IADR Abstract Archives
Effect of artificial saliva on fracture toughness of glass ionomers measured using two different methods
Objectives: Glass Ionomer Cements (GICs) are brittle materials with low fracture strength. Therefore, understanding the fracture toughness (FT) is an important parameter to know, due to GICs being promoted for load-bearing restorations. In addition, little is known about the effects of artificial saliva (AS) on FT of GICs. The aims of this project were to study the effects of storage and compare two different FT test methods, namely: Compact-Tension test and 4-point bending test.
Methods: Samples were made from a Zinc-reinforced-GIC (ChemFil), High viscosity bulk-fill-GIC (HV) and LC-coating (EQUIA), Resin-Modified GIC (RM-GIC) (Riva-LC) and HV-RMGIC (Riva-HV-LC) using a custom-made mould. Specimens were stored in either AS or distilled-water (DW) for 7 or 30 days. After storage in AS or DW, specimens were tested for FT. Results were analysed with ANOVA, Mann-Whitney and Weibull statistics.
Results: ANOVA showed significant difference between groups. (p>0.05) A trend was observed for higher mean FT values for materials stored in DW for 30 days. Comparing the results for different storage media and same storage time it was shown that a lower FT occurred in AS groups (Range of Change(RoC)= -0.01to-0.09), except for Equia. Comparing results for the same storage media and different times for each material showed a lower FT for 7 days (RoC=-0.03to-0.13), except for Equia.
Conclusions: No significant difference was seen between the mean values of the two FT test methods. The maturation of GICs was obvious showing a difference between 7 and 30 day results. Considering AS is highly saturated with ions, this may have led to increased solubility of GICs leading to the reduced FT values.The results revealed that coating has a protective effect against damage from the storage media.
Methods: Samples were made from a Zinc-reinforced-GIC (ChemFil), High viscosity bulk-fill-GIC (HV) and LC-coating (EQUIA), Resin-Modified GIC (RM-GIC) (Riva-LC) and HV-RMGIC (Riva-HV-LC) using a custom-made mould. Specimens were stored in either AS or distilled-water (DW) for 7 or 30 days. After storage in AS or DW, specimens were tested for FT. Results were analysed with ANOVA, Mann-Whitney and Weibull statistics.
Results: ANOVA showed significant difference between groups. (p>0.05) A trend was observed for higher mean FT values for materials stored in DW for 30 days. Comparing the results for different storage media and same storage time it was shown that a lower FT occurred in AS groups (Range of Change(RoC)= -0.01to-0.09), except for Equia. Comparing results for the same storage media and different times for each material showed a lower FT for 7 days (RoC=-0.03to-0.13), except for Equia.
Conclusions: No significant difference was seen between the mean values of the two FT test methods. The maturation of GICs was obvious showing a difference between 7 and 30 day results. Considering AS is highly saturated with ions, this may have led to increased solubility of GICs leading to the reduced FT values.The results revealed that coating has a protective effect against damage from the storage media.