During surgery, one sheep showed acute sinusitis at the test site. The sinus mucosa was perforated to allow sinus drainage and surgery was completed. During the healing period, no evident clinical complications were observed.

At the histomorphometric analysis, one sinus of the control group and one of the test group (corresponding to the sinusitis case) appeared to have lost almost all biomaterial. The results have thus been calculated on n = 6 and can be seen in Table 1. In one test site, the repositioned bone plate was apparently lost during the histological processing. Mean values and SDs are indicated in text and tables. The statistically significant differences are marked with an asterisk (*).

The newly formed bone was found surrounding and partially interpenetrating the particles of the biomaterial and in continuity with the lateral and medial walls of the sinus (Fig. 4a) and, when present, in continuity with the repositioned bony window (Fig. 4b).

After 4 months of healing, the newly formed bone proportions within the augmented sinus were 16.4 ± 5.6% at the test sites and 12.0 ± 3.7% at the control sites. In both groups, large amounts of interpenetrated graft were observed, in which bone propagated within the porosities of the biomaterial at fractions of 37.1 ± 7.5% and 35.3 ± 6.8% at the test and control sites, respectively (Fig. 4c, d). The total bone, composed of newly formed bone and interpenetrated graft, was 53.5 ± 7.6% at the test site (replaced bony window) and 47.3 ± 9.9% at the control site (Fig. 5).

The largest amounts of newly formed bone and total bone (composite bone) were found in the close-to-window region at the test sites. In this region, the proportion of the newly formed bone was 22.1 ± 12.6%* and 7.5 ± 64.5%* (P = 0.028) at the test and control sites, respectively. The respective percentages of the total composite bone (new bone plus bone interpenetrated to the graft material) were 66.1 ± 14.7%* at the test sites and 44.2 ± 15.1%* at the control sites (P = 0.046). In the middle region, a statistically significant difference in soft tissue amount was seen between the test (29.7 ± 4.9%*) and control (37.5 ± 10.1%*) sites (P = 0.046). No substantial differences were found in the submucosal and base regions (Fig. 6).