To treat furcation involvement is a crucial challenge to periodontists, not only because of the limitation in pocket reduction by osteoplasty and apically positioned flap, but also because of the unpredictability in regenerative approaches. Therefore, if the first molar is absent and the second molar has to be retained strategically for prosthetic reasons, very few alternatives besides nonsurgical/surgical debridement can be taken in treating the furcation of the second molar, where the interradicular root proximity and fusion frequently occur. On the other hand, root amputation/hemisection has long been considered a contraindication in treating furcations with two close roots; however, this impression is only empirical. A series of clinical cases involved in the treatment of intrabony defects associated with interradicular root proximity and fusion by root amputation/hemisection has been reported. Without any help of regenerative material, thorough root debridement and pocket reduction were attained. Based on these cases, we suggested that the cut surface created by odontoplasty during root amputation was compatible for periodontal healing and the extraction socket provided striking potential for defect repair. We re-examined the clinical feasibility and benefit of treating intrabony defects associated with interradicular root proximity and fusion in molar furcations by root amputation/hemisection, and suggested that its role should be favorably reconsidered on case basis. The short-term success in periodontal and prosthetic aspects needed to be further evaluated at long-term follow-up.