Feasibility of Application of the Newly Developed Nano-Biomaterial, ß-TCP/PDLLA, in Maxillofacial Reconstructive Surgery: A Pilot Rat Study.

This study was performed to examine the applicability of the newly developed nano-biocomposite, ß-tricalcium phosphate (ß-TCP)/u-HA/poly-d/l-lactide (PDLLA), to bone defects in the oral and maxillofacial area. This novel nano-biocomposite showed several advantages, including biocompatibility, biodegradability, and osteoconductivity. In addition, its optimal plasticity also allowed its utilization in irregular critical bone defect reconstructive surgery. Here, three different nano-biomaterials, i.e., ß-TCP/PDLLA, ß-TCP, and PDLLA, were implanted into critical bone defects in the right lateral mandible of 10-week-old Sprague-Dawley (SD) rats as bone graft substitutes. Micro-computed tomography (Micro-CT) and immunohistochemical staining for the osteogenesis biomarkers, Runx2, osteocalcin, and the leptin receptor, were performed to investigate and compare bone regeneration between the groups. Although the micro-CT results showed the highest bone mineral density (BMD) and bone volume to total volume (BV/TV) with ß-TCP, immunohistochemical analysis indicated better osteogenesis-promoting ability of ß-TCP/PDLLA, especially at an early stage of the bone healing process. These results confirmed that the novel nano-biocomposite, ß-TCP/PDLLA, which has excellent biocompatibility, bioresorbability and bioactive/osteoconductivity, has the potential to become a next-generation biomaterial for use as a bone graft substitute in maxillofacial reconstructive surgery.

Bioactive Regeneration Potential of the Newly Developed Uncalcined/Unsintered Hydroxyapatite and Poly-l-Lactide-Co-Glycolide Biomaterial in Maxillofacial Reconstructive Surgery: An In Vivo Preliminary Study.

Uncalcined/unsintered hydroxyapatite (HA) and poly-l-lactide-co-glycolide (u-HA/PLLA/PGA) are novel bioresorbable bioactive materials with bone regeneration characteristics and have been used to treat mandibular defects in a rat model. However, the bone regenerative interaction with the periosteum, the inflammatory response, and the degradation of this material have not been examined. In this study, we used a rat mandible model to compare the above features in u-HA/PLLA/PGA and uncalcined/unsintered HA and poly-l-lactic acid (u-HA/PLLA). We divided 11 male Sprague-Dawley rats into 3- and 16-week groups. In each group, we assessed the characteristics of a u-HA/PLLA/PGA sheet covering the right mandibular angle and a u-HA/PLLA sheet covering the left mandibular angle in three rats each, and one rat was used as a sham control. The remaining three rats in the 16-week group were used for a degradation assessment and received both sheets of material as in the material assessment subgroup. At 3 and 16 weeks after surgery, the rats were sacrificed, and mandible specimens were subjected to micro-computed tomography, histological analysis, and immunohistochemical staining. The results indicated that the interaction between the periosteum and u-HA/PLLA/PGA material produced significantly more new bone regeneration with a lower inflammatory response and a faster resorption rate compared to u-HA/PLLA alone. These findings may indicate that this new biomaterial has ideal potential in treating maxillofacial defects of the midface and orbital regions.

Bone Regeneration Capacity of Newly Developed Uncalcined/Unsintered Hydroxyapatite and Poly-l-lactide-co-glycolide Sheet in Maxillofacial Surgery: An In Vivo Study.

Uncalcined/unsintered hydroxyapatite and poly-l-lactide-co-glycolide (u-HA/PLLA/PGA) is a new bioresorbable nanomaterial with superior characteristics compared with current bioresorbable materials, including appropriate mechanical properties, outstanding bioactive/osteoconductive features, and remarkably shorter resorption time. Nevertheless, the bone regeneration characteristics of this nanomaterial have not been evaluated in maxillofacial reconstructive surgery. In this study, we used a rat mandible model to assess the bone regeneration ability of u-HA/PLLA/PGA material, compared with uncalcined/unsintered hydroxyapatite and poly-l-lactide acid (u-HA/PLLA) material, which has demonstrated excellent bone regenerative ability. A 4-mm-diameter defect was created at the mandibular angle area in 28 Sprague Dawley male rats. The rats were divided into three groups: u-HA/PLLA/PGA (u-HA/PLLA/PGA graft + defect), u-HA/PLLA (u-HA/PLLA graft + defect), and sham control (defect alone). At 1, 3, 8, and 16 weeks after surgeries, the rats were sacrificed and assessed by micro-computed tomography, histological analysis with hematoxylin and eosin staining, and immunohistochemical analyses. The results confirmed that the accelerated bone bioactive/regenerative osteoconduction of u-HA/PLLA/PGA was comparable with that of u-HA/PLLA in the rat mandible model. Furthermore, this new regenerative nanomaterial was able to more rapidly induce bone formation in the early stage and had great potential for further clinical applications in maxillofacial reconstructive surgery.

Navigation-Assisted Isolated Medial Orbital Wall Fracture Reconstruction Using an U-HA/PLLA Sheet via a Transcaruncular Approach.

Purpose: We investigated the feasibility of isolated medial orbital wall fracture reconstruction using an unsintered hydroxyapatite particles/poly L-lactide (u-HA/PLLA) sheet implant with the assistance of intraoperative navigation via the transcaruncular approach. Patients and methods: Ten consecutive patients (5 males and 5 females; mean age, 57.5 years) were included based on the clinical and imaging criteria. All patients underwent surgical treatment of the isolated medial orbital wall fracture using transcaruncular incision and the u-HA/PLLA implant under navigation. The follow-up time was greater than 6 months. Preoperative and postoperative clinical data regarding the presence of diplopia, eye motility restriction, and enophthalmos were assessed. The orbital volumes of the injured and uninjured orbit were also evaluated using computed tomography images. Results: All patients had improved ophthalmologic functional and esthetic outcomes and were successfully treated without any long-term complications arising during follow-up. There was a significant difference between the preoperative and postoperative injured orbits due to herniation of the orbital contents. Moreover, the orbital volume of the postoperative injured side following surgery was the same as that of the unaffected side, indicating that anatomically good reconstruction had been obtained. Conclusions: Surgical treatment using the transcaruncular approach and u-HA/PLLA materials with intraoperative navigation is a safe, promising, and effective technique for isolated medial orbital wall fracture reconstruction.

Bone Regeneration Potential of Uncalcined and Unsintered Hydroxyapatite/Poly l-lactide Bioactive/Osteoconductive Sheet Used for Maxillofacial Reconstructive Surgery: An In Vivo Study.

Uncalcined and unsintered hydroxyapatite/poly l-lactide (u-HA/PLLA) material has osteoconductive characteristics and is available for use as a maxillofacial osteosynthetic reconstruction device. However, its bone regeneration ability in the maxillofacial region has not been fully investigated. This study is the first to assess the bone regenerative potential of osteoconductive u-HA/PLLA material when it is used for repairing maxillofacial bone defects. A total of 21 Sprague-Dawley male rats were divided into three groups-the u-HA/PLLA, PLLA, or sham control groups. A critical size defect of 4 mm was created in the mandible of each rat. Then, the defect was covered with either a u-HA/PLLA or PLLA sheet on the buccal side. The rats in each group were sacrificed at 2, 4, or 8 weeks. The rats' mandibles were sampled for histological analysis with hematoxylin and eosin staining, histomorphometry, and immunohistochemistry with Runx2 and osteocalcin (OCN) antibody. The amount of newly formed bone in the u-HA/PLLA group was significantly higher than that of the PLLA group. The expression of Runx2 and OCN in the u-HA/PLLA group was also significantly higher. These results demonstrate that the u-HA/PLLA material has excellent bone regenerative ability and confirm its applicability as a reconstructive device in maxillofacial surgery.