Intentional Replantation is an indispensable procedure that can be applied lastly for tooth preservation in situations where non-surgical endodontic treatment and apical surgery are unfeasible. However, there are many practitioners who are afraid of the outcome of the procedure, because it accompanies the extraction process and we have few studies that predict the prognosis. This lecture presents 10 year-outcomes of intentional replantation with contemporary technique. The success rate by strict criteria was 77%. If ankylosis is not regarded as a failure, the success rate will rise to 85%. External root resorption occurred in just 3% of all the cases and mostly due to cervical trauma during extraction process. This low incidence rate is thanks to proper case selection and good retro-filling materials. On the other hand, recurred periapical radiolucency was found in 5% cases, which accompany MTA wash-out. Less traumatic extraction will reduce external root resorption and use of fast-setting MTA will prevent from wash-out. This lecture also shares the method for less-traumatic extraction based on the results of finite element analysis.