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Concept
Mineral trioxide aggregate
Résumé
Mineral trioxide aggregate (MTA) was developed for use as a dental root repair material by Mahmoud Torabinejad. It is formulated from commercial Portland cement, combined with bismuth oxide powder for radio-opacity. MTA is used for creating apical plugs during apexification, repairing root perforations during root canal therapy, and treating internal root resorption. This can be used for root-end filling material and as pulp capping material. Originally, MTA was dark gray in color, but white versions have been on the market since 2002.
Portland cement is a term applied to a class of materials covering a range of compositions (between silica alumina and calcia). The composition, fineness, setting time and strength of Portland cement are not controlled or guaranteed. Portland cement is an unsuitable substitute for MTA based on several characteristics that are essential to the performance: freedom from heavy metals, dimensional stability and fineness. The FDA requires dental materials to have high purity and be lead and arsenic-free, unlike commercial Portland cement.
MTA is composed of tricalcium silicate, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, calcium sulfate, and bismuth oxide. The later 4 phases vary among the commercial products available.
Newly developed fast-set MTAs were developed by Pozzolan Cement or Zeolite Cement. These were used by pozzolanic reaction. Pozzolan Cement is a mineral aggregate with watery calcium silicate hydration.
Biocompatible with periradicular tissues
Non cytotoxic, but antimicrobial to bacteria
Non-resorbable
Minimal leakage around the margins.
Very basic AKA alkaline (high pH when mixed with water).
As a root-end filling material MTA shows less leakage than other root-end filling materials, which means bacterial migration to the apex is diminished.
Treated area needs to be infection free when applying MTA, because an acidic environment will prevent MTA from setting.
Compressive strength develops over a period of 28 days, similar to Portland cement.
Source officielle
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