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

Abstract

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.

Recent Advances on Magnetic Sensitive Hydrogels in Tissue Engineering

“…Due to the type, severity, and post-injury time of trauma, an injectable hydrogel matrix with minimal invasion and suitable elasticity for the regeneration of various damaged tissues has been developed (Yu and Ding, 2008;Macaya and Spector, 2012;Cheng et al, 2013;Li et al, 2014Li et al, , 2015. Therefore, the rod-shaped MNP-incorporated microgels were formed, then dispersed in a biocompatible gel precursor, organized unidirectional alignments under a weak external magnetic field exposure, and finally developed a magnetoresponsive hydrogel "Anisogel."…”

Repair of Bone Defects with Chitosan-Collagen Biomembrane and Scaffold Containing Calcium Aluminate Cement

“…Different biomaterials are used for stimulating bone repair, attaining satisfactory results (3). These biomaterials must not only fill the space previously occupied by bone tissue, but also promote a specific biologic response (4).…”

“…Chitosan is obtained by the reaction of deacetylation of chitin in an alkaline medium (3). Chitin is a natural polymer with a highly organized crystalline structure, making it practically insoluble in most organic solvents (10).…”

“…The interaction of these biomaterials with minerals has been widely reported (3,7,8,11). Chitosan in association with hydroxyapatite was shown to maximize the in vivo osteogenic capacity, allowing internal growth of the compound with accelerated resorption of the matrix (9).…”

Environment and bone regeneration: how biomaterials, host mediators and even bacterial products can boost bone cells towards better clinical outcomes.

“…Accordingly, biomaterials such as alginate hydrogels can effectively mimic extracellular matrices, and consequently improve cell migration process and regeneration outcome 3 , 5 . In fact, in this issue of the JAOS Li, et al 13 (2015) demonstrate that an injectable thermo-sensitive alginate scaffold can enhance alveolar ridge augmentation in a minimally traumatic technique. In addition, alginate hydrogels have additional significant properties; such as the potential as drug delivery vehicles, and indeed, the sustained delivery of BMP-2 was demonstrated to improve the material properties in vivo , increasing the local activity of bone formation marker alkaline phosphatase.…”