Whether or not a second molar should be replaced after its removal is debatable. To assess the evidence and discuss the pros and cons of replacing a missing second molar with a dental implant restoration, the authors searched the literature for articles that evaluated the following factors: chewing efficiency, tooth loss, super-eruption, extrusion, over-eruption, and occlusal interferences. The ... [Show full abstract] data indicated that replacing a second molar provides some increased masticatory performance, but first-molar occlusion facilitates 90% chewing efficiency. Super-eruption of unopposed posterior teeth occurs frequently, and approximately 20% of these teeth extrude 2 mm, but the degree of over-eruption is not strongly related to the incidence of occlusal interferences. It was concluded that after a patient/dentist discussion regarding second-molar replacement, it is the patient's preference that usually dictates the decision. In this regard, if a patient perceives a chewing deficiency or dislikes having a gap in his or her dentition after the loss of a second molar, the tooth could be replaced with an implant-supported restoration. However, if the patient does not recognize any reduced masticatory efficiency, replacement of a second molar typically is unnecessary. This is due to the findings that most extrusion over time is minor and usually does not affect occlusal function; also, concerns about over-eruption can be managed in a preventive manner, and/or unopposed second molars can be monitored. Nevertheless, super-eruption of teeth can complicate restorative cases.