Linh Vo-Cheng


June 2007

Document Type


Degree Name

Certificate in Pediatric Dentistry


Dept. of Pediatric Dentistry


Oregon Health & Science University


Purpose: The aim of this study is to rank 3 commercially available posterior pre-veneered SSCs in the order of load to esthetic failure after a simulated year of dynamic cyclic fatigue. Method: 16 crowns were used from 2 manufacturers and 21 crowns from another manufacturer were used. The 3 different laboratories: Cheng Crowns (Peter Cheng Orthodontic Laboratory); Kinder Krowns (Mayclin Dental Studio Inc); NuSmile Crowns (Orthodontic Technologies, Inc) were used for a total of 53 crowns. Each crown was cemented on a steel die that was welded to a steel plate which was mounted onto an aluminum platform. Each crown underwent a year worth (666,666 cycles) of dynamic cyclic fatigue at an average physiologic load of 265N using the Proto-Tech Fatigue Cycler. Postfatigue crowns were then placed into a universal testing machine and a vertical force was applied, with a crosshead speed of 0.01mm/minute, to the veneered buccal cusp of the crown until the veneer fractured and delaminated from the stainless steel crown. Result: The mean load required to cause the esthetic failure was: NuSmile (119.5 ± 16.04 Kg), Cheng (66.6 ± 28 Kg), Kinder Krowns (81.15 ± 21.91 Kg). Analysis of variance (ANOVA) indicated a significant difference between the groups at P<0.0001. Scheffe's Post hoc comparison demonstrated that the NuSmile crowns required significantly more force to delaminate the veneer from the SSC than the Cheng or Kinder crowns, a = 0.05. No crowns broke while undergoing fatigue for the determined number of cycles. Conclusion: NuSmile pre-veneered posterior stainless steel crowns requires significantly more load before failure after a year of dynamic cyclic fatigue than Cheng or Kinder crowns. The data supports that after a year of fatigue none of the crowns delaminated and the peak of load to failure is what ultimately causes the crowns to have esthetic failure.




School of Dentistry



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