Determinants of Early and Late Complications After Lateral Window Sinus Elevation: A Two-Year Retrospective Cohort Study

Objectives: To evaluate early postoperative complications and 1- and 2-year implant-related outcomes following lateral window maxillary sinus floor augmentation by correlating CBCT-based anatomical parameters with surgical and prosthetic variables.Materials and Methods: This retrospective single-center cohort study included 134 patients who underwent lateral window sinus augmentation between 2020 and 2023. Preoperative CBCT imaging was used to assess residual bone height, lateral wall thickness, palatal–nasal recess angle, ostium diameter, Schneiderian membrane thickness (2 mm). Early postoperative complications were recorded within the first month. Implant-related outcomes at 1 and 2 years were classified as implant failure or peri-implant crestal bone resorption (CBR). Statistical analyses included univariate tests and multivariate logistic regression (p2 mm, with bleeding/hematoma occurring exclusively in this group (p=0.006). Other anatomical parameters, including ostium diameter, showed no significant association with early complications. At 1 year, implant outcomes were significantly associated with prosthetic superstructure type, residual crestal bone height, intraoperative complications—particularly Schneiderian membrane perforation—and postoperative complication management strategy. These associations were primarily driven by increased CBR rather than implant failure. At 2 years, prosthetic superstructure type remained significantly associated with outcomes, while Schneiderian membrane thickness ≥3 mm was linked to higher CBR rates. Implant failure remained infrequent throughout the follow-up period.Conclusions: Lateral window sinus augmentation yielded predictable short- and mid-term outcomes when guided by CBCT-based presurgical assessment and structured postoperative management. Vascular anatomy, particularly AAA diameter, was the main determinant of early bleeding-related complications, whereas prosthetic design was the most consistent factor influencing long-term crestal bone changes.