Browsing by Author "Capin, Oriana Reis"

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    Effect of Toothbrushing on a Monolithic Dental Zirconia Submitted to an Accelerated Hydrothermal Aging
    (2022) Almajed, Norah; Sochacki, Sabrina Feitosa; Cook, Norman Blaine; Capin, Oriana Reis
    Objectives: The objectives of this study were (1) to evaluate the biaxial flexural strength of monolithic 3Y-TZP ceramic specimens and (2) to assess their surface roughness after being submitted to accelerated hydrothermal aging (simulation 1-10 years of aging); and simulated toothbrushing (simulation 1-10 years of toothbrushing). Materials/Methods: 84 discs of monolithic zirconia (Lava Plus High Translucency Zirconia, 3M ESPE) were prepared, sintered (1450°C, 2h), and randomly allocated into four experimental groups as follows: Control group (CT): no HA and no toothbrushing; 1-year group (1YR): 20 minutes of HA and 10,000 cycles of toothbrushing; 5 years group (5 YR): 100 minutes of HA and 50,000 cycles of toothbrushing; and 10 years group (10 YR): 200 minutes of HA and 100,000 cycles of toothbrushing. Specimens were submitted to autoclave hydrothermal aging at 134°C and 2.0 bar, followed by toothbrush simulation. After aging, specimens in each group were submitted to the biaxial flexural strength test (ISO 6872) using a universal testing machine, and the number of fragments was evaluated. Surface roughness was performed before and after aging using a noncontact profilometer (Ra, Rq, and Rz parameters). For the statistics, one-way analysis of variance (ANOVA) and pairwise comparison were used (α=0.05). Hypothesis: The accelerated hydrothermal aging and simulated toothbrushing will affect the results of the biaxial flexural strength and surface roughness of the zirconia specimens. Results: No significant aging effects were detected for the biaxial flexural strength (p=0.239) for groups CT (874.25±124.61 MPa), 1YR (869.56±132.60 MPa), 5YR (854.40±122.34 MPa), and 10YR (948.55±144.85 MPa). In addition, no significant aging effects were detected comparing the number of fragments, with a minimum of two and a maximum of five fragments (p=0.325). The collected data on the changes in surface roughness after hydrothermal aging and toothbrush simulation showed that for the parameters Ra and Rq, group 1YR presented significantly higher surface roughness than groups 5YR and 10YR. For the parameter Rz, group 1YR presented significantly higher surface roughness than groups 5YR and 10YR. In addition, group 5YR showed higher surface roughness than group 10YR. Conclusion: Hydrothermal aging associated with simulated toothbrushing did not significantly impact the biaxial flexural strength of monolithic 3Y-TZP zirconia. However, there was a significant initial increase in the zirconia surface roughness, which decreased after simulating five and ten years of aging.
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    Efficacy of resin-based materials against erosive-abrasive wear in vitro
    (2015) Capin, Oriana Reis; Hara, Anderson T.; Cook, N. Blane; Platt, Jeffrey A.; Masatoshi, Ando; Lippert, Frank
    Background: Increasing prevalence of dental erosion has been observed in many countries, in both children and adults. This condition is often associated with softening of the dental surface by acid exposure, which may lead to severe and irreversible damage. The use of fluoride, pit and fissure sealants, dental adhesives and more recently a resin infiltrant has been suggested to manage dental erosion. Objective: To compare the protective effect of a resin infiltrant and other resin-based materials against dental erosion/toothbrushing abrasion in vitro. Materials and methods: Bovine enamel and dentin slabs were prepared, embedded, flattened and polished. Dental erosion lesions were created using 0.01 M of hydrochloric acid (pH 2.3 for 30 sec) and treated with resin-based materials (HS: Helioseal pit and fissure sealant; SP: Seal and Protect dentin 78 sealant, and IC: Icon resin infiltrant) or fluoride varnish (FV: Duraphat). A no-treatment group represented the negative control (C). The specimens were subjected to an erosion-abrasion cycling model for a total of 10 days. Each cycling day consisted of 2 min immersion in 0.01M HCl, at room temperature, for 4 times; and toothbrushing with either of the abrasive suspensions (low and high, as previously determined by the radioactive dentin abrasivity method). Enamel and dentin surfaces were scanned at baseline, after treatment, at 5 days and at 10 days using an optical profilometer. Surface change (loss/gain) was determined by subtracting the treated area from the reference (protected) areas. Significance level of 5% was adopted for the statistical analysis. Results: No differences were found among groups at baseline, regardless of substrate. After treatment, surface deposition was found for all test groups except for IC, which did not differ from C. For enamel, at day 5, FV, HS and SP had less surface loss than C and IC (p<0.0008), which did not differ from each other (p=1.00). At day 10, similar trend was observed except for FV, which showed surface loss similar to C, when brushed with high abrasive suspension. High abrasive caused more surface loss than low abrasive only for C at day 5 (p=0.0117) and 10 (p=0.0162). For dentin, at day 5, FV, HS and SP had less surface loss than C and IC (p≤0.0001), which did not differ from each other (p=1.00). At day 10, HS and SP had less surface loss than C, IC, and FV (p<0.0001), and FV had less surface loss than C for low abrasive (p=0.0009). Overall, high abrasive had significantly more surface loss than low abrasive at 10 days (p=0.0280). Conclusion: HS was the most effective material protecting enamel and dentin from erosion-abrasion, followed by SP. FV offered limited protection, while no benefit was observed for resin infitrant IC.