An Experimental Method for Stereolithic Mandible Fabrication and Image Preparation

Reproduction of anatomical structures by rapid prototyping has proven to be a valid adjunct for craniofacial surgery, providing alternative methods to produce prostheses and development of surgical guides. The aim of this study was to introduce a methodology to fabricate asymmetric human mandibles by rapid prototyping to be used in future studies for evaluating mandibular symmetries. Stereolithic models of human mandibles were produced with varying amounts of asymmetry in the condylar neck, ramus and body of the mandible by means of rapid prototyping. A method for production of the synthetic mandibles was defined. Model preparation, landmark description and development of the experimental model were described. A series of synthetic mandibles ranging in asymmetry were accurately produced from a scanned human mandible. A method for creating the asymmetries, fabricating, coating and landmarking the synthetic mandibles was formulated. A description for designing a reproducible experimental model for image acquisition was also outlined. Production of synthetic mandibles by stereolithic modeling is a viable method for creating skeletal experimental models with known amounts of asymmetry

Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery

<p>Abstract</p> <p>Background</p> <p>A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides.</p> <p>Methods</p> <p>In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes.</p> <p>Results</p> <p>A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates.</p> <p>Conclusions</p> <p>The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology.</p

Novel composite implant in craniofacial bone reconstruction

Bioactive glass (BAG) and polymethyl methacrylate (PMMA) have been used in clinical applications. Antimicrobial BAG has the ability to attach chemically to surrounding bone, but it is not possible to bend, drill or shape BAG during the operation. PMMA has advantages in terms of shaping during the operation, but it does not attach chemically to the bone and is an exothermic material. To increase the usefulness of BAG and PMMA in skull bone defect reconstructions, a new composite implant containing BAG and PMMA in craniofacial reconstructions is presented. Three patients had pre-existing large defects in the calvarial and one in the midface area. An additive manufacturing (AM) model was used preoperatively for treatment planning and custom-made implant production. The trunk of the PMMA implant was coated with BAG granules. Clinical and radiological follow-up was performed postoperatively at 1 week, and 3, 6 and 12 months, and thereafter annually up to 5 years. Computer tomography (CT) and positron emission tomography (PET-CT) were performed at 12 and 24 months postoperatively. Uneventful clinical recovery with good esthetic and functional outcome was seen. CT and PET-CT findings supported good clinical outcome. The BAG–PMMA implant seems to be a promising craniofacial reconstruction alternative. However, more clinical experience is needed

Nanofibrous Scaffolds Incorporating PDGF-BB Microspheres Induce Chemokine Expression and Tissue Neogenesis In Vivo

Platelet-derived growth factor (PDGF) exerts multiple cellular effects that stimulate wound repair in multiple tissues. However, a major obstacle for its successful clinical application is the delivery system, which ultimately controls the in vivo release rate of PDGF. Polylactic-co-glycolic acid (PLGA) microspheres (MS) in nanofibrous scaffolds (NFS) have been shown to control the release of rhPDGF-BB in vitro. In order to investigate the effects of rhPDGF-BB release from MS in NFS on gene expression and enhancement of soft tissue engineering, rhPDGF-BB was incorporated into differing molecular weight (MW) polymeric MS. By controlling the MW of the MS over a range of 6.5 KDa–64 KDa, release rates of PDGF can be regulated over periods of weeks to months in vitro. The NFS-MS scaffolds were divided into multiple groups based on MS release characteristics and PDGF concentration ranging from 2.5–25.0 µg and evaluated in vivo in a soft tissue wound repair model in the dorsa of rats. At 3, 7, 14 and 21 days post-implantation, the scaffold implants were harvested followed by assessments of cell penetration, vasculogenesis and tissue neogenesis. Gene expression profiles using cDNA microarrays were performed on the PDGF-releasing NFS. The percentage of tissue invasion into MS-containing NFS at 7 days was higher in the PDGF groups when compared to controls. Blood vessel number in the HMW groups containing either 2.5 or 25 µg PDGF was increased above those of other groups at 7d (p<0.01). Results from cDNA array showed that PDGF strongly enhanced in vivo gene expression of the CXC chemokine family members such as CXCL1, CXCL2 and CXCL5. Thus, sustained release of rhPDGF-BB, controlled by slow-releasing MS associated with the NFS delivery system, enhanced cell migration and angiogenesis in vivo, and may be related to an induced expression of chemokine-related genes. This approach offers a technology to accurately control growth factor release to promote soft tissue engineering in vivo