*3.4. Quantitative Histomorphometric Evaluation*

Table 3 shows the individual histomorphometric indices. An average vital bone volume of 29.9% (BV/TV) was measured in the complete biopsies (SD ± 10.1) of which 7.1% (OV/BV, SD ± 4.8) was osteoid. The osteoid surface (OS/BS) covered 26.0% (SD ± 13.4) of the bone surface. The BS/TV covered 4.7 mm2/mm3 (SD <sup>±</sup> 2.3). As can be read from Table 3, Patient #4 had extremely high values for trabecular bone volume (BV/TV and Tb.Th.). This high BV/TV is in accordance with the high T0 value, most likely caused by an oblique section of the cortical maxillary sinus wall (Table 1). A low bone surface (BS/TV: 2.2 mm2/mm3) and a high osteoid thickness (O.Th: 481.9 μm) were observed in the bone biopsy of patient #5 (Table 3).

**Figure 3.** Increased bone formation following the shape of the grafted particles in a maxillary bone biopsy after a maxillary sinus floor elevation procedure from a patient with autogenous bone mixed with Straumann® bone ceramic (60:40) after 6 months healing time, stained with Goldner trichrome staining. No Howship's lacunae could be detected on the characteristic outlines of the calcium phosphate particles. (original magnification ×100).

**Figure 4.** (**a**) Overview of an example of a bone biopsy from the maxilla of a patient, 6 months after a maxillary sinus floor elevation procedure using a mixture of autogenous bone and Straumann® bone ceramic (60:40), stained with Goldner trichrome staining. Bone is scattered throughout the entire biopsy (original magnification ×10). (**b**) Overview of a not previously shown bone biopsy from the maxilla of a patient, 6 months after a maxillary sinus floor elevation procedure using pure Straumann® bone ceramic (60:40) as studied by Frenken et al. [12], stained with Goldner trichrome staining. Bone formation at the first 3 mm immediately cranially from the former floor of the maxillary sinus (original magnification ×10).


**Table 3.** Histomorphometric evaluation of the six biopsies from five patients in whom a maxillary sinus floor elevation (MSFE) procedure was performed with a mixture of autogenous bone from the maxillary tuberosity and Straumann® bone ceramic (60:40) after 6 months healing time.

M, male; F, female; age in years at biopsy retrieval; BV/TV: vital bone volume/total volume; BS/TV: bone surface/total volume; Tb.Th: trabeculae thickness; OV/BV: osteoid volume/vital bone volume; OS/BS: osteoid surface/bone surface; O.Th: osteoid thickness; N.Oc/BPM: number of osteoclasts per bone perimeter.

Table 3 shows the individual histomorphometric indices. An average vital bone volume of 29.9% (BV/TV) was measured in the complete biopsies (SD ± 10.1) of which 7.1% (OV/BV, SD ± 4.8) was osteoid. The osteoid surface (OS/BS) covered 26.0% (SD ± 13.4) of the bone surface. The BS/TV covered 4.7 mm2/mm3 (SD <sup>±</sup> 2.3). As can be read from Table 3, Patient #4 had extremely high values for trabecular bone volume (BV/TV and Tb.Th.). This high BV/TV is in accordance with the high T0 value, most likely caused by an oblique section of the cortical maxillary sinus wall (Table 1). A low bone surface (BS/TV: 2.2 mm2/mm3) and a high osteoid thickness (O.Th: 481.9 μm) were observed in the bone biopsy of patient #5 (Table 3).

An overview of the histomorphometric findings from the present study (6-months mixed graft) and previously reported studies with pure BCP after 6-, 9- and 12 months healing time is shown in Table 4. A non-parametric Kruskal–Wallis test showed significant differences between OS/BS (*p* = 0.0233) and Tb.Th. (*p* = 0.0244). Other tested histomorphometric indices (BV/TV, OV/BV, and N.Oc/BPM) were not different.

**Table 4.** Histomorphometric evaluation of the total section: overview of the mean values of the 6-month mixed graft group (autogenous bone mixed with Straumann® bone ceramic (60:40)) compared to the 6-, 9- and 12-month results with pure Straumann® bone ceramic (60:40), as previously published, in a maxillary sinus floor elevation procedure.


BV/TV: vital bone volume/total volume; BS/TV: bone surface/total volume; Tb.Th: trabeculae thickness; OV/BV: osteoid volume/vital bone volume; OS/BS: osteoid surface/bone surface; O.Th: osteoid thickness; N.Oc/BPM: number of osteoclasts per bone perimeter. \* Study by Frenken et al. (2010) [12]; \*\* Study by Bouwman et al. (2017) [46]; \*\*\* N.Oc/BPM not measured as an insignificant number of osteoclasts were available.
