Citric acid concentration in MTAD is:
Composition

Tetracycline:

– It is bacteriostatic, broad spectrum antibiotic.
– It has low pH and acts as calcium chelator.
– It removes smear layer.
– It has property of substantivity. 
– It promotes healing.

Citric acid (4.25%): It is bactericidal in nature and removes smear layer.
Detergent (Tween 80): It decreases surface tension.
4.25%
3.75%
1%
0.50%