Fracture strength of direct versus indirect laminates with and without fiber application at the cementation interface.
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.
Gresnigt
Marco M M
MM
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
Ozcan
Mutlu
M
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
D003188:Composite Resins; D008689:Methacrylates; D011140:Polyurethanes; D019279:Resin Cements; C496140:everStick; C523291:quadrant anterior shine; C091839:urethanetrimethacrylate