Even the most difficult cases, such as Eichner classification C1 and edentulous jaw with severe ridge resorption, start with only one or two missing teeth. Therefore, when faced with a case of missing teeth, prosthetic treatment must be performed to prevent further tooth loss. The cause of the loss, the condition of the remaining teeth, and risk factors must be considered. However, the cases of missing teeth encountered in clinical practice are extremely diverse, and even if similar prosthetic treatment is performed, there are often large differences in the postoperative course.

This paper reviews 10 cases with relatively long progression, including cases with poor prognoses, and examines what type of implant prosthetic treatment may stop further loss. In order to prevent the loss from expanding, appropriate prosthetic treatment should be performed while the area of loss is small to ensure continuity of the dentition, and sufficient occlusal support should be secured to stabilize the occlusion. Risk factors that promote further tooth loss, such as the patient's age, the distribution of tooth loss, occlusal support, condition of periodontal tissues, parafunction, occlusal force, and inferior condition of opposing teeth, must be accurately determined. Careful preoperative examination and diagnosis, flexible intraoperative modification of the treatment plan, and a continuous postoperative approach are very important. Further, constant maintenance after delivering the superstructure, force control, plaque control, and early response to changes are essential.