title: Effect of ultrasonication on physical properties of mineral trioxide aggregate.
abstract: OBJECTIVE
  To evaluate the effect on physical properties of Mineral Trioxide Aggregate (MTA) of using direct hand compaction during placement and when using hand compaction with indirect ultrasonic activation with different application times.
  
  
  METHODS
  One hundred acrylic canals were obturated in 3 increments with MTA in sample sizes of 10. One group was obturated by hand with an endodontic plugger and the remainder obturated with indirect ultrasonic application, with times ranging from 2 seconds to 18 seconds per increment. Microhardness values, dye penetration depths, and radiographs of the samples were evaluated.
  
  
  RESULTS
  As ultrasonic application time per increment increased, microhardness values fell significantly (P < 0.001) while dye penetration values increased (P < 0.001). Microhardness of MTA ultrasonicated for 2 seconds was significantly higher than hand compaction (P = 0.03). Most radiographic voids were visible in the hand-compacted group (P < 0.001), which also had higher dye penetration depths than the 2-second ultrasonicated samples. Ultrasonication of MTA for 10-18 seconds resulted in significantly more voids than 2-8 seconds of ultrasonication (P = 0.02).
  
  
  CONCLUSIONS
  The use of ultrasonics with MTA improved the compaction and flow of MTA, but excessive ultrasonication adversely affected MTA properties. A time of 2 seconds of ultrasonication per increment presented the best compromise between microhardness values, dye penetration depths, and lack of radiographic voids.
authors.affiliation: Melbourne Dental School, University of Melbourne, 720 Swanston Street, Melbourne, VIC 3010, Australia.
authors.forename: Peter
authors.identifier: 0000-0001-7191-0560
authors.initials: P
authors.lastname: Parashos
authors.affiliation: Melbourne Dental School, University of Melbourne, 720 Swanston Street, Melbourne, VIC 3010, Australia.
authors.forename: Amanda
authors.identifier: 0000-0001-6226-0682
authors.initials: A
authors.lastname: Phoon
authors.affiliation: Melbourne Dental School, University of Melbourne, 720 Swanston Street, Melbourne, VIC 3010, Australia.
authors.forename: Chankhrit
authors.initials: C
authors.lastname: Sathorn
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry* / Q000528:radiation effects*; D017610:Calcium Compounds / Q000737:chemistry* / Q000528:radiation effects*; D019245:Compressive Strength / Q000528:radiation effects; D004338:Drug Combinations; D006244:Hardness / Q000528:radiation effects; D019220:High-Energy Shock Waves; D008422:Materials Testing / Q000379:methods; D010087:Oxides / Q000737:chemistry* / Q000528:radiation effects*; D016062:Porosity / Q000528:radiation effects; D011829:Radiation Dosage; D017640:Silicates / Q000737:chemistry* / Q000528:radiation effects*; D013010:Sonication / Q000379:methods*; D013499:Surface Properties / Q000528:radiation effects; D014783:Viscosity
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D017640:Silicates; C086631:mineral trioxide aggregate