Many articles have detailed local accidents and complications in dental implant treatment. Comparisons of the data they report are not always easy because different criteria have been followed in the various classifications and there is confusion between the terms accident and complication. The aim of this paper is to propose a classification that considers the timing of the events and makes a distinction between the two terms. Accidents are events that occur during surgery, and complications are any pathologic conditions that appear postoperatively. The proper diagnostic procedures and surgical techniques for their prevention and treatment are also described.