Ashish Khadka

Computer-Aided Design and Manufacturing and Rapid Prototyped Nanoscale Hydroxyapatite/Polyamide (n-HA/PA) Construction for Condylar Defect Caused by Mandibular Angle Ostectomy

The fracture or defect of the mandibular condyle is one of the serious complications during angle-reduction ostectomy. Reconstruction of such defects also is a daunting task. The case report describes a method based on computer-aided design/computer-aided manufacturing (CAD/CAM) and rapid prototyping nanoscale hydroxyapatite/polyamide (n-HA/PA) for individual design, fabrication, and implantation of a mandibular condyle. A 27-year-old woman with a square-shaped face who had previously undergone mandibular angle reduction reported with malocclusion, deviated mouth, collapse of the right side of the face, and masticatory problems. The reason for the problems was the unintended removal of the condyle during the ostectomy procedure. Using computed tomography (CT) data, a biomimetic n-HA/PA scaffold, and CAD/CAM for rapid prototyping by three-dimensional (3D) printing, a perfect-fitting condylar implant was fabricated. A surgical guide system also was developed to reproduce the procedures accurately so a perfect fit could be obtained during surgery. The patient ultimately regained reasonable jaw contour and appearance, as well as appreciable temporomandibular joint (TMJ) function.

Autogenous grafts for condylar reconstruction in treatment of TMJ ankylosis: current concepts and considerations for the future

Temporomandibular joint (TMJ) ankylosis is characterized by difficulty or inability to open the mouth due to fusion of the temporal and the mandible, resulting in facial symmetry/deformity, malocclusion and dental problems. The only treatment option for TMJ ankylosis is surgical with or without condylar reconstruction. Various autogenous grafts are available for condylar reconstruction after freeing the ankylotic mass such as costochondral, sternoclavicular, fibular, coronoid, and metatarsophalangeal. Costochondral graft is preferred by surgeons, but distraction osteogenesis is slowly gaining popularity and may ultimately become the standard procedure, providing a cost-effective approach with low morbidity and excellent functional outcomes. Tissue engineering is another budding field which has shown promising results in animal studies but has not been applied to humans. To date, there is no ideal autogenous graft for condylar reconstruction that satisfies the complex anatomy and the myriad of functions of a missing condyle.

Ectopic osteochondral formation of biomimetic porous PVA-n-HA/PA6 bilayered scaffold and BMSCs construct in rabbit

In this work, the novel poly vinyl alcohol/gelatin-nano-hydroxyapatite/polyamide6 (PVA-n-HA/PA6) bilayered scaffold with biomimetic properties for articular cartilage and subchondral bone is developed. Furthermore, when these osteochondral scaffolds were seeded with induced bone mesenchymal stem cells (BMSCs) and implanted at ectopic sites, showed the potential for an engineered cartilage tissue and the corresponding subchondral bone. BMSCs were expanded in vitro and induced to chondrogenic or osteogenic potential by culturing in suitable media for 14 days. Subsequently, these induced cells were seeded into PVA-n-HA/PA6 separately, and the constructs were implanted into the rabbit muscle pouch for upto 12 weeks. Ectopic neocartilage formation in the PVA layer and reconstitution of the subchondral bone which remained confined within the n-HA/PA6 layer with the alteration of the cellular phenotype were identified with Massons trichrome stain. Simultaneously, the RT-PCR results confirmed the expression of specific extracellular matrix (ECM) markers for cartilaginous tissue, such as collagen type II (Col-II), or alternatively, markers for osteoid tissue, such as collagen type I (Col-I) at the corresponding layers. During ectopic implantation, the underlying subchondral bone layer was completely integrated with the cartilage layer. The result from the ectopic osteochondral scaffolds implantation suggests that PVA-n-HA/PA6 with induced BMSCs is a possible substitute with potential in cartilage repair strategies.

CAD/CAM and rapid prototyped titanium for reconstruction of ramus defect and condylar fracture caused by mandibular reduction.

Fracture or defect of the mandible is a serious complication of mandibular angleplasty, and precise reconstruction for such defect is still a huge challenge. This case report provides a new method based on CAD/CAM and rapid prototyped titanium for individual design, fabrication, and implantation of a mandibular ramus and angle. A 25-year-old woman with a square-shaped face, who had undergone mandibular outer cortex split ostectomy (MOCSO) 3 months earlier, was afflicted by a series of symptoms: asymmetric face, collapse of the right face, masticatory problems, deviation during mouth opening, malocclusion, and TMJ clicks. These symptoms were caused by unintentional removal of the fractured ramus during MOCSO. By means of CT scan data, rapid prototyping, reverse engineering, 3D display, and CAD/CAM, the individualized titanium implant was designed and fabricated. The 3D demo system of operative scheme demonstrated the operative procedure, and determined the position of the implant so as to obtain a perfect fit. Postoperatively, the patient regained satisfactory morphologic symmetry, facial appearance, occlusion, and TMJ functions.

Contouring of a square jaw on a short face by narrowing and sliding genioplasty combined with mandibular outer cortex ostectomy in orientals.

Background: A square face is considered unattractive in Orientals; thus, it has become a frequently encountered reason for patients undergoing face contouring surgery. While reviewing the unsatisfactory cases of mandibular reduction, the authors discovered that some failed cases were related to a square jaw on a short face. The conventional procedures fix only the posterior region of the mandible, resulting in increased prominence of the stunted or square chin and short face. Thus, the authors applied a narrowing and sliding genioplasty procedure combined with a mandibular outer cortex ostectomy technique to reshape a wide, weak chin, and a square jaw on a short lower facial contour into a slender and attractive oval face. Methods: From July of 2005 to October of 2009, there were a total of 57 patients in this study who underwent a narrowing and sliding genioplasty combined with a mandibular outer cortex ostectomy procedure to correct a square jaw on a short face. Results: The postoperative appearance of all 57 cases showed that the lower face had narrowed and had become softer, slender, and oval, with a slick mental region. Conclusion: Narrowing and sliding genioplasty combined with a mandibular outer cortex ostectomy procedure could efficiently adjust the shape and position of the chin to obtain a good proportion of the lower face and change a square, short face to a slender, oval one in a single operation in accordance with fashionable aesthetics in Orientals.

Correction of zygoma and zygomatic arch protrusion in East Asian individuals

OBJECTIVE Prominent zygoma is commonly seen in the East Asian population with the clinical characteristics of anteriorly and/or laterally projected zygoma and zygomatic arch resulting in an increased midfacial width. The esthetic surgical modification of zygoma is one of the major aspects of facial-contouring surgery in certain parts of the world. This article aims to evaluate the effectiveness of various surgical methods for reducing the prominent zygoma so as to obtain a harmonious and natural facial contour. METHODS Surgical approaches, such as zygomatic complex shaving, I-shaped osteotomy, L-shaped osteotomy, and C-shaped osteotomy were used according to the clinical characteristics of zygoma and zygomatic arch protrusion. The corrective effectiveness was then evaluated through cephalometric radiographs, 3D-CT, and pre- and postsurgical standard facial photographs. RESULTS The zygoma and zygomatic arch protrusion was effectively corrected resulting in improved facial contours in all cases postoperatively. The postoperative period was uneventful except for the slight limitation in mouth opening, which recovered fully after mouth-opening exercises. Serious complications, such as facial nerve injury, were not witnessed in our study. CONCLUSIONS Malar reduction is an effective and a safe method for the treatment of prominent zygoma. The selection of surgical procedure should be based on different presenting characteristics of zygoma and zygomatic arch protrusion. The correction of prominent zygoma should be designed well, performed precisely, and observed carefully to avoid severe complications so as to achieve a harmonious facial contour.

Evaluation of hybrid porous biomimetic nano-hydroxyapatite/polyamide 6 and bone marrow-derived stem cell construct in repair of calvarial critical size defect.

Nano-hydroxyapatite/polyamide 6 (n-HA/PA6) composite scaffolds were prepared by a combined method of phase separation and particle leaching processing technique. The porous matrices were seeded with allogenic bone marrow-derived stem cells (BMSCs) and implanted in the critical-size calvarial defect (8-mm diameter) in rats. The adhesion, proliferation, and differentiation of BMSCs were demonstrated by (3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazoliumbromide) assay, immunohistochemical staining, and scanning electron microscopy in vitro. Cell survival was tracked via fluorescent labeling in vivo. The regeneration process was evaluated by several techniques at 4, 8, and 16 weeks after implantation. According to the results, the porous n-HA/PA6 scaffolds are biocompatible and have no negative effects on the BMSCs in vitro. Nano-hydroxyapatite/polyamide 6 composite combined with BMSCs exhibited good biocompatibility and osteoconductivity and enhanced osteogenesis at the initial stage after implantation. The results demonstrated that porous n-HA/PA6 scaffold is a potential matrix for bone tissue engineering, and using BMSCs as seed cells on porous n-HA/PA6 might be an alternative procedure in repair of large defect due to enhanced osteogenesis and osteointegration.

Sliding reconstruction of the condyle using posterior border of mandibular ramus in patients with temporomandibular joint ankylosis

The traditional approach for ankylosis is gap arthroplasty or interpositional arthroplasty followed by reconstruction of the condyle using, for example, costochondral grafts. As these are non-pedicled grafts, there is eventual resorption with subsequent decrease in height of the ramus, facial asymmetry and deviated mouth opening. The authors have applied the method of total and partial sliding vertical osteotomy on the posterior border of the mandibular ramus for reconstruction of the mandible condyle as a pedicled graft for the correction of temporomandibular joint (TMJ) ankylosis. From 2004 to 2008, 18 patients who were diagnosed with TMJ ankylosis underwent operations for resection of the ankylosed condyle. Two methods were performed depending on the level of osteotomy on the posterior part of the mandibular ramus. All patients were followed-up for an average of 36 months (range 24-48 months). All patients showed apparent improved joint function with no cases of re-ankylosis. The results showed that sliding vertical osteotomy on the posterior border of the mandibular ramus seems to be an alternative and promising method for condylar reconstruction in patients with TMJ bony ankylosis.

Total or partial inferior border ostectomy for mandibular contouring: indications and outcomes.

Among the East Asian population, a long or square face produces a characteristic coarse and masculine appearance and is therefore considered undesirable and unattractive. Because of this many Orientals seek to achieve a harmonious contour of their face by undergoing various cosmetic surgical procedures. Mandibular contouring for a long or asymmetrical face with/without square jaw is rarely reported in the literature and the objective of this study was to investigate the effectiveness of total or partial inferior border ostectomy for mandibular contouring and to discuss its indications. From July 2005 to November 2009, 74 patients in this study received mandibular contouring by total or partial inferior border ostectomy procedure to correct a disharmonious facial contour. Postoperatively the appearance of all 74 cases showed that the length of the lower 3rd of the face and the width of the mandible were decreased effectively, and the mandibular contour was improved. The final aesthetic outcomes were satisfactory for both the surgeons and the patients. The results suggest that facial contour could be improved by using total or partial inferior border ostectomy of the mandible thus achieving a harmonious facial outline based on East Asian aesthetics.

Denervation impairs bone regeneration during distraction osteogenesis in rabbit tibia lengthening

Background and purposes The nervous system plays an important role in bone metabolism. However, the effect of denervation on bone formation during distraction osteogenesis (DO) remains unclear. We studied neural influence on bone regeneration during DO in a rabbit model. Methods 24 New Zealand male white rabbits underwent left tibial osteodistraction. Before distraction, the animals were randomly divided into group R (resected left sciatic nerve) and group I (intact left sciatic nerve). 8 weeks after completion of distraction, the animals were killed and the lengthened tibias were harvested for radiography, micro-CT, histological evaluation, and mechanical testing. Results New regenerated bone was present in the distraction gaps of all animals at the end of the study, as revealed by radiography, micro-CT, and histology. However, less new bone formation and a lower degree of mineralization were observed in group R. The mechanical strength of the distraction gap in group I was 1.3-fold greater than that in group R when measured using the 3-point bending test. Interpretation The results suggest that the nervous system plays an essential role during DO: the denervation appears to have an inhibitory effect on bone formation.