ผลของสารทำความสะอาดที่มีเซอร์โคเนียเป็นองค์ประกอบต่อค่าความแข็งแรงยึดเฉือนระดับจุลภาคกับเซอร์โคเนียที่ปนเปื้อนด้วยน้ำลาย

Abstract

Objective: To observe the effect of different cleaning methods on micro-shear bond strength (µSBS) between saliva contaminated zirconia and resin cement, in conjunction with thermocycling. Methods: Ninety-six cylindrical plates of Cercon® ht zirconia, were embedded in metal molds and polished. The specimens were randomly divided into 8 groups according to human saliva contamination and surface decontamination methods: group 1 (NC) no contamination (control group), group 2 (WS) water-spray rinsing after contamination, group 3 (AA) sandblasted with aluminum oxide particle after contamination, group 4 (IC) applied with Ivoclean® after contamination, group 5 (SH) applied with sodium hydroxide with zirconia powder after contamination, group 6 (SHC) applied with sodium hypochlorite with zirconia powder after contamination, group 7 (SH) applied with EDTA with zirconia powder after contamination, group 8 (PA) applied with polyacrylic acid with zirconia powder after contamination. Two samples from each group were randomly selected for surface morphology examination by a scanning electron microscope (SEM) and surface elemental analysis with X-ray photoelectron spectroscopy (XPS) accordingly. Multilink N resin cement was cemented on each specimen by injecting into polyethylene tubes (4 resin cement rods per sample). After storing in distilled water at 37 ºC for 24 hours, the specimens in each group were randomly divided into 2 subgroups; subgroup 1 was defined as a short-term test and subgroup 2 was thermocycled (5 and 55 ºC, 5,000 cycles). The specimens were subjected to a micro-shear bond strength (µSBS) test at a cross-head speed of 1 mm/min. Data were analyzed using two-way ANOVA, followed by the Tukey’s multiple comparison test (p <0.05). Modes of failure were categorized by using the SEM. Results: Before aging, mean µSBS of NC (27.36 ± 2.38 MPa), SH (29.25 ± 2.61 MPa), IC (28.25 ± 2.31 MPa), SHC (26.62 ± 2.04 MPa), AA (26.66 ± 2.62 MPa) group were significantly higher than that of PA (22.35 ± 3.00 MPa), EDT (22.18 ± 2.26 MPa) and WS (19.31 ± 2.03 MPa) group (p<0.05). After aging, µSBS tends to decline in all groups but not significantly different (p>0.05). Failure mode analysis showed predominantly adhesive failure in WS and PA group, while mixed and cohesive failure were found in the other groups. Surface analysis show group AA had the most detectable groove on the surface. According to the elemental analysis, AA group had the lowest detected surface elements carbon and nitrogen to zirconium ratio. Conclusion: There were statistically significant differences in µSBS between surface decontamination groups. Sodium hydroxide conjunction with zirconia powder, Ivoclean®, sandblast and sodium hypochlorite conjunction with zirconia powder were effective in restoring the µSBS between saliva contaminated zirconia and resin cement. Thermocycling not significantly reduced µSBS in all group.