Implants are well accepted as a means of dental rehabilitation. While integration success rates are high, crestal bone loss can occur, and it may not become apparent until stage II surgery and implant uncovering. The purpose of this study was to quantify the relationship between exposure of implants through the oral mucosa between stage I and stage II implant surgery and early changes in crestal bone height. Bone levels were measured during placement of 275 implants in the maxillae of 50 subjects. Repeated bone height measurements were obtained at implant uncovering. Fourteen implants in 7 patients were exposed to the oral cavity through the mucosa at stage II surgery. Patients with 1 or more exposed sites demonstrated a likelihood of bone loss 3.9 times greater than patients with nonexposed sites (Fisher exact test, P = .0003). These results suggest that exposure of an implant between stage I and stage II implant surgery might serve as a potential indicator of the occurrence of early bone loss.