title: Mechanical properties, fracture resistance, and fatigue limits of short fiber reinforced dental composite resin.
abstract: BACKGROUND
  Cycling masticatory loads decrease the strength of particulate filler composites (PFCs) and initiate the failure process by fatigue. The life expectancy of a composite resin restoration under stress remains difficult to predict.
  
  
  OBJECTIVE
  The purpose of this study was to determine the fracture resistance and the compressive fatigue limits (CFL) of anterior crown restorations made of a short-fiber reinforced composite resin (SFC), to investigate selected mechanical properties of the material following standard test methods, and to observe their correlation with the CFL.
  
  
  METHODS
  Specimens (n=10) were fabricated either from SFC (everX Posterior, GC Corp) or PFC (G-ænial anterior, GC Corp). The properties investigated were flexural strength (FS), compression strength (CS), diametral-tensile strength (DTS), and single-edge-notched-bend fracture toughness (FT) following ISO standards. Fracture resistance was determined by static load (n=10) and the CFL at 10000 cycles was determined using a staircase approach (n=20), both on anterior composite resin crowns. The results were analyzed with 1-way ANOVA (α=.05) or 2-way ANOVA (α=.05) followed by a Tukey B post hoc test and the Pearson-correlation analysis.
  
  
  RESULTS
  The SFC crowns had higher fracture resistance (954 ±121 N) than the PFC crowns (415 ±75 N) (P<.001) and higher CFL (267 ±23 N) than the PFC crowns (135 ±64 N) (P<.001). SFC revealed also higher FT (2.6 ±0.6 MPa·m(1/2)) than the PFC (1.0 ±0.2 MPa·m(1/2)) (F=69.313, P<.001). A significant correlation was observed only between the FT and the CFL (r(2)=0.899; P<.001).
  
  
  CONCLUSIONS
  SFC crowns showed good performance under static and fatigue loading. FT was the only in vitro test method that filtered as a clinically relevant parameter.
authors.affiliation: Doctoral student, Department of Biomaterials Science and Turku Clinical Biomaterials Centre-TCBC, Institute of Dentistry, University of Turku, Turku, Finland. Electronic address: jabije@utu.fi.
authors.forename: Jasmina
authors.initials: J
authors.lastname: Bijelic-Donova
authors.affiliation: Adjunct Professor in Dental Materials Science, Department of Biomaterials Science and Turku Clinical Biomaterials Centre-TCBC, Institute of Dentistry, University of Turku, Turku, Finland; and Department of Restorative Dentistry and Periodontology, Institute of Dentistry, Libyan International Medical University, Benghazi, Libya.
authors.forename: Sufyan
authors.initials: S
authors.lastname: Garoushi
authors.affiliation: Professor and Chair of Biomaterials Science, Director of Turku Clinical Biomaterials Centre-TCBC, Institute of Dentistry, University of Turku, Turku, Finland, and City of Turku Welfare Division, Oral Health Care, Turku, Finland.
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
authors.affiliation: Laboratory Head, Turku Clinical Biomaterials Centre-TCBC, Institute of Dentistry, University of Turku, Turku, Finland.
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
mesh_terms: D003188:Composite Resins; D019245:Compressive Strength; D003442:Crowns; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D013314:Stress, Mechanical
chemical_list: D003188:Composite Resins