*3.2. Radiological Evaluation*

The results of the alveolar tissue height measurements on panoramic radiographs in time are shown in Table 1. On average an 8.7 mm (SD ± 1.6) increase in height of the grafted area was accomplished using the mentioned MSFE.

**Table 1.** Alveolar tissue height measurements on panoramic radiographs (in true mm) in 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) and 6 months healing time.


M, male; F, female; age in years at biopsy retrieval; tissue height corrected for magnification (×1.25) on panoramic radiograph; T0: (native bone height) preoperative alveolar bone height; T1: directly after MSFE procedure; T2: immediately after dental implant placement (6 months after MSFE); T3: 1 year after dental implant placement; T4: 5 years after dental implant placement; NA: not available.

The measured tissue height appeared to be stable between 1- and 5-years follow-up (Figure 2). The results of the present study (6-month mixed graft) when compared with the results of our former MSFE procedures with pure BCP, also show a stable gain in tissue height (a total of four studies).

An overview of the results of the present study (6-months mixed graft) and the results of previously reported studies with pure BCP after 6-, 9- and 12 months healing time [12,44] is shown in Table 2. Comparing the results, the gained tissue height appears to be stable in all four studies.

**Table 2.** Alveolar tissue height measurements on panoramic radiographs (in true mm), 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 (MSFE) procedure. Tissue height corrected for magnification (×1.25) on panoramic radiographs.


T0: (native bone height) preoperative alveolar bone height; T1: directly after MSFE procedure; T2: immediately after dental implant placement; T3: 1 year after dental implant placement; T4: 5 years after dental implant placement; NA: not available. \* Study by Frenken et al. (2010) [12]; \*\* Study by Bouwman et al. (2017) [46].

**Figure 2.** Mean alveolar tissue height (in true mm) over a 5-year period in five patients in whom a maxillary sinus floor elevation procedure was performed with autogenous bone from the maxillary tuberosity and Straumann® bone ceramic (60:40) with 6 months healing period. T0: (native bone height) preoperative alveolar bone height (SD ± 1.9); T1: directly after a maxillary sinus floor elevation (MFSE) procedure (SD ± 2.1); T2: immediately after dental implant placement (6 months after an MSFE; SD ± 1.6); T3: 1 year after dental implant placement (SD ± 1.7); T4: 5 years after dental implant placement (SD ± 1.9).

#### *3.3. Qualitative Histological Evaluation*

The histological evaluation in six biopsy specimens was executed on the complete section, comprising native bone, newly formed bone and residual graft material. BCP particles were scattered and detected throughout the entire biopsy from caudal to cranial (Figures 3 and 4a). The BCP particles were surrounded by connective tissue, osteoid islands and newly formed bone. The newly formed bone comprised of both woven and lamellar bone; it appeared as vital bone tissue containing osteoblasts, osteoid covering the border of BCP and osteocytes inside bone lacunae (Figure 4b). No inflammatory cells in the tissue adjacent to the bone substitute particles were found during histological analysis. Bone marrow-like tissue, including blood vessels, was observed in between the bone trabeculae. Fragments of the BCP particles as shown by Von Kossa staining showed in four biopsies <25% of BCP, in one biopsy 25%–50% of BCP and in one biopsy 50%–75% of BCP. The presence of >75% of BCP fragments was not detected.
