Long-term effects of sinus membrane perforation on dental implants placed with transcrestal sinus floor elevation: A case-control study

Background There is a little comparative data on implants placed transcrestally with/without sinus membrane (SM) perforation. Purpose To compare the clinical and radiological outcomes of implants with maxillary sinus perforation and those without SM perforation. Materials and methods Among 560 transcrestally placed implants in 324 patients, the patients who underwent cone-beam computed tomographic radiography (CBCT) were included. The following groups were established: implants with SM perforation (group P) and implants without SM perforation based on postoperative panoramic radiographs and patient records (group NP). Group NP was further divided into subgroups based on CBCT taken at the last patient visit: group NP1 consisting of implants with no protrusion or <1 mm of protrusion and group NP2 consisting of implants with >= 1 mm of protrusion. Mixed linear regression was performed for the factors affecting SM thickening and marginal bone loss. Mixed survival analysis was also performed. Results A total of 379 implants in 221 patients were eligible. The mean follow-up period was 112.03 +/- 54.2 months. Twenty-six implants failed (2 and 24 implants in groups P and NP, respectively), mainly due to peri-implant bone loss. No statistically significant difference was noted between the groups in SM thickness (2.4 +/- 2.8 mm, 2.1 +/- 3.4 mm, and 2.5 +/- 3.5 mm in groups P, NP1, and NP2, respectively, p > 0.05). Marginal bone loss in group NP1 was significantly greater than that in the other groups. In the mixed model, SM perforation was not a determinant of sinus membrane thickening and implant survival in the mixed models and the survival analysis, respectively. Conclusions SM perforation in transcrestal sinus augmentation did not affect implant survival and SM thickening.