Evaluation and comparison of three graftless implant methods for maxillary rehabilitation: All-on-4®, All-on-6 and zygomatic implants - a retrospective observational study.

BACKGROUND: Edentulism and posterior maxillary edentulous spaces lead to functional limitations as well as aesthetic and psychosocial consequences. In recent decades, implant-supported prosthetic rehabilitation has become the gold standard for the treatment of patients with tooth loss. OBJECTIVES: The aim of this retrospective comparative study was to evaluate the clinical effectiveness and incidence of complications associated with different graftless implant techniques used for the rehabilitation of the edentulous maxilla and posterior maxillary edentulous spaces. MATERIAL AND METHODS: The study was conducted based on the medical records of patients who underwent implant treatment performed by the same surgical team at 4 private dental clinics in Poland between 2015 and 2020. A total of 667 dental implants placed in 153 patients of different ages and sexes were included in the analysis. The follow-up period ranged from 1 to 5 years. Three types of dental implants were evaluated. The χ2 test and Fisher's exact test were used for the statistical analysis. RESULTS: The most frequently selected implantation technique for maxillary rehabilitation was the All-on-6 method, which was associated with a complication rate of 3.70%. The All-on-4® method was the least frequently used and demonstrated a failure rate of 7.05%. A lack of osseointegration was observed in 4.81% of the zygomatic implants. The statistical analysis did not reveal any statistically significant differences in osseointegration rates among the evaluated methods. CONCLUSIONS: The All-on-4®, All-on-6 and zygomatic implant techniques are effective alternatives to conventional approaches for the rehabilitation of the edentulous, atrophic maxilla or posterior maxillary edentulous spaces. All three techniques are associated with comparable complication rates. These methods shorten treatment and rehabilitation time and reduce trauma by minimizing the number of surgical interventions, eliminating the need for guided bone regeneration procedures and interventions into the sinus (sinus lift). Further studies with follow-up periods exceeding 5 years and larger patient cohorts are warranted to confirm these findings.