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-51-CERASMART0131 Cyclic Loading Fatigue Affects Fracture Toughness of CAD/CAM Restorative MaterialsOral Presentation8:45 AM–9:00 AM Mar 22, 2017CC, Room 2010 Authors:Authors:AlaaKensara(Presenter)Henry M. Goldman School of Dental Medicine,BostonUniversityYuweiFan, Henry M. Goldman School of Dental Medicine,BostonUniversityDan Nathanson, Henry M. Goldman School of Dental Medicine,BostonUniversityAbstract: Objectives: To compare the effect of cyclic loading fatigue on fracture toughness (K1C) of contemporary dental restorative CAD/CAM materials.contemporary dental restorative CAD/CAM materials.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 4×2×14mm (n=30) were prepared from mill blocks for each material. A single notch (0.5-1mm in depth, 0.5mm width) was made at the center of the non loading (tensile) edge. Ten specimens per group for each material were randomly selected for 1) static mode, 2) 100k cyclic loads, and 3) 200k cyclic loads. Fatigue was performed on the specimens in three point bending mode at a peak load of 40N and a frequency of 1Hz in a pneumatic driven cyclic loading machine. mode at a peak load of 40N and a frequency of 1Hz in a pneumatic driven cyclic loading machine. The surviving bars after the fatigue treatment were subjected to a three-point flexural test in a universal testing machine (Instron5566A). K1Cvalues were determined using ‘single-edge-pre-crack-beams’ (SEPB) method. Results were analyzed via ANOVA with Tukey’sHSD test or least square regression model using JMP Pro 12.0.Results: Figure 1 shows mean fracture toughness (K1C) of the material tested in static mode, 100k cycles, and 200k cycles of fatigue. The Cerasmartand Lava Ultimate groups exhibited higher K1Cvalues after cyclic loading. Empress was not affected by fatigue. The e.max CAD showed higher values and higher variance after 100K cycles and significantly lower K1Cvalues showed higher values and higher variance after 100K cycles and significantly lower K1Cvalues after 200k loading. Enamicexhibited no significant difference after fatigue compared to the static group.Conclusions: Ceramics and composite CAM/CAM materials showed different trends of K1Cafter cyclic loading fatigue.Image(s):Student PresenterDisclosure Statement:The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: N/AI have read the IADR policy on licensing.Reprinted with permission from the Journal of Dental Research, J Dent Res 96 (Spec Iss A):-51-I have read the IADR policy on licensing.Signed by A Kensaraabstract number 0131, https://iadr2017.zerista.com/event/member/330077, 2017