title: Fracture resistance of computer-aided design/computer-aided manufacturing-generated composite resin-based molar crowns.
abstract: The aim of this study was to investigate whether different fabrication processes, such as the computer-aided design/computer-aided manufacturing (CAD/CAM) system or the manual build-up technique, affect the fracture resistance of composite resin-based crowns. Lava Ultimate (LU), Estenia C&B (EC&B), and lithium disilicate glass-ceramic IPS e.max press (EMP) were used. Four types of molar crowns were fabricated: CAD/CAM-generated composite resin-based crowns (LU crowns); manually built-up monolayer composite resin-based crowns (EC&B-monolayer crowns); manually built-up layered composite resin-based crowns (EC&B-layered crowns); and EMP crowns. Each type of crown was cemented to dies and the fracture resistance was tested. EC&B-layered crowns showed significantly lower fracture resistance compared with LU and EMP crowns, although there was no significant difference in flexural strength or fracture toughness between LU and EC&B materials. Micro-computed tomography and fractographic analysis showed that decreased strength probably resulted from internal voids in the EC&B-layered crowns introduced by the layering process. There was no significant difference in fracture resistance among LU, EC&B-monolayer, and EMP crowns. Both types of composite resin-based crowns showed fracture loads of >2000 N, which is higher than the molar bite force. Therefore, CAD/CAM-generated crowns, without internal defects, may be applied to molar regions with sufficient fracture resistance.
authors: Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors: Akio
authors: A
authors: Harada
authors: Keisuke
authors: K
authors: Nakamura
authors: Taro
authors: T
authors: Kanno
authors: Ryoichi
authors: R
authors: Inagaki
authors: Ulf
authors: U
authors: Örtengren
authors: Yoshimi
authors: Y
authors: Niwano
authors: Keiichi
authors: K
authors: Sasaki
authors: Hiroshi
authors: H
authors: Egusa
mesh_terms: D000465:Algorithms; D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008963:Molar; D018583:Pliability; D011140:Polyurethanes / Q000737:chemistry; D016062:Porosity; D013314:Stress, Mechanical; D013499:Surface Properties; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C508050:IPS e.max Press; D008689:Methacrylates; D011140:Polyurethanes; C493120:lithia disilicate; C091839:urethanetrimethacrylate; D003776:Dental Porcelain; C023506:Glass ceramics
keywords: CAD/CAM; composite resin; fracture resistance; lithium disilicate; micro-CT