title: Microleakage and fracture patterns of teeth restored with different posts under dynamic loading.
abstract: BACKGROUND
  Many studies concerned with the microleakage of endodontically treated teeth restored with posts and cores and subjected to loading can be found in the literature. However, no studies have investigated microleakage under dynamic loading with simultaneous dye penetration, which is more relevant to clinical situations.
  
  
  OBJECTIVE
  The purpose of this study was to compare microleakage and to classify fracture patterns of endodontically treated teeth restored with various post systems under dynamic loading.
  
  
  METHODS
  The crown portions of 40 human mandibular incisors were sectioned at the cementoenamel junction, and the teeth were endodontically treated. Teeth were divided into 4 groups (n=10): teeth restored with a cast post and core, prefabricated metal post (ParaPost), fiber-reinforced composite resin post (FRC Postec), and ceramic post (Cosmopost). After preparing the post space, each post was cemented with dual-polymerized resin cement (DuoLink). With the exception of the cast post-and-core group, the cores were formed directly using a light-polymerized composite resin (Light-Core). An intermittent load of 98 N at 1 Hz was applied for 50,000 cycles at an angle of 135 degrees to the long axis of the restored teeth, which were immersed in a 0.5% basic fuchsin solution. The ratio of the dyed surface area to the total area of the sectioned root surface was determined using an image analysis program. The data were analyzed by a 1-way ANOVA and Duncan's multiple range test (alpha =.05). The fracture patterns of the teeth were classified according to their fracture propagation lines.
  
  
  RESULTS
  The cast post group showed a significantly higher level of microleakage compared to the other groups (P=.001). Regarding the failure mode, the FRC Postec and Cosmopost groups showed fracture patterns that would favor retreatment. The number of cycles of repeated loading was not significantly different among the groups (P=.161).
  
  
  CONCLUSIONS
  Both FRC Postec and Cosmopost groups showed less microleakage under dynamic loading and fracture patterns favoring a retreatment of fractured specimens.
authors.affiliation: Department of Conservative Dentistry, College of Dentistry, Wonkwang University, Iksan City, Korea.
authors.forename: Sung-Ho
authors.initials: SH
authors.lastname: Jung
authors.forename: Kyung-San
authors.initials: KS
authors.lastname: Min
authors.forename: Hoon-Sang
authors.initials: HS
authors.lastname: Chang
authors.forename: Sung-Do
authors.initials: SD
authors.lastname: Park
authors.forename: Soon-Nyu
authors.initials: SN
authors.lastname: Kwon
authors.forename: Ji-Myung
authors.initials: JM
authors.lastname: Bae
mesh_terms: D000704:Analysis of Variance; D002516:Ceramics; D004396:Coloring Agents; D003188:Composite Resins; D003722:Dental Alloys; D003763:Dental Leakage / Q000175:diagnosis / Q000209:etiology*; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D011176:Post and Core Technique / Q000009:adverse effects*; D014082:Tooth Fractures / Q000209:etiology*
chemical_list: D004396:Coloring Agents; D003188:Composite Resins; D003722:Dental Alloys