The current study demonstrated that sinus mucosal thickening does not correlate with implant survival. This result is consistent with a previously published report by Jungner et al. In their study, the presence of sinus thickening was not significantly associated with implant failure. Similarly, our study found a 100% implant survival rate for both patients with and without sinus mucosal thickening. It is worth mentioning that none of the CBCT images evaluated in the current study showed signs of sinusitis or periapical pathoses, despite indications of physiologic mucosal thickening. All the selected images presented clear sinuses without signs of infection. Therefore, it could be postulated that physiologic mucosal thickening does not contribute to implant failure. However, an association between pathologic mucosal thickening and implant survival cannot be drawn. If sinusitis is suspected, it is suggested that clinicians consult the appropriate medical specialists before implant placement.

Based on the findings of the current study, a history of periodontal disease is the only identified parameter significantly associated with sinus mucosal thickening. This finding indicates that clinicians should expect some degree of mucosal thickening when performing sinus augmentation procedures in a previously periodontally involved site. This finding is consistent with several previously published studies. Phothikhun et al. reported that sinuses with severe periodontal bone loss were three times more likely to have mucosal thickening. In a more recent study, Ren et al. reported an odds ratio of 4.62 for patients with severe periodontal bone loss with mucosal thickening. A possible explanation for this phenomenon is that increased inflammatory cytokines resulting from periodontal diseases might also reach the maxillary sinus, and thereby trigger an increased membrane thickening. With regards to implant treatment outcomes, while our study found that there is no association between mucosal thickening and future implant survival, a higher chance of sinus membrane perforation during sinus lift procedures has been reported when a thicker membrane is present.