The choice of intracanal irrigants and medicaments is multi-factorial, solely and entirely depending on the mechanism of action of irrigant/medicament and knowledge of the clinician. With the advent of single-sitting root-canal treatment the use of intra-canal medicaments has decreased. In correlation with the advances in the methods of preparation of root canal spaces, the use of irrigants has advanced to complete cleaning and disinfection of the complex root-canal system. The variation in the anatomy of the root canal ( C-shaped canals, multiple lateral and accessory canals) accompanied with the minimal preparation ethics need copious amount of irrigation to facilitate complete disinfection and debridement. The judicial use of intracanal irrigants and medicaments can to some extent eliminate surgical endodontics in patients with periapical pathologies but cannot completely overtake surgical procedures. This book emphasizes on the effect of intra-canal irrigants and medicaments on the peri-radicular tissues when advertently and inadvertently they come in contact with the periodontium.