Effect of food-simulating liquids on flexural strength, Vickers microhardness, and surface roughness of IPS e.max Press and CEREC Tessera
DOI:
https://doi.org/10.2340/biid.v13.46275Keywords:
Ceramics, citric acid, ethanol, saliva, artificial, flexural strength, mechanical tests, surface propertiesAbstract
Background: Lithium disilicate ceramics are widely used for indirect restorations, yet their mechanical performance may be influenced by fabrication route and chemical challenge from foods and beverages.
Objective: To compare the effects of food-simulating liquids (FSLs) on flexural strength, Vickers microhardness, and surface roughness of pressed lithium disilicate (IPS e.max Press) and Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) advanced lithium disilicate (CEREC Tessera).
Materials and methods: One hundred fifty rectangular specimens were prepared using IPS e.max Press and CEREC Tessera (n = 75 each) and allocated into five groups per material (n = 15): one unconditioned control group, artificial saliva (7 days at 37°C), 0.02% citric acid, 20% ethanol, or 50% ethanol. Citric acid and ethanol groups underwent three 5-minute challenge cycles followed by re-storage in artificial saliva. Flexural strength was assessed by three-point bending. Microhardness (Vickers HV1/10) and surface roughness (Ra) were measured on independent specimens. Data were analysed using two-way analysis of variance with Tukey’s post hoc test for flexural strength and surface roughness. For microhardness, factorial analysis was limited to the comparable shared conditions because ethanol-exposed IPS e.max Press specimens did not yield reliable Vickers measurements.
Results: CEREC Tessera showed higher flexural strength than IPS e.max Press across conditions (control: 362.6 ± 15.4 vs 331.0 ± 8.5 MPa). Ethanol reduced strength in both materials, with the greatest reduction in 50% ethanol (238.0 ± 9.6 vs 147.4 ± 7.5 MPa). Across comparable conditions, CEREC Tessera also showed higher microhardness, while reliable Vickers measurements could not be obtained for ethanol-exposed IPS e.max Press specimens. Surface roughness increased after acidic and alcoholic exposure in both materials, although CEREC Tessera remained smoother overall (control: 0.06 ± 0.02 vs 0.67 ± 0.36 µm).
Conclusion: CEREC Tessera demonstrated superior flexural strength, microhardness, and surface integrity compared with IPS e.max Press after exposure to FSLs, suggesting that fabrication route influences laboratory performance under chemical challenge.
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