The clinical and radiographic characteristics of the implant sites are presented in Table 1. In total, 3 implants were located in the maxilla, while two implants were located in the mandible. While all implants showed bleeding on probing, only 2 implants presented with suppuration on gentle probing. Mean probing depth was 6.3 ± 0.4 mm corresponding to a mean marginal bone loss (MBL) of 4.7 ± 1.0 mm at the buccal and 7.6 ± 1.3 mm at the palatal/lingual aspects.

Defect length, residual bone extension, bone density, as well as BIC values are presented in Table 2. The mean defect length amounted to 4.7 mm (95% CI 3.12–4.88). Bone density (B.Ar/T.Ar) as exemplified in Fig. 2 was 85.5% (95% CI 79.1–91.3) in the peri-implant tissue thereby indicating a strong corticalization. The implants revealed a mean bone-to-implant contact of 74% (95% CI 70.5–77.5), not reduced at marginal regions (0–500 μm segment) when compared with the more apical regions (Fig. 2). Osteocyte lacunae with signs of stained osteocytes and such with no viable cells exhibited mean values of 191.2/mm² (95% CI 132–251) and 164.6/mm² (95% CI 103–225), respectively (Table 3).

Two specimens revealed a mixed chronic inflammatory cell infiltrate in the marginal connective tissue compartments adjacent to the bone surface. One specimen showed signs of osteoclastic activity (Fig. 3b), 3 specimens presented inactive crestal bone surfaces, and 1 specimen showed active bone formation (Fig. 3c) at marginal regions. According to the histomorphometric data, the residual bone was predominantly cortical with scarce and small-sized vascular channels. Importantly, the cortical bone exhibited areas of lamellar bone in-between and parallel to the surface of older trabeculae, depicting signs of compaction of former cancellous bone (Fig. 3a). Secondary osteons and reversal lines were frequently present, while osteoclasts were found only occasionally. Cancellous bone was merely present at the most apical region of two specimens.