As endodontists, we know that our job is more than doing root canal treatments for giving to patient's body a good environment to prevent or heal periapical pathosis. Our labor goes beyond the limits of a root canal space needing to be cleaned, shaped and filled. From an optimistic point of view, endodontist's advisable goal should be a first step intervention focused in the treatment of pulp disease, providing the organism a proper environment to allowed tissue recovery when it is damaged. The main goal of the lecture is to provide clinical techniques and scientific information related to the moment in which the clinician must decide on a root canal treatment or to give the pulpo-dentinal complex the opportunity to survive, maintaining in this way the important biological functions that the pulpal tissue performs. Always keeping in mind the fact that as long as we don’t know what we treat, overtreatment seems to be easier and more predictable than preservation of vital tissues. (Rechemberg, D. Zehnder, M. 2014).