title: Measurement of J-integral in CAD/CAM dental ceramics and composite resin by digital image correlation.
abstract: Ceramic and composite resin blocks for CAD/CAM machining of dental restorations are becoming more common. The sample sizes affordable by these blocks are smaller than ideal for stress intensity factor (SIF) based tests. The J-integral measurement calls for full field strain measurement, making it challenging to conduct. Accordingly, the J-integral values of dental restoration materials used in CAD/CAM restorations have not been reported to date. Digital image correlation (DIC) provides full field strain maps, making it possible to calculate the J-integral value. The aim of this study was to measure the J-integral value for CAD/CAM restorative materials. Four types of materials (sintered IPS E-MAX CAD, non-sintered IPS E-MAX CAD, Vita Mark II and Paradigm MZ100) were used to prepare beam samples for three-point bending tests. J-integrals were calculated for different integral path size and locations with respect to the crack tip. J-integral at path 1 for each material was 1.26±0.31×10(-4)MPam for MZ 100, 0.59±0.28×10(-4)MPam for sintered E-MAX, 0.19±0.07×10(-4)MPam for VM II, and 0.21±0.05×10(-4)MPam for non-sintered E-MAX. There were no significant differences between different integral path size, except for the non-sintered E-MAX group. J-integral paths of non-sintered E-MAX located within 42% of the height of the sample provided consistent values whereas outside this range resulted in lower J-integral values. Moreover, no significant difference was found among different integral path locations. The critical SIF was calculated from J-integral (KJ) along with geometry derived SIF values (KI). KI values were comparable with KJ and geometry based SIF values obtained from literature. Therefore, DIC derived J-integral is a reliable way to assess the fracture toughness of small sized specimens for dental CAD/CAM restorative materials; however, with caution applied to the selection of J-integral path.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Comprehensive Care, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Akkus
authors.affiliation: Department of Comprehensive Care, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Renato
authors.initials: R
authors.lastname: Roperto
authors.affiliation: Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA; Department of Orthopaedics, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. Electronic address: Ozan.akkus@case.edu.
authors.forename: Ozan
authors.initials: O
authors.lastname: Akkus
authors.affiliation: Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Comprehensive Care, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Lang
authors.affiliation: Department of Comprehensive Care, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Sorin
authors.initials: S
authors.lastname: Teich
mesh_terms: D002516:Ceramics; D003188:Composite Resins; D017076:Computer-Aided Design; D003776:Dental Porcelain; D008422:Materials Testing; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003776:Dental Porcelain
keywords: Composite resin; Digital Image Correlation; IPS E-MAX CAD; J-integral; SIF; Vita Mark