Abstract: Objective　To compare the 5-year clinical outcomes between tilted implants and axial implants in All-on-4 implant restoration through a retrospective study. Methods　A total of 26 patients who accepted maxillary and/or mandibular All-on-4 rehabilitation treatment in the Department of Oral Implantology, Nanjing Stomatological Hospital, Medical School of Nanjing University from October 2013 to October 2015 were followed up. A total of 120 implants were included, including 60 tilted implants and 60 axial implants. Immediate fixed rehabilitation supported by implants was performed after operation, and final rehabilitation was performed 3-6 months later. After 5 years of follow-up, the differences of implant survival rate, marginal bone level changes and the incidence of complications between tilted and axial implants, among tilted implants with different angles and between implants in upper and lower jaws were statistically analyzed. Results　①The overall 5-year implant survival rate of implants in All-on-4 implant restoration was 98.33% (tilted implants 96.67%, axial implants 100%). There was no significant difference between the two groups (P=0.496). ② After 5 years of loading, the average marginal bone resorption of inclined implant was (1.16±0.98) mm, and that of axial implant was (1.11±0.76) mm. There was no significant difference in marginal bone level changes between the two groups (P=0.709). ③ There was no significant difference in the incidence of complications between tilted and axial implants. Conclusion　In all-on-4 implant rehabilitation, tilted implants have a high 5-year implant survival rate and a relatively stable marginal bone level, which is similar to that of axial implants. The application of distal tilted implants has satisfactory 5-year clinical outcomes.

Key words: All-on-4, tilted implants, implant survival rate, marginal bone level changes, restrospective study