The aim of this study was to evaluate the effect of closed sinus lift surgery on dental vitality and periodontal sensitivity of teeth adjacent to the surgery area. Thirty patients undergoing closed sinus lift surgery by osteotomes were evaluated for dental vitality and periodontal sensitivity of adjacent teeth. Dental vitality and sensitivity were evaluated using the electric pulp tester (EPT) and cold spray once before surgery and one week, one month, and six months after surgery. In order to increase the validity of the study, one contralateral tooth in each patient was considered the control. In the test group, the number of teeth that did not respond to EPT and cold stimuli increased from baseline to six months after surgery and showed a significant difference between the four time intervals (P = 0.015 for EPT; P = 0.007 for cold stimuli). Thus, the vitality of teeth adjacent to the closed sinus lift area was lost over time. There was no significant difference between the two groups at any time for either stimuli. According to this research, tooth sensitivity to EPT and cold stimuli was not significantly different between test subjects and controls. For both cold and electrical stimulation, the number of teeth that did not respond was highest at one week after surgery and significantly different from baseline. However, after six months postsurgery, this number decreased, indicating recovery. However, some teeth were considered necrotic in the sixth month. It can be concluded that closed sinus lift surgery may cause necrosis in adjacent teeth, but more studies are required.