Furcation is an area of complex anatomic morphology, that once involved is difficult to treat and maintain by routine periodontal therapy. The invasion of the bifurcation and trifurcation of multirooted teeth by the disease is termed as furcation involvement.Various contributing factors for furcation involvement are periodontal disease, pulpal disease, iatrogenic factors (root fractures and root perforations) during endodontic therapy, anatomical factors such as cervical enamel projections, enamel pearls, bifurcation ridges, and trauma from occlusion. It is the anatomic location of the pathology that defines the lesion and hence, it is essential to have a good knowledge of the anatomy of furcation, to ensure the correct diagnosis and optimal treatment planning and to understand how these anatomic factors may influence the etiology and pathogenesis of this lesion. Thus, the purpose of this book is to review the intricacies related to the furcation and its involvement and also throw some light on the various proposed treatment strategies for the furcation involvement.