All 22 inserted dental implants were clinically tested for good primary stability. Osseointegration at abutment connection was tested with a 35-Ncm torque. One experienced oral and maxillofacial surgeon (CB) carried out all follow-up examinations.

Panoramic radiographs were made at patient’s intake (T0); immediately after the MSFE procedure (T1); immediately after dental implant placement (T2); 1 year after dental implant placement (T3); and 5 years after dental implant placement (T4). On the panoramic radiographs, changes in tissue height (mm) of the grafted area were measured at the implant site on the following time points: T0, T1, T2, T3, and T4. An average magnification of ×1.25 was taken into account to calculate true tissue heights.

Bone biopsies were obtained during implant surgery as previously described [37]. Trephines were split and opened in order to secure the orientation of the biopsies. The biopsies were fixed overnight in 4% phosphate-buffered formaldehyde and transferred to alcohol 70% [38]. After dehydration, the bone specimens were embedded without prior decalcification in methylmethacrylate supplemented with 20% dibuthylphtalaat and 0.008 g/ml Lucidol. The biopsies were cut into 5-μm longitudinal sections (Polycut S., Leica microtome type sm2500s, Leica, Wetzlar, Germany). Bone mass indices and osteoid surface were measured in Goldner’s trichrome stained sections [39]. Tartrate-resistant acid phosphate (TRAP) staining was performed to visualize osteoclasts. Measurements were performed semi-automatically using a digitizer and image analysis software (Osteomeasure, Atlanta, GA, USA). In this study, the Von Kossa staining was used to verify remnant particles of BCP (Straumann® Bone Ceramic). BCP particles were detected semi-quantitatively by three independent observers and classified into quartiles (<25% of BCP, >25% and <50% of BCP, >50 <75% of BCP, >75% of BCP). Nomenclature was used according to the American Society for Bone and Mineral Research (ASBMR) nomenclature committee [40].

Since it was impossible to discriminate between resident and augmented bone, histomorphometric measurements were performed over the total section of the biopsy, including native and newly formed bone. The parameters were measured in consecutive fields of a complete section, in four 150-μm separated sections throughout the biopsy, covering a total measured area of 60 mm². The specimens were examined for the following parameters: