Physical and Biological Properties of the Paste-type Mineral Trioxide Aggregates

Objectives: The purpose of this study was to compare the physical properties of the powder-liquid mix-type MTA and the newly introduced paste-type MTA, and evaluate the implantation of powder-liquid mix type MTA, paste type MTA, and resin-based endodontic sealer in tibia of rabbits for 12 weeks.
Methods: Physical properties (such as flow, film thickness, setting time, solubility, and radiopacity) of the newly introduced paste type MTA (Well-Root ST; Vericom, Korea) were compared to the powder-liquid mix type MTA (ProRoot MTA; Dentsply, USA) in accordance with ISO 6876:2012. Intraosseous implantation test was performed using ProRoot MTA, Well-Root ST, and AH Plus (Dentsply, Germany) according to ISO 10993-6:2016. Three or two holes were formed (2 mm in diameter × 6 mm in depth) at the each tibia of rabbits. The mixed materials according to manufacturer’s instruction were placed into the cylindrical holes. After implantation, all animals received visual inspection at least once a week and inflammation, complication, and other specific figures were recorded. All animals were euthanized 12 weeks after implantation, and the specimens received visual and histologic evaluation, then following results were obtained.
Results: Physical properties of paste-type MTA such as flow, film thickness, and setting time were improved to those of powder-liquid mix-type MTA, and solubility and radiopacity of paste type MTA were similar or more excellent to those of powder-liquid mix type MTA. New bone formation were most-abundant and uniformly in the experimental group of implantation of paste-type MTA, and were observed to some extent in the experimental group of implantation of powder-liquid mix-type MTA and microvascular invasion around MTA was examined. As the control groups of implantation of epoxy resin based endodontic sealer, severe lymphocytes and neutrophils were observed. Histologic evaluation revealed that both paste-type MTA and powder-liquid mix-type MTA were non-irritant compared with AH Plus that had no potential risk biologically, and were seemed to meet the criteria of implantation test.
Conclusions: As the paste-type MTA showed similar physical and biological properties to the powder-liquid mixed type MTA, so it could be used as alternative materials for the powder-liquid mix-type MTA.