title: Microleakage of porcelain and composite machined crowns cemented with self-adhesive or conventional resin cement.
abstract: OBJECTIVE
  Resistance of machined crowns to microleakage when cemented with new self-adhesive cements has not been fully investigated. This study evaluated microleakage of machined crowns milled from porcelain and composite blocks and bonded to teeth with self-adhesive and conventional resin cement.
  
  
  METHODS
  Thirty-two freshly extracted premolars of similar shape and size were sterilized and mounted in resin blocks. Teeth received standard crown preparations with 1-mm circumferential shoulder finish line, flat occlusal surface reduced by 2 mm, and ideal angle of convergence. Prepared teeth were divided into two equal groups and assigned to either porcelain (Vita Mark II, Vident) or composite (Paradigm MZ100, 3M ESPE) blocks for crown fabrication. Optical impressions were captured for each tooth with the intraoral camera of a CEREC 3D machine. Crowns were designed and milled from both materials. Each group was then subdivided into two subgroups (n = 8) according to cement used (self-adhesive resin cement, RelyX Unicem, 3M ESPE or resin cement with self-etching adhesive, Panavia F 2.0, Kuraray). Following seating, a 5-kg weight was applied on the occlusal surface of the crown for 5 minutes. Specimens were then stored in water at 37°C for 24 hours. Specimens were thermocycled for 3000 cycles between 5°C and 55°C, then coated with nail varnish and immersed in a 2.0% basic red fuchsine dye solution for 24 hours. Teeth were then rinsed and sectioned mesiodistally and assessed under magnification for microleakage. A five-point scale was used to score degree of microleakage. Data were statistically analyzed with 2-way ANOVA and Kruskal-Wallis nonparametric test.
  
  
  RESULTS
  Crown material had no significant effect on microleakage (p= 0.67); however, cement type had a significant effect (p < 0.0001), with Panavia F 2.0 resulting in lower microleakage scores than RelyX Unicem.
  
  
  CONCLUSIONS
  Compared to the self-adhesive cement, the resin cement with separate primer/bonding agent resulted in significantly lower microleakage scores, irrespective of crown material.
authors: Department of Conservative Dentistry and Fixed Prosthodontics, Faculty of Dentistry, University of Mansoura, Mansoura, Egypt. mghazy@mans.edu.eg
authors: Mohamed
authors: M
authors: Ghazy
authors: Omar
authors: O
authors: El-Mowafy
authors: Renato
authors: R
authors: Roperto
mesh_terms: D000268:Adhesiveness; D000704:Analysis of Variance; D002484:Cementation; D003188:Composite Resins; D017076:Computer-Aided Design; D003442:Crowns; D045662:Dental Etching / Q000379:methods; D003763:Dental Leakage / Q000517:prevention & control*; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D006801:Humans; D019279:Resin Cements; D018709:Statistics, Nonparametric
chemical_list: D003188:Composite Resins; C438843:Panavia-Fluoro; C483701:Rely X Unicem; D019279:Resin Cements; D003776:Dental Porcelain