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dc.contributor.authorKensara, Alaa Ahmeden_US
dc.date.accessioned2016-10-26T15:34:41Z
dc.date.issued2016
dc.identifier.urihttps://hdl.handle.net/2144/18716
dc.description.abstractOBJECTIVES: To test and compare the effects of static and cyclic loading on fracture toughness (K1C) and microhardness of dental restorative CAD/CAM materials. MATERIAL AND METHODS: Five commercially available CAD/CAM restorative materials were included in this study: Lava™ Ultimate Restorative (3M ESPE), IPS Empress® CAD (Ivoclar Vivadent), Enamic® (VITA), IPS e.max® CAD (Ivoclar Vivadent), and CERASMART™ (GC Dental). Polished rectangular bars 4×2×14 mm (n=30) were prepared from mill blocks for each material. Single notch of 0.5-1 mm in depth was made on the center of one length edge. Ten specimens per group for each material were randomly selected for 1) static mode, 2) after 100k cyclic loads, and 3) after 200k cyclic loads. The survival bars after the fatigue test were then subjected to a three-point flexural test. K1C values were determined on ‘single-edge-pre-crack-beams’ (SEPB) method. In addition, random specimens after the flexural test were selected for Vickers microhardness test from each group. Additionally indentation fracture method (IF) was used to determine surface fracture toughness for e.max CAD and Empress CAD. All the results were analyzed via ANOVA with Tukey’s HSD test or least square regression model using JMP Pro 12.0. RESULTS: The mean fracture toughness (K1C) of the material tested in static mode (3.2 MPa.m1/2 for e.max CAD, 2 MPa.m1/2 for Lava Ult, 1.95 MPa.m1/2 for Empress CAD, 1.92 MPa.m1/2 for Enamic, and 1.65 MPa.m1/2 for Cerasmart). The 100k fatigue group (4.02 MPa.m1/2 for e.max CAD, 3.06 MPa.m1/2 for Cerasmart, 2.55 MPa.m1/2 for Lava Ult, 2.01 MPa.m1/2 for Enamic, 1.94 MPa.m1/2 for Empress CAD) The 200k fatigue group (3.14 MPa.m1/2 for Cerasmart, 2.83 MPa.m1/2 for Lava Ult, 2.68 MPa.m1/2 for e.max CAD, 2.01 MPa.m1/2 for Enamic, 1.72 MPa.m1/2 for Empress CAD). While there was a significant difference in the mean fracture toughness (K1C) and (VHN) after fatigue of material tested (p<0.05). CONCLUSION: The CAD/CAM materials tested exhibited a higher K1C values after cyclic loading, along with lower K1C compared to the static group. In addition, K1C values by IF method exhibit lower K1C values after fatigue that was not a good way to test the fracture toughness value.en_US
dc.language.isoen_US
dc.subjectDentistryen_US
dc.subjectCAD/CAMen_US
dc.subjectCyclic loadingen_US
dc.subjectFatigueen_US
dc.subjectFracture toughnessen_US
dc.subjectIndentationen_US
dc.subjectMicrohardnessen_US
dc.titleStatic and cyclic loading effects on fracture toughness of contemporary CAD/CAM restorative materialsen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2016-09-28T16:08:54Z
dc.description.embargo2018-09-28T00:00:00Z
etd.degree.nameDoctor of Science in Dentistryen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineRestorative Sciences & Biomaterialsen_US
etd.degree.grantorBoston Universityen_US


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