title: In vitro evaluation of bacterial leakage resistance of an ultrasonically placed mineral trioxide aggregate orthograde apical plug in teeth with wide open apexes: a preliminary study.
abstract: OBJECTIVE
  The purpose of this study was to compare the sealing ability of an ultrasonically placed orthograde mineral trioxide aggregate (MTA) apical plug in open apices.
  
  
  METHODS
  Thirty extracted human maxillary incisors were used. Experimental teeth were instrumented up to #100 file at the apex, and the 5 mm MTA apical barrier was placed with (group A; n = 11) or without (group B; n = 11) ultrasonic activation. Eight teeth served as control group. Bacterial leakage was assessed daily for 180 days using a double-chamber bacterial leakage model with Enterococcus faecalis. The results were analyzed with Fisher exact test.
  
  
  RESULTS
  After 60 days, the ratio of leaked samples showed significant difference between groups A (2 out of 10) and B (8 out of 11) (P < .05). The mean time elapsed before leakage showed significant difference between groups A (158 days) and B (23 days) (P < .05).
  
  
  CONCLUSIONS
  Ultrasonically placed orthograde MTA apical plugs were effective at delaying bacterial leakage.
authors.affiliation: Department of Conservative Dentistry, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Un-Sung
authors.initials: US
authors.lastname: Kim
authors.forename: Su-Jung
authors.initials: SJ
authors.lastname: Shin
authors.forename: Seok Woo
authors.initials: SW
authors.lastname: Chang
authors.forename: Hyun-Mi
authors.initials: HM
authors.lastname: Yoo
authors.forename: Tae-Seok
authors.initials: TS
authors.lastname: Oh
authors.forename: Dong Sung
authors.initials: DS
authors.lastname: Park