title: The influence of ultrasound on removal of prefabricated metal post cemented with different resin cements.
abstract: BACKGROUND
  Ultrasonic vibrations are used to remove a cemented post from a root canal requiring endodontic retreatment. Various results have been reported from the studies that evaluated the effect of ultrasonic instruments in removing the posts cemented with resin cements. The aim of this study was to evaluate the effect of ultrasonic energy on the retention of prefabricated metal post cemented with Panavia or Maxcem Elite cements.
  
  
  METHODS
  In this in vitro study, forty eight extracted single root premolars were decoronated with a diamond disc leaving a 13 mm long root and endodontically treated. The root canals were obturated by gutta-percha up to 5 mm with vertical condensation method and the 8 mm post-space was prepared to receive a no. 2 long Dentorama post. The roots were placed in an incubator for 48 h in 37°C and 100% humidity. After mounting the teeth in acrylic blocks, posts were cemented in the root canals using Panavia F2.0 in 24 specimens and Maxcem Elite in 24 others. For half of the specimens in each subgroup, an ultrasonic device was applied for 4 min. Universal testing machine was used to measure the force needed to remove the posts with a crosshead speed of 1 mm/min until the post came out of the canal. Kruskal-Wallis test was used for statistical analysis at 5% level of significance.
  
  
  RESULTS
  The removal force was not significantly different among the groups (P > 0.05).
  
  
  CONCLUSIONS
  Ultrasonic energy did not decrease the retention of posts cemented with Panavia or Maxcem Elite cements. Furthermore, it seems that there is no significant difference between removal force of self-etch (Panavia) and the self-etch self-adhesive (Maxcem Elite) resin cements.
authors.affiliation: Dental Materials Research Center and Department of Operative Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Atiyeh
authors.initials: A
authors.lastname: Feiz
authors.affiliation: Dental Implants Research Center and Department of Endodontic, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Behnaz
authors.initials: B
authors.lastname: Barekatain
authors.affiliation: Torabinejad Dental Research Center and Department of Periodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Roohollah
authors.initials: R
authors.lastname: Naseri
authors.affiliation: Dental Materials Research Center and Department of Operative Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Zarezadeh
authors.affiliation: Dental Materials Research Center and Department of Operative Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Askari
authors.affiliation: Torabinejad Dental Research Center and Department of Periodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Saman
authors.initials: S
authors.lastname: Nasiri
keywords: Post removal; prefabricated metal post; resin cement; ultrasound