title: In vitro evaluation of the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with composite fillings after cyclic loading.
abstract: OBJECTIVE
  There is insufficient data regarding the durability of porcelain laminate veneers bonded to existing composite fillings. The aim of the present study was to evaluate the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with existing composite fillings.
  
  
  METHODS
  Thirty maxillary central incisors were divided into three groups (for each group, n=10): intact teeth (NP), teeth with class III composite fillings (C3) and teeth with class IV cavities (C4). Porcelain laminate veneers were made using IPS-Empress ceramic and bonded with Panavia F2 resin cement. The microleakage of all of the specimens was tested before and after cyclic loading (1 × 10(6) cycles, 1.2 Hz). The fracture resistance values (N) were measured using a universal testing machine, and the mode of failure was also examined. The statistical analyses were performed using one-way ANOVA and Tukey post hoc tests (α=.05).
  
  
  RESULTS
  There was a significant difference in the mean microleakage of group C4 compared with group NT (P=.013). There was no significant difference in the fracture loads among the groups.
  
  
  CONCLUSIONS
  The microleakage and failure loads of porcelain laminate veneers bonded to intact teeth and teeth with standard class III composite fillings were not significantly different.
authors.affiliation: Dental Research Center, Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Leyla
authors.initials: L
authors.lastname: Sadighpour
authors.affiliation: Dental Implant Research Center, Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Farideh
authors.initials: F
authors.lastname: Geramipanah
authors.affiliation: Dental Research Center, Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Allahyari
authors.affiliation: Research Institute for Nuclear Medicine, Shariati Hospital, Tehran university of Medical Sciences, Tehran, Iran.
authors.forename: Babak
authors.initials: B
authors.lastname: Fallahi Sichani
authors.affiliation: Department of Epidemiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohamd Javad
authors.initials: MJ
authors.lastname: Kharazi Fard
keywords: Fracture resistance; Microleakage; Porcelain laminate veneer