Mechanical properties of new hybrid ceramic CADCAM restorative materials
Awada, Abdallah Ali
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STATEMENT OF PROBLEM: The recent rise in the popularity and effectiveness of dental CAD/CAM systems has spurred the introduction of a new class of hybrid ceramics that incorporate a polymer component in their microstructure. Due to the lack of literature and independent studies on these materials, it is essential to evaluate their properties in order to determine their viability. OBJECTIVES: The objectives of this study are to determine and compare mechanical properties (flexural strength, flexural modulus, modulus of resilience and margin roughness) and milling time of three hybrid ceramic CAD/CAM materials and evaluate against other commercially available composite resin and ceramic CAD/CAM materials. MATERIALS AND METHODS: The following materials were included in this study: 3M[TM] ESPE[TM] Lava[TM] Ultimate Restorative, VITA[R] Enamic[R], GC[R] Flexible Nano Ceramic, IPS Empress[R] CAD, Vitablocs[R] Mark II and 3M[TM] ESPE[TM] Paradigm[TM] MZ100. Polished 4x1x13.5 mm bars (n=25) were prepared from standard-sized mill blocks for each of the materials to be tested. The bars were then subjected to a three-point flexural test on a 10 mm span and with a crosshead speed of 0.5 mm/min. Flexural strength and flexural modulus measurements were calculated and used to compute the modulus of resilience values. In addition, a total of 42 crowns (7 per material) were milled from the materials included in this study. Milling times were recorded and margin roughness was then evaluated by means of macro photography and optical microscopy measurements. Results were analyzed via ANOVA with Tukey's HSD test (p[greater than]0.05). RESULTS: The mean flexural strength of the materials tested ranged from 219[plus or minus]20 MPa (GC[R] Flexible Nano Ceramic) to 105[plus or minus]9 MPa (Vitablocs[R] Mark II). The mean flexural modulus ranged from 32316[plus or minus]1867 MPa (IPS Empress[R] CAD) to 7945[plus or minus]248 MPa (GC[R] Flexible Nano Ceramic). The mean modulus of resilience ranged from 3.07[plus or minus]0.45 MPa (GC[R] Flexible Nano Ceramic) to 0.21[plus or minus]0.02 MPa (Vitablocs[R] Mark II) and the mean margin roughness ranged from 63[plus or minus]20 megam (GC[R] Flexible Nano Ceramic) to 195[plus or minus]21 megam (IPS Empress[R] CAD). As for milling time, the mean values ranged from 607[plus or minus]11 s for IPS Empress[R] CAD, Vitablocs[R] Mark II and Paradigm[TM] MZ100 Ultimate Restorative. While there was a significant difference in the mean flexural IPS Empress[R] CAD, Vitablocs[R] Mark II and Paradigm[TM] MZ100 to 616[plus or minus]8 s for Lava[TM] Ultimate Restorative. While there was a significant difference in the mean flexural strength, flexural modulus, modulus of resilience and margin roughness of materials tested (p[less than]0.05), no significant difference in the mean milling time was found (p=0.348). CONCLUSION: In general, the new hybrid ceramic CAD/CAM materials tested exhibited a higher flexural strength and modulus of resilience, along with lower flexural modulus compared to the purely ceramic materials tested. In addition, crowns milled from these new materials tended to exhibit smoother margins, but the mean milling time of identical crowns was not significantly different across all of the materials tested. At the 95% confidence level, GC[R] Flexible Nano Ceramic had significantly higher values for flexural strength and modulus of resilience, as well as significantly lower values for flexural modulus compared to all the remaining materials tested.
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact firstname.lastname@example.org.Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2013 (Department of Restorative Sciences and Biomaterials).Includes bibliographic references: leaves 67-71.
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