Immediate versus non-immediate implantation for full-arch fixed reconstruction following extraction of all residual teeth: A retrospective comparative study

Background: Immediate implants placed into fresh extraction sites are considered a predictable and acceptable procedure. The main biological advantage is the preservation of bone height and width. However, there is no direct proof of the clinical and surgical importance of this. The purpose of this study was to evaluate the correlation between implant dimensions, anatomic factors, and survival rates of immediate versus non-immediate implants. Methods: From 1989 to 1996, 380 implants (117 immediate and 263 non-immediate) were placed in 43 patients (50 jaws) following extraction of all residual teeth. A total of 253 implants were placed in the maxilla and 127 in the mandible, with a mean of 7.65 and 7.9 per jaw, respectively. Of the implants, 31% were placed immediately into fresh extraction sites. Results: Total 5-year cumulative survival rate (CSR) was 92%, mandibular 96% and maxillary 90%. Immediate implants had a better 5-year CSR (96%) versus non-immediate implants (89.4%). The maxilla mainly contributed to this difference (95% versus 88%). The mean potential contact surface area (PCSA) was 230 mm(2) Implants with significantly higher values yielded a higher 5-year CSR in the maxilla (96.6% versus 82.9%). Immediate implants in the posterior maxilla had a 100% 5-year CSR versus 72% with the non-immediate implants. Conclusions: 1) Implant-supported fixed ceramo-metal prosthesis is a predictable treatment modality for edentulous patients; 2) factors favorably affecting the survival of implants placed to support full-arch ceramo-metal prosthesis include immediate implantation, higher PCSA values, and implant location; 3) immediate implantation exerts its effect through higher PCSA values and by a compensatory effect to bone quality; 4) immediate implantation does not carry additional morbidity; and 5) potential contact surface area (PCSA) is a reliable mean that accurately represents implant dimensions and may replace length and diameter in future studies.