Evaluation of Edentulous Maxillary and Mandibular Full Arch Implant Supported Rehabilitation Using the All-on-Four Treatment Concept: An 8-Year Follow-Up Retrospective Study

The "all-on-four" treatment modality is a treatment in which four implants are surgically placed in the completely edentulous jaw in order to restore immediately loaded implant supported fixed restoration. The aim of the present study was to compare clinical, radiological and prosthetic outcomes of immediately loaded maxillary and mandibular four implant supported cross-arch fixed denture prosthesis. A total of 112 edentulous patients who were rehabilitated for their complete maxillary and mandibular edentulism using All-on-four concept between January 2010 to August 2012 in four private dental clinics were included in this study for retrieve their data for marginal bone loss, implant survival rate, and prosthetic complication for a period of 8 years of follow-up. A total of 12 patients lost 18 implants, provided a cumulative survival estimate of 97.99% at 8 years in the maxillary arch implants in 8 years of follow-up. After 1 year of follow-up, the mean bone loss with in comparison to baseline at implant level was 1.14 ± 0.86 (mean ± SD), and after 8 years it was 1.63 ± 1.24. In the maxillary arch the marginal bone loss was more when compared to mandibular arch, it showed 1.58 ± 1.22 and 1.89 ± 1.18 for 1 year and 8 years, respectively, for the implants in the maxillary arch. Cumulative implant survival rate recorded in 8 years of follow-up was 97.99%. With a prosthetic survival rate of 78.6%, The prosthetic failure was mainly due to the type of restoration (acrylic wrap-around).