title: Deconvolution of the particle size distribution of ProRoot MTA and MTA Angelus.
abstract: ObjectiveMineral trioxide aggregate (MTA) cements contain two types of particles, namely Portland cement (PC) (nominally 80% w/w) and bismuth oxide (BO) (20%). This study aims to determine the particle size distribution (PSD) of PC and BO found in MTA.Materials and methodsThe PSDs of ProRoot MTA (MTA-P) and MTA Angelus (MTA-A) powder were determined using laser diffraction, and compared to samples of PC (at three different particle sizes) and BO. The non-linear least squares method was used to deconvolute the PSDs into the constituents. MTA-P and MTA-A powders were also assessed with scanning electron microscopy.ResultsBO showed a near Gaussian distribution for particle size, with a mode distribution peak at 10.48 μm. PC samples milled to differing degrees of fineness had mode distribution peaks from 19.31 down to 4.88 μm. MTA-P had a complex PSD composed of both fine and large PC particles, with BO at an intermediate size, whereas MTA-A had only small BO particles and large PC particles.ConclusionsThe PSD of MTA cement products is bimodal or more complex, which has implications for understanding how particle size influences the overall properties of the material. Smaller particles may be reactive PC or unreactive radiopaque agent. Manufacturers should disclose particle size information for PC and radiopaque agents to prevent simplistic conclusions being drawn from statements of average particle size for MTA materials.
authors.affiliation: School of Dentistry, Oral Health Centre, The University of Queensland , Herston , Queensland , Australia.
authors.forename: William Nguyen
authors.initials: WN
authors.lastname: Ha
authors.affiliation: School of Dentistry, Oral Health Centre, The University of Queensland , Herston , Queensland , Australia.
authors.forename: Fardad
authors.initials: F
authors.lastname: Shakibaie
authors.affiliation: School of Dentistry, Oral Health Centre, The University of Queensland , Herston , Queensland , Australia.
authors.forename: Bill
authors.initials: B
authors.lastname: Kahler
authors.affiliation: School of Dentistry, Oral Health Centre, The University of Queensland , Herston , Queensland , Australia.
authors.forename: Laurence James
authors.initials: LJ
authors.lastname: Walsh
keywords: Deconvolution; mineral trioxide aggregate; particle size distribution