Influence Of Schneiderian Membrane Conditions On The Endo-sinus Bone Remodeling After Osteotome Sinus Floor Elevation:a Retrospective Study

Influence of Schneiderian Membrane Conditions on the Endo-sinus BoneRemodeling after Osteotome Sinus Floor Elevation:a Retrospective StudyObjectives:To evaluate the effect of Schneiderian membrane conditions on bone remodeling in maxillary sinus after osteotome sinus floor elevation without grafting.Material and methods:A total of 51 implants placed in 36 patients from January 2013 to June2018 were retrospectively studied.All implants were placed in atrophic posterior maxillae（5in premolar sites and 46 in molar sites）simultaneously after osteotome sinus floor elevation（OSFE）surgery without grafting.Cone-beam computed tomography（CBCT）was taken before surgery to measure the residual bone height（RBH）and group according to sinus membrane conditions.Standardized periapical and panoramic radiographs were taken immediately after surgery（T_i）,at 6 months（T₂）,1 year（T₃）,and 3 year（T₄）after implant surgery.Implant protrusion length（IPL）was measured at Tl.Endo-sinus bone gained（ESBG）of the elevated region were measured from T₂ to T₄ for evaluation on radiographic images.Results:Survival rate of all implants was 100%after 3-year follow-up.No obvious mobility or severe marginal bone loss was observed.According to the preoperative CBCT scans,30implant sites were below normal Schnerderian membrane（Group A）,11 implants sites were below thickening sinus membrane（Group B）,and 10 implant sites were below pseudocysts（Group C）.Before surgery,the mean RBH of the 3 groups was 5.94±1.16 mm?5.93±0.93mm,and 5.37士0.75mm,respectively,without significant difference（/?>0.05）.The mean IPL of the 3 groups at T_i was 2.72土0.70 mm,2.41士0.80 mm,and 2.69士0.78 mm,respectively,without significant difference either{p>0.05).At each follow-up time point,there was no significant difference in ESBG among the 3 groups（p>0.05）.After 3 years,the mean remodeling of endo-sinus bone of the 3 groups was 1.59士0.96 mm,0.98士0.76 mm,1.23士0.75 mm,respectively,without significant difference（p>0.05）.Results:The radiographic and clinical results showed that OSFE without grafting is a safe and predictable surgical procedure in atrophic posterior maxillae.Mild flat thickening and small?sized pseudocysts without clinical symptoms may not be contraindications to OSFE surgery.