Objective: To conduct a systematic mid-to-long-term efficacy evaluation of the small window lateral maxillary sinus floor elevation surgery, using the ratio of the window area to the volume of bone graft material as an innovative evaluation metric; to provide clinical evidence for the treatment and assessment of maxillary sinus elevation surgery. Research Content and Methods: The study included all patients who underwent lateral wall small window surgery performed by Dr. Xie Liangkun from 2017 to 2024 in Affiliated Stomatology Hospital of Kunming Medical University. Seventy-seven patients underwent cone-beam computed tomography (CBCT) at each stage before grafting, before the surgery,immediately after the surgery, 6 months postoperatively, and after tooth placement. The CBCT data were imported into Mimics software to measure the volume of bone graft material at different periods (b value), and The photos which recording window size during surgery were imported into ImageJ software to measure the window area (a value). CBCT was also used to measure the distance from the window to the sinus floor, the thickness of the lateral wall bone plate, and the thickness of the Schneiderian membrane as secondary measurement indicators. The ratio of a/b was statistically analyzed for correlation with various secondary indicators, and conclusions were drawn. Bone cores taken 6 months after grafting (before implant placement) were subjected to Micro-CT scanning and histological analysis to evaluate the bone formation effects.

Research significance:The first part is the elevation of maxillary sinus floor through minimally invasive window side wall small window. Through retrospective study of implant retention rate, complications, patient subjective perception, anatomical factors and other indicators, it is used to comprehensively evaluate the clinical efficacy of this surgical procedure. In the second part, representative bone columns are taken for Micro CT scanning to evaluate the osseointegration from a histological perspective. Mimics software performs three-dimensional scanning of the transplant area, and the ratio of the window area to the volume of the transplant part is used as the main measurement index to demonstrate that minimally invasive window opening can achieve ideal bone grafting effects. Further verify the success or failure of minimally invasive side wall fenestration surgery. At present, relevant studies use this ratio as the main research data, and there is no use of 3D scanning to study changes in bone transplant areas. There are also few studies evaluating the binding of bone tissue using Micro CT, and most of them use CBCT 2D measurement data for evaluation.

Inclusion Criteria:

1. Aged 18 years or older;
2. Missing posterior maxillary teeth;
3. The missing tooth area has been edentulous for at least 3 months;
4. No acute severe maxillary sinus inflammation, and no tumor or other space-occupying lesions within the maxillary sinus;
5. The residual bone height (RBH) in the missing tooth area is less than 4mm;
6. Sufficient alveolar bone width in the missing tooth area to ensure implant placement;
7. Signed an informed consent form and can return for follow-up visits as scheduled.

Exclusion Criteria:

1. Patients with systemic diseases not suitable for implantation: such as uncontrolled hypertension, diabetes, cardiovascular and cerebrovascular diseases, bone metabolic diseases, head and face radiotherapy, etc.;
2. Uncontrolled periodontitis or mucosal disease patients;
3. Patients with bruxism;
4. Patients who have undergone implant placement or artificial bone material implantation in the missing tooth area;
5. Patients with mental illness.

Collected all patients who underwent small lateral window maxillary sinus elevation surgery performed by Dr. Xie Liangkun from 2017 to 2024.