This study aims to evaluate graft volumetric changes and stability up to 12 years after lateral sinus floor elevation with deproteinized bovine bone mineral (DBBM) as a filling material.

This study aims to assess graft volume changes and stability up to 12 years after lateral sinus floor elevation using natural bovine bone. The research will involve patients who underwent external sinus lifts starting 2011 and had pre-operative and post-operative CBCT scans. The study will include a retrospective comparison of graft volume changes using three time points: T0 (pre-operative CBCT, showing residual bone height), T1 (post-operative CBCT acquired at different time points, including immediately after the procedure T' and 9-months post-operative scans T''), and T2 (long-term post-operative CBCT). The residual bone height from T0 will be excluded in subsequent scans to focus on evaluating changes in graft volume.

For the primary outcome evaluate radiographically in 3D using CBCT volumetric changes in region of lateral sinus lift using deproteinized bovine bone graft material.

For the secondary outcome is to evaluate potential differences in graft volumetric changes among different age groups, genders, smoking vs. non-smoking patients and to evaluate implant survival. In addition to that, to detect a potential pattern in graft resorption/ stabilization for only 11 patients from Ghosn et al's study (with immediate post-operative CBCT and 9 months post-operative CBCT).

For this, a minimum sample size of 52 patients (increasing the sample size as much as possible > 60 for more accurate results) are needed for statistical analysis to detect a significant difference in graft volume and an additional 11 patients are needed from Ghosn's et al study for an additional analysis (exploratory purpose).

Patient's inclusion criteria include:

• Lateral sinus floor elevation using deproteinized bovine bone graft after 2011 at the faculty of dentistry.
• At least 18 years old at baseline.
• Systemically healthy.
• Signing a new informed consent.
• Smokers (≥ 10 cigarettes/ day) and non-smokers ( < 10 cigarettes/ day)

Patient's exclusion criteria include:

• No CBCT taken within 1 year after surgery.
• Inflammatory lesions present near surgical site.
• History of radiation therapy in head/ neck region.
• Use of bisphosphonates. CBCT comparisons will be done using 3D Slicer starting with CBCT superimposition for the different CBCTs at different time points for initial alignment followed by automatic alignment by best fit matching (for re-approximation with minimal deviation) and exclusion of the mobile mandible. Then, bone graft segmentation and volume calculation will be done by excluding the RBH to detect the exact bone graft volume from pre-implant placement followed by long-term follow-up.

This will be followed by statistical analysis for the analysis of the collected results and manuscript writing for the conclusions drawn.

Inclusion Criteria:

• Patients who underwent lateral sinus floor elevation with natural bovine bone as filling material after 2011 at the Faculty of Dentistry, Saint Joseph University of Beirut.
• At least 18 years old at baseline
• Systemically healthy
• Patients who sign a new informed consent.
• Smokers (≥ 10 cigarettes/ day) and non-smokers (< 10 cigarettes/ day)

Exclusion Criteria:

• Patients who did not take a CBCT within 1 year after the initial surgery.
• Presence of inflammatory lesions at the surgical site (eg, sinusitis as assessed by CBCT).
• History of radiation therapy in the head/neck region.
• Use of bisphosphonates.

Patients who underwent lateral external sinus lift at the Faculty of dentistry at Saint Joseph University of Beirut