In the present study, a lesser amount of bone was registered subjacent to the sinus mucosa compared with the other regions. This is in agreement with another experiment, in which a similar material was used for sinus augmentation in sheep [24]. A similar outcome was also reported in another study [27] that used DBBM xenograft for sinus augmentation in sheep. In that study, a collagen membrane was placed subjacent to the elevated sinus mucosa at the test sites, while no membranes were used at the control sites. Lesser amounts of the new bone were found underneath the sinus mucosa compared with the other regions at both the test and control sites. Moreover, similar amounts of the new bone were observed at both the test and control sites in all regions. This finding allowed the conclusion that the presence of the collagen membrane did not influence the results of healing. These results are in agreement with several other experiments that studied the role of the sinus mucosa in the bone formation [28,29,30].

In this study, a polylactic membrane was used, while Omori et al. [17] used a collagen membrane. The reason is the greater stiffness on the synthetic membrane compared with the collagen one, that could limit the introflection of the membrane in the augmented area. We found no difference in the bone formation, confirming Omori’s results; membrane’s material does not seem to influence bone formation.

In the analysed histological slides, no cyanoacrylate was observed. This outcome is not in complete agreement with the previously mentioned study [17] where few remnants of cyanoacrylate were observed in the gap between the bone plate and the edges of the antrostomy, which seemed to interfere with bone formation, although the adhesive showed a progressive degradation during the analysed periods of healing. The authors suggest the use of a cyanoacrylate with high viscosity. A way to increase the viscosity could be to keep the adhesive in cold conditions, as in our experiment. In the present study, no inflammatory response to cyanoacrylate was seen, confirming what has already been observed in other studies that excluded the cytotoxicity of cyanoacrylate [18] and negative systemic effects [31].