The sinus elevation procedure is a safe and predictable technique that allows the placement of implants in atrophic posterior maxillae. However, some recommendations have to be followed by the patient to ensure reliable healing. It is particularly important to avoid inducing trauma in the region concerned and through the sinuses. This report describes a rare complication that occurred after the grafting of a sinus, which was attributed to a violent sneeze a few hours after the intervention. The diagnosis of emphysema following air entry was confirmed by the suddenness of the swelling and associated crepitation, and by the radiographic observation of a delimited radiolucent zone in the grafted sinus. The immediate diagnosis and subsequent management prevented further adverse events. This case report supports the need for complete comprehensive instruction of patients after oral surgery, swift diagnosis, and management of emphysema.