Minimally traumatic alveolar ridge augmentation with a tunnel injectable thermo-sensitive alginate scaffold

Injectable bone substitutes and techniques have been developed for use in minimally invasive procedures for bone augmentation. objective: to develop a novel injectable thermo-sensitive alginate hydrogel (tsah) as a scaffold to induce bone regeneration,using a minimally invasive tunnelling technique. material and methods: an injectable tsah was prepared from a copolymer solution of 8.0 wt% poly(n-isopropylacrylamide) (pnipaam) and 8.0 wt% aalg-g-pnipaam. in vitro properties of the material,such as its microstructure and the sustained release of recombinant human bone morphogenetic protein-2 (rhbmp-2),were investigated. then,with the subperiosteal tunnelling technique,this material,carrying rhbmp-2,was injected under the labial periosteum of the maxillary anterior alveolar ridge in a rabbit model. new bone formation was evaluated by means of x-ray,micro-computed tomography (micro-ct),fluorescence labelling,histological study,and immunohistochemistry study. results: the material exhibited good injectability and thermo-irreversible properties. sem showed an interconnected porous microstructure of the tsah. the result of alp activity indicated sustained delivery of bmp-2 from the tsah from days 3 to 15. in a rabbit model,both tsah and tsah/rhbmp-2 induced alveolar ridge augmentation. the percentage of mineralised tissue in the tsah/rhbmp-2 group (41.6±3.79%) was significantly higher than in the tsah group (31.3±7.21%; p<0.05). the density of the regenerating tissue was higher in the tsah/rhbmp-2 group than in the other groups (tsah group,positive control,blank control; p<0.05). conclusions: the tsah provided convenient handling properties for clinical application. to some extent,tsah could induce ridge augmentation and mineral deposition,which can be enhanced when combined with rhbmp-2 for a minimally invasive tunnelling injection. © 2015,faculdade de odontologia de bauru. all rights reserved.