Root canal irrigation

The aims of root canal irrigation are the chemical dissolution or disruption and the mechanical detachment of pulp tissue, dentin debris and smear layer (instrumentation products), microorganisms (planktonic or biofilm), and their products from the root canal wall, their removal out of the root canal system. Each of the endodontic irrigation systems has its own irrigant flow characteristics, which should fulfill these aims. Without flow (convection), the irrigant would have to be distributed through diffusion. This process is slow and depends on temperature and concentration gradients. On the other hand, convection is a faster and more efficient transport mechanism. During irrigant flow, frictional forces will occur, for example, between the irrigant and the root canal wall (wall shear stress). In this chapter the irrigant flow and wall shear stress produced by different irrigation systems will be described. Furthermore, the effect of the flow on the biofilm and the chemical effect of irrigants on the biofilm will be discussed.