Alon Wexler

Computerized Navigation for Surgery of the Lower Jaw: Comparison of 2 Navigation Systems

PURPOSE To evaluate the accuracy and applicability of 2 computerized navigation systems for surgery of the lower jaw. PATIENTS AND METHODS Two patients diagnosed with a mucoepidermoid carcinoma of the lower jaw were prepared for tumor resection applying 2 different computerized navigation systems: the Image-Guided Implantology (IGI) system (DenX Advanced Dental Systems, Moshav Ora, Israel), which is specialized for dental implant surgery and the LandmarX system (Medtronic Xomed, Inc, Jacksonville, FL), which is designed for ear, nose, and throat surgery. Intraoperative accuracy of navigation of each of the systems was evaluated from the precision of targeting of distinctive anatomical landmarks in the mandible, including a preoperatively placed titanium screw. RESULTS The navigational error of the IGI system was less than 0.5 mm, while that of the LandmarX system was between 3 mm and 4 mm. Tumor resection was performed with the guidance of the IGI system, and resulted in complete resection with tumor-free margins. CONCLUSIONS The mobile nature of the lower jaw complicates its synchronization during surgery with the preacquired imaging data. The accuracy of navigation based on tracking of the patients head is compromised by asynchronous movements of the mandible during surgery. Direct tracking of the lower jaw, via a teeth-mounted sensor frame, is superior to its indirect tracking. The teeth also provide a more secure basis for the fiducial markers than soft tissue attachment. We conclude that a computerized navigation system using a teeth-mounted sensor frame and teeth-supported fiducial markers enables more accurate navigation for surgery of the lower jaw.

Computerized navigation for immediate loading of dental implants with a prefabricated metal frame: a feasibility study.

PURPOSE To study the probability of using Image Guided Implantology (IGI) for planning and execution of a dental plan of 3 implants in a geometric pattern that fits a prefabricated metal frame accurately, simulating provisional restoration in immediate loading. MATERIAL AND METHODS Ten mandible models were imaged by standard computed tomography. Three implants, two in the premolar and one in the molar area on each side of the jaws, were planned by use of the IGI system (Image Navigation Ltd, Moshav Ora, Israel). Two millimeter drilling and subsequent 3 millimeter widening drilling was performed with the real-time computerized navigation technology in the 120 sampling sites. In each step, parallel pins were inserted, and metal gauging frames with preplanned holes of incremental diameters and in the predefined geometric pattern were placed on the pins to evaluate the precision of fit. RESULTS Full success was obtained in fitting all three 3-mm pins, with frames having clearance of 0.5 or 1 mm, and in matching pairs of pins 2 or 3 mm in diameter at clearances of 0.5 mm or greater. With more constrained clearances, matching of all 3 pins was 80% and 95% successful with 2-mm pins (clearance of 0.25 and 0.5 mm, respectively) and 60% and 95% successful with 3-mm pins (clearance of 0 and 0.25 mm, respectively). Some laterality bias was observed. CONCLUSIONS This preliminary study shows that the IGI system enables accurate planning of implant number and location to be achieved together with planning for a prefabricated metal frame for immediate loading.

Oral candidiasis prevention in transplantation patients: a comparative study.

Abstract:  Aim:  Oral candidiasis occurs commonly in haematopoietic –stem cell transplantation (HSCT) patients carrying a risk of systemic candidemia and mortality. The aim of this pilot study was to design an effective protocol that prevents oral candidiasis and improves tolerability.