title: Comparison of Mechanical and Indirect Ultrasonic Placement Technique on Mineral Trioxide Aggregate Retrofill Density in Simulated Root-end Surgery.
abstract: BACKGROUND
  The objective of this study was to evaluate the density of mineral trioxide aggregate (MTA) root-end filling placed by either manual condensation or manual condensation with indirect ultrasonic activation under simulated root-end surgery conditions in vitro.
  
  
  METHODS
  Extracted human molar teeth were obtained and sectioned to provide single-rooted samples (n = 50). Roots were instrumented to a size of 40 with a .04 taper and obturated with a warm vertical technique. The coronal end of each root was embedded in resin. A root-end resection and root-end preparation were completed on each root. Samples were randomly assigned to receive root-end fillings with ProRoot MTA (Dentsply, Tulsa, OK) by 1 of 2 techniques: manual condensation alone (group M, n = 25) or manual condensation with indirect ultrasonic activation (group U, n = 25). MTA was placed incrementally to the level of the root end using the enumerated technique. Samples were weighed immediately before and after filling placement. MTA was removed from all samples so as not to change the root-end preparation, rinsed, and dried. Each sample then underwent MTA placement by the opposite technique, and weight was again measured immediately before and after MTA placement. MTA filling weights for each technique were analyzed statistically using a technique for repeated measures analysis. Statistical analysis was conducted to account for any carryover or order effects.
  
  
  RESULTS
  After adjustment for carryover effects, it was found that regardless of the order of placement, the mean fill weight of MTA produced by the indirect ultrasonic method was on average 4.42 mg heavier than that produced by manual condensation alone. This result was statistically significant (P < .0003).
  
  
  CONCLUSIONS
  Under simulated root-end surgery conditions, indirect ultrasonic condensation of MTA root-end fillings was shown to produce a filling that was significantly denser than MTA placed by manual condensation alone.
authors.affiliation: University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Friedl
authors.affiliation: University of Iowa College of Dentistry, Iowa City, Iowa. Electronic address: anne-williamson@uiowa.edu.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Williamson
authors.affiliation: University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Deborah V
authors.initials: DV
authors.lastname: Dawson
authors.affiliation: University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Manuel R
authors.initials: MR
authors.lastname: Gomez
authors.affiliation: University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D004338:Drug Combinations; D006801:Humans; D010087:Oxides / Q000737:chemistry*; D011897:Random Allocation; D012184:Retrograde Obturation / Q000379:methods; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012390:Root Canal Therapy / Q000379:methods*; D017640:Silicates / Q000737:chemistry*; D019227:Tooth Apex / Q000033:anatomy & histology / Q000601:surgery; D014092:Tooth Root / Q000033:anatomy & histology / Q000601:surgery*; D014464:Ultrasonic Therapy / 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
keywords: Root end filling; root end preparation