title: Fatigue strength of fragmented incisal edges restored with a fiber reinforced restorative material.
abstract: OBJECTIVE
  The aim of this study was to determine the compressive fatigue limits (CFLs) of fractured incisor teeth restored using either a conventional adhesive-composite technique or using fiber-reinforced composites (FRCs).
  
  
  METHODS
  Fifteen extracted sound upper incisor teeth were prepared by cutting away the incisal one-third part of their crowns horizontally. The teeth were restored using three techniques. Group A (control group) was restored by reattaching the original incisal edge to the tooth. Group B was restored using particulate filler composite (PFC). Group C was restored with PFC and FRC by adding a thin layer of FRC to the palatal surface of the teeth. The bonding system used was a conventional etch system with primer and adhesive. All restored teeth were stored in water at room temperature for 24 h before they were loaded under a cyclic load with a maximum controlled regimen using a universal testing machine. The test employed a staircase approach with a maximum of 103 cycles or until failure occurred. Data were analyzed using analysis of variance (ANOVA) (p=0.05). Failure modes were visually examined.
  
  
  RESULTS
  Group A (reattaching fractured incisal edge) revealed the lowest CFL values, whereas the creation of a new incisal edge with PFC revealed a 152% higher CFL value compared to Group A. Group C (teeth restored with FRC) revealed a 352% higher CFL than the control group. ANOVA revealed the restoration technique significantly affected the compressive fatigue limit (p<0.001). The failure mode in Group A and B was debonding of the restoration from the adhesive interface. While in Group C, the sample teeth fractured below their cemento-enamel junctions.
  
  
  CONCLUSIONS
  These results suggested an incisally fractured tooth restored with the combination of PFC and FRC-structure provided the highest CFL.
authors.affiliation: Institute of Dentistry, University of Turku, Turku, Finland. sufgar@utu.fi
authors.forename: Sufyan K
authors.initials: SK
authors.lastname: Garoushi
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D019245:Compressive Strength; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D004338:Drug Combinations; D006801:Humans; D007180:Incisor / Q000293:injuries*; D008437:Maxilla; D019904:Polymethyl Methacrylate; D018709:Statistics, Nonparametric; D019228:Tooth Crown / Q000293:injuries; D014082:Tooth Fractures / Q000628:therapy*
chemical_list: D003188:Composite Resins; D004338:Drug Combinations; C485628:Stick resin; C496140:everStick; D019904:Polymethyl Methacrylate