MTA-Mineral Trioxide Aggregate

MINERAL TRIOXIDE AGGREGATE

• Mineral trioxide aggregate is a new biocompatible material with numerous exciting clinical application in endodontics.
• MTA prevents microleakage, is biocompatible and promotes regeneration of original tissues when placed in contact with periradicular tissues or dental pulp.
• Marketed as Gray MTA(GMTA) and White MTA(WMTA).
• The main reason for introducing WMTA as a substitute for GMTA was to provide a hue matched more closely to that of the colour of teeth as opposed to contrasting Gray colour of GMTA.
• COMPOSITION: MTA consists of fine hydrophilic particles. The material is primarily derived from calcium oxide ,silicon dioxide , and aluminium oxide .It also contains trace amount of silicon dioxide ,calcium oxide, magnesium oxide,iron oxide, potassium sulphate and sodium sulphate.
• Differences in FeO concentration is thought to be primarily responsible for variation in colour of WMTA (off white )in comparison to Gray MTA GMTA was un aesthetic in cervical area of anterior tooth .
• MANIPULATION: Each pack of MTA comes with pre measured unit dose of water for convenience in mixing. To use MTA simply pour the powder onto pad supplied ,add water and mix to working consistency. Water powder ratio should be 3:1 according to manufacturer. Variation on part of water powder ratio could account for increased solubility and porosity of material.
• SETTING REACTION:On addition of water compound in MTA react to produce calcium silicate hydrate gel that is calcium hydroxide contained in a silicate matrix.
• SETTING TIME : 2 hours 45 min – 4 hours
• pH :10.2 at start of mix ,rises to 12.5 after 3 hours. In experimental setting MTA is capable of maintaining high ph for long time. The high pH of MTA could be of clinical significance when used in apical barrier technique since alkalinity creates a favourable environment for cell division and matrix formation. Due to high ph MTA shows antibacterial action similar to calcium hydroxide.
• SOLUBILITY:It has been shown that set MTA’s solubility is a function of water powder ratio (for optimum properties recommended w/p ratio is 3:1) MTA is mainly composed of a insoluble matrix of silica gel that maintains its integrity even in contact with water.
• SEALING ABILITY/MARGINAL ADAPTATION: The sealing ability and marginal adaptation of MTA outperforms other material compared (amalgam, Super EBA IRM e.t.c. ). A stable barrier to bacterial and fluid leakage is one of the key factors in creating clinical success of root repair material.
• Clinically a barrier of 3-5 mm should be considered if root end surgery is a treatment option.
• MTA’ s sealing ability and better marginal adaptation is probably due to its hydrophilic nature, longer setting time and slight expansion when it is cured in moist environment. MTA contains 5% gypsum that expands during setting contributing to better adaptation .
• REGENERATIVE CAPABILITIES Regeneration has been defined as the replacement of tissue components in the appropriate location, in the correct amount and the correct relationship to each other. This means reformation of the bone in the surgical site, adjacent to fully reconstituted PDL, attached to newly formed cementum, over resected root end and root end filling material.
• Clinically a barrier of 3-5 mm should be considered if root end surgery is a treatment option.
• MTA is not an inert material in a simulated oral environment, it is “ BIOACTIVE ”.
• ADVANTAGES :Biocompatible;Non toxic;Non resorbable;Good marginal sealing;No irritation to surrounding tissues;Stimulates hard tissue formation ;moisture insensitivity;Radio opaque
• DISADVANTAGES: Difficult to manipulate;Longer setting time;Need two appointments.