title: A micro-computed tomography evaluation of mineral trioxide aggregate root canal fillings.
abstract: BACKGROUND
  The aim of this study was to assess the effect of indirect ultrasonic activation on the incidence of voids within mineral trioxide aggregate (MTA) root canal fillings and at their interface with the canal walls by using a nondestructive 3-dimensional (3D) micro-computed tomography (micro-CT) analysis.
  
  
  METHODS
  Extracted human teeth with single canals and minimal curvatures were decoronated, instrumented to size 50/05 apically, and randomly allocated into 4 groups (n = 12). MTA was compacted manually by using hand pluggers in group A (MC). Indirect ultrasonic activation was applied to each increment of manually compacted MTA for 1 second in group B (1 sec-UC), 5 seconds in group C (5 sec-UC), and 10 seconds in group D (10 sec-UC). Filled roots were scanned with a micro-CT device, and 3D analysis of void incidence was carried out by using the SkyScan software.
  
  
  RESULTS
  Statistical analysis showed a significantly lower incidence of voids (P < .05) in the manual compaction (MC) group (0.7%) compared with the ultrasonic activation for 1 second (3.8%), 5 seconds (1.7%), and 10 seconds (1.6%) groups.
  
  
  CONCLUSIONS
  Manual compaction produced significantly denser root fillings than those achieved with ultrasonic activation.
authors.affiliation: School of Dentistry, University of Manchester, Manchester, United Kingdom. ahmadmaayta@hotmail.com
authors.forename: Ahmad M
authors.initials: AM
authors.lastname: El-Ma'aita
authors.forename: Alison J E
authors.initials: AJ
authors.lastname: Qualtrough
authors.forename: David C
authors.initials: DC
authors.lastname: Watts
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D004338:Drug Combinations; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D016062:Porosity; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012389:Root Canal Obturation / Q000295:instrumentation / Q000379:methods*; D017640:Silicates / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014465:Ultrasonics; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate