Clinical and histological evaluation of a new approach in alveolar ridge preservation technique in the aesthetic zone: a prospective single cohort study

Aim: Recently, oral surgery became rich with new means to improve the relationship between the bone substitutes, surrounding tissue and human organism: the regeneration led by the tissues represents one of the most encouraging examples. Many bone substitutes have been applied for sinus regeneration procedure, such as autogenous bone, inorganic bovine bone, porous and resorbable hydroxyapatite, tricalcium phosphate, bioactive glass, and blood clot. The application of bone grafts is oriented to promote bone formation with faster resorption processes and new combinations of osteoinductive scaffolds. The aim of the study was to evaluate in vivo a biomimetic nanostructured matrix composed by MgHA/collagenbased scaffold as a sinus augmentation graft. Methods: Eleven healthy patients (mean age: 52yo; range 48–65 yo) were treated and for sinus augmentation and implant rehabilitations. The maxillary sinuses were filled with MgHA/collagen-based scaffold with a porous three-dimensional design (3D) with a composite architecture, mimicking the complex hierarchically organized bone structure. Cone Beam Computed Tomography evaluation (3D CBCT) was performed for preoperative and post-surgical sinus augmentation. Bone specimens were obtained by trephine bur to achieve histological and histomorphometrical analysis to evaluate the residual grafted material, the percentages of newly-formed bone and marrow spaces. Results: CBCT scans bone augmentation showed in all patients treated hyperdensity in comparison between immediate postoperative period and late postoperative period, with more density than native bone at both times (mean volume after graft elevation= 2906 mm3, min=2148.8 mm3 max= 3146.4 mm3). In the late postoperative period (6 months) the mean volume after graft elevation was 2806.7 mm3 (min=2010.9 mm3 max=3008.9 mm3). The statistical analysis demonstrated a significant difference for volume change (P <0.01%). Histological analysis shows that at low magnification trabecular mature bone was present in all specimens without any pathological inflammatory cell infiltrate. No foreign body reactions were present and the graft were completely resorbed. Mature bone deriving from the endosteal surface filled the external portion of the bone sinus, and the periphery and central portion of the cavities showed mineralized new bone formation. The sinuses were completely healed and no particles or MgHA/ collagen-based scaffolds were visible. Furthermore it was observed seams of osteoblasts and unmineralized matrix with collagen fibrils at areas of new bone apposition. The tissues present in the sample were composed of 2 ± 2% of lamellar bone, 36 ± 1% of woven bone and 58 ± 4% of marrow spaces. Conclusions: MgHA/collagen-based scaffold evaluated is an highly biocompatible bone substitute which particles have an almost complete resorbable quality; infact no residual material was found. The biomaterial which is gradually replaced by new bone apposition. The clinical and histological evidences show that MgHA/collagen-based scaffold can be used, successfully, for sinus augmentation procedures.