Immediate and long-term results of unsintered hydroxyapatite and poly L-lactide composite sheets for orbital wall fracture reconstruction

Degradation of Unsintered Hydroxyapatite and Poly-L-Lactide Composite Sheets In Vivo and In Vitro

Bioabsorbable sheet-shaped implants made of forged composites of unsintered hydroxyapatite and poly-L-lactide (F-u-HA/PLLA) have been used for orbital fracture repair with good results. This is the first report using multiple specimens implanted in the human orbit to demonstrate the biodegradation and loss of strength of F-u-HA/PLLA sheets. Among the patients who underwent various facial fracture repairs with F-u-HA/PLLA sheets implanted in their orbits, those whose sheets were subsequently extracted were included in the study. Viscosity-average molecular weight, crystallinity, and bending strength of the extracted implants were measured. An in vitro degradation test was also performed for comparison. Among the 111 patients who underwent F-u-HA/PLLA sheet implantation, 13 subsequently underwent surgical extraction of implants; the majority were due to secondary correction of complex fractures. One patient developed an infection; none developed foreign body reactions. Overall, 11 specimens from 10 patients with consent were examined. The time from implantation to extraction ranged from 43 to 632 days (median: 210 d). Compared with the results of the in vitro degradation test, the viscosity-average molecular weight and bending strength had a slower decrease. The F-u-HA/PLLA sheets retained more than 50% of their initial bending strength after 12 months. Crystallinity varied widely. F-u-HA/PLLA sheets implanted in human orbits did not degrade faster than those of in vitro testing. Sheet-shaped implants made of forged composites of unsintered hydroxyapatite and poly-L-lactide can be considered appropriate reconstructive materials for orbital fractures as they retained sufficient strength to support the orbital contents at 12 months postoperatively, and no case of delayed foreign body reactions was observed.

Vancomycin-loaded methylcellulose aerogel scaffolds for advanced bone tissue engineering

Scaffolds grafting combined with local delivery of antibiotics at the injury site may promote bone regeneration along with prevention of infections. In this work, a processing strategy combining the 3D-printing of polysaccharide-based inks with supercritical (sc)CO2 technology was employed to manufacture drug-loaded, nanostructured, and personalized-to-patient aerogels for the first time. Methylcellulose (MC) was employed as graft matrix endowed with nanohydroxyapatite (nHA) to confer bioactivity as required in bone tissue engineering (BTE). MC-nHA aerogels were obtained through the 3D-printing of hydrogel-based scaffolds followed by scCO2 drying. Aerogels were loaded with vancomycin (VAN), an antibiotic employed in the management of bone infections. Textural properties and printing fidelity of scaffolds were studied as well as VAN release, long-term bioactivity, and pre-osteoblasts mineralization. In vitro cell studies and in vivo Artemia salina tests were carried out to evaluate the potential toxicity of the antibiotic-loaded aerogels. Aerogels efficacy in inhibiting bacterial growth was assessed by antimicrobial tests with Staphylococcus aureus. Textural stability of the aerogels after 7 months of storage was also evaluated. Obtained results showed that the scaffolds promoted the intended two-in-one effect (bone repair and infection management simultaneously) in a personalized way, regulating formulation design, drug dose, and porosity.

Nano Sized Hydroxyapatite-Polylactic Acid-Vancomycin in Alleviation of Chronic Osteomyelitis

Background

Objective

Methods

Results

Conclusion

Is Surgery Needed for Diplopia after Blowout Fractures? A Clarified Algorithm to Assist Decision-making

Diplopia is a common symptom after blowout fractures, with an incidence of 43.6%–83%. Although there is some consensus toward surgical correction, diplopia is not always resolved by surgery. Thus, there is a clinical dilemma for surgeons with regard to performing surgery at a specific time. This review aimed to create an algorithm to support accurate and effective decision-making.

A Narrative Review of u-HA/PLLA, a Bioactive Resorbable Reconstruction Material: Applications in Oral and Maxillofacial Surgery

The advent of bioresorbable materials to overcome limitations and replace traditional bone-reconstruction titanium-plate systems for bone fixation, thus achieving greater efficiency and safety in medical and dental applications, has ushered in a new era in biomaterial development. Because of its bioactive osteoconductive ability and biocompatibility, the forged composite of uncalcined/unsintered hydroxyapatite and poly L-lactic acid (u-HA/PLLA) has attracted considerable interest from researchers in bone tissue engineering, as well as from clinicians, particularly for applications in maxillofacial reconstructive surgery. Thus, various in vitro studies, in vivo studies, and clinical trials have been conducted to investigate the feasibility and weaknesses of this biomaterial in oral and maxillofacial surgery. Various technical improvements have been proposed to optimize its advantages and limit its disadvantages. This narrative review presents an up-to-date, comprehensive review of u-HA/PLLA, a bioactive osteoconductive and bioresorbable bone-reconstruction and -fixation material, in the context of oral and maxillofacial surgery, notably maxillofacial trauma, orthognathic surgery, and maxillofacial reconstruction. It simultaneously introduces new trends in the development of bioresorbable materials that could used in this field. Various studies have shown the superiority of u-HA/PLLA, a third-generation bioresorbable biomaterial with high mechanical strength, biocompatibility, and bioactive osteoconductivity, compared to other bioresorbable materials. Future developments may focus on controlling its bioactivity and biodegradation rate and enhancing its mechanical strength.

Orbital haematoma after orbital fracture repair using silicone, polytetrafluorethylene, and poly-L-lactic acid/hydroxyapatite implants

The purpose of this paper was to report the incidence of orbital haematoma formation following the repair of orbital fractures with silicone, polytetrafluorethylene (PTFE), and poly-L-lactic acid/hydroxyapatite (PLLA/HA) implants. This retrospective review examined 234 patients (235 sides) who underwent repair of orbital wall fractures over a six-year period. Of these, 36 patients received a silicone sheet; 49 patients received a silicone sheet with superimposed PTFE implant; and 149 patients (150 sides) received PTFE with or without an underlying PLLA/HA implant. Orbital haematomas were documented in 13 out of 36 patients (36.1%) who underwent fracture repair with a silicone sheet; seven out of 49 patients (14.3%) who had a silicone sheet with a superimposed PTFE implant; and three out of 150 sides (2.0%) with PTFE with or without underlying PLLA/HA. The difference in incidence of orbital haematoma formation was significant among the groups (p < 0.001, Pearson's chi squared test). In the silicone sheet group, haematomas formed within two weeks of surgery in 11 patients (84.6%). In the silicone sheet with superimposed PTFE implant group, five patients (71.4%) developed orbital haematomas no earlier than after two weeks postoperatively. This study showed that the incidence of orbital haematoma formation following orbital fracture repair is different among the implant materials. The use of PTFE and PLLA/HA implants may minimise this complication.

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 Coverage around Hydroxyapatite/Poly(L-Lactide) Composite Is Determined According to Depth from Cortical Bone Surface in Rabbits

Composites of unsintered hydroxyapatite (HA) and poly(_L-lactide) (PLLA) reinforced by compression forging are biodegradable, bioactive, and have ultrahigh strength. However, foreign body reactions to PLLA and physical irritation can occur when not covered by bone. We aimed to confirm the relationships between the depth of the implanted HA-PLLA threaded pins and the new bone formation. We inserted HA-PLLA composite threaded pins (diameter: 2.0 or 4.5 mm) into the femoral and tibial bones of 32 mature male Japanese white rabbits (weight 3.0–3.5 kg) with the pin head 1 or 0 mm below or protruding 1 or 2 mm above surrounding cortical bone. Eight euthanized rabbits were radiologically and histologically assessed at various intervals after implantation. Bone bridging was complete over pins of both diameters at ~12 weeks, when inserted 1 mm below the surface, but the coverage of the pins inserted at 0 mm varied. Bone was not formed when the pins protruded >1 mm from the bone surface. No inflammation developed around the pins by 25 weeks. However, foreign body reactions might develop if composites are fixed above the bone surface, and intraosseous fixation would be desirable using double-threaded screws or a countersink to avoid screw head protrusion.

Repair of orbital floor fractures via the transantral approach with osteosynthesis plate

INTRODUCTION

The most common surgical access techniques employed in patients with orbital floor fractures are associated with a risk of complications, such as implant infection, migration, epiphora, lower eyelid retraction, ectropion, diplopia worsening, retrobulbar hematoma, emphysema, "white-eyed" syndrome, enophthalmia relapse, hypoglobus, and persistent diplopia due to periorbital atrophy. Consequently, alternative access techniques precluding these complications have to be found.

STUDY OBJECTIVE

To assess the efficacy of transantral approach in the surgical treatment of patients with orbital floor fractures based on results of retrospective analysis of our clinical experience.

MATERIALS AND METHODS

We performed a retrospective study of medical records and X-ray data of 52 patients with fractures of the floor of the orbit, 18 to 68 years old, treated using transantral approach as described in the article. Titanium plates of special shape were used for orbital floor reconstruction.

RESULTS

In 94.2% of the cases, adequate restoration of the floor of the orbit was achieved. It led to regression of the ocular signs. In 4 patients, diplopia remained in extreme gaze positions, which did not require surgical correction. The failed cases were related to incorrect positioning of the plate or fixing screws. No inflammatory complications were observed.

CONCLUSION

Transantral access approach may be a technique of choice in treating patients with orbital floor fractures; it is safe, minimally traumatic, and effective in the early posttraumatic period when the injured area is located in the posterior parts of the floor of the orbit.

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.

Navigation-Assisted Orbital Trauma Reconstruction Using a Bioactive Osteoconductive/Bioresorbable u-HA/PLLA System

Orbital fractures with orbital wall defects are common facial fractures encountered by oral-maxillofacial surgeons, because of the exposed position and thin bony walls of the midface. The primary goal of surgery is to restore the pre-injury anatomy and volume of hard tissue, and to free incarcerated or prolapsed orbital tissue from the fracture by bridging the bony defects with reconstructive implant material and restoring the maxillofacial-orbital skeleton. Numerous studies have reported orbital fracture repair with a wide variety of implant materials that offer various advantages and disadvantages. The ideal orbital implant material will allow conformation to individual patients' anatomical characteristics, remain stable over time, and are radiopaque, especially for the reconstruction of relatively large and/or complex bony walls. Based on these requirements, novel uncalcined and unsintered hydroxyapatite (u-HA) particles and poly-L-lactide (PLLA; u-HA/PLLA) composite sheets could be used as innovative, bioactive, and osteoconductive/bioresorbable implant materials for orbital reconstruction. In addition, intraoperative navigation is a powerful tool. Navigation- and computer-assisted surgeries have improved execution and predictability, allowing for greater precision, accuracy, and minimal invasiveness during orbital trauma reconstructive surgery of relatively complex and large orbital wall defects with ophthalmological malfunctions and deformities. This review presents an overview of navigation-assisted orbital trauma reconstruction using a bioactive, osteoconductive/bioresorbable u-HA/PLLA system.

Effects of hydroxyapatite@poly-lactide-co-glycolide nanoparticles combined with Pb and Cd on liver and kidney parenchyma after the reconstruction of mandibular bone defects

Reconstruction of bone defects with the use of biomaterials based on hydroxyapatite (HAp) has been a popular approach in medicine and dentistry. Most often the process of new bone formation is analyzed with the focus only on the region of the reconstructed defect. The effects of the therapy on distant organs have been rarely reported in the literature, especially not in synergy with the exposure to other bioactive chemicals. In this study, reconstruction of the mandibular bone in vivo using poly-lactide-co-glycolide-coated HAp (HAp/PLGA) nanoparticles was monitored with a simultaneous histopathological analysis of distant organs, specifically kidney and liver parenchyma. Heavy metals are among the most prominent environmental pollutants and have a high affinity for the crystal lattice of HAp, where they get incorporated by replacing calcium ions. Lead (Pb) and cadmium (Cd) are two such metals that can be found in food, water and air, but are most commonly present in cigarette smoke, the frequent contaminant of hospital settings in the developing world. The influence of their presence in the repaired bone on the content of calcium (Ca) in the reconstructed bone defect was analyzed, along with the histopathological changes in liver and kidneys. A study performed on 24 female Wistar rats demonstrated that the reconstruction of mandibular bone defects using HAp/PLGA particles induced an increase in the content of Ca in the newly created bone without causing any pathological changes to the liver and the kidneys. The presence of Pb and Cd in the defects reconstructed with HAp/PLGA nanoparticles impeded the regenerative process and led to a severe and irreversible damage to the liver and kidney parenchyma.