The role of tricalcium silicates in endodontic therapy Flashcards
Tricalcium silicates in endodontic therapy (2)
MTA
Biodentine
What is Portland Cement? (2)
A ‘Hydraulic’ Cement
Cement that not only hardens by reacting with water but also forms a water-resistant product
Composition of Portland Cement - clinkers (8)
Portland cement ‘clinkers’ are comprised of:
Tricalcium silicate (CaO)3 · SiO2 45-75% Dicalcium silicate (CaO)2 · SiO2 7-32% Tricalcium aluminate (CaO)3 · Al2O3 0-13% Tetracalcium aluminoferrite (CaO)4 · Al2O3 · Fe2O3 0-18% Gypsum CaSO4 · 2 H2O 2-10%
Clinkers are pulverized to form a powder
Powdered clinkers make up over 90% of the final powder
Calcium sulphate is added which controls setting time
Up to 5% other constituents (fillers)
Composition of Portland cement - typical constituents (5)
Calcium oxide CaO 61-67% Silicone dioxide SiO2 19-23% Aluminium oxide Al2O3 2.5-6% Ferric oxide Fe2O3 0-6% Sulphate 1.5-4.5%
Composition of MTA (5)
Same as Portland cement but:
Without traces of Arsenic and Lead
Addition of bismuth oxide (20%) for radiopacity
Smaller and more uniform particle size
Contains less gypsum which is an inhibitor, to control working time
‘Medical grade’ Portland cement
Features of Mineral Trioxide Aggregate (7)
Biocompatible Non-toxic Non-resorbable No leakage around the margins Very alkaline when mixed with water Compressive strength equal to IRM Bactericidal
Uses of MTA (5)
Root-end restorations following apical surgery
Repair of lateral/furcation root perforations
Pulp capping (primary and secondary dentition)
Apexification in immature roots
Repair of resorption defects
How to use MTA (5)
Mix powder with sterile water in a 3:1 ratio on a glass slab
Your nurse will need to keep adding small amounts of water to keep the handling properties correct
Deliver MTA using appropriate instrument
If using internally place a cotton wool pellet in contact with the MTA to allow it to set
If using external to the tooth (eg RRF) moisture will be taken from the surrounding tissues
After placement of MTA (3)
Upon hydration, MTA forms a colloidal gel that solidifies to a hard structure in 3-4 hours
Initial pH of 10.2 which rises to 12.5 after 3 hours
Strength increases in the presence of moisture for up to 21 days
MTA vs Dycal as pulp capping material (2)
Research has showed favourable results for MTA
More consistent formation of hard tissue barrier
Much better pulp tissue response - dentine bridge formation
Inadequacies of MTA (5)
Takes several hours to set Can be washed away before it is set Handling properties Acidic environment will interfere with the setting process-placement site needs to be ‘infection free’ Cost
Biodentine (3)
The liquid contains
-calcium chloride as an accelerator
-a hydrosoluble polymer as a water reducing agent
The setting period is therefore reduced to 9-12 minutes (initial set)
Compressive strength during setting - Biodentine, Fuji IX and MTA (2)
In that order high to low
- Biodentine compressive strength reaches the same level as human dentine after 28 days
- Biodentine cuts like dentine giving similar sensation under the bur. Its ivory shade and its opacity allow to differentiate it easily from the tooth structure
Biodentine - micro-mechanical anchorage (2)
Biodentine labelled with fluorescein dye which has moved from the cement into the dentine tubules
BIOACTIVE
Mineral tags inside the dentine tubules
Biodentine is the first all-in-one biocompatible and bioactive crown-root dentine substitute to use wherever dentine is damaged
- Tooth vitality preservation thanks to reactionary dentine genesis
- Reduction of therapeutic failures thanks to its microleakage resistance
- Both endo and restorative indications thanks to physical properties similar to human dentine
