Evaluation of Secondary Alveolar Cleft Reconstruction

Overview

The rehabilitation of the disorganized maxilla is the primary objective of secondary alveolar bone grafting (SABG) for alveolar clefts, as the bony reconstruction of the discontinued maxillary arch would permit proper anterior teeth eruption, improve their orthodontic movements, restore the nasal and alar base symmetry, counteract the growth disturbance effects and seal the oronasal communication. By the time the transverse growth of the maxillary arch is nearly complete during the mixed dentition stage, (SABG) intends to bridge the maxillary continuity by a quantitative bone graft entity that minimizes the maxillary collapse and growth impairment after an appropriate separation and elevation of the nasal and mucosal flaps.

By its ample content of subcutaneous autogenous cancellous bone particulates, the iliac crest is considered the gold standard for (SABG) of alveolar clefts, with optimal restoration of the maxillary continuity, and fair subsequent teeth eruption, orthodontic movements or implant placement. However, several studies have demonstrated that the final volume of the sole iliac crest particulate graft is unpredictable. Sohn et al. in 2010 introduced the growth-factors enriched bone matrix "sticky bone" concept that incorporates the platelet-rich fibrin (PRF) into the particulate grafts to enhance their moldability and enrich them with three-dimensional (3D) fibrin networking scaffold and high concentrations of growth factors, which promote cell division, modulate tissue healing and induce angiogenesis, such as vascular endothelial growth factors (VEGF), recombinant human platelet-derived growth factor (rhPDGF), transforming growth factors ß-1 (TGFß-1), bone morphogenic protein-2 (rhBMP2), insulin growth factor-I (IFG-I), and epithelial growth factor (EGF), and interleukins. During the last decade, various (PRF) preparations and centrifuge protocols have been developed, forming various platelet products with different biological constitutions and potential applications. The (PRF) evolution began with the development of the leukocyte- and platelet-rich fibrin (L-PRF) by an increased centrifuge time and speed, followed by advanced platelet-rich fibrin (A-PRF), injectable platelet-rich fibrin (I-PRF), horizontal platelet-rich fibrin (H-PRF), Concentrated PRF (C-PRF) and most recently the albumin-PRF (Albumin gel). The (L-PRF) employs the extract of the platelet-rich plasma (PRP) in the form of a fibrin clot, meanwhile discarding the platelet-poor plasma (PPP). On the other hand, the albumin gel preparation employs the aspiration and heating of the platelet-poor plasma (PPP), the upper layer, then remixing it with the (PRP) layer and the buffy coat; the lower layers, after being allowed to cool. Although the heating and cooling process would threaten the vitality of cells and the growth factor of the (PPP) layer, this will polymerize its plasmatic proteins and denature the high albumin content as a result of the replacement of the weak hydrogen bond linkages within the protein molecule, with densely organized ones, in addition to the formation of thermal aggregate cross-linkage fibrin networks with an overall endured mechanical strength, prolonged degradation time up to 4-6months, and extended release of growth factors up to ten days.