Influence of various factors on the effectiveness of sinus lifting and the role of augmented depot morphology: a retrospective clinical study

BACKGROUND: Subantral augmentation is widely used for bone deficiency in the posterior maxilla. However, the relationship between the configuration of the augmented space, subsequent bone remodeling, and long-term clinical outcomes has not been described in sufficient detail.

AIM: To assess the association between cone-beam computed tomography (CBCT)-based configuration of the augmented subantral space, augmented bone stability, and dental implant survival after sinus floor elevation.

METHODS: This retrospective observational case-series study included 193 consecutively operated patients. According to postoperative CBCT morphology, five configurations of the augmented subantral space were identified: dome-shaped elevation, sinus recess filling, uniform Schneiderian membrane elevation, transcrestal (closed) sinus lifting with a mound-shaped contour, and island-like configuration. Follow-up CBCT was performed at 6 months, 1 year, 3 years, and ≥5 years. Implant survival, augmented bone height changes, and inflammatory sinus-related complications were assessed. The statistical analysis was descriptive.

RESULTS: Over ≥5 years, the highest frequency of successful outcomes was observed with recess filling (100%) and uniform elevation (approximately 99%), slightly lower with dome-shaped elevation (approximately 83%) and mound-shaped configuration (approximately 62%), and the lowest with island deposits (approximately 33%). Uniform distribution of the graft and targeted correction of recesses were associated with minimal resorption, absence of significant inflammatory complications, and implant survival of 98%–100% at the five-year mark.

CONCLUSION: In this retrospective case series, the configuration of the augmented subantral space was associated with bone remodeling and implant stability after sinus floor elevation. The most favorable outcome profiles were observed for uniform Schneiderian membrane elevation and sinus recess filling, whereas island-like configuration was more often associated with unfavorable remodeling. These findings should be interpreted as exploratory clinical trends requiring prospective validation.