Between January of 1998 and May of 2002, 25 prefabricated osseous free flaps (23 fibula and two iliac crest flaps) were transferred in 24 patients to repair maxillary (six flaps) or mandibular (eight flaps) defects after tumor resection, severe maxillary (four flaps) or mandibular (one flap) atrophy (Cawood VI), maxillary (one flap) or mandibular (three flaps) defects after gunshot injury, and maxillary (two flaps) defects after traffic accidents. Prefabrication included insertion of dental implants, positioned with a drilling template in a preplanned position, and split-thickness grafting. Drilling template construction was based on the prosthetic planning. The template determined the position of the implants and the site and angulation of osteotomies, if necessary. The mean delay between prefabrication and flap transfer was 6 weeks (range, 4 to 8 weeks). While the flap was harvested, a bar construction with overdentures was mounted onto the implants. The overdentures were used as an occlusal key for exact three-dimensional positioning of the graft within the defect. The bar construction also helped to stabilize the horseshoe shape of the graft. The follow-up period ranged from 2 months to 4 years (mean, 21 months), during which time two total and three partial flap losses occurred. One total loss was due to thrombosis of the flap veins during the delay period, whereas the other total loss was caused by spasm of the peroneal artery. Two partial losses were due to oversegmentation of the flaps with necrosis of the distal fragment, whereas one partial loss was caused by disruption of the vessel from the distal part. Of the 90 implants that were inserted into the prefabricated flaps during the study period, 10 were lost in conjunction with flap failure; of the remaining 80 implants, four were lost during the observation period, for a success rate of 95 percent. Flap prefabrication based on prosthetic planning offers a powerful tool for various reconstructive problems in the maxillofacial area. Although it involves a two-stage procedure, the time for complete rehabilitation is shorter than with conventional procedures.
"Other studies have also reported the preparation of a customized titanium plate for the surgical area before tumor resection, and once the tumor has been removed, the plate can be used as a template for arranging the segments of fibula [11-13]. Rohner et al.  and Kernan et al.  suggested designing a cutting template based on the occlusal position, which allows the doctor to cut the fibula along the template. However, as the cutting template needs to be prepared before the operation, it is difficult to modify if any changes are required during the operation. "
[Show abstract][Hide abstract] ABSTRACT: Background
This study aimed to establish surgical guiding techniques for completing mandible lesion resection and reconstruction of the mandible defect area with fibula sections in one surgery by applying additive manufacturing technology, which can reduce the surgical duration and enhance the surgical accuracy and success rate.
A computer assisted mandible reconstruction planning (CAMRP) program was used to calculate the optimal cutting length and number of fibula pieces and design the fixtures for mandible cutting, registration, and arrangement of the fibula segments. The mandible cutting and registering fixtures were then generated using an additive manufacturing system. The CAMRP calculated the optimal fibula cutting length and number of segments based on the location and length of the defective portion of the mandible. The mandible cutting jig was generated according to the boundary surface of the lesion resection on the mandible STL model. The fibular cutting fixture was based on the length of each segment, and the registered fixture was used to quickly arrange the fibula pieces into the shape of the defect area. In this study, the mandibular lesion was reconstructed using registered fibular sections in one step, and the method is very easy to perform.
Results and conclusion
The application of additive manufacturing technology provided customized models and the cutting fixtures and registered fixtures, which can improve the efficiency of clinical application. This study showed that the cutting fixture helped to rapidly complete lesion resection and fibula cutting, and the registered fixture enabled arrangement of the fibula pieces and allowed completion of the mandible reconstruction in a timely manner. Our method can overcome the disadvantages of traditional surgery, which requires a long and different course of treatment and is liable to cause error. With the help of optimal cutting planning by the CAMRP and the 3D printed mandible resection jig and fibula cutting fixture, this all-in-one process of mandible reconstruction furnishes many benefits in this field by enhancing the accuracy of surgery, shortening the operation duration, reducing the surgical risk, and resulting in a better mandible appearance of the patients after surgery.
[Show abstract][Hide abstract] ABSTRACT: Canada's first Earth observation satellite, RADARSAT-I was
launched in a polar, sun-synchronous, dawn-dusk orbit by a Delta II
rocket on November 4, 1995. The satellite carries a multi-mode C-band,
HH polarization synthetic aperture radar (SAR) which provides choices in
incidence angles (from less than 20° to more than 50°),
resolutions (from 10 m to 100 m), and swath widths (from 45 km to 500
km). The satellite is programmed and commanded through a S-band link
from the Control Centre at the Canadian Space Agency (CSA) in St.
Hubert, Quebec to acquire the SAR data in the required mode as per user
requests and to dump at X-band the corresponding data to ground
receiving stations. The satellite has global acquisition capability
through the on-board tape recorders. User requests for new acquisitions
or processing archived SAR data are entered into the RADARSAT system
through order desks. The corresponding data or products are delivered to
users by data processing facilities. The system has been commissioned
through months of on-orbit testing of the satellite along with
operational demonstrations. The operation phase began on 1 April 1996
and should last for 5 years, the designed lifetime of the satellite.
During this phase, RADARSAT data will be supplied to users around the
world for a variety of applications and the satellite will be turned
from right looking to left looking orientation twice to map the
Antarctic. An overview of the RADARSAT-I system and operation is
presented along with examples of the imagery
Electrical and Computer Engineering, 1996. Canadian Conference on; 06/1996
[Show abstract][Hide abstract] ABSTRACT: A new man-made shadowing model was proposed. This model enables us to estimate deterministically the man-made shadowing effects, which are one of the dominant factors with indoor radio communication. The model can be used with the numerous propagation prediction methods based on ray prediction. Moreover, it allows the selection of appropriate locations and antenna characteristics for macroscopic diversity branches for the base station. The increase in loss due to man-made shadowing is a function of frequency, polarization, antenna height, etc
Antennas and Propagation Society International Symposium, 1996. AP-S. Digest; 08/1996
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