Disinfection of the root canal by sonic, ultrasonic and laser-activated irrigation

Irrigants are chemically inactivated after their reaction with the biofilm and therefore need to be mixed with fresh irrigants. Insight in the flow of the irrigant during a root canal treatment is crucial to understand the importance of the disinfection of the root canal system. This chapter discusses the operational characteristics, fluid dynamics, and mechanical and chemical interactions involved with sonic activated irrigation (SAI), ultrasonic activated irrigation (UAI), and laser activated irrigation (LAI). Biofilm consists of a substantial extracellularmatrix of mainly proteins and polysaccharides (EPS, extracellular polymeric substance), which effectively protects microorganisms. Forces on the biofilm exerted by irrigant flow could disrupt the top layers of biofilm, or its EPS matrix, or could completely remove the biofilm. To obtain an optimal chemical effect of irrigants, they should be delivered throughout the root canal system and be refreshed and mixed as effectively as possible.