One implant was lost in the perforation group due to early-onset peri-implantitis, whereas all implants in the control group were still in place. As we had previously prospectively reported on the first 6 months after dental implantation in this cohort [11], there was no further impact of membrane perforation on implant loss for at least 12 to 24 months in this retrospective evaluation. The appearance of peri-implantitis was more often observed in patients who experienced a procedure with an intraoperative perforation. However, this finding might be because the control group did not fully represent the patients without membrane perforation as only one third engaged in a sufficient follow-up. The reduced time span of the patients’ observation time in the control group might be due to the lack of postoperative complications in this group who did have follow-up examinations in the department. Therefore, we cannot conclude whether there is or is not an impact based on the results in our study cohort. Sakkas et al. reported no impact of membrane perforation on the overall implant within a 1-year evaluation [12], whereas Proussaefs et al. reported a decreased implant survival in two-stage procedures and membrane tear compared to intact membranes (69.56 vs. 100%) [10], as did a study published by Khoury [7].

In our study, bone resorption in the augmented area did not differ significantly between sinus lifting procedures with or without perforations. It is now widely accepted that following initial bone remodeling after an augmentation procedure followed by a dental implantation, bone loss within the following 3 years with implants in the interproximal space should be less than 0.5 mm in radiographic evaluations [26, 27]. Consistent with the results of Sakkas et al., there was no impact of bone graft origin or postoperative complications in patients with perforation of the Schneiderian membrane [12], similar to a study by Moreno Vazquez et al., which also did not find a correlation between complications, graft failure, and membrane perforation, assessing 8 years postoperatively [24]. In contrast to these studies, Proussaefs et al. reported a significant negative impact of membrane tear on bone formation in the sinus, more soft tissue formation, and less contact of graft particles to the residual bone [10].