conventional glass ionomer cement and Riva Light Cure light-cured glass ionomer cement (n = 9). The Martens hardness and Eit values were measured before and after immersion in deionized water, citric acid and hydrochloric acid at distances of 10 m, 30 m, 50 m, and 70 m from the interface. Results: After cycling, the Martens hardness of dentin decreased for all the materials. The distance of 10 m exhibited lower values compared with the other distances, for both materials, only before erosive pH cycling. The Eit values of the dentin restored with both glass ionomer cements (Riva Self Cure and Riva Light Cure) decreased with increasing distance from the bonding interface; however, after 30 m, this difference was no longer significant. Conclusion: The fluoride present in the materials interfered without completely preventing dentin demineralization adjacent to restorations. http://dx.doi.org/10.1016/j.dental.2015.08.024 24 Evaluation of a fluoro-alumino-calcium silicate-based desensitizer using an ultrasonic device R. Kawamoto ∗ , H. Endo, T. Takamizawa, M. Miyazaki Nihon University School of Dentistry, Japan Purpose: The purpose of this study was to evaluate the effect of a fluoro-alumino-calcium silicate-based desensitizer on demineralization of bovine dentin, by measuring changes in ultrasonic velocity to determine the change in mineral content. The ultrasound velocity is a characteristic of a material through which sound is passing, and its importance depends upon its relationship with the elastic modulus. Methods and materials: Desensitizer used in this study was Nanoseal (Nippon Shika Yakuhin, Yamaguchi, Japan). Bovine dentin specimens with and without application of
d e n t a l m a t e r i a l s 3 1 S ( 2 0 1 5 ) e1–e66
22 Flexural strength of experimental highly viscous conventional glass ionomers
ural strength of experimental glass ionomer was comparable to those of commercially available glass ionomer cements. This study was supported by Grants-in-Aid for Scientific Research (C) No. 26462954.
Y. Hibino ∗ , Y. Nagasawa, H. Shigeta, J. Omatsu, H. Nakajima
http://dx.doi.org/10.1016/j.dental.2015.08.023 23
Meikai University School of Dentistry, Sakado, Japan Purpose: The objective of this study was to examine the flexural strength of experimental highly viscous conventional glass ionomers for restorative filling under various storage conditions. Methods and materials: A commercially available highly viscous conventional glass ionomer (Fuji IX GP EXTRA, GC, A) and an experimental highly viscous conventional glass ionomer (SI-R21402, Shofu, B) were tested. Rectangular specimens (2 mm wide, 2 mm thick and 25 mm long) were prepared according to each manufacturer’s recommended ratio (Cement A: P/L = 3.4/1.0, Cement B: P/L = 2.8/1.0, respectively). One hour after the start of mixing for both cements, specimens were stored in deionized water at 37 ± 2 ◦ C up to 1 week, or were subjected to thermal cycling between 5 ◦ C and 55 ◦ C water up to 3000 cycles for 60 s each using thermal cycling equipment (K178-15, Tokyo-Giken). The flexural strengths of each glass ionomer were determined at 1 h, 24 h or 1 week after the start of mixing using a universal testing machine (3366, Instron) at a cross-head speed of 1.0 mm/min using a three-point bending test at 23 ± 2 ◦ C in air. Five specimens were fabricated and tested for each experimental condition. The results were analyzed using ANOVA/Scheffe’s test (a = 0.05). Results: Table 1 shows the measured flexural strength (MPa, mean ± sd, n = 5) for the cements. The flexural strength for Cement A increased significantly with time elapsed after cement mixing (p < 0.05). The flexural strength for Cement B increased significantly at 1 week compared to that at 1 h (p < 0.05). The flexural strengths of both cements after 3000 thermal cycles were greater than those at 1 h (p < 0.05). The strength of Cement A at 24 h after the start of mixing was lower than after 3000 thermal cycles (p < 0.05); however, Cement B showed no significant differences in flexural strengths between 24 h immersion in deionized water and 3000 thermal cycles (p > 0.05). Statistically no significant differences in flexural strengths of both Cements A and B were observed between thermal cycling and 1 week (p > 0.05). Conclusion: Under the present experimental conditions, the flexural strength of highly viscous conventional glass ionomer for restorative filling increased with time. The flex-
Table 1 Storage condition
Cement A
1h 24 h 1 week 3000 thermal cycles
8.8 13.4 21.3 22.4
± ± ± ±
0.9 1.4 2.3 1.7
Cement B 7.2 13.5 23.5 17.9
± ± ± ±
1.1 2.1 4.5 2.4
Mechanical properties of dentin restored with glass ionomer cements P.H. Dos Santos 1,∗ , A.P. Guedes 1 , M.D. Moda 1 , T.Y. Suzuki 1 , A.G. Godas 1 , S. Pavan 2 , R.H. Sundfeld 1 , A.L. Briso 1 1 2
São Paulo State University, UNESP, Brazil FAI University, Brazil
Purpose: To evaluate the effect of erosive pH cycling using solutions on the mechanical properties of dentin restored with glass-ionomer materials. Methods and materials: Eighteen bovine dentine slabs (6.0 mm × 6.0 mm) were restored with Riva Self Cure conventional glass ionomer cement and Riva Light Cure light-cured glass ionomer cement (n = 9). The Martens hardness and Eit values were measured before and after immersion in deionized water, citric acid and hydrochloric acid at distances of 10 m, 30 m, 50 m, and 70 m from the interface. Results: After cycling, the Martens hardness of dentin decreased for all the materials. The distance of 10 m exhibited lower values compared with the other distances, for both materials, only before erosive pH cycling. The Eit values of the dentin restored with both glass ionomer cements (Riva Self Cure and Riva Light Cure) decreased with increasing distance from the bonding interface; however, after 30 m, this difference was no longer significant. Conclusion: The fluoride present in the materials interfered without completely preventing dentin demineralization adjacent to restorations. http://dx.doi.org/10.1016/j.dental.2015.08.024 24 Evaluation of a fluoro-alumino-calcium silicate-based desensitizer using an ultrasonic device R. Kawamoto ∗ , H. Endo, T. Takamizawa, M. Miyazaki Nihon University School of Dentistry, Japan Purpose: The purpose of this study was to evaluate the effect of a fluoro-alumino-calcium silicate-based desensitizer on demineralization of bovine dentin, by measuring changes in ultrasonic velocity to determine the change in mineral content. The ultrasound velocity is a characteristic of a material through which sound is passing, and its importance depends upon its relationship with the elastic modulus. Methods and materials: Desensitizer used in this study was Nanoseal (Nippon Shika Yakuhin, Yamaguchi, Japan). Bovine dentin specimens with and without application of