William N Ha1, Bill Kahler1, Laurence James Walsh2. 1. University of Queensland School of Dentistry, Brisbane, Queensland, Australia. 2. University of Queensland School of Dentistry, Brisbane, Queensland, Australia. Electronic address: l.walsh@uq.edu.au.
Abstract
INTRODUCTION: Mineral trioxide aggregate (MTA) is commonly supplied in 1-g packages of powder that are used by some clinicians across several treatments against the manufacturer's instructions. ProRoot MTA cannot be resealed after opening, whereas MTA Angelus has a resealable lid. This study assessed changes in particle size distribution once the packaging had been opened. METHODS: Fresh ProRoot MTA and MTA Angelus powder were analyzed by using laser diffraction and scanning electron microscopy and compared with powder from packages that had been opened once and kept in storage for 2 years. The ProRoot packet was folded over, whereas the MTA Angelus jar had the lid twisted back to its original position. RESULTS: After 2 years, ProRoot MTA powder showed a 6-fold increase in particle size (lower 10% from 1.13 to 4.37 μm, median particle size from 1.99 to 12.87 μm, and upper 10% from 4.30 to 34.67 μm), with an accompanying 50-fold change in particle surface area. MTA Angelus showed only a 2-fold increase in particle size (4.15 to 8.32 μm, 12.72 to 23.79 μm, and 42.66 to 47.91 μm, respectively) and a 2-fold change in particle size surface area. CONCLUSIONS: MTA reacts with atmospheric moisture, causing an increase in particle size that may adversely affect the properties and shelf life of the material. Smaller particles have a greater predisposition to absorb moisture. Single-use systems are advised.
INTRODUCTION:Mineral trioxide aggregate (MTA) is commonly supplied in 1-g packages of powder that are used by some clinicians across several treatments against the manufacturer's instructions. ProRoot MTA cannot be resealed after opening, whereas MTA Angelus has a resealable lid. This study assessed changes in particle size distribution once the packaging had been opened. METHODS: Fresh ProRoot MTA and MTA Angelus powder were analyzed by using laser diffraction and scanning electron microscopy and compared with powder from packages that had been opened once and kept in storage for 2 years. The ProRoot packet was folded over, whereas the MTA Angelus jar had the lid twisted back to its original position. RESULTS: After 2 years, ProRoot MTA powder showed a 6-fold increase in particle size (lower 10% from 1.13 to 4.37 μm, median particle size from 1.99 to 12.87 μm, and upper 10% from 4.30 to 34.67 μm), with an accompanying 50-fold change in particle surface area. MTA Angelus showed only a 2-fold increase in particle size (4.15 to 8.32 μm, 12.72 to 23.79 μm, and 42.66 to 47.91 μm, respectively) and a 2-fold change in particle size surface area. CONCLUSIONS: MTA reacts with atmospheric moisture, causing an increase in particle size that may adversely affect the properties and shelf life of the material. Smaller particles have a greater predisposition to absorb moisture. Single-use systems are advised.
Authors: Roberta Bosso-Martelo; Juliane Maria Guerreiro-Tanomaru; Raqueli Viapiana; Fábio Luis Camargo Vilella Berbert; Maria Inês Basso Bernardi; Mario Tanomaru-Filho Journal: Int Sch Res Notices Date: 2015-02-23