Shizhu Bai

Computer-assisted technique for the design and manufacture of realistic facial prostheses.

We describe a technique for the design and fabrication of realistic facial prostheses using three-dimensional optical imaging and computer-aided design and manufacturing (CAD/CAM). A three-dimensional dataset of the facial surface of a patient who needed a facial prosthesis was obtained using a sensing system, and the three-dimensional image of the face was reconstructed. A decreased and thinned virtual prosthesis was designed based on the facial image and converted into a rapid prototyping wax prosthesis using a selective laser sintering technique. The rapid prototyping wax prosthesis was then dipped into melted base-plate wax which generated a layer of wax on the internal and external surfaces to record its size and thickness. The modified prosthesis was evaluated and refined, and processed to generate a realistic silicone prosthesis. Three-dimensional data acquisition using the sensing system and computer-assisted design and manufacture of the prosthesis allows us to see a whole face without damaging the soft tissues or causing discomfort to the patient or exposure to radiation. The final prosthesis was of satisfactory size, shape, and cosmetic appearance, matched the malformed area, and suited the patients requirements.

Influence of sex and body mass index on facial soft tissue thickness measurements of the northern Chinese adult population

Forensic facial reconstruction is a mixture of science and art, as it attempts to reestablish the contours of the soft tissues over the skull. From a forensic point of view, identification of an unknown body relies heavily on this visual aspect of recognition. To obtain acceptable results in forensic facial reconstruction, accurate facial soft tissue thickness data are essential. Until now, despite numerous works related to soft tissue thickness, there is little information in this area for the Chinese population. To this end, this study developed soft tissue thickness data for the Chinese adult population. Spiral computed tomography (CT) data and the body mass index (BMI) of 200 northern Chinese aged 18-32 years were collected. Soft tissue thickness measurements at 20 anthropological landmarks on the skull were taken, based on the three-dimensional models of the skull and face reconstructed from the spiral CT data of each subject. Considering the sex and BMI of the individuals, general descriptive analyses of soft tissue thickness were determined. Statistical analyses were performed between males and females in each BMI group, as well as between each of the BMI categories for males and females, respectively. The results revealed that males have thicker soft tissues than females at most of the anthropological landmarks in the Chinese population, similar to other populations. However, only one-third of these differences were statistically significant between males and females. Taking into consideration the nutritional status, the soft tissue thickness measurements increased with increased BMI levels for both sexes at each landmark, and the statistically significant differences were depicted between the different BMI categories at most of the landmarks. In conclusion, this study has provided useful reference points of the adult northern Chinese population for forensic facial reconstruction, and recommends that the nutritional status of the subject be considered during skull reconstruction procedures.

Odontoblast-like cell differentiation and dentin formation induced with TGF-β1

OBJECTIVE To investigate the inductive potential of scaffold material combing with transforming growth factor-β1 (TGF-β1), and to induce odontoblast differentiation and dentin formation from dental pulp cells both in vitro and in vivo. METHODS Primarily cultured dental pulp cells were used for MTT, ALP activity assay and Alizarin red staining in the presence of TGF-β1. Pelleted cells were put on the filters combining with or not with TGF-β1 and cultured in vitro or in vivo. The in vitro and in vivo cell response and tissue formation were analysed with Haematoxylin-Eosin (HE), transmission electron microscopy (TEM) and immunohistochemical staining. RESULTS TGF-β1 increased the mineralization and ALP activity of dental pulp cells as revealed by Alizarin red staining and ALP activity assay. After in vitro culture for 7 days, cells polarized in the TGF-β1 group and expressed dentin sialoprotein (DSP), osteopontin (OPN) and type I collagen (Col I). After in vivo transplantation for 7 days, columnar odontoblast formed on the surface of filter in experimental group, and tubular dentin expressing DSP formed after 3 months transplantation. CONCLUSION It was concluded that TGF-β1 combining with transfilter could induce odontoblast differentiation and dentin formation. Our results implied that suitable substrate for the progenitors of odontoblast to anchor on and inductive signals to initiate the differentiation of odontoblast should be taken into consideration when designing scaffold material for inducing dentin tissue engineering.

Parylene coating hinders Candida albicans adhesion to silicone elastomers and denture bases resin.

OBJECTIVE To investigate whether parylene coatings over denture bases and silicone elastomers can effectively reduce Candida albicans adhesion and thus to decrease the incidence of denture stomatitis. DESIGN Specimens of silicone elastomers A-2186 or lucitone 199 resin were prepared, and the measurements of contact angle, assay of XTT reduction and cell count of C. albicans adhesion were taken before and after parylene treatment. Furthermore, morphology of C. albicans adhesion for 48 h was observed by scanning electron microscope (SEM), and C. albicans adhesion for 4h was illustrated by confocal scanning laser microscopy (CLSM) in combination with fluorescent dyes FUN-1 and Concanavalin A. RESULT There was a statistical difference between mean contact angles of silicone elastomer A-2186 before and after parylene coating (P<0.05). The amount of C. albicans adhesion to the surface of silicone elastomer A-2186 and lucitone 199 resin after parylene treatment was significantly less than before parylene treatment by cells count and XTT reduction assay (P<0.05). In SEM and CLSM analysis, C. albicans biofilm was more apt to generate on the surface of silicone elastomer A-2186 than other three groups, and more C. albicans aggregation formed on the surface of silicone elastomer A-2186 and lucitone 199 resin before parylene treatment than after parylene treatment. CONCLUSION Parylene coating reduced C. albicans adhesion and aggregation on the surface of silicone elastomer A-2186 and lucitone 199 resin, and improved the wettability of silicone elastomer A-2186.

Three-dimensional anthropometric analysis of the Chinese nose

Information about normal nasal dimensions is essential to rhinoplasty, but reports of anthropometric measurements of the Chinese nose are limited. Three-dimensional (3D) measuring apparatuses have been introduced into craniofacial anthropometry and have demonstrated advantages over conventional methods. This study aims to introduce a new 3D method for anthropometry and to provide guidance for plastic surgeons treating the Chinese nose. A total of 289 young Chinese adults (146 males and 143 females) were recruited for this study and a 3D stereo photogrammetry system (3DSS -II, Shanghai Digital Manufacturing Corporation, China) was used to acquire their facial image data. Geomagic Studio 10.0 software was used to process the data and to realign the images in a unified co-ordinate system. For each image, the co-ordinate values of 17 landmarks of the nose were collected, and the mean was calculated for males and females separately. Points based on the mean co-ordinate values were used to establish 3D stereo models. Subsequently, nasal parameters--including nine linear measurements, three angular measurements and seven proportions--were obtained by analysing these models. The 3D stereo models representing the Chinese male and female nasal shapes were built and the nasal parameters were acquired. Some differences between male and female nasal shapes were identified. This study describes a new method for 3D anthropometric analysis of the nose; the method would be applicable to anthropometry of other parts of the body as well. The 3D models of Chinese noses built in this study will provide very useful guidance for plastic surgeons in clinical practice.

CAD/CAM surface templates as an alternative to the intermediate wafer in orthognathic surgery

OBJECTIVE A new simple technique using a pair of surface templates fabricated by CAD/CAM technique as an alternative to the use of intermediate surgical wafer is presented. STUDY DESIGN A patient with transverse maxillary cant and maxillary midline deviation was scanned using computed tomography (CT) to create a 3D model of the maxillofacial bone. Eight virtual cylindrical markers were placed on the selected locations of maxilla. Subsequently, the locations of these cylinders were expressed as drill holes in the preosteotomy templates. The maxillary segment was separated and repositioned in the computer according to preoperative plans. Postosteotomy surface templates were then designed and resin templates were fabricated by a rapid prototyping machine. After investing and casting, metal templates were fabricated. At the beginning of operation, surgical fixation holes on the maxilla were drilled with the preosteotomy templates. Once maxillary osteotomy and segmentation were finished, screws were placed through the holes in the postosteotomy templates into the predrilled holes on the bone correspondingly, and maxillary segments were fixed with the titanium plates. RESULTS After the postosteotomy templates were positioned and fixed, the maxillary segment was placed to the desired position. Maxillary transverse cant and midline deviation were corrected as the preoperative plan and simulation. CONCLUSION The use of the surface templates before and after osteotomy as an alternative to intermediate wafer in orthognathic surgery can minimize labor and errors contained in the traditional way, reducing preoperative work as well as a reduction in operation time.

The use of platelet-rich fibrin combined with periodontal ligament and jaw bone mesenchymal stem cell sheets for periodontal tissue engineering

Periodontal regeneration involves the restoration of at least three unique tissues: cementum, periodontal ligament tissue (PDL) and alveolar bone tissue. Here, we first isolated human PDL stem cells (PDLSCs) and jaw bone mesenchymal stem cells (JBMSCs). These cells were then induced to form cell sheets using an ascorbic acid-rich approach, and the cell sheet properties, including morphology, thickness and gene expression profile, were compared. Platelet-rich fibrin (PRF) derived from human venous blood was then fabricated into bioabsorbable fibrin scaffolds containing various growth factors. Finally, the in vivo potential of a cell-material construct based on PDLSC sheets, PRF scaffolds and JBMSC sheets to form periodontal tissue was assessed in a nude mouse model. In this model, PDLSC sheet/PRF/JBMSC sheet composites were placed in a simulated periodontal space comprising human treated dentin matrix (TDM) and hydroxyapatite (HA)/tricalcium phosphate (TCP) frameworks. Eight weeks after implantation, the PDLSC sheets tended to develop into PDL-like tissues, while the JBMSC sheets tended to produce predominantly bone-like tissues. In addition, the PDLSC sheet/PRF/JBMSC sheet composites generated periodontal tissue-like structures containing PDL- and bone-like tissues. Further improvements in this cell transplantation design may have the potential to provide an effective approach for future periodontal tissue regeneration.

Platelet-rich plasma promotes angiogenesis of prefabricated vascularized bone graft.

PURPOSE The objective was to assess the impact of platelet-rich plasma (PRP) on angiogenesis and bone formation of tissue-engineered bone in the prefabricated stage. MATERIALS AND METHODS Both thighs of New Zealand white rabbits were used as prefabricated vascularized bone grafts using a combination of bone mesenchymal stem cells and vascular bundles in a titanium cage filled with β-tricalcium phosphate ceramic. PRP was applied in the test group, and the same procedure was performed in the control group without the application of PRP. After 4, 8, and 12 weeks, delayed static bone scanning with technetium-99m methylene diphosphonate was performed before sacrifice, and the tissue-engineered bone samples were collected for immunohistochemical analysis using a monoclonal antibody against CD31 and histologic analysis. RESULTS The results showed superior angiogenesis in the PRP group compared with the control group at each time point as determined by bone scintigraphy and immunohistochemical examinations. The results of histologic analysis also showed that there was more bone formation in the PRP group than in the control group at each time point. CONCLUSIONS The application of autologous PRP was an effective strategy for increasing angiogenesis and bone formation in tissue-engineered bone and had potential significance for clinical applications.

Microarc-oxidized titanium surfaces functionalized with microRNA-21-loaded chitosan/hyaluronic acid nanoparticles promote the osteogenic differentiation of human bone marrow mesenchymal stem cells

Dental implants have been widely used for the replacement of missing teeth in the clinic, but further improvements are needed to meet the clinical demands for faster and tighter osseointegration. In this study, we fabricated safe and biocompatible chitosan (CS)/hyaluronic acid (HA) nanoparticles to deliver microRNA-21 (miR-21) and thereby accelerate osteogenesis in human bone marrow mesenchymal stem cells (hBMMSCs). The CS/HA/miR-21 nanoparticles were cross-linked with 0.2% gel solution onto microarc oxidation (MAO)-treated titanium (Ti) surfaces to fabricate the miR-21-functionalized MAO Ti surface, resulting in the development of a novel coating for reverse transfection. To characterize the CS/HA/miR-21 nanoparticles, their particle size, zeta potential, surface morphology, and gel retardation ability were sequentially investigated. Their biological effects, such as cell viability, cytotoxicity, and expression of osteogenic genes by hBMMSCs on the miR-21-functionalized MAO Ti surfaces, were evaluated. Finally, we explored appropriate CS/HA/miR-21 nanoparticles with a CS/HA ratio of 4:1 and N/P ratio 20:1 for transfection, which presented good spherical morphology, an average diameter of 160.4±10.75 nm, and a positive zeta potential. The miR-21-functionalized MAO Ti surfaces demonstrated cell viability, cytotoxicity, and cell spreading comparable to those exhibited by naked MAO Ti surfaces and led to significantly higher expression of osteogenic genes. This novel miR-21-functionalized Ti implant may be used in the clinic to allow more effective and robust osseointegration.

Computed tomography measurement of the auricle in Han population of north China

A large number of anthropometric studies of the human auricle have been conducted in various populations. However, data from Han Chinese population are currently not available. The morphology of the auricle is highly complex. Consequently, traditional direct measurement techniques are unable to provide sufficient detail and accuracy. The present study sought to provide anthropometrical data on the auricles of Han Chinese individuals using a three-dimensional (3D) computed tomography (CT) reconstruction technique. A total of 485 data sets were utilised for this study. This sample consisted of data from 241 females aged 18-75 years and 244 males aged 18-74 years. All participants were categorised by gender and further into three age groups. Twelve anthropometrical dimensions of normal auricles were measured with 3D CT. Auricular, tragal, lobular and conchal indices were calculated to further examine the auricles. Earlobes were classified into three basic groups according to the angle of the junction of the earlobe with the cheek. Few of the anthropometrical data showed significant bilateral differences in auricular dimensions. The height of the tragus, lobular length, lobular width, conchal width, protrusion at tragal level and inclination angle of auricles showed no significant differences between males and females. All the linear dimensions of auricles, except the height of the tragus, conchal length and width, increased with age for both males and females. Protrusion at the superaurale and tragal levels showed a decrease of between 4% and 9% for males and 4% and 10% for females across all age groups. This study is the first to report CT measurement of normal auricles in a northern Han Chinese population. We found that this method enabled the complexity of the ear to be measured easily and accurately. Increasing our knowledge of normal auricular dimensions will be beneficial for plastic surgeons.