Dental Tribune Middle East & Africa

Dental Tribune Middle East & Africa Edition | May - June 2013 Virtual planning of extensive jaw reconstructions Centre for Advanced Professional Practices (CAPP) is an ADA CERP Recognized Provider. ADA CERP is a service of the American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. By Dr. Dr. Ahmad Al-Dam, Dr. Dr. Henning Hanken, Dr. Clarissa Precht, Prof. Dr. Dr. Max Heiland ___________________________________ mCME articles in Dental Tribune have been approved by HAAD as having educational content for CME credit hours. This article has been approved for 2 CME credit hours. CAPP designates this activity for 2 continuing education credits. S urgery is still the essential component of curative therapy of malignant neoplasms of oral cavity. The resection with sufficient safety margins has an immediate impact on the prognosis. Therefore, a partial resection of the jaw is often required. In contrast to the upper jaw defects, which can be treated non-surgically with individual prosthetics and obturators, continuity defects of the lower jaw cause massive restrictions of swallowing, communication and the external appearance. Nowadays, extensive defects are covered in many cases using microsurgical grafts. The extension of the accompanying soft tissue deficit influences the selection of the donor region. The microvascular fibula graft has become the “working horse” in many departments all over the world, when it comes to reconstruction of the mandible, it can be transplanted with or without a skin island and separated in several segments. Advantages of this bone containing flap in particular are a reliable anatomy at the donor site with few variances of the supplying vessels, a large diameter of the pedicle vessels and a comparatively straightforward technique of flap raising. Alternative donor regions are the iliac crest and the scapula. In our hands, we favour the primary reconstructions of the mandible. That means that the tumour resection - with verifying of the in sano resection using intraoperative frozen sections of the soft tissue margins - and consecutive reconstruction in the same operative session, which can be ideally perfomed synchronically in two operation teams. Thus, strain for the patient thereby can be reduced and the adjuvant therapy can begin earlier. However, the exact recovery of the presurgical jaws relation, which is a prerequisite for establishing a facial-surgical interventions The computer-based virtual planning of complicated surgical interventions in the face contains a planning phase, a production phase and the operation phase. The planning phase begins with acquiring a defect-related, high-resolution, axial scan of the facial skeleton. This can be performed using a conventional CT or a cone-beam CT (thus minimising of exposure to radiation). When malignant disease is present, the CT of the head and neck, which is necessary in respect of tumour staging, can be used for the planning. In addition, a high-resolution scan of the donor region is required -e.g. the lower leg- which should be combined with an angiography to exclude vessel anomalies. The received data are made anonymous and sent online to the processing company (Materialise (Leuven, Belgium)) via password-protected ftp server. The company then produces a virtual 3D model of both the defect (face) and the transplant donor site (fibula). Now with these data, a web meeting with the engineers of the company and the treating surgeons takes place. In this meeting the resection margins are defined, the segmentation of the bone transplant is discussed and the osteotomy lines are defined. Besides, the positioning of the vascular pedicle and the side of the microsurgical vessel anastomosis in the neck will be defined. After the virtual resection of the jaw, the segmentation of the bone transplant is carried out and positioned virtually into the defect of the mandible. The clinical and angiographic findings and the defect size determine whether the graft is taken from the right or left lower leg. The planned resection and osteotomies of the bone transplant can be transferred from the virtual planning into the OR by the surgeon using prefabricated templates. Now the production of the surgical resection templates for the facial bone and osteotomy templates for the bone transplant takes place. After the production procedure, a 3D stereolithographic model of the postoperative situation (after insertion of the fibula), templates for the osteotomies of the flap and for the tumor resection will be available in the OR. With the help of the 3D model, a 2.0 locking reconstruction plate is manufactured (Synthes, Oberdorf, Switzerland), which is precisely adapted to the postoperative, virtually planned situation. Intraoperatively, the mandible is surgically exposed so that the resection templates can be positioned to allow performing satisfying occlusion, is difficult. Even with preoperatively customized osteosynthesis plates, the osseous graft must often be segmented after harvesting to simulate the curve of the mandible. Nevertheless, the exact creation and positioning of the graft is of great importance for the rehabilitation of the facial symmetry and the masticatory function. Increasing the predictability of the surgical reconstruction outcome can be achieved using a new computer-aided, three-dimensional planning method. This planning enables us to implement precisely the virtually planned jaw resection and the creation of a suitable osseous graft with the help of CAD/CAM templates and an individual osteosynthesis plate. In this article, the technology used by us is described with the aid of an illustrative example in which the reconstruction of the mandible was performed using a CAD/CAM preplanned microsurgical fibula graft. Process of the planning of complicated A) Intraoral clinical findings C) Operative findings after tumour resection E) Placed reconstruction plate between the bone stumps B) Macroscopic appearance of the tumour D) Surgical specimen F) Appearance of the patient after soft tissue reconstruction ” See FILLING, page 7 G) Radiological findings of the patient after tumour resection I) Virtual overlapping of the planned fibula reconstruction into the current bone situation H) Radiological findings of the patient after tumour resection K) Osteomyocutaneous fibula flap after segmentation K) Radiological findings after the bone reconstruction L) Fibula after harvesting is positioned in its virtually planned position to reconstruct the mandible, J) Lateral view of the virtual planned segmentation of the fibula showing the osteotomy template in the lower image 6 Media CMe

Dental Tribune Middle East & Africa

Overview