[Clinical report on defective dentition]

The "8020" objective seems difficult to achieve, but at least 20 teeth are needed based on difficult cases of defective dentition. Our clinical experience shows that at least 18 teeth are needed to keep 4 occlusal supports. If the number of occlusal supports falls below 4, defective dentition may easily deteriorate to more clinically difficult cases. From our long-term experience, patients over 80 years old who still have 20 teeth usually have stabilized occlusal supports, while many cases who have partially lost their occlusal support do not achieve the 8020 goal. Prevention of partial defects of teeth for restoration of caries and active prosthesis for defects are important to achieve the 8020 goal. Furthermore, continuous follow-up and preventive support are important. If continuous clinical correspondence is possible, 8020 may be achievable in about 80% of all cases.