Immediate Occlusal Loading of Full-Arch Rehabilitations: Screw-Retained Versus Cement-Retained Prosthesis. An 8-Year Clinical Evaluation

Purpose: The aim of this study was to evaluate the survival and success of screw-retained versus cement-retained implant restorations in immediately loaded implants at 8-year follow-up. Materials and Methods: Patients who were scheduled for full-arch ceramic prosthetic restorations were divided into two groups by randomization: in one group, prosthetic frameworks were screwed onto implants (screw-retained group, SRG), and in the second group, the frameworks were cemented on abutments (cement-retained group, CRG). Dental implants were placed both in postextraction and in healed sites. A temporary full-arch prosthesis was placed immediately after implant placement. Intraoral digital radiographic examinations (evaluating marginal bone levels) were made at baseline, 6 months, and each year after implant placement. Results: In 28 patients, 24 full arches and 192 implants were placed in the maxilla and 10 full arches and 80 implants in the mandible (17 rehabilitations in each group). After an 8-year follow-up period, a survival rate of 99.27% was reported for all implants. Within the first year after implant placement, bone loss was recorded as follows: the CRG showed mean bone levels of -1.23 +/- 0.45 mm, while the SRG showed mean bone levels of -1.01 +/- 0.33 mm. After a 3-year follow-up, a slight increase was found (0.30 +/- 0.25 mm in CRG and 0.45 +/- 0.29 mm in SRG). After that point, marginal bone levels remained stable over time, up to the 8-year follow-up. No statistically significant differences were found between groups (P > .05). Conclusion: Definitive cement- and screw-retained ceramic restorations are highly predictable, biocompatible, and esthetically pleasing, and the two groups presented no statistically significant differences in bone loss.