Bone induction in craniofacial defects1

Open Reduction and Internal Fixation of Mandibular Fracture without Rigid Maxillomandibular Fixation

Introduction The ability to treat fracture with open reduction and internal fixation (OR/IF) has dramatically revolutionized the approach to mandible fracture. With OR/IF, the postoperative role of rigid maxillomandibular fixation (MMF) has declined, but it is used to maintain proper occlusion until internal fixation of the fracture is achieved. Objective To assess intraoperative manual MMF during OR/IF of selected cases of mandibular fractures. Methods This prospective study was conducted on 80 patients with isolated mandibular fractures managed by OR/IF using two titanium miniplates. The patients were classified into two groups: a control group (40 patients) treated by OR/IF after intraoperative rigid MMF followed by immediate MMF removal, and a study group (40 patients) treated by rigid MMF, which was replaced by temporary intraoperative manual MMF (3MF) until plate fixation. Results There were no significant differences of the postoperative complication and dental occlusion, although a highly significant reduction of operative time was achieved in the 3MF group. Patient who received the 3MF technique had statistically significantly better average intrinsic vertical mouth opening in the early postoperative period (1 week after surgery), and normal mouth opening could be achieved in all cases in both groups 8 weeks after surgery. Conclusions Intraoperative rigid MMF is not mandatory and can be replaced in selected cases of fracture mandible by manual maintenance of proper dental occlusion until hardware fixation, gaining the advantages of shorter operative time and less risk of blood-transmitted diseases to the surgical team and the patient in addition to the benefits of immediate postoperative mandible mobilization.

Internal fixation of single mandibular fracture under mandibular nerve block

OBJECTIVE

The aim of this study was to assess the results of open reduction and internal fixation (OR/IF) of isolated mandibular fracture under regional anesthesia using mandibular nerve block.

PATIENTS AND METHODS

This prospective study was carried out on 44 patients who had isolated traumatic parasymphyseal mandibular fractures. All patients were managed by OR/IF by two titanium miniplates using manual maxillomandibular fixation (MMF). All patients were sedated by (0.05 mg/kg) midazolam and (2 μg/kg) fentanyl. The patients were randomly classified into two groups: the control group (22 patients) treated under general anesthesia (GA) and the study group (22 patients) repaired under regional anesthesia. The results were assessed as regards dental occlusion, average intrinsic vertical mouth opening, actual operative time, complication, tolerance and patient's satisfaction, and postoperative hospital stay time.

RESULTS

Both groups were matched for age and sex. There were no statistically significant differences of the postoperative complication, dental occlusion, and mouth opening between both groups. Duration for anesthesia induction, intubation, and anesthesia recovery was not needed in regional anesthesia. Regional anesthesia was tolerable and highly satisfactory in all patients with no intraoperative or postoperative anesthesia-related problems and no reported complications.

CONCLUSION

Regional anesthesia can effectively replace GA in selected cases of mandibular fracture obviating the risks of GA.

The potential of adipose-derived stem cells in craniofacial repair and regeneration

The recent identification of a mesenchymal stem cell population in adipose tissue has led to an abundance of research focused on the regenerative properties of these cells. As such, adipose-derived stem cells (ASCs) and potential therapies in craniofacial regeneration have been widely studied. This review will discuss the identification and potential of ASCs, and specifically, preclinical and clinical studies using ASCs in craniofacial repair. Studies involving ASCs in the repair of defects caused by craniosynostosis and Treacher Collins syndrome will be discussed. A comprehensive review of the literature will be presented, focusing on fat grafting and biomaterials-based approaches that include ASCs for craniofacial regeneration.

Histological evaluation of bone healing using organic bovine bone in combination with platelet-rich plasma (an experimental study on rabbits)

OBJECTIVES

This study was carried out to histologically assess the effect of bone grafting materials extracted from bovine origin on the bone healing process either alone or when mixed with autologous platelet-rich plasma which could be used in many procedures of oral and maxillofacial bone and implant reconstructive surgery.

MATERIALS AND METHODS

Sixteen rabbits were used; three intrabony defects in the femur bone of each rabbit were created, one left unfilled for normal healing process and served as control, the second filled with xenogenic graft (Gen-Ox-lyophilized bovine bone organic matrix), and the third filled with (Gen-Ox-lyophilized bovine bone organic matrix) mixed with autologous platelet-rich plasma. Histological examination of the sections was performed after staining with H&E and Van Geison stains. The histomorphometric analysis including counting of bone cells (osteoblasts, osteocytes, and osteoclasts) with performance of osteon diameter and lamellar thickness at the end of the fourth week postoperatively was obtained.

RESULTS

It has been shown that with the use of autologous platelet-rich plasma in combination with the xenogenic bone graft prepared from bovine origin, new bone formation and neovascularization were enhanced significantly when compared with xenogenic graft alone.

CONCLUSION

The addition of PRP to xenogenic bone substitute in small bone defects of the rabbit femur showed a histomorphometric increase in bone formation (at the fourth week of healing).

CLINICAL RELEVANCE

Platelet concentrate might be used to accelerate the osseointegration of enosseous dental implants.

Nonintegrating knockdown and customized scaffold design enhances human adipose-derived stem cells in skeletal repair

An urgent need exists in clinical medicine for suitable alternatives to available techniques for bone tissue repair. Human adipose-derived stem cells (hASCs) represent a readily available, autogenous cell source with well-documented in vivo osteogenic potential. In this article, we manipulated Noggin expression levels in hASCs using lentiviral and nonintegrating minicircle short hairpin ribonucleic acid (shRNA) methodologies in vitro and in vivo to enhance hASC osteogenesis. Human ASCs with Noggin knockdown showed significantly increased bone morphogenetic protein (BMP) signaling and osteogenic differentiation both in vitro and in vivo, and when placed onto a BMP-releasing scaffold embedded with lentiviral Noggin shRNA particles, hASCs more rapidly healed mouse calvarial defects. This study therefore suggests that genetic targeting of hASCs combined with custom scaffold design can optimize hASCs for skeletal regenerative medicine.

Effect of different storage media on the regenerative potential of autogenous bone grafts: a histomorphometrical analysis in rabbits

The success of autogenous bone graft is related to the graft cell viability. In bone-grafting procedures, harvested grafts are often maintained in extraoral media while the recipient site is prepared. The aim of this study was to evaluate in vivo the effect of storage media over autogenous bone grafts during the transsurgical time. Two grafts were removed bilaterally from the calvaria of 18 rabbits. One graft was immediately fixed in the mandibular angle (control group), and the other was maintained in air exposure (dry group), 0.9% NaCl solution (saline group), or platelet-poor plasma (PPP group) during 30 minutes and stabilized in the symmetrical location of control grafts. After 28 days, the animals were euthanized and the bone fragments were removed, demineralized, and embedded in paraffin. Histological evaluation was performed under light microscope. Empty lacunae and bone graft area quantification were carried out for the sections. The histomorphometrical analysis revealed reduction of the graft area and increase of empty lacunae in the dry group when compared with control. No significant differences were found in the number of empty lacunae or bone graft area between the saline group and its control and also between the PPP group and its control. The dry group showed more empty lacunae and less graft area than the saline and PPP groups. In accordance with the results, PPP and physiologic solution demonstrated osteocyte preservation and bone graft area maintenance, being satisfactory storage media for autogenous bone grafts during the transsurgical period.

Human adipose-derived stromal cells stimulate autogenous skeletal repair via paracrine Hedgehog signaling with calvarial osteoblasts

Human adipose-derived stromal cells (hASCs) have the proven capacity to ossify skeletal defects. The mechanisms whereby hASCs stimulate bone repair are not fully understood. In this study, we examined the potential for hASCs to stimulate autogenous repair of a mouse calvarial defect. Immunofluoresence, osteogenic stains, and surface electron microscopy were used to demonstrate osteogenic differentiation of hASCs. hASCs were engrafted into 4 mm calvarial defects in athymic mice using an osteoconductive scaffold. Analysis included microcomputed tomography, histology, in situ hybridization, and quantitative real-time-polymerase chain reaction. Next, the in vitro interaction between hASCs and mouse calvarial osteoblasts (mOBs) was assessed by the conditioned medium and coculture assays. The medium was supplemented with Hedgehog signaling modifiers, including recombinant N-terminal Sonic hedgehog, smoothened agonist, and cyclopamine. Finally, cyclopamine was delivered in vivo to hASC-engrafted defects. Significant calvarial healing was observed among hASC-engrafted defects compared with control groups (no treatment or scaffold alone) (*P<0.05). hASCs showed evidence of stimulation of host mouse osteogenesis, including (1) increased expression of bone markers at the defect edge by in situ hybridization, and (2) increased host osteogenic gene expression by species-specific quantitative real-time polymerase chain reaction. Using the conditioned medium or coculture assays, hASCs stimulated mOB osteogenic differentiation, accompanied by Hedgehog signaling activation. N-terminal Sonic hedgehog or smoothened agonist replicated, while cyclopamine reversed, the pro-osteogenic effect of the conditioned medium on mOBs. Finally, cyclopamine injection arrested bone formation in vivo. hASCs heal critical-sized mouse calvarial defects, this is, at least in part, via stimulation of autogenous healing of the host defect. Our studies suggest that hASC-derived Hedgehog signaling may play a paracrine role in skeletal repair.

Reconstruction of critical size calvarial bone defects in rabbits with glass–fiber-reinforced composite with bioactive glass granule coating

The aim of this study was to evaluate glass-fiber-reinforced composite as a bone reconstruction material in the critical size defects in rabbit calvarial bones. The bone defect healing process and inflammatory reactions were evaluated histologically at 4 and 12 weeks postoperatively. Possible neuropathological effects on brain tissue were evaluated. The release of residual monomers from the fiber-reinforced composite (FRC) was analyzed by high performance liquid chromatograph (HPLC).

RESULTS

At 4 weeks postoperatively, fibrous connective tissue ingrowth to implant structures was seen. Healing had started as new bone formation from defect margins, as well as woven bone islets in the middle of the defect. Woven bone was also seen inside the implant. Inflammation reaction was slight. At 12 weeks, part of the new bone had matured to lamellar-type, and inflammation reaction was slight to moderate. Control defects had healed by fibrous connective tissue. Histological examinations of the brain revealed no obvious damage to brain morphology. In HPLC analysis, the release of residual 1,4-butanedioldimethacrylate and methylmethacrylate from polymerized FRC was low.

CONCLUSIONS

This FRC-implant was shown to promote the healing process of critical size calvarial bone defect in rabbits. After some modifications to the material properties, this type of implant has the potential to become an alternative for the reconstruction of bone defects in the head and neck area in the future.