Risk Factor Analysis Following Maxillary Sinus Augmentation: A Retrospective Multicenter Study

Purpose: Implant-supported rehabilitation of the atrophic posterior maxilla often necessitates maxillary sinus surgery to augment existing bone volumes. Recent systematic reviews have reported implant survival rates above 90% following sinus elevation. However, statistical assessment of the effect of anatomic factors, implant design and surface, individual risk factors, and complications related to sinus floor elevation procedures on implant survival through analyzing patient data has not yet been performed. The aim of this study is to identify risk factors that might affect implant survival following sinus elevation. Materials and Methods: Three centers were involved in this retrospective multicenter study; 106 patients were treated with 144 sinus elevation procedures and received 328 implants. The mean follow-up was 48.4 months, and the longest follow-up period was 72 months. The analysis considered patient age, gender, health status, and smoking habit; implant size, shape, and surface; residual ridge height; timing of implant placement with respect to grafting; graft material; and the occurrence of surgical complications. For quantitative variables, the Pearson correlation was used. The chi-square test and Fisher exact test (for samples smaller than five units) were used for qualitative variables. Results: The cumulative implant survival rate was 93.0% up to 5 years. Complications occurred in 41 patients. Intraoperative sinus membrane perforation occurred in 40 sinuses (28%) and was not a significant risk factor for implant survival. Six patients experienced postoperative infection leading to graft failure, and two patients had considerable intraoperative bleeding. Smoking more than 15 cigarettes/day and a residual ridge height 4 mm were significantly associated with reduced implant survival. Conclusions: Smoking habits and residual ridge height should be evaluated carefully prior to sinus elevation procedures. Keywords: atrophic maxilla, maxillary sinus elevation, residual ridge, sinus membrane perforation, smoking