title: Fracture strength of direct versus indirect laminates with and without fiber application at the cementation interface.
abstract: OBJECTIVE
  This study compared the fracture strength of direct and indirect resin composite laminate veneers and evaluated the effect of a bidirectional E-glass woven fiber application at different locations at the cementation interface.
  
  
  METHODS
  Standard preparations on canines (N=50, 10 per group) were made using a depth cutting bur (0.7mm depth) designed for laminate veneer restorations. Forty indirect laminates using a highly filled polymeric material (Estenia) and 10 direct laminates (Quadrant Anterior Shine) were prepared according to the manufacturer's instructions. Bidirectional E-glass woven-fiber sheet (0.06mm) (Everstick) was applied at different locations at the cementation interface. The control group received no fibers. The specimens were stored in water at 37 degrees C for 1 month prior to fracture testing performed in a universal testing machine where the load was applied from the incisal direction at 137 degrees (1mm/min).
  
  
  RESULTS
  No significant differences were found between the five groups (P>0.01) (one-way ANOVA). While indirect laminate veneers showed mean fracture strength of 247+/-47N, direct laminate veneers revealed 239+/-104N. The use of E-glass fibers at the cementation interface at different locations did not increase the fracture strength significantly (286-313N) (P>0.01). Failure analysis showed mainly cohesive fracture of the veneer restoration (20/50) and adhesive failure between the cementation interface and the laminate with fiber exposure (19/50) covering more than half of the restorations.
  
  
  CONCLUSIONS
  Direct and indirect resin composite laminate veneers showed comparable mean fracture strengths. The use of E-glass woven-fiber sheet at the cementation interface did not increase the fracture strength of the polymeric laminate veneers.
authors.affiliation: University Medical Center Groningen, University of Groningen, Department of Dentistry and Dental Hygiene, Clinical Dental Biomaterials, Antonius Deusinglaan 1, Groningen, The Netherlands. marcogresnigt@yahoo.com
authors.forename: Marco M M
authors.initials: MM
authors.lastname: Gresnigt
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
mesh_terms: D000704:Analysis of Variance; D002484:Cementation; D003188:Composite Resins; D003481:Cuspid; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates; D011140:Polyurethanes; D019279:Resin Cements
chemical_list: D003188:Composite Resins; D008689:Methacrylates; D011140:Polyurethanes; D019279:Resin Cements; C496140:everStick; C523291:quadrant anterior shine; C091839:urethanetrimethacrylate