title: [A study on marginal leakage of crown after cyclic loading test].
abstract: OBJECTIVE
  This study examined how the occlusal force is related to the marginal leakage of an abutment tooth where a crown is luted.
  
  
  METHODS
  Abutment teeth of the same standard were prepared from extracted human molars and crowns were luted using six kinds of cement. Cyclic loading was then applied to the load point of each tooth under water, at an angle of 45 degrees to the tooth axis in the direction towards the outside or the inside of the occlusal surface with a force of 30 kgf, frequency of 1 Hz, and 100,000 times. After the test, the specimens were immersed for 2 hours in 0.5% basic fuchsin solution and the area of the marginal penetration of each abutment tooth was measured and compared. After loading, the cement at the margin of the crown was observed under a scanning electron microscope (SEM).
  
  
  RESULTS
  Elite Cement 100 (EL) showed severe penetration in the control group. As for Fuji I (FI), Vitremer Luting Cement (VT), Fuji Luting S (FL), and Panavia Fluoro Cement (PF), the marginal penetration directly under the load side of the crown was significantly (p<0.01) greater than at other measurement conditions when the load was applied in the direction towards the outside of the occlusal surface. Panavia Fluoro Cement with the AD gel method (AD) and Relay-X ARC (RX) showed excellent marginal closure even after loading. For SEM observations after loading, FI and FL showed cohesion failure in the cement and VT and PF showed detachment at the dentin interface. AD and RX did not vary from those in the control group.
  
  
  CONCLUSIONS
  This study concluded that the crown luting components of Panavia Fluoro Cement with the AD gel method and Relay-X ARC provide excellent durability against occlusal force.
authors.affiliation: The Second Department of Prosthetic Dentistry, Tsurumi University School of Dental Medicine. morita@yamateavenue-dent.com
authors.forename: Makoto
authors.initials: M
authors.lastname: Morita
mesh_terms: D001732:Bite Force; D003763:Dental Leakage / Q000503:physiopathology*; D006801:Humans; D066298:In Vitro Techniques; D019228:Tooth Crown / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology