SUMMARY
Objective:
To evaluate the composite-to-composite repair interfacial fracture toughness (iFT) as a function of adhesive and composite repair material.
Methods and Materials:
Beam-shaped composite specimens (21×4×3±0.2 mm) were prepared for each substrate material (Filtek Supreme Ultra [FSU] or Clearfil Majesty ES-2 [CME]) and artificially aged for 50,000 thermocycles (5-55°C, 20-second dwell time). Aged specimens were sectioned in half, and the resulting hemispecimens were randomly assigned to one of the different repair methods (n=10) based on the following variables: type of substrate composite (FSU or CME), acid etch (yes or no), adhesive type (Scotchbond Universal or Clearfil SE Bond 2), and type of repair composite (FSU or CME). The repair surface was prepared with a course diamond bur (Midwest #471271). When used, 37% phosphoric acid was applied for 20 seconds, rinsed, and dried. All adhesives and composites were applied according to manufacturers' instructions. After postrepair storage (100% humidity, 37°C, 24 hours), iFT was measured and expressed as MPa. Data were analyzed for statistical significance using a three-way analysis of variance and Tukey post hoc tests (α=0.05).
Results:
iFT values ranged from 0.64 ± 0.19 MPa to 1.28 ± 013 MPa. Significantly higher iFT values were achieved when FSU was used as the repair composite resin regardless of the substrate composite resin (p<0.001). Clearfil SE Bond 2 adhesive was associated with significantly higher iFT values for FSU substrate (p<0.001). The etching procedure had no significant effect on the iFT values of the repair procedures (p>0.05).
Conclusions:
Composite repair strength is adhesive and composite dependent. Repair strength appears to be higher when FSU is the repair composite regardless of the adhesive used.
Purpose
To determine the effect of changing the dispensing or mixing method of resin‐modified glass ionomer (RMGI) cements on their water sorption, solubility, film thickness, and shear bond strength.
Materials and Methods
Disc‐shaped specimens of RMGI cements (RelyX: Luting [handmix], Luting Plus [clicker‐handmix], Luting Plus [automix], GC: Fuji PLUS [capsule‐automix], FujiCEM 2 [automix], [n = 10]) were prepared according to ISO standard 4049 for water sorption and solubility tests. Furthermore, the percentage of mass change, percentage of solubility, and percentage of water absorbed was also determined. Film thickness was measured according to ISO standard 9917‐2; the mean of 5 measurements for each cement was calculated. Shear bond strength for each cement was determined according to ISO standard 29022 before and after thermocycling at 20,000 cycles, temperatures 5 to 55°C with a 15‐second dwell time (n = 10/subgroup). Two‐ and one‐way ANOVA were used to analyze data for statistical significance (p < 0.05).
Results
Water sorptions of the RMGI cements were in close range (214‐250 μg/mm3) with no statistical differences between counterparts (p > 0.05). RelyX Luting Plus (clicker‐handmix) displayed lower solubility than its handmix and automix counterparts (p < 0.05). Film thickness of RelyX cements was significantly different (p < 0.05). RelyX Luting Plus (automix) had the lowest film thickness (19 μm) compared to its handmix (48 μm) and clicker‐handmix (117 μm) counterparts (p < 0.05). GC Fuji PLUS (capsule‐automix, 22 μm) was significantly lower than the automix version (GC FujiCEM 2, 127 μm) (p < 0.05). Shear bond strength of RelyX Luting Plus (automix) was significantly lower than its handmix and clicker‐handmix versions (p < 0.05). GC Fuji PLUS (capsule‐automix) was significantly higher than GC FujiCEM 2 (automix) (p < 0.05). The binary interaction of the two independent variables (dispensing/mixing method and thermocycling) was significant for the shear bond strengths of the GC cements only (p < 0.05).
Conclusions
Change in the dispensing/mixing method of RMGI cement from the same brand may have an effect on its physical properties, in addition to its film thickness and shear bond strength. Newer, easier, and faster cement delivery systems are not necessarily better. Clinical outcomes of these differences are yet to be confirmed.
Introducing alternative dispensing/mixing methods for mixing RMGIs to reduce time and technique sensitivity may affect mechanical properties and is brand dependent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.