Abstract
Objective. The aim of this study was to evaluate the effect of decontamination methods on shear bond strength of resin cement to translucent monolithic zirconia. Material and Methods. Eighty 4-mol yttria-stabilized tetragonal zirconia polycrystal specimens were fabricated. All specimens were subjected to saliva contamination and divided into four groups (n=20) according to the decontamination methods: 70% isopropanol (AL); zirclean (ZC); 5.25% sodium ypochlorite (NaOCL); and no cleaning (NC). All specimens were bonded by using self-adhesive resin cement. Half of the specimens in each group (n=10) were subjected to thermocycling. All specimens were subjected to shear bond strength test in a universal testing machine. Failure modes were evaluated by using a scanning electron microscope (SEM). The data obtained were statistically analyzed by using one-way ANOVA followed by the HSD Tukey test (P < 0.05). Results. ANOVA test revealed a significant difference among the different decontamination methods (P < 0.05). No significant differences were found among NaOCL, ZC, and AL groups as revealed by the HSD Tukey test (P > 0.05). The effect of thermocycling was significantly different in all groups (P < 0.05); whereas, no significant difference was found in group ZC (P > 0.05). (SEM) analysis showed mixed failures in all groups except in group NC where only adhesive failure was observed. Conclusion. Saliva contamination during clinical evaluation significantly decreases the shear bond strength between self-adhesive resin cement and translucent monolithic zirconia. The cleaning gel has an impact on improving the bond strength between resin cement and translucent monolithic zirconia. KEYWORDS Monolithic zirconia; Resin cement; Shear bond strength test; Translucent zirconia; Zirclean.
Highlights
T raditional 3-mol yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) restorations have been widely used in prosthetic dentistry due to their acceptable optical properties, superior mechanical properties, excellent biocompatibility, and less wear to the opposing dentition [1,2]
Monolithic zirconia restorations can be luted by using conventional cement [12] or bonded by using adhesive resin cement which are considered the cement of choice for many clinical applications [13,14]
One-way ANOVA test revealed that different decontamination methods had a statistically significant effect on the shear bond strength between (4Y-TZP) and the resin cement (p < 0.05); no statistically significant difference was found among NaOCL, ZC, and AL groups as revealed by the HSD Tukey test (p > 0.05)
Summary
T raditional 3-mol yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) restorations have been widely used in prosthetic dentistry due to their acceptable optical properties, superior mechanical properties, excellent biocompatibility, and less wear to the opposing dentition [1,2]. Zirconia manufacturers increased the yttria content from 3 to 5 mol% enabling low phase transformation toughening where the tetragonal phase can be retained at room temperature; accomplishing high translucency resulted in diminished fracture toughness of 2.5 to 3.5 MPa\m1/2 and flexural strength of approximately 700 to 800 MPa [57]. Another noticeable reason for introducing these restorations is the high incidence of porcelain chippings (6% to 25% after 3 years) in bilayered zirconia ceramic restorations, which is significantly higher than the rates reported for metal-ceramic restorations [8,9,10]. Monolithic zirconia restorations can be luted by using conventional cement [12] or bonded by using adhesive resin cement which are considered the cement of choice for many clinical applications [13,14]
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