Five-Year Marginal Bone-Level Changes Around Immediately Loaded or Immediately Restored Implants After Maxillary Sinus Floor Elevation: A Retrospective Cohort Analysis of Three Implant-Site Preparation Techniques

Background/Objectives: Peri-implant marginal bone stability is a relevant indicator of the medium-term outcomes of implants placed simultaneously with maxillary sinus floor elevation. This study aimed to describe peri-implant marginal bone levels after at least 60 months and to assess their association with three implant-site preparation and condensation techniques: osteotomes, Densah/Versah burs, and DASK Simple, used in conjunction with transcrestal or lateral sinus floor elevation. Methods: This retrospective cohort study included 248 patients and 528 Dentium SuperLine bone-level implants placed in the posterior maxilla. Immediate restoration without occlusal contacts was used for single-unit or splinted prostheses, whereas immediate loading was applied exclusively to All-on-X rehabilitations. Marginal bone levels were assessed by cone-beam computed tomography (CBCT) at delivery of the definitive restoration, 3–6 months after implant placement, and at the final follow-up, 63–66 months after implant placement. The primary analysis used a linear mixed-effects model to account for dependence among implants within the same patient. Results: Six documented implant losses occurred before the final assessment, representing 1.1% of the implants in the selected cohort. Paired radiographic measurements were available for 522 implants. The mean marginal bone level at the final assessment was 0.11 ± 0.18 mm, and the mean change from baseline was 0.03 ± 0.06 mm. Inter-examiner reproducibility was excellent (ICC = 0.994, 95% CI, 0.992–0.996), with a standard error of measurement (SEM) of 0.0085 mm and a 95% minimum detectable change (MDC95) of 0.0235 mm. Repeated intra-examiner measurements showed no numerical differences at the recorded measurement precision. The mean longitudinal change remained substantially below the nominal 0.125-mm CBCT voxel size and should therefore be interpreted cautiously with respect to measurement precision and clinical relevance. After adjustment for the available covariates and clustering of implants within patients, the implant-site preparation and condensation technique was not independently associated with the 5-year marginal bone level. Conclusions: No adjusted association was detected between implant-site preparation technique and the 5-year marginal bone level in this retrospective cohort. The very small observed longitudinal changes should be interpreted cautiously in view of measurement uncertainty, potential selection bias, and residual confounding, and the findings should not be interpreted as evidence of equivalence among the three techniques.