Browsing by Author "Al-Angari, Sarah S."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Color stability, Roughness, and Microhardness of Enamel and Composites Submitted to Staining/Bleaching Cycles
    (Elsevier, 2021-05) Al-Angari, Sarah S.; Eckert, George J.; Sabrah, Alaa H.A.; Biostatistics, School of Public Health
    Objective: To compare the effect of two bleaching systems (bleaching gel and whitening strips) on the color change, roughness, and microhardness of enamel and two resin composites. Material and methods: Two cavities were prepared on bovine enamel specimens (n = 16) and restored with two composites: a nano-hybrid [Herculite Ultra (HU)] and a micro-hybrid composite [TPH Spectra (TS)]. Baseline color (CIE L*a*b*), roughness (μm), and microhardness (kgf/mm2) were measured using a spectrophotometer, optical profilometer, and Vickers microhardness (VHN) tester, respectively. The specimens were stained with coffee for 14 days, and randomized into two bleaching groups: gel and strips (n = 8), then submitted to a 10-day bleaching/staining test. Color, roughness, and microhardness were re-measured. The outcomes were analyzed using two-way ANOVA and Fisher's-PLSD test (α = 0.05). Results: Gel significantly improved the color (ΔE 4.9-8.3) and increased the roughness (Ra 0.04-0.08 μm) of all substrates (p < 0.0001) compared to strips. Enamel color was significantly improved (ΔE 5.4-8.3) compared to that of HU (ΔE 2.6-4.9) and TS (ΔE 2.0-4.9) with either gels or strips. TS roughness (0.03-0.08 μm) was significantly higher than that of enamel (0.01-0.05 μm) and HU (0.02-0.04 μm). Enamel had significantly reduced microhardness compared to HU (p = 0.0144). Conclusion: Gels produced the greatest color improvement and roughness compared to strips. Enamel had significant color improvement but had the greatest decrease in microhardness. Clinical significance: There was unacceptable color change between enamel and the composites after the combined cyclic effects of staining and bleaching.
  • Thumbnail Image
    Item
    Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study
    (XMLink, 2017-08) Al-Shehri, Eman Z.; Al-Zain, Afnan O.; Sabrah, Alaa H.; Al-Angari, Sarah S.; Al Dehailan, Laila; Eckert, George J.; Özcan, Mutlu; Platt, Jeffrey A.; Bottino, Marco C.; Biomedical and Applied Sciences, School of Dentistry
    Objectives To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al2O3) particles at different pressures. Materials and Methods Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ2 tests (α = 0.05). Results The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. Conclusions CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.
  • Thumbnail Image
    Item
    Physicomechanical properties of a zinc-reinforced glass ionomer restorative material
    (2014) Al-Angari, Sarah S.; Hara, Anderson T.; Chu, Tien-Min; Platt, Jeffrey; Eckert, George; Cook, N. Blaine; Department of Restorative Dentistry, School of Dentistry
    We compared a zinc-reinforced glass ionomer restorative material (ChemFil Rock) with three commercially available glass ionomer cements (GICs), namely, Fuji IX GP Extra, Ketac Molar Quick Aplicap, and EQUIA Fil, with respect to fracture toughness, microhardness, roughness, and abrasive wear. Fracture toughness (KIC) was tested according to ISO 13586 (n = 10). Hardness, roughness, and abrasive wear were also tested (n = 9). Data were analyzed using the Wilcoxon rank-sum test with adjustment for multiple comparisons (α = 0.05). As compared with the other GICs ChemFil Rock exhibited a greater increase in surface roughness (P < 0.05) and lower microhardness (P < 0.01). The wear resistance of ChemFil Rock was comparable to that of the other GICs (P > 0.05). ChemFil Rock had significantly lower fracture toughness as compared with EQUIA Fil (P = 0.01) and significantly higher fracture toughness as compared with the other GICs (P < 0.02). In conclusion, as compared with the three other commercially available GICs, ChemFil Rock had intermediate fracture toughness, the lowest microhardness, and the greatest change in surface roughness.