Effectiveness and influencing factors of strip-cushioning transcrestal sinus floor elevation: a clinical retrospective study.

OBJECTIVES: To evaluate effectiveness of the strip-cushioning TSFE with simultaneous implant placement; and to investigate its potential influencing factors, including anatomical variations. The primary outcome was endo-sinus bone gain (ESBG) before prosthesis. MATERIALS AND METHODS: This retrospective study assessed ESBG and crestal bone level (CBL) using cone-beam computed tomography (CBCT) before surgery (T0), immediately after surgery (T1), and before prosthesis (T2), along with peri-apical radiographs at prosthesis (T3) and during post-loading follow-ups (T4 to T6). One-way repeated measures ANOVA assessed bone height changes. Univariate and multivariate generalized linear mixed models (GLMM) identified the factors influencing ESBG and Schneiderian membrane perforation rate. RESULTS: A total of 88 patients with 107 implants were included. Bone height under sinus floor significantly increased at five peri-implant positions from T0 to T1 and T2. The mean ESBG was 5.55 mm (T1) and 4.62 mm (T2). GLMM revealed the first molar site (p = 0.036) and RBH < 5 mm (p < 0.001) were significantly associated with higher ESBG. Schneiderian membrane perforation occurred in 12 sites (11.2%). T1 ESBG/mesiodistal elevation width (MEW) > 0.8 was significantly associated with higher perforation risk (p = 0.011). ESBG and CBL significantly declined during post-loading follow-ups (T4 to T6) compared to T3. CONCLUSIONS: The strip-cushioning technique led to radiographically detectable ESBG before prosthesis, which appeared related to RBH and implant site. Membrane perforation was more likely with a higher T1 ESBG/MEW ratio. Notably, as challenging anatomical variations did not adversely affect these outcomes, this technique may be considered a viable option in demanding clinical situations. CLINICAL RELEVANCE: The strip-cushioning TSFE should be considered a viable option for sinus floor elevation in cases with challenging maxillary sinus anatomical variations.