title: [Wear test of 4-unit posterior resin bonded fixed partial dentures with non-rigid connector].
abstract: OBJECTIVE
  The aim of this study was to test the difference of fatigue longevity between the 4-unit posterior resin-bonded fixed partial dentures (RBFPD)with non-rigid connector and rigid connector,a wear test to stimulate masticatary function was used.
  
  
  METHODS
  Extracted intact human teeth were used to prepare specimens,a first premolar and a second molar as the abutment teeth with a space equivalent to a second premolar and a first molar. Ten specimens were seperated into two groups randomly. The control group was prepared to receive conventional RBFPDs; in the test group a non-rigid connector was used on the distal side of the first premolar. The specimens were put on the thermocycling and mechanical loading (TCML) chewing simulator until the prostheses were broken,and the loading times were recorded.
  
  
  RESULTS
  The loading times of the test group and the control group were respectively (134.34 ± 8.17) ten thousand and (92.58 ± 19.73) ten thousand, there was a significant difference between the test group and the control group (P<0.05) analyzed by independent-samples t test (α=0.05). So that the fatigue longevity of 4-unit posterior RBFPDs with non-rigid connector was greater than that of the rigid connector RBFPDs.
  
  
  CONCLUSIONS
  The non-rigid connector could allow independent movement between the two parts of RBFPD and to decrease the stress between the tooth and the wing, and thus increases the fatigue longevity of long-span RBFPDs.
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Jiang
authors.forename: Jing
authors.initials: J
authors.lastname: Tan
authors.forename: Xin-zhi
authors.initials: XZ
authors.lastname: Wang
mesh_terms: D003198:Computer Simulation; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis / Q000379:methods*; D003779:Denture Design; D016379:Denture, Partial, Fixed, Resin-Bonded; D006801:Humans; D008409:Mastication; D008422:Materials Testing / Q000379:methods*; D008954:Models, Biological; D008963:Molar / Q000502:physiology; D013314:Stress, Mechanical