title: Effect of post length and type of luting agent on the dislodging time of metallic prefabricated posts by using ultrasonic vibration.
abstract: BACKGROUND
  The purpose of this study was to determine and compare the times needed to dislodge prefabricated titanium posts of different luting lengths with various cements.
  
  
  METHODS
  Eighty-one intact extracted, single-canal human teeth were selected and endodontically treated. Specimens were randomly divided into 9 groups, which were arranged according to the post space length (5, 7, and 9 mm) and cement type (zinc phosphate, glass ionomer, and resin cement). Titanium posts were cemented into the post spaces, and after 1 week of storage they were subjected to ultrasonic vibration. The dislodging times were recorded and analyzed by using the Kruskal-Wallis and Mann-Whitney tests (P < .05).
  
  
  RESULTS
  A significant difference was observed between the dislodging times on the basis of post length and luting agent (P < .001). There were also significant differences between different cements luted with the same length posts (P < .001). Significant differences were observed between the 5-mm posts and both the 7- and 9-mm posts for each cement, but the differences between the 7-mm and 9-mm posts were not significant (P < .05).
  
  
  CONCLUSIONS
  Changes in the cement type and post length alter the time required to dislodge a post with an ultrasonic device.
authors.affiliation: Department of Endodontics, School of Dentistry, I.A.U. Khorasgan branch, Isfahan. Electronic address: ebrahimimd@gmail.com.
authors.forename: Maziar
authors.initials: M
authors.lastname: Ebrahimi Dastgurdi
authors.forename: Masud
authors.initials: M
authors.lastname: Khabiri
authors.forename: Abbasali
authors.initials: A
authors.lastname: Khademi
authors.forename: Maryam
authors.initials: M
authors.lastname: Zare Jahromi
authors.forename: Peimaneh
authors.initials: P
authors.lastname: Hosseini Dastnaei
mesh_terms: D000497:Alloys; D003722:Dental Alloys / Q000737:chemistry*; D003738:Dental Cements / Q000737:chemistry*; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D019553:Tooth, Nonvital / Q000534:rehabilitation; D014465:Ultrasonics; D014732:Vibration; D015036:Zinc Phosphate Cement / Q000737:chemistry
chemical_list: D000497:Alloys; D003722:Dental Alloys; D003738:Dental Cements; D005899:Glass Ionomer Cements; D019279:Resin Cements; C031462:titanium alloy (TiAl6V4); D015036:Zinc Phosphate Cement; D014025:Titanium
keywords: Dental cement; dislodging time; length; prefabricated post; ultrasonic vibration