Fillings placed on teeth with too much damage or material loss can often fail. For this reason, nail and screw-like structures applied in such risky teeth with the support of existing or root canal treatment performed by us are called "posts". The post allows us to get support from the root of the tooth. It is planned and applied in a size appropriate to the channels within the root. The prosthesis superstructure built on it is called "core". The whole of this structure is called "post-core".