Recent developments of functional scaffolds for craniomaxillofacial bone tissue engineering applications

Abstract

Autogenous bone grafting remains a gold standard for the reconstruction critical-sized bone defects in the craniomaxillofacial region. Nevertheless, this graft procedure has several disadvantages such as restricted availability, donor-site morbidity, and limitations in regard to fully restoring the complicated three-dimensional structures in the craniomaxillofacial bone. The ultimate goal of craniomaxillofacial bone reconstruction is the regeneration of the physiological bone that simultaneously fulfills both morphological and functional restorations. Developments of tissue engineering in the last two decades have brought such a goal closer to reality. In bone tissue engineering, the scaffolds are fundamental, elemental and mesenchymal stem cells/osteoprogenitor cells and bioactive factors. A variety of scaffolds have been developed and used as spacemakers, biodegradable bone substitutes for transplanting to the new bone, matrices of drug delivery system, or supporting structures enhancing adhesion, proliferation, and matrix production of seeded cells according to the circumstances of the bone defects. However, scaffolds to be clinically completely satisfied have not been developed yet. Development of more functional scaffolds is required to be applied widely to cranio-maxillofacial bone defects. This paper reviews recent trends of scaffolds for crania-maxillofacial bone tissue engineering, including our studies.

Figure 1

Guided bone regeneration with PLGC macroporous membrane in lateral bone defects of a canine mandible [33]. Clinical appearance of the surgically created bone defects and membrane placement. (a) Intraoperative view of the two lateral bone defects created in the mandible, and (b) view of the PLGC macroporous membrane closely adapted to the bone and stabilized with PLLA pins.

Figure 2

Histological microphotographs of coronal sections at 6 months postoperatively [33]. The Villanueva-Goldner staining: (a) control (virgin) group, (b) GBR using PLGC membrane, (c) GBR using PLGC+bone chips group, and (d) GBR using TR-PTFE membrane. PM: PLGC macroporous membrane. TM: TR-PTFE membrane, and arrow: regenerated bone.

Figure 3

Alveolar bone regeneration using poly(L-lactide-co-ε-caprolactone)/β-TCP membrane and bFGF-gelatin sponge in the mandible of a canine [32]. Micro-CT images of frontal and sagittal sections in the mandible 6 months postoperatively. (a) Group using only GBR membrane, and (b) group using membrane and bFGF-gelatin sponge circles: regenerated bone; and arrow: GBR membrane.

Figure 4

Alveolar ridge augmentation using bFGF-incorporated gelatin sponge and collagen membrane. (a) Preoperative intraoral photograph shows narrow alveolar ridge (arrows); (b) frontal plane of the preoperative dental CT is shown, and (c) bFGF-incorporated gelatin sponge (arrows) is implanted. Inserted photograph demonstrates bFGF-incorporated gelatin sponge, and (d) the narrow alveolar ridge is reconstructed (arrows) 8 months postoperatively.

Figure 5

Regeneration of the jaw using PLLA mesh and PCBM [163]. (a) PLLA mesh tray and (b) keratocystic odontogenic tumor of the left mandible, preoperative panoramic X-ray. Multilocular radiolucent area (arrow) and segmental resection line (dotted line). (c) Reconstruction using the PLLA mesh tray and PCBM and (d) X-ray image 1 year and 586 months after the reconstructive surgery. Formation of the matured regenerated bone and mandibular canal.

Figure 6

Bone density measurement using CT images and values [163]: (a) the regenerated bone shows no resorption 8 years postoperatively. The bone density was measured in 2 areas (one healthy bone area (1) and one regenerated bone area (2)) (arrows), and (b) the bone density. The peak of the cortical bone density was remarkably not different for the regenerative bone and the healthy bone.