Immediate implants are those that are placed immediately after extraction of teeth. 

Teeth replacement using dental implants has proven to be a successful and predictable treatment procedure; different placement and loading protocols have evolved from the first protocols in order to achieve quicker and easier surgical treatment times. Immediate placement of a dental implant in an extraction sock

Immediate implant placement is a well-accepted treatment that offers the advantages of treatment time reduction and potentially increased patient satisfaction and treatment acceptance. In addition to reduced treatment time, several authors have suggested that immediate implants helped preserve the integrity of the extraction socket.  

Immediate implants can be the best solution to have your tooth/teeth restored immediately. You don’t have to wait for the bone to form in the extraction site . Normally new the bone formation takes 3-4 months time after that only one can place implant in it. Because you need to have strong bone for the implant to take support from.