A new classification of bone defects adjacent to dental implants is proposed. The classification highlights the importance of defect anatomy in the progression of the regenerative process. Defects were divided into two main groups: (1) closed defects, characterized by the maintenance of intact surrounding bone walls; and (2) open defects, which lack one or more bone walls. The open defect group was then divided into several subgroups that include the majority of situations encountered in clinical practice. The classification could be a useful tool for planning the correct regenerative procedure for each type of defect.